ABSTRACT. Managed Aquifer Recharge (MAR) is used across the globe to meet a variety of water management objectives (Dillon et al. 2020). In arid and semi-arid regions of the Southwestern United States, MAR has enabled indirect reuse of effluent for meeting drinking water demands (Hutchinson and Woodside 2021) and other water management goals (Seasholes and Megdal 2021 and Megdal 2007). The presentation will highlight how a sound state-level regulatory framework for MAR has a water-scarce, growing region in meeting water management goals, including reducing groundwater overdraft and optimizing the use of renewable supplies. Since 1980, groundwater management in Arizona has been practiced in the regions designated as Active Management Areas (AMAs). The presentation’s focus will be Central Arizona, which includes the Phoenix, Pinal, and Tucson AMAs. Semi-arid Central Arizona is home to Phoenix, the fifth largest city in the United States, and is one of the fastest growing regions in the United States. Groundwater overdraft is a critical problem in the region, home also to large agricultural operations and sovereign Tribal Nations.

The presentation will explain Arizona’s regulatory framework for MAR, which includes stringent permitting, monitoring, and accounting. It will describe the different types of recharge facilities, including the mechanism whereby farming lands substitute alternative sources of water for groundwater. Examples of how MAR has been used in Arizona will include: (1) Tucson, Arizona’s deployment of MAR to use Colorado River water delivered through the Central Arizona Project (Megdal and Forrest 2015); and (2) how Arizona Water Banking Authority (AWBA) has stored significant quantities of water in anticipation of low Colorado River flows (AWBA 2021). Also discussed will be the innovative approach to MAR of the Gila River Indian Community (Megdal 2021). A fourth example will be the role of MAR in groundwater replenishment for those who are using groundwater to accommodate community growth in Central Arizona through the Central Arizona Groundwater Replenishment District (CAGRD 2019).

Along with the innovations, successes, and opportunities associated with MAR in Arizona, some associated weaknesses or concerns will be presented. The presentation will underscore that MAR can be an important water management mechanism as arid and semi-arid regions endeavor to meet their water needs.

References are included in the attached Word Document, as is a Figure (and reference to it).

ABSTRACT. Australia's water reform journey has been on-going for more than 40 years. As the driest inhabited continent on earth, Australia's water challenges are immense. So how has Australia succeeded in achieving such a broad range of substantive reforms including:

Water pricing based on full cost recovery Separation of water policy and water service businesses Separation of water property rights from land title Establishment of tradeable water entitlements and seasonal allocations Water trading including across borders Transboundary Basin-wide Catchment Water Management Planning Redress of overallocation of water resources

In this keynote address, former South Australian Minister for Water Security and Chair of the Australian National Water Commission, the Hon Karlene Maywald will share the decision making processes, the governance arrangements and the programs implemented to enable this remarkable journey.

ABSTRACT. The concept of groundwater sustainability is rooted in intuitive notions of quantity and quality. Specifically, in the extreme we know that overdraft will ultimately exhaust the groundwater basin, and unrestrained contamination will ultimately render the groundwater unusable without expensive treatment. It is also widely accepted that prevention of these catastrophic consequences requires two fundamental actions: (1) eliminate the overdraft by balancing the water budget and stabilizing groundwater levels, and (2) eliminate or reduce the sources of groundwater contamination. In this work we demonstrate a third condition necessary for sustainability – that the basin must be hydrologically open. In contrast to open basins, closed (endorheic) basins lack outlets for circulating groundwater and surface water other than evaporation, resulting in salt accumulation. Numerous cases of closed (endorheic) basins, such as the Dead Sea and playas of the Great Basin (USA), provide stark examples of basin closure consequences. Importantly, groundwater basin closure is happening increasingly around the world due mainly to heavy production of groundwater for irrigated agriculture, which consumes most of the global water pumped or diverted by humans. Pumping from wells commonly lowers groundwater levels to the point that natural exits for groundwater such as baseflow to streams are extinguished. Simultaneously, irrigation with the pumped groundwater, together with any available surface water, results in evaporative concentration and downward movement of brackish to saline water back to the water table. As this cycle repeats, progressive salinization of the groundwater basin occurs. We refer to this process as ABCSal (anthropogenic basin closure and groundwater salinization) and use simple mass balance models and flow and transport models of a portion of California’s Central Valley aquifer, the Tulare Lake Basin, to estimate time scales of salinization and to explore long-term water quality dynamics. Mixing-cell model results agree with existing TDS data and indicate progressive salinization (>1,000 mg/L) of shallow aquifers (36 m) within decades. Intermediate (132 m) and deep aquifers (187 m) are impacted within two to three centuries, which is the same timescale over which overdraft would effectively exhaust groundwater stores in this basin. In other words, the ABCSal sustainability limit for this system operates on a similar timescale as the quantity (overdraft) sustainability limit, even if overdraft is halted and groundwater levels are stabilized. Flow and transport simulations provide the first insights into the spatiotemporal dynamics of ABCSal, illustrating the development of surprisingly structured patterns of salinization controlled by interplay between irrigation recharge and sources of clean water recharge from mountain fronts and losing streams. This results in large swaths of the basin containing either saline or fresh groundwater, depending predictably on the regional groundwater circulation patterns. Most importantly, this modeling demonstrates that if pumping and recharge are regulated enough to maintain open hydrologic conditions, with sufficient groundwater discharge to streams, the ABCSal process halts, and groundwater salinity stabilizes at acceptable levels. This work points to the need for maintaining higher groundwater levels through greater emphasis on subsurface storage of water and modern hydrogeologic techniques, representing an advanced paradigm of groundwater management.

ABSTRACT. In many countries of the developed world in the temperate zone Decision Support Systems (DSS) have become an important tool for water resources management. In general data availability increased massively over the last decade due to the rapid development of sensor and network technologies, while at the same time the technological evolution improved the storage, handling, modelling and visualization of data. These developments make the implementation and use of a DSS even more important for agencies in which decisions are made. We deal with agencies that are concerned with water management in arid and semi-arid climates. This contribution is a report on the current state of a project of Wageningen University (The Netherlands) and the Ministry of Agriculture, Fisheries and Water Resources (MAFWR) in Oman with subcontractors Nelen & Schuurmans and German Univ. of Technology in Oman (GUtech).

ABSTRACT. Climate change inevitably bring about numerous environmental problems including alterations to the hydrological cycle. Erratic rainfall, population explosion, diminishing of water bodies due to urbanization, deterioration of water quality and over-extraction led to water crisis in many parts of Indian sub-continent. Climate change effects on groundwater create difficulties such as long-term decline in groundwater storage, severity of droughts and floods, mobilization of pollutants and saline water intrusion in coastal aquifers. The heavy dependence on groundwater has increased construction of number of deep wells each year for domestic and agricultural use that led to the over-extraction of groundwater resources. Continuous decline of water levels observed in the Tirupati (37 mbgl, 2015) and Delhi (48 mbgl, 2003) urban areas. The rapid urbanization process and increase of population eventually lead to the diminishing of natural water bodies (tanks/ponds) in many urban areas of India. Decline of groundwater levels and space constraints due to urbanization, recharge pits were constructed to harvest rainwater from the rooftop and storm water in the mega city of New Delhi. Rainwater harvesting allow the development of water resources in the alluvial aquifer regions as well as the prevention of seawater intrusion into the fresh water alluvial aquifers. Hence, these would improve groundwater levels and quality which ultimately facilitated the domestic water supply and agricultural activities. In view of the water shortage for irrigation and domestic uses in parts of semi-arid Andhra Pradesh, subsurface dams preferred across ephemeral rivers with base flows to rise water levels. Around 3,000 Mcft of base flow is available in the Swarnamukhi River course and part of this flow is arrested at suitable locations by constructing subsurface dams across the river. The impact analysis of the piezometers indicates that there was an average rise of 1.5 m of groundwater levels after the construction of few subsurface dams. In general, community involvement of the maintenance of local rainwater harvesting systems is impetus for the sustainable water resources management as well as to improve the socio-economic conditions through increased agricultural production.

ABSTRACT. Inefficient irrigation is a significant threat on freshwater availability to both urban and agricultural water consumers. This threat amplifies with supply shortages due to climate change and the increase in demand from population growth. In the southwestern United States, the Colorado River provides water to about 40 million people and over 5 million acres of irrigated agriculture. In 2022, water shortages will be applied in the Colorado River basin.

Forecasts show a potential for deeper cuts extending for a decade or more going forward. Because irrigation accounts for over 70 percent of freshwater use, water utilities have focused on agricultural water users and attempt to provide solutions that save water. A common solution to the water deficit problem is a limited purchase of water supplies by water utilities from farmers for a defined time. This method leads to an immediate loss in productivity and yield for farmers, but provides a secured water saving.

As another solution, water utilities often offer subsidies to farmers to shift to more efficient irrigation methods, such as pressurized drip irrigation. Furrow or flood irrigation is the most dramatic example of inefficient irrigation – wasting more than half of the water – yet is the most common irrigation method in the world. The barrier to implementation of more efficient irrigation methods is the high initial capital costs and length of the return on investment. Because most irrigation technologies require high capital investment and ongoing energy and filtration costs, the solution is economically inefficient and does not secure the required water saving for multiple seasons. N-Drip and Central Arizona Project (CAP) developed a revolutionary water management solution that achieves the seemingly incongruent goals of maintaining agricultural productivity for farmers while providing a secured water savings for water utilities. This innovative farmer–water utility solution shifts water provider funds that were previously directed towards the purchase of water or system subsidies for the installation of expensive efficient irrigation systems to the installation of N-Drip’s highly efficient, affordable technology. The N-Drip technology is an inexpensive drip irrigation system that provides the benefits of pressurized drip irrigation while offering the simplicity of furrow or flood irrigation. Unlike energy-intensive pressurized drip irrigation (and other irrigation methods), the system requires no external energy source or water filtration, using only gravity on a previously flood irrigated field to deliver water to crops. This precision irrigation and yield management technology, coupled with in-situ data collection and monitoring plus support from N-Drip’s world class agronomists, allows farmers to achieve high water efficiency at a low ongoing cost.

The N-Drip-CAP approach demonstrated significant water savings through the application of the N-Drip technology, while maintaining, and in many cases, enhancing crop yields. Going forward, N-Drip and CAP will implement a subscription model with farmers to generate targeted water savings and crop yields. This innovative irrigation efficiency and water management approach is a path to achieve regional food security through the preservation of irrigated agriculture and to build water supply resilience for the entire Colorado River basin.

ABSTRACT. In semi-arid and arid regions, groundwater is often the only reliable source of water for human livelihood and economic activities. In those climates, recharge of groundwater can often be a highly episodic process with recharge dominated by occasional large rainfall events every few years. Understanding such groundwater systems to improve their management and protection is challenging, but the challenge is even more difficult if the host formation is karstified or fractured. Many of the methods traditionally used for studying karst – such as active tracer tests and time series of discharge and hydrochemistry - may not work well in such an environment because aquifers in arid regions tend to function across larger areas or the next recharge event may not occur for multiple years.

Environmental tracers are a set of tools that can still provide useful information to better conceptualize and characterize such groundwater systems. Environmental tracers are compounds or isotopes that are naturally present in the environment and allow tracing certain processes, such as groundwater recharge and flow.

Over several years, a very diverse set of environmental tracers (including ¹⁸O and ²H of water, tritium, ¹⁴C, CFCs and SF₆, stable noble gases, radioactive noble gases (⁸⁵Kr and ³⁹Ar), ⁸⁷Sr/⁸⁶Sr, sulphate isotopes, rare earth elements, and basic hydrochemistry) has been applied to the Cambrian Limestone Aquifer (CLA) in northern Australia. The karstified CLA extends over several hundred kilometres from a dry savanna climate to a monsoon-dominated climate and is the key groundwater resource in a region which holds one of Australia’s largest prospective shale gas resources. The CLA feeds culturally significant springs in the Mataranka region and provides baseflow to the Roper River. The CLA is partly confined and has an unsaturated zone which varies in thickness from a few metres to >100 m.

This presentation is intended as a high-level overview of different processes that were investigated with environmental tracers, together with some of the surprises along the way: a) developing a consistent conceptual model to quantify recharge when different tracers seem to indicate very different results; b) understanding recharge processes and pathways to provide measurement-based evidence for testing existing conceptual ideas; c) investigating contributions of different water sources to springs; and d) identifying potential upward leakage of groundwater from deeper aquifers to investigate fluid pathways between the CLA and the shale gas resource.

These results served to establish baseline data and underpin environmental risk assessments and have implications for managing the aquifer sustainably and investigating and minimizing the risk from potential oil and gas extraction activities. For example, there was evidence in the tracers for recharge through sinkholes quickly bypassing the unsaturated zone, which has implications for the groundwater contamination risk in case of a surface spill. The relative importance of shallow and fast local flow paths and slower regional paths to springs as quantified based on tracers informs the risk level of different springs to pollution and changes in hydrological boundary conditions.

ABSTRACT. A keynote Speech

ABSTRACT. The Prince Sultan Institute for Environmental, Water and Desert Research at King Saud University contributes to supporting water sustainability in the Kingdom of Saudi Arabia by conducting research and carrying out projects to find solutions to the challenges facing the country in this vital sector. The Institute’s efforts in this field inspired the idea of establishing an international scientific prize for water, which was submitted as a proposal to His Royal Highness Prince Sultan bin Abdulaziz Al Saud. As a result, His Highness established the Prince Sultan Bin Abdulaziz International Prize for Water (PSIPW) and announced its first call for nominations on 21 October 2002. The Prize’s General Secretariat is located at the Institute, and the Prize’s aim is to encourage scientists around the world to develop innovative scientific solutions in various water-related fields that will achieve the successful conservation, sustainability and availability of water for all people, and especially in arid regions. In numerous research programmes, the Institute focuses on water conservation, equitable distribution, and sustainable use. A particular focus was given to the development of rain and floodwater harvesting and storage techniques that can respond to the country’s changing climatic conditions. Under the patronage and guidance of the Custodian of the Two Holy Mosques, King Salman bin Abdulaziz Al Saud and with the generous support of His Royal Highness Prince Sultan bin Abdulaziz Al Saud, the Institute implemented the King Fahd Project for Rain and Floodwater Harvesting and Storage as well as the Prince Sultan Project for the Rehabilitation of Villages and Hamlets in the Kingdom. Through these two projects, the Institute has developed effective strategies appropriate for Saudi climate conditions. The first strategy is to harvest and collect rainwater in artificial ponds near natural wadi courses. During the rainy season, this infrastructure also contributes to reducing flood risk. The second strategy relies on constructing state-of-the-art recharge wells in dam reservoirs, optimized for local conditions, to store rain and floodwater in the upper aquifers, safe from erosion factors. The Institute has implemented these methods in 21 dams in the regions of Riyadh, Qassim, Hail and Al Medina Al Munawarah. The Institute carries out research projects and conducts studies in conjunction with these two programmes while monitoring their implementation. Study results have clearly demonstrated the success of these methods in providing a new source of water in an efficient, low-cost, and environmentally friendly manner. This has contributed to reducing water loss by evaporation, and to maximizing its use for prolonged periods by area farmers near the wadi concourses and in the drainage areas below the dams. Periods of water pumping have been significantly prolonged and well salinity has decreased. This contributes to the rehabilitation of villages and the sustainability of desert communities in these areas. The Institute is supported by many scientists and scientific organizations, especially the Arab Water Council, in calling for the adoption and widespread implementation of the rain and floodwater harvesting and storage methods it has developed throughout the Kingdom and the world’s arid areas.

ABSTRACT. In light of the dry climatic conditions of most regions in the Kingdom of Saudi Arabia, agricultural production relies mainly on the non-renewable groundwater resources from shallow and deep aquifers. With the extension in agricultural production over the past decades, the total consumption of irrigation water has increased from about 1.850 MCM in 1980 to 23.000 MCM in 2020. With most of this irrigation water coming from groundwater, the storage of non-renewable groundwater was greatly depleted, which threatens sustainable development and poses great challenges for future generations. Therefore, water conservation and sustainable irrigation water management are extremely important to maintain crop productivity and enhance plant cover to ensure environmental sustainability. To cope with water resources limitation, it is inevitable to maximize water use efficiency and adopt a national policy for using brackish water and recycling wastewater (e.g., agricultural drainage, industrial wastewater, and municipal wastewater). However, untraditional water resources are limited in quantity and have certain usage restrictions. Therefore, the adaption of modern water saving technologies is a key factor in increasing water use efficiency while maintaining good production. Thus, the application of soil amendments such as biochar and natural clay deposits has been increasingly reviewed as an effective strategy for improving the physical and hydrological properties of light-textured soils, which will improve irrigation efficiency and water conservation. The application of natural and synthesized soil amendments in the past years has always been carried out using the raw materials in a general form. The different sizes of biochar and clay deposits particles can play a significant role in increasing the efficiency of these amendments. Smaller particle sizes can greatly affect the percentage and distribution nature of soil pores, subsequently altering soil structure to reduce water infiltration and enhance water storage in sandy soils. In addition, reducing macropores and the increase in microporosity will increase water retention and enhance irrigation management. In this regards, series of experiments were conducted to investigate the role of the application of biochar and clinoptilolite zeolite on physical properties of sandy soils and on irrigation water saving.

ABSTRACT. The idea of using solar energy for seawater or brackish water desalination has been contemplated for many years. However, progress towards commercialization has been slow due to a number of factors, including the high levelized cost of water and intermittency of solar energy. Furthermore, water desalination is currently characterized by high rate of rejection of brine back to the sea, which can have a detrimental effect on marine life. This work highlights a new partnership between the European Union (EU) and GCC countries to tackle the above-mentioned issues. The project, titled “DESOLINATION”, is funded by the EU with in-kind contributions from GCC institutions, including King Saud University. 19 research institutes, universities, and companies from 13 countries (including Saudi Arabia, Bahrain, and Oman) are working together to develop an innovative integrated system in which concentrated solar thermal energy is used to generate power, while a bottoming system is used to desalinate water. This project includes a host of innovative features. First, a new concept is leveraged, in which heat is collected and stored in solid particles. This feature allows very high temperatures to be attained (around 1000°C) and also allows thermal energy to be stored inexpensively in hot particles for long hours that can cover the entire nighttime. Second, two power cycles are considered; one of them is the innovative supercritical CO2 cycle, and the other is the air-Brayton cycle. Third, the project is introducing efficient thermal desalination system using several processes, including waste heat recovery at tunable temperature, innovative membranes for forward osmosis, tuned draw solution to extract water from seawater, coupling of forward osmosis and membrane distillation, and extraction of relevant minerals from the rejected brine. With these innovations, it is estimated that the cost of seawater desalination using solar thermal energy will become quite competitive, approaching $1 per cubic meter, with long storage hours and minimal impact on the environment. Furthermore, one of the most important outcomes of the project is strengthened collaboration between the EU and the GCC in a high-impact and critical research area for the GCC, namely water desalination.

ABSTRACT. Hydrochemical assessment of 124 groundwater samples from Wadi Fatima in Western Saudi Arabia was carried out in this study. The silica concentration of the samples was used to calculate the temperature of circulation of the groundwater using the chalcedony geothermometer with no steam loss. The samples were categorized into two groups based on the obtained temperatures. Those having temperatures above 60°C were classified as geothermal water where as those below 60°C were classified as cold water. The geothermal samples showed high TDS content (4389 mg/L) whereas the cold samples had average TDS value of 1254 mg/L. The high circulation temperature of geothermal water results in a greater degree of mineral dissolution which is reflected in their high TDS values. The Durov and Piper plots also indicate some degree of mixing between the fresh shallow groundwater with deeper saline water. Silicate weathering is the main hydrochemical process active in the area. The geothermal water was undersaturated with respect to amorphous silica under equilibrium conditions to oversaturated with respect to chalcedony and quartz. Chalcedony geothermometer can be used effectively for classifying groundwater from low-temperature reservoirs as geothermal and cold. Further groundwater facies analysis, ionic relationships, and saturation indices can be employed to determine hydrochemical characteristics of these waters.

ABSTRACT. The Kingdom of Saudi Arabia (KSA) is an arid country facing the challenge of renewable freshwater availability. KSA has an area of about 2.25 million km2. KSA has no perennial rivers or permanent freshwater bodies. KSA has low rainfalls with high evaporation rates which makes it very dry country. After discovering oil, KSA has witnessed remarkable economic development and rapid increase in population with migration to the urban areas in the past four decades. KSA population increased from about 4 million in 1960 to about 32.5 million in 2018. These developments lead to more pressure due to increased demand on the scarce freshwater resources. In order to meet the growing water demands, the limited renewable freshwater resources have been heavily overexploited. Groundwater aquifers are the main natural renewable freshwater source in the country. The average per capita daily water use in KSA has been increasing since 2009 when it hit 227 l/day and recorded a gradual increase to touch 270 l/day in 2016 which is the 3rd highest in the world. Faced with increasing water scarcity and gaps between water supply and demand, policymakers in KSA started to consider the treated wastewater as a major renewable water source and aim to achieve full utilization and reuse of treated wastewater by 2025. With a desalination capacity of about 2500 million cubic meters per year which represents 30% of the world’s desalination capacity, KSA is the largest seawater desalination producing country. However, desalinated water alone will not be able to supply enough freshwater to meet the increasing future water demand. However, with only 10% of the total municipal wastewater generated currently being reused, KSA is projected as the third largest reuse market after China and the USA, and reuse capacities are projected to increase by 800% by 2020. The projected growth and change in water portfolios offer tremendous opportunities to integrate novel approaches of water reclamation and reuse. Table (1) shows the water resources availability in KSA (2019). The population growth rate has been dropped significantly in the recent years. For example, the population growth was 3.28 % in 2000, which has been dropped to 1.5 % in 2019. However, this increase will still impact the water demand in KSA.

ABSTRACT. Please see extended abstract attached - a shorter abstract can be prepared in due course. Advice is appreciated on a deadline for doing this. We would also appreciate advice on a deadline for submitting a final extended abstract for publication, as some minor additional changes will ideally be made to the attached.

ABSTRACT. Meteorological drought is a natural phenomenon whose probability and frequency of occurrence increases with increasing global air temperature. Over the last 138 years, the average annual air temperature in Slovakia has increased between (1.7 to -1.8°C). This paper presents analysis of drought in the eastern part of Slovakia using Standardized Precipitation Index (SPI) computed in 24 months’ time scales for classification of historical drought events for the period (1972-2014). The analysis was done at four precipitation stations localized in sub-catchment Bodrog that situated in the Eastern part of Slovakia. Then, the RUN method was used to identify the extreme drought event. If the SPI-24 value is less than -2 we are in a drought condition. A one-dimensional frequency analysis of the risk of drought was performed in order to determine the probability of its occurrence and evaluating the negative effects of long-term precipitation deficits on surface and groundwater levels, aquatic fauna and flora. The results showed that the year 2003 was a significant year in which extreme meteorological drought was recorded at all precipitation stations. The most vulnerable area with an extreme rainfall deficit is the area in the middle of Bodrog basin, where meteorological droughts can rarely be expected, but can persist longer period. This methodology can be applied in different locations of the world as it considered as broad methodology for drought analysis that based on the availability of data at certain locations.

ABSTRACT. Groundwater is the primary source of freshwater for domestic and industrial usage in the Arabian Peninsula countries. Besides, it is becoming a limited resource due to human activities leading to contamination; therefore, it is essential to ensure the groundwater is properly managed. The majority of groundwater in the Arabian Peninsula countries are transboundary systems (TBS) such as the Wajid, Umm er Radhuma, and Wasia Aquifers shared between Saudi Arabia, Yemen, Iraq, Kuwait, Bahrain, Qatar, and United Arab Emirates. These systems have no groundwater sharing agreements, which leads to lack of sharing data, unsustainable and uncoordinated development, increased water depletion, water quality deterioration, and subsidence. This study focuses on quantifying the spatiotemporal variations of water resources, evolving water demand and withdrawal practices in the above- mentioned TBS by combining climate, ground and earth observations from the Gravity Recovery and Climate Experiment (GRACE), Follow on (GRACE-FO). and other remote sensing missions. We compare the depletion rates and associated water demand and usage practices during the last thirty years for both the study area and the TBS in North Africa that have groundwater- sharing agreements such as the Nubian Sandstone Aquifer System (NSAS), and North- Western Sahara Aquifer System (NWSAS). Results emphasize the need for remote sensing-based geospatial monitoring of groundwater depletion patterns and sharing them with the decision-makers in aquifer riparian countries to reduce depletion rates and allow sustainable development and management of the groundwater resources.

ABSTRACT. According to the Clausius–Clapeyron relationship, the water holding capacity of the atmosphere will increase with global warming, giving rise to increased evaporation, moisture, moist static energy, and more intensive storms. Because the increase in evaporation is constrained by the availability of surface moisture and energy budget, warming could also increase the frequency of dry days and exacerbate droughts. As the hydrologic cycle accelerates, occurrences of hydrologic extremes will increase, which can reduce the reliability of water resources in drought-prone regions, such as the Sahara and Sahel of Africa, and the Canadian Prairies (CP). Past and present studies show that CP has become warmer and drier since the mid-twentieth century. However, long-term climate projections involve many uncertainties: climate, economy, population growth, physiographic changes, social changes, and water demand that complicate our efforts to prepare against future droughts. With uncertainties on the potential impact of climatic change and other uncertainties, several strategies are proposed to increase the resiliency of the Prairies against future droughts, where surface water is the primary water supply and agriculture is the major water user: (1) Continue implementing small-scale water resources projects and increase water storage through snow management; (2) increase integration between existing water resources systems, and (3) promote water conservation measures in agricultural practices, water pricing, and water metering. For drought-prone regions in Africa, adaptation measures such as restoring land fertility, zero-tillage farming and direct planting of crops into the stubble of the previous crops, rehabilitation, rainfall harvesting, diversified crop and animal production, promotion of drought-resistant crop varieties, breeding of crop seeds that could use water more efficiently, reforestation, etc. can be implemented to mitigate the impact of droughts.

ABSTRACT. The climate change matter set in at the forefront of the news and public opinions’ concerns for a long time. These climate changes have negatively affected the water reserves which are necessary for any social and economic development. In Algeria, the deficit of this blue gold becomes worrying, confirming various expertises starting from assumptions and using different methodologies which all have concluded that our country will be confronted to this shortage in the next coming years. To better work out the importance of those impacts, we have analyzed the average water flows of five basins of Algerian northwest, in the Central Maghreb, over the reference period (1970-2000) and we have compared them to those that could result from the changes in the main climatic stress (temperature and rains). The methodology used rests on the model GR2M in order to make simulations on the flows of five basins of the Central and West of Algeria in view of the climate changes by the years 2025 and 2050. The results obtained show a coming decrease in the flows, of the order of 15%, from January to April for the basins of the Central and Chéliff, and which will exceed 25% for the basins of the West. For the first months of the warm season, the aforementioned decrease, for 2050 and for the pessimistic scenario, will be more than 40%.

ABSTRACT. Groundwater plays a critical role in supplying drinking water and supporting economy and livelihood of communities and sustaining important native terrestrial ecosystems. Groundwater use in many arid and semi-arid region is increasing rapidly for agriculture and other uses. The consequence of this is that groundwater pumping is far in excess of the annual rainfall recharge, and as result aquifers are under serious threat in many of the arid regions in Asia, the Middle East and Africa. The groundwater level represents the integration of recharge, pumping and flow processes and is a direct measure of groundwater availability and the success of any collective management practices. Local 'groundwater informed volunteers', called Bhujal Jankaars (BJs), are an effective, trusted and valuable interface between village communities and government agencies, NGOs and researchers. The experience from the MARVI project indicates that a transdisciplinary and participatory approach is likely to be more effective in enabling farmers, other village community members and NGOs to work together with researchers and government agencies to understand the groundwater situation and design interventions that are holistic and have wider ownership at the village and Gram Panchayat (i.e., Village Council) levels. Also, such an approach is expected to deliver longer-term sustainability of groundwater at a regional or basin scale but will require substantial external and prolonged support.

ABSTRACT. This paper provides an overview of a hydroeconomic model for managing groundwater resources in arid regions. The theoretical underpinning of the model is based on estimating the costs and benefits of extracting groundwater from a multi-salinity aquifer system composed of several zones each representing unique hydrogeological characteristics and types of water use. Multi-salinity is represented by modeling the aquifer as a stacked groundwater layers of varying salinity. The model features an interactive user interface that provides access to several hydrogeological and economic parameters to formulate alternative groundwater management schemes and produce projections of groundwater levels and net present values (NPV). The model has been set up to manage groundwater resources in Abu Dhabi.

ABSTRACT. Agriculture activities are the main driver of freshwater consumption worldwide, and irrigation practices often impact heavily on groundwater resources, but on the other hand agriculture is the fundamental activity for food security and possibly the main driving sector in poverty reduction and sustainable development. Water resources management in agriculture needs to address the exigence of managing water in an integrated way, by using innovative technologies, by assuring more efficiency in using water networks and by making distribution systems more reliable, and also by promoting a more active participation of the community in the management of the territory and in the application of environmental policies. All this is necessary to address the projected effects of climate change on both rainfall patterns variability and crop yield decline, the latter being projected to impact more significantly in the tropics and subtropics (IPCC, 2019). In this work we present a novel, spatially-distributed, GIS-based application of Benfratello's method to assess the soil water balance and the irrigation deficit of the semiarid Capitanata plain (Apulia region, Southern Italy), one of the most important agricultural districts in Italy. Due to its simplicity and to the small number of needed parameters, Benfratello's method might be regarded to as an effective tool to assess the effects of climatic, landuse and anthropogenic change scenarios on the soil water balance and on the irrigation deficit. The first results of the application of this practical approach seem encouraging, as by using a limited amount of parameters we estimated an irrigation demand which is in fairly agreement with the data provided by the Bonifica della Capitanata consortium. Future steps will see the implementation of climate change scenarios within the GIS-based Benfratello’s model and the comparison with more complex and parameter-demanding simulation approaches.

ABSTRACT. Surface water resources in South Australia are scarce, therefore groundwater resources are heavily relied upon to supply water for all purposes. The Eyre Peninsula region of South Australia is characterised by thin karstic limestone aquifers which are the principal source of water for town water supply, irrigation, stock and domestic purposes. Groundwater sourced from within the Southern Basins and Musgrave Prescribed Wells Areas contributes around 85% of Eyre Peninsula’s total reticulated water demand (not including Whyalla). Due to the heavy reliance on groundwater, a Water Allocation Plan (WAP) provides the framework for the sustainable management of the prescribed groundwater resources by considering the competing environmental, social and economic demands for groundwater.

Recharge and groundwater storage is known to vary strongly in response to changes in climatic conditions and therefore an effective adaptive management process is essential for sustainable water resource management. The first WAP implemented in 2001 introduced annual allocations based on a ten-year moving average of calculated recharge. This methodology worked well until the 2006 drought highlighted that this approach did not take into account declines in storage volumes caused by natural discharge.

The revision of the WAP in 2016 allowed the introduction of a new adaptive management approach. Arc Hydro Groundwater was used to create a 3-D hydrostratigraphic model to define the aquifer geometry and the saturated extent of the aquifer in order to calculate the volume of groundwater in storage. The model is updated annually with the most-recent monitoring data to calculate changes in storage volumes which are then used to determine annual allocations. The magnitude of the changes to the annual allocation depends on the assessed level of storage relative to resource condition triggers. This approach ensures that the levels of allocation reflect the condition of the groundwater resource to a much greater extent.

ABSTRACT. Background: Growing economic pressures on water resources have caused many countries to rethink mechanisms to improve the economic performance from growing water scarcity. The role of desalination in semi-arid regions is crucial to determine the potential venue to overcome the scarcity problem. This is especially true for conflict resolution mechanisms in transboundary waters that include water sharing agreements as well as increasing demand for non-market water uses. Exclusive reliance on either supply enhancement or demand management is likely to raise the cost of averting these shortages. But desalination cost reduction may shift the dynamics of policy over time.

Objective: The contribution of this paper is to describe results of an exercise that identifies an economically efficient combination of supply augmentation and demand management to avert shortages. This is a simulation based analysis with decreasing desalination cost and applied to the Israel-Palestinian water conflict and cooperation as well as increasing environmental demand for water such as rivers rehabilitations etc.

Methods: A constrained quadratic cost optimization was used. Minimum adjustment costs are calculated for several combinations of future desalination costs, minimum environmental flow requirements, and transboundary water sharing agreements. These two constraints were added to domestic and industrial uses. Remaining supply plus treated wastewater are used to calculated equilibrium price for the agricultural sector in particular and to the rest of users in general. Results also indicate the optimal timing in moving for demand management to supply management.

Results: Our findings from a constrained optimization system show that the costs of increased deliveries for the environment and water sharing obligations can be as low as $US 1.46 billion price tag, in present value terms. This is the cost from using integrated water resources management (IWRM), defined as the least cost. Adjustment costs of averting shortages will decline with anticipated reductions in desalination costs. Combining an efficient package of supply expansion with price-sensitive demand reduction provides important savings. The total expense of the least cost combination of measures to find the 275 MCM is $US 104 million. It saves $US 3-7 million compared to complete specialization.

Most reluctant scenario in terms of environmental and peace agreements constraints indicate an optimal timing for desalination by the year of 2032. However, tightening these constraints brings forward the optimal desalination year as much as 2013.

Discussion: IWRM can contribute to moderating regional tensions and protecting key ecological assets while addressing water scarcity in a volatile corner of the world. The importance of desalination technology has its merits which are monetized in this paper. As such it points out on a national social net benefit of meeting agreed upon constraints. Given increasing water scarcity and growing non-market demand, such models can prove beneficial to other countries in the region.

ABSTRACT. Scarcity in fresh surface water resources combined with over-exploitation of groundwater reserves across the Middle East has increased the strict reliance on seawater desalination to meet the demand for potable water. The prevalence of high humidity and temperatures within this region, however, offers unprecedented potential for atmospheric water harvesting and generation to complement classical desalination technologies. Challenges in the area are however related to declining water and current research and development trend indicate that AWG has potential to overcome this challenge. This presentation will review emerging technologies developed for atmospheric water generation and critically assess their performance in terms of water production yield and quality. A technico-economical analysis of both capital and operating costs considering local regulations and standards will also be discussed in light of the potential of the technology for the UAE and the Middle East in general.

ABSTRACT. The project region, including Jordan, Israel and the Palestinian Territories, is characterized by semi-arid to arid conditions and suffers from acute water scarcity. The region's natural freshwater resources are largely depleted and partially over-exploited. Present studies show that both Jordan and Palestine are heading towards a serious water crisis unless additional freshwater resources can be made available. Economically feasible and implementable solutions are urgently required to tackle the freshwater deficit problem of the region. The projected enormous freshwater deficits in Jordan and Palestine can only be met by seawater desalination (SWD) coupled with water transfers to the demand centers in the region. The main objective of this paper is therefore to present a conceptual approach for the development of alternative water strategies based on SWD and water transfer, capable of covering the projected freshwater deficits, and to apply the concept to the region. The results present the current stand of the 2nd phase of the SALAM initiative, which involves 20 institutions from Palestine, Jordan, Israel and Germany. The conceptual approach can be summarized in the following 10 steps: (1) Delineation of freshwater demand clusters and definition of connection points, (2) Definition of baseline scenarios for determining the future freshwater deficits in Palestine and Jordan, (3) Water budget assessment at cluster level, (4) Selection of suitable sites for SWD, (5) Identification of optimal pathways between potential production and connection points, (6) Definition of alternative water production and transfer options, (7) Integration of renewable energies, (8) Calculation of water costs (€/m³) and cost optimization, (9) Elicitation of economic, political, technical, environmental and social criteria (indicators), and (10) Multi-criteria analysis of water strategies. According to the water budget studies, the freshwater deficit in both countries will increase to about 1.3 billion m³ per year by 2050. The water deficits of both countries cannot be covered by a single water transfer project. Independent of water transfer considerations, the Gaza Strip will depend on SWD to compensate for the projected freshwater deficits. In total, 12 alternative water strategies have been developed, taking into consideration 6 potential locations for SWD at the Mediterranean Sea and Red Sea and water transfer by pipelines to the regional demand centers. Water production and transfer cost has been assessed for all strategies. In this article, two water strategies have been selected to be discussed in more detail. The projected freshwater deficits indicate the urgent need for action. Regional transboundary water strategies prove to be far more cost-effective than purely national solutions. In particular, a water transfer from Israel's Mediterranean coast to central and northern Jordan proves to be much more economical compared to Aqaba solutions, simply because of the significantly shorter distances. For the expansion of irrigated agriculture in both countries, high-quality treated effluents should be considered. Due to the regional topography and climate, conditions are suitable for energy generation from hydropower and solar energy, with the potential of further reducing water costs and emissions. This provides a favourable ground for water-energy SWAP concepts.

ABSTRACT. Abstract Agriculture is the main consumer of fresh water sources worldwide; however, changing climate is disturbing the rainfall pattern and leading to sever water scarcity in different countries around the world. Thus, using the alternative water sources for crops irrigation is very important since the demand for food, feed and fuel have been increased due to the rapid increase in the world population. Using treated wastewater (TWW) in agriculture is a desirable alternative source of irrigation, and gaining attraction worldwide. Therefore, the current study was designed to assess the effect of TWW and groundwater (GW) along with synthetic fertilizer doses (50% and 100% of the recommended NPK dose; 150–60–60 kg N–P2O5–K2O ha-1) on total biomass, gross energy, and elemental analysis of safflower (Carthamus tinctorius L.), oilseed rape (Brassica napus L.), and triticale (×Triticosecale Wittmack) grown on old-soil and virgin soil as potential bioenergy crops during the winter seasons of 2019/2020 and 2020/2021 at the Research Station of the College of Food and Agriculture Sciences of King Saud University, Riyadh, Saudi Arabia. The old-soil has been irrigated with TWW during last 15 years and continued to be irrigated with TWW (L1+TWW) in the current study. The virgin soil was divided into two parts: the first part was irrigated with TWW (L2+TWW), while the second part was irrigated with GW (L3+GW). The experimental design for each bioenergy crop irrigated with TWW in two types of soil or GW in virgin soil and fertilized with 50% and 100% doses of the recommended NPK was a split-plot design with a randomized complete block arrangement and four replications. The outcomes showed that the crops irrigated with TWW grown in old or virgin soil, showed higher plant height, leaf area plant-1, total chlorophyll, total biomass, energy content and gross energy as compared to those irrigated with GW and grown in virgin soil. Similarly, tested crops grown in old soil irrigated with TWW showed higher (but lower than permissible limits) contents of macro- (N, P, K), and trace elements (B, Zn, Mn, Cu, Cd, Pb, Ni) compared with those from crops grown in virgin soil and irrigated with GW. Furthermore, 50% recommended dose applied to old soil irrigated with TWW resulted in significant improvement in all measured parameters as compared to virgin soil irrigated with GW along with 100% recommended dose of NPK. Conclusions Briefly, the TWW can be used to irrigate field crops grown for bioenergy purpose because TWW does not pose any harmful effect on energy crops and environment as well. It provides additional nutrients to soil, and thus decreases the rate of synthetic fertilizer requirement up to 50% without any negative effect on dry matter yield of crops, thereby protecting the environment and reducing the leaching of excessive fertilizers into GW.

ABSTRACT. Jordan is heading towards a serious water crisis, facing a freshwater deficit of about 712 million m³ per year by 2050. Seawater desalination is the only suitable option to mitigate water scarcity in the region. However, Jordan has only a short coastline at Aqaba in the South, at a great distance to the demand center Amman in the North. Therefore, transboundary water production and transfer (WPT) strategies are essential. In this respect, Israel and Jordan have recently signed a declaration of intent (DoI) to intensify their cooperation through freshwater supply in exchange for renewable energy. This article assesses and discusses the feasibility and economic viability of a water-energy SWAP between Israel and Jordan, based on the results from the SALAM II initiative. The following steps were taken: (1) identification of alternative sites for seawater desalination (SWD) on the Mediterranean coast of Israel, (2) identification of optimal routes for water transfer between the SWD-plants and demand centers, (3) selection of promising strategies for water production and transfer, (4) selection of options for renewable energy production by photovoltaics in Jordan, (5) analysis of energy transfer to Israel. This article indicates that doubling the SWAP capacity compared to the recently signed DoI by Israel and Jordan will be necessary by 2050. In addition, a promising bartering strategy consists of the water production and transfer of 400 MCM/y freshwater from large-scale SWD North of Haifa bay in exchange for 12.8 TWh/y in renewable energies produced in Jordan. Installing a 5.8 GWp PV plant with an area of ~72.9 km² in the Disi area in Jordan could provide the necessary energy production for such a SWAP concept.

ABSTRACT. Agricultural activities in arid regions, like Kuwait, require large volume of water for irrigation purposes. Saline groundwater quality, shortage in treated wastewater supply, and expensive freshwater force farmers to use on-site brackish groundwater reverse osmosis (RO) units to treat brackish to saline groundwater. One of RO units’ primary limitations is the large volume of concentrated brine (reject water) that is generated from these units. Due to the absence of proper policies and regulations to handle reject water from RO units, it is often disposed of illegally over open land surface or unlined pits. Concentrated reject water could have negative impacts on groundwater quality, and uncontrolled pumping of groundwater could affect groundwater levels. Soil salinization due to brine disposal has negative impacts on crops, threatening partial food security attempts of the authorities. The study presented here has been conducted with the objective to assess the impact of RO reject brine on groundwater quality and levels in agricultural farms of Kuwait. This paper presents the initial activities and results of the study to evaluate impacts of RO reject water on groundwater quality and levels and recommend rational utilization of available water reserves for agricultural purposes. Groundwater levels and salinity were measured and first round of sample collection was carried out from groundwater wells serving the feed water for RO units, product water and reject water from RO units. Samples are analyzed for major ions, trace metals and nutrients. Groundwater levels are regularly monitored to evaluate their fluctuations. Initial results indicate the decline in groundwater table and quality deterioration over the period of time. Preliminary data of this ongoing study and future plans is discussed in this paper.

ABSTRACT. The human body requires fresh water to survive, but fresh water is unavailable to everyone or challenging to obtain. This is because the freshwater source is unsafe, far, or even unavailable. Solar still can help people quickly and safely get potable water from saline water. Solar still is a device that desalinates saline water using solar energy without moving or rotating parts. Solar still is a cheap, convenient device. However, it has low efficiency. The utilization of nanomaterials applications can improve the efficiency of the solar still. Herein, the main components of the solar still are discussed. Also, the recent studies on improving the solar still performance using nanomaterials applications are summarised. The most important and common techniques and advantages and disadvantages of each are presented. The main applications of nanomaterials are discussed. This review paper illustrated that solar still is a simple system to convert available saline water into drinkable water by utilizing solar energy, but its efficiency is low. Using nanotechnology is one of the most effective options to improve its performance. Some suggested techniques using nanomaterials for more performance improvement are presented.

ABSTRACT. Managed aquifer recharge (MAR) is the intentional recharge of water to aquifers for subsequent recovery or environmental benefit. MAR can potentially: increase water security in drought more economically than new dams; augment existing dams with higher efficiency storage (low evaporation); facilitate conjunctive use of surface and groundwater resources. MAR has a long history of operation in Australia and by 2015 reached an installed recharge capacity of over 400 Mm3/yr or about 8% of total groundwater use (Dillon et al., 2019). Beginning in the mid-1960s, infiltration basins were constructed to recharge around 45 Mm3/yr on the Burdekin Delta, Queensland to support sugar cane farming and manage seawater intrusion. Development of ASR began in the 1980s in Langhorne Creek to support viticulture and manage groundwater salinity. These sites remain active and since the 1990s, there has been considerable progress of MAR in urban environments in Australia with stormwater and wastewater for urban water supply. Stormwater aquifer storage and recovery (ASR) for non-potable urban water use was first trialed at Andrews Farm, South Australia in the 1990s (Pavelic et al. 2006). Following the success of the Andrews Farm trial, uptake of stormwater ASR has grown in Adelaide to supply approximately 20 Mm3/yr currently, with potential to increase toward a target of 60 Mm3/yr by 2050. Stormwater contribution to drinking water supply via aquifer storage transfer and recovery (ASTR) was trialed at Parafield, South Australia in the early 2000s, but since then has only been used to supply water for non-potable uses such as municipal open scape irrigation and industrial process water (Page et al. 2010). Wastewater ASR for irrigation supply was trialed at Bolivar, South Australia in the late 1990s (Pavelic et al. 2007). The Bolivar ASR concept has now proceeded to a fully operational scheme (Northern Adelaide Irrigation Scheme) with a design capacity of 12 Mm3/yr to supply irrigated agriculture while concurrently reducing nitrogen loads discharging to the marine environment. From 2010, potable use of wastewater via groundwater replenishment (ASTR) was trialed at Beenyup, Western Australia (Higginson et al. 2021). Following the success of this trial, groundwater replenishment with treated wastewater was chosen as the next new climate resilient water source for Perth. A 28 Mm3/yr groundwater replenishment scheme is scheduled for operation in 2022. Much of the expansion of urban MAR applications during the mid-late 2000s can be attributed to government investment spurred by prolonged drought conditions and critical need for water security at the time and underpinned by the world’s first risk-based management guidelines for water recycling and MAR published in 2009 (Dillon et al., 2020). Reinjection of water from mine dewatering processes is important in many countries and was introduced at several iron-ore mines in Western Australia to protect groundwater dependent ecosystems and secure water supplies for mining operations. Mine water reinjection accounted for over 100 Mm3/yr of Australia’s installed MAR capacity growth in the 2000s (Dillon et al., 2019).

ABSTRACT. Water table depth is declining in most part of the world, especially in those countries which have high temperature almost throughout the year and receive very less precipitation throughout the year. Due to increasing population, intensive agricultural and industrial practices, the demand of freshwater is increasing and is predicted to increase in upcoming years. The countries which receive less rainfall throughout the year have limited groundwater recharge, resulting in declining of water table. United Arab Emirates belong to this category of countries where there is high temperature almost throughout the year and receives very less rainfall (less than 200 mm annually). Modeling groundwater in such an arid climate is of serious concern. This paper proposes LSTM models for prediction of water table depth at six different wells in different parts of United Arab Emirates. Data obtained for this study comprises of times series monthly water table depth data in meters from ground level from six different wells. Analysis of the data showed the drastic decline of water table depth between 1977 and 2011. These data were used to generate the input and target variables by adding three time-step lags in the given data. The time-step lag data was used as input to predict the current water table depth. In other words, the water table depth data of current target month was predicted using the previous three months water table depth data as input. Training of LSTM models was carried forward using TensorFlow libraries in python programming language. The trained models provided good accuracy in testing dataset. The training R2 values of all the six models were more than 0.96 and the testing R2 values of all the six models were more than 0.91.

ABSTRACT. Measuring and monitoring the depth and/or water level is fundamental for hydrometry and free surface flow studies, e.g., water bodies, water treatment plants, laboratory installations. These tasks are usually costly in terms of time and money; however, even these expenses sometimes do not guarantee reliable and/or accurate results. Free surface flows are complex to study because of the instability caused, e.g., by turbulence, wind, or air emulsion that can cause important spatial and temporal fluctuations of the free surface. This work presents an image segmentation and processing technique based on computer vision, to be used in channels with glass or acrylic walls. The technique is non-intrusive and guarantees the detection and measurement of fluctuations in the free surface over space and time. Laboratory tests were carried out under steady and unsteady regime conditions, with different bed roughness, channel slopes, and discharges. Under steady flow, the technique showed a very good fit with measurements taken manually with a point gauge. Under variable flow, this technique has also shown to be successful with conditions requiring high spatiotemporal resolution when taking depth and/or water level measurements. In the tests carried out and described in this study, the cameras allowed to evaluate the water depth with a temporal and vertical spatial resolution of, respectively, 1/60 s (60 fps) and 0.37 mm (one pixel). This spatial resolution depends on the distance from the camera to the channel wall, thus changing accordingly to the laboratory or field installation.

ABSTRACT. Optimum allocation of the limited water resources to the fast-growing demand requires new approaches. In this study, a new generation tool that considers a conjunctive use of surface-groundwater resources to assess both supply and demand-side perspectives is proposed. Using dynamically coupled Water Evaluation and Planning (WEAP) and three-dimensional groundwater flow (MODFLOW) models, a basis for an integrated water management Decision Support System (DSS) is configured for the Middle Awash sub-basin, central Ethiopia. The coupled models characterize water demands for domestic, industry, irrigation, and livestock and water supply from surface and groundwater sources. Using systematically structured near-future scenarios, the likely impacts of natural and anthropogenic stresses (population growth, climate change, and groundwater irrigation) on the surface and groundwater supply sources were evaluated up to the year 2030. The model results under the reference scenario indicated that the annual average industrial, livestock, domestic, and irrigation water demands are 1.3MCM, 21MCM, 41MCM, and 1.6BCM, respectively. If a 2.6% annual population growth rate is considered, the domestic water demand will be more than double (90MCM) in 2030. With the existing domestic water supply infrastructure, the population growth will cause a significant shortage of domestic water supply (70MCM), resulting in maximum domestic unmet water demands from October to December. The highest water supply deficit is recorded for irrigation water demand, with the annual average estimated at 393MCM. The maximum shortfalls of irrigation water demand occurred from January to March. Awash River is the only irrigation water supply source for large-scale irrigation schemes in the basin. However, groundwater can supplement surface water irrigation of large irrigation schemes with careful use that will not deplete the groundwater storage of the basin. Groundwater irrigation scenario tested for the Middle Awash sub-basin reduced the average annual irrigation unmet demand from 393MCM to 265MCM. The effects of climate change were analyzed under four climate scenarios: increase in Temperature, High Precipitation (HPPT), Medium Precipitation (MPPT), and Low Precipitation (LPPT). The climate change scenarios indicated more irrigation water deficiency would occur under the LPPT (443MCM) and increased Temperature (415MCM), while unmet irrigation water demand will be reduced by 366MCM and 328MCM if the MPPT and HPPT scenarios are prominent, respectively. To evaluate the combined effects of population growth, climate change, and groundwater abstraction for irrigation, META scenarios were tested. If the LPPT and increased temperature would be a likely near-future scenario, the irrigation unmet demand will increase from 393MCM to 468MCM. The annual average irrigation unmet demand would be reduced from 393MCM to 294MCM, even when the precipitation is low and the temperature is high, indicating groundwater can endure some of the stresses that might result from low precipitation and an increase in temperature. The WEAP-MODFLOW results can be used as a basis to develop a better-integrated water management decision support system in the Basin.

ABSTRACT. Balancing differences in water demand and availability is on of the major tasks in water resource management, even more so when dealing with seawater desalination. The usage of managed aquifer recharge to store desalination surpluses in order to accommodate for peaks in demand is proposed in this study. Evaluation criteria are compiled to assess the suitability of various fractured rock aquifers in the Middle East for managed aquifer recharge strategies. Some selected aquifers are investigated further using process based mathematical models. The results show, that managed aquifer recharge may very well be used to store desalination surpluses and that against previous considerations the karstic Western Mountain Aquifer has a high storage potential.

ABSTRACT. Extended abstract is attached as a separate file.

ABSTRACT. Climate change has already increased variability in precipitation and extreme weather episodes. Longer periods of droughts and floods due to climate change have been observed worldwide, which largely affects availability and dependency on groundwater. In long periods of drought events there is a higher risk of over-exploited aquifers, especially in arid and semi-arid areas that heavily rely on groundwater to meet their water demands. Sustainable use of groundwater in a changing climate is becoming more and more important. This paper assesses changes in groundwater levels responding to seasonal and annual precipitation variability when groundwater storage is more dependent on the amount of precipitation and complete dependency on groundwater in non-rainy months. Erbil province in Iraq was chosen as an example case study for many arid and semi-arid areas, suffering from unsustainable use of groundwater resources. Climate change has already put additional pressure and stress on groundwater availability and increases environmental concerns. Long-term falling of groundwater levels is also investigated. Monthly records of groundwater level between January 2004 and January 2016 observed at 54 observation wells in Erbil were examined. About 91% of the observation wells are associated with a drop in groundwater level, the remaining 9% were linked to steady or slight rising in groundwater level. Approximately 50% of those linked to a drop in groundwater level are associated with a significant drop (>1.73 m/year), and 24% are linked to moderate drops (0.58 m/year≤drop≤1.73 m/year), whereas the remaining 26% relate to low falls (<0.58 m/year) in groundwater level. The slopes of groundwater level fall between 0.005 and 0.32, with a mean of 0.11. This study will enable a more sustainable use of groundwater in the study area and other similar areas. Moreover, the study represents an important step towards launching nation-wide groundwater assessment programmes to achieve sustainable abstraction and rational utilization and management of groundwater resources.

ABSTRACT. Climate change and variability is arguably one of the greatest challenges facing humankind. Developing countries in Sub-Saharan Africa (SSA), such as Ghana, are particularly at risk because temperatures in SSA are rising faster than the global mean temperature. They are also more vulnerable because they are mainly dependent on agriculture, which is the most climate sensitive sector. The Volta River Basin (VRB) is an important transboundary basin in West Africa that covers approximately 410,000 square kilometers across six countries: Benin, Burkina Faso, Côte d'Ivoire, Ghana, Mali, and Togo. Its natural resources sustain the livelihoods of its population and contribute to economic development in Ghana and neighboring countries. The objective of this study is to investigate climate change impacts and adaptation strategies to optimize resource use in the VRB. River basin modeling of hydrology and cropping systems using Cli-Run (model for climate change simulations), Cli-Crop (model for crops yield impacts) and IMPEND (model for watershed optimization) to simulate dry and wet climate change scenarios. Based on these results, various adaption scenarios in the water and agriculture sectors are recommended. These adaptation measures are accorded a high priority for short and long-term adaptation to climate changes. In the various Ghana agroclimatic zones, construction of more dams for irrigation projects and sub-surface water storage are identified as necessary for sustainable water management. Measures rated as high priority include setting up monitoring systems, managing water resources more efficiently, and identifying specific crop/livestock adaptation needs suitable in the various ago-ecological zones. Other required measures include construction of small to mid-size irrigation facilities, improvement of the land tenure system, and promoting entrepreneurial skills to generate off-farm income (alternative livelihoods) and to improve access to loans and microcredit. Finally, climate adaptation practices are needed at strategic national and regional levels to assure wider stakeholders’ participation and to be more resilient against climate change.

ABSTRACT. The rainfall patterns are no longer stationary due to changing climate. The non-stationary extreme rainfall resulted in the high flood risk in the urban area such as Surat city. In the current study, non-stationary extreme rainfall of the Surat city is analysed using 68-years (1951-2018) observed daily rainfall data. Total five (physical processes) covariates namely, Local temperature anomaly (LT), Global temperature anomaly (GT), IOD-Dipole mode index (ID), ENSO-Sea surface temperature Index (ES) and, Time is used. Firstly, the stationary Generalised Extreme Value (GEV) model is developed using extreme daily rainfall. Secondly, non-stationary GEV model using location parameter is developed with aforesaid covariates. Thirdly, non-stationary GEV model using location and scale parameters are developed using aforementioned covariates. Total 27 GEV based models are developed and the significant covariate and best non-stationary model for extreme precipitation is evaluated using likelihood ratio test. Out of 27 constructed GEV models 13 models are showing significant effect of covariate on extreme precipitation analysis. The combination of LT-ES based GEV model using non-stationary location and scale parameter gives the best model with lowest AIC, and extreme daily rainfall for corresponding return levels are compared with stationary GEV model. The 2-year, 5-year, 10-year, 25-year, 50-year, and 100-year return period extreme daily rainfall are 146 mm (162 mm), 200 mm (247 mm), 235 mm (305 mm), 283 mm (381 mm), 319 mm (440 mm), and 356 mm (500 mm) respectively for GEV stationary (Non-stationary LT-ES) model for the Surat city. Moreover, the trend analysis using Modified-Mann Kendall (MMK) test and Innovative trend test analysis (ITA) shown the non-significant increasing trend in the extreme daily rainfall of Surat city. The current study can be useful in evaluating the risk of the hydraulic or hydrologic infrastructure of Surat city under changing climate.

ABSTRACT. The Upper Indus Basin (UIB) is a major source of fresh water to 1.4 billion people in South Asia. Projecting future hydrological regime over the UIB is always a challenging task due to the limited availability of reliable reference data and uncertainties in future climate projections and hydrological modelling approaches. This study attempts to address these issues by employing state-of-the-art regional climate models and the Physical based Distributed Snow Land and Ice Model (Grossi et al., 2013, Ranzi and Rosso, 1991) in the UIB for the Naltar catchment (area of 242.41 km2, with 42 km2 glacierized), located in the Hunza river basin (Karakorum, Pakistan), in order to project snow and glacier melt and daily streamflow. First, the calibration and validation of the model were successfully carried out using observed historical data from high altitude meteorological stations. The accuracy of the model in simulating distributed snow cover is crosschecked using MODIS- and LANDSAT-based snow cover areas both at temporal and spatial scales. Results exhibited overall satisfactory model performance, as shown by the coefficient of determination, R2 = 0.97 and Nash-Sutcliffe Efficiency, NSE= 0.96 when comparing the model against satellite-based snow cover area for all simulated melting periods. Daily streamflow measurement at the outlet of the Naltar catchment at Naltar Bala station was used as a reference for the evaluation of simulated summer streamflow. Runoff simulations revealed good agreement with observed discharge, with NSE of 0.88 and 0.90 for the calibration and validation periods, respectively. Secondly, the model was subsequently integrated with state-of-the-art regional climate projections for near future (2040-2059) and far future (2080-2099) under three Representative Concentration Pathways (RCPs), each of them representing a different radiative forcing by 2100 with respect to the preindustrial period, namely RCP2.6, RCP4.5, and RCP8.5. We used all relevant meteorological variables from an ensemble of 38 simulations in total, which were performed by 3 RCMs driven by 11 different global climate models (GCMs) and were developed under the CORDEX Experiment, (Giorgi et al., 2009, Jones et al., 2011)-South Asia initiative.. Climate models often present systematic biases and, despite their rather high spatial resolution (here approximately 50km x 50km) they are still too coarse for hydrological impact assessments. In order to produce localized and unbiased climate projections, we scaled the observed climate according to the simulated changes by means of the delta change method as described in (Räisänen and Räty, 2013, Räty et al., 2014). Changes in the mean and standard deviation for all meteorological variables were obtained for the near and far future periods compared to the historical period (1991-2010) for each simulation.

ABSTRACT. Prepared by: Dr. Modathir Zaroug and Dr. Michael Kizza Nile Basin Initiative Secretariat, Entebbe, Uganda.

Nile Basin countries are already experiencing the effects of climate variability and change. There is evidence for increase in temporal variability of rainfall in recent years. Yet, there is a large degree of uncertainty in establishing concrete climate trends and impacts, particularly in the Nile Basin. Furthermore, upper and lower Nile Basin are projected to experience quite different precipitation trends (increase e.g., in the upper Blue Nile, decrease further downstream). Blue Nile and White Nile have different flow regimes and different natural storage capacity, so that the impacts of increasing variability will be different. Changes in frequency and intensity of extreme climate events in the Nile Basin offer a very complicated picture. In some countries, mean annual rainfall is projected to increase slightly and decrease in others. Shifts in rainfall seasonality — including delayed onset and decreased duration of the rain season — will cause an increase in frequency and intensity of extreme rainfall events, flooding and soil erosion. The Nile Basin is also likely to experience an increase in mean annual temperature of around 1.5-2°C by the 2050s. Droughts are projected to become more frequent and intense across the entire region. The prolonged dry season and increased temperatures will intensify droughts and their impacts on agriculture and therefore vulnerable communities in the eight countries. Frequent severe droughts affect the livelihoods and food security of millions of people, leading to a famine, migrations and even death. Addressing these and similar challenges is crucial for effective adaptation to climate change and enhance resilience of the basin countries’ economies. Moreover, the early warning systems are in their nascent stages of development. Every dollar invested in disaster mitigation and climate-resilient infrastructure 6 dollars are saved. Hydro-meteorological hazards account for 90% of natural disasters in East Africa region. It enables NBI to foster cooperation in the Nile Basin around the topic of better informed decision making consider current and future available resources. NBI developed strategy, policies, action plan, tools, and knowledge products to mitigate the impact of climate change. Over the past several years, the NBI has built its capacity in the generation data, information, and provision of climate services. The NBI will share its experience in this conference on climate change adaptation.

ABSTRACT. Water is a key to economic development and food security; it is a main factor for food production processing and preparation. Globally, agriculture requires large quantities of water for irrigation which accounts for 70% of all water withdrawn from surface water, groundwater aquifers, and treated wastewater. Several regions all over the world are already facing acute physical fresh water scarcity such as North Africa, South Asia, and the arid and hyper arid regions of sub-Saharan Africa.Arab countries cover 10% of the world’s area but receive only 2.1% of its average annual precipitation. Most of the region is classified as arid or semi-arid. Only Sudan, southern Sudan, the Atlantic and Mediterranean coastlines and the southwestern Arabian Peninsula receive high rainfall. Coupled with rapid population growth since the mid-1970s, these conditions have caused dramatic shrinkage in per capita renewable water resources, from an average of 2,925 cubic meters a year in 1962 to 813.07 in 2011 below the poverty line level of 1,000 cubic meters a year and far below the world average of 7,240 cubic meter a year. Although urban demand for water has been rising steadily, agriculture continues to consume the most water. Agricultural water use rose from about 160 Billion cubic meters in 1995 to more than 207 Billion cubic meters in 2013. While embarking on a path towards enhancing food security through promoting domestic food production, Arab countries need to adopt policies and take many actions to enhance food self sufficiency of food as; Strengthen regional cooperation among Arab countries, reverse the deteriorating state of agricultural resources, enhancing water productivity, improving water-use efficiency, Reducing post-harvest and other losses, and promoting the use of treated wastewater for irrigation. Modern irrigation is one of the success stories of the 20th century. As the world’s population doubled, irrigated farming expanded from 40 Million hectares to almost 300 Million hectares in 201, a seven-fold increase. Can efficient agricultural water management and new irrigation and agriculture technologies provide innovative solutions that meet this challenge of feeding a growing population in the Arab region by producing more food but with less water resources? This chapter reviews the water-food nexus in the Arab region and examines the role that water management and new technologies may play in achieving Arab food and water security.

ABSTRACT. Water scarcity is a serious problem in many areas of the world, and severe droughts have threatened water, energy, food, and nutritional security in arid regions. With climate change and diminishing freshwater availability, there is a regional interest to develop alternate sources of water. These include brackish groundwater, produced water, and municipal water sources. There are large amounts of brackish groundwater in arid southwest and New Mexico. The oil and gas exploration in this area also produces large volumes of produced water, which is injected back into deep aquifers. By using appropriate treatment technology, these waters can be brought into the irrigation portfolio to meet water shortfalls for agriculture. In order to reduce the cost of the treated water, options to treat at crop appropriate salinity levels as well as dilution wherever available could be explored. Agricultural sustainability in arid and semi-arid regions of the world depends on proper use of available brackish waters. The objectives of this research is to report brackish water impacts on soil and plant health and suggest crops that can be grown across irrigation water salinity gradients to improve quality of life in arid and semi-arid regions of the world. Studies were carried out in a greenhouse located at the Fabian Garcia Science Center of New Mexico State University (NMSU), Las Cruces, New Mexico. Irrigation water available at research farm (control), natural brackish well water and concentrate coming out of the reverse osmosis (RO) system were used for irrigation. Both well water and RO concentrate were provided by the Brackish Groundwater National Desalination Research Facility (BGRNDRF), Alamogordo, NM. The produced water was supplied by NGL Water Solutions. Chile peppers, tomato and pecan were found to be salt sensitive and beyond an irrigation water salinity of 2 dS/m showed declines in evapotranspiration (ET) and yield. The abiotic stress due to the brackish water irrigation decreased time to flowering and increased the number of chile pepper flowers. The salinity increased the sugar content in tomatoes, and changed oil content in Pecan. Beyond 4 dS/m of irrigation water salinity, ET and biomass yields declined for alfalfa while for triticale no decline in biomass and ET was noted. Among the six known halophytes (Atriplex canescens, barley, mesa pepperwort, inland saltgrass, triticale, and switchgrass), no limitation were observed related to salinity induced abiotic stress and all six species performed well, and biomass yields increased with salinity. Using diluted produced water, Atriplex Conescence and Atriplex Lentiformis showed no limitation until 70 dS/m. A novel irrigation scheduling protocol based on the crop water needs, depth to the groundwater table, and location (degraded versus agriculture areas) will need to be developed to control soil salinization and help sustain agriculture in the water-starved arid areas, provide food security, and improve quality of life. Further research should focus on using salinity as a value added product for both salt sensitive and salt tolerant crops.

ABSTRACT. The shrinking of the Aral Sea awakened a huge chain of ecological processes that led to the emergence of the Aralkum desert as a result of soil and vegetation degradation. Based on morphometric data of the water resource for the period 1960-2010, changes in the sea area, water volume, water level and salt concentration in the Aral Sea from 1960 to 2020 are analyzed. The area (68478 km²-7088 km²) and water volume (1093 km3-105km3) of the Aral Sea have decreased by more than 10 times since 1960, the water level (53,5m- 27,53m) has decreased by 2 times, and its salinity (9,93 g/l- 102 g/l) has increased by 10 times. In this study, soil maps and a map of the Aral Sea water area for 1986, 2000, 2020 periods were prepared based on field work on soil cover studies and multi-temporal Landsat images (NDWI, MSAVI). According to the results of the field studies, the assessment of soil cover shows a poor development of soil formation processes on the background of strong initial salinity and carbonation. The following types of soils have been identified: 1) meadow and meadow-swamp; 2) takyr-like with overlaid sandy cover; 3) takyr solonchak and typical coastal solonchak; 4) brown desert unsaline; 5) sandy desert semi-hilly fixed.

ABSTRACT. The achievement of adequate an equitable access to sanitation for all by 2030 is at the core of the United Nations Sustainable Development Goal (SDG) #6. Despite all the efforts being made towards the achievement currently, it is estimated that this goal cannot be met by 2030, biggest hurdles being the 1) considerable cost associated with wastewater infrastructure and 2) lack of estimation how much money a country or a region needs for reaching the SDG#6. Within this study, we therefore, present a GIS-based assessment method for the estimation of wastewater infrastructure required for increasing the current connection rate. The assessment method enables not only an estimate of required infrastructure but also the development of several wastewater management scenarios including the cost assessment for comparison. The study starts with a detailed explanation of the creation of the data-base and step-by step methodology of the approach. The approach is applied to Jordan for which a set of two main scenarios is defined: centralized and decentralized (+ the expansion of current wastewater infrastructure to meet the future demand). Decentralized scenario considers that each settlement is to be connected to its own wastewater treatment plant (reduced pipe length), while the centralized scenario considers to connect settlements confined within a catchment to a common wastewater treatment plant (reduced number of wastewater treatment plants). The estimated specific treatment cost varied from catchment to catchment ranging between 0.88 JOD/m³ and 2.61 JOD/m³ for decentralized scenario and between 0.72 JOD/m³ and 2.54 JOD/m³ for centralized scenario. The high resolution of the analysis method enabled the cost estimation at the level of individual settlements, catchments and the whole country. Using globally available data, the method can be applied worldwide. In view of SDG#6, we present a methodology that enables a countrywide estimate on wastewater infrastructure that has a high resolution.

ABSTRACT. CO2 plume geothermal production (CPG) is an emerging approach not only to reduce atmospheric CO2 concentration, but also to generate non-carbon renewable geothermal energy to meet increasing power demands. Hydrogeological data indicates potential geothermal resources in North Oman area. The depleting oil reservoirs in this area, which are usually fault blocked, are good candidates for CPG after CO2-enhanced oil recovery. The purpose of this study is to evaluate technical performance in a fault-bounded reservoir in North Oman Foreland basin. The porosity and permeability are considered slightly heterogeneous according to the field data. A numerical model is developed to simulate CPG for 50 years. CO2 circulation, reservoir pressure and temperature dynamics, produced geothermal energy capacity, are quantitatively assessed. The findings could provide a useful guidance to accelerate prospecting, engineering and operation of similar type of geothermal reservoirs.