Water Scarcity Management to Ensure Food Scarcity through Sustainable Water Resources Management in Saudi Arabia

: Saudi Arabia (SA) faces a water shortage, and it further challenges sustainable agriculture, industrial development and the well-being of people. SA uses more than 80% of its water resources for agricultural purposes. Groundwater extractions account for most of this demand, which is not sustainable. Hence, this study aims to analyze water management practices used in SA to propose viable and workable solutions to achieve sustainable management of scarce water resources. This study is based on a critical evaluation of information available on the water sector in SA. About 89% of the water demand in the Kingdom is non-sustainably met through over-pumping from groundwater resources and 9.3% by energy-intensive desalination. SA invested in dams and developed rainwater harvesting to enhance surface water availability and increase the recharge capacity of renewable aquifers. As there is a huge demand–supply gap, water demand management tools are the viable solutions leading to sustainability compared to supply enhancement that is capital intensive. A national agricultural policy, together with a water policy, can make agricultural systems more input efﬁcient with higher productivity. Region-speciﬁc sustainable water resources management plans need to be implemented to match the demand–supply gap. Conjunctive water uses utilizing and prioritizing different water sources viz. harvested rainwater, treated wastewater, desalinized water, and groundwater, is vital in sustainable water resources management. In addition, climate change has exerted pressure on the available water resources and water uses as well as users, leading to adaptation for measures that are more sustainable in terms of water management. The most pressing problem SA faces in water resources management is the depletion and degradation of surface and subsurface water sources. SA has to implement many technological and legislative changes in addition to service management, conservation measures, paying a reasonable and justiﬁable price for water, and strengthening state agencies that will make water resources management in SA sustainable.


Introduction
Water scarcity is quite a common phenomenon, not only impacting arid and semi-arid regions of the world but also adversely affecting the areas receiving heavy rainfalls.Water scarcity is related to the quantity and quality of water and damaged water infrastructure, and contaminated sources that cannot meet demand or cannot maintain much-needed quality standards.The long-term performance of ecosystems also depends on the availability of water resources.Water resources of a country are being used for many useful purposes, mainly to supply domestic, industrial, and agricultural needs and also to fulfil environmental requirements.Irrigation water and other water supplies for domestic and industrial needs are essential to a country's economy and social well-being.
Irrigation uses more than 70% of water resources used worldwide [1].Regional water shortages and a disproportionate share of water allocated to agriculture have led to increased regional water shortages challenging industrial and economic growth [1] and environmental protection.The uneven distribution of global freshwater resources [2], unsustainable irrigation practices [3], and over-exploitation of groundwater resources [4] are challenging food security globally.In West Asia and North Africa (WANA) countries, water scarcity is closely linked to food and health security [5].GCC countries face a severe water shortage that threatens the sustainable development of agricultural and industrial sectors [6].Water resources in the GCC countries are predicted to reduce by more than 50% by 2030 [6].Due to the shortage of water, GCC countries are facing difficulties in meeting the basic and essential requirements aggravating agricultural activities, especially in Saudi Arabia, which is the biggest agricultural producer in the region.
To meet its food demands, Saudi Arabia undertook its largest agricultural livelihood effort in the 1980s.Saudi Arabia has become the world's sixth-largest wheat exporter despite having limited and low access to water resources to meet crop production targets.One of the nations with the greatest water shortage in the world, Saudi Arabia, largely relies on the extraction of water from its fossil and non-renewable water resources to meet its needs [7].Saudi Arabia's water supply decreased from 20.74 billion cubic meters (BCM) during the Sixth Development Plan to 16.31 BCM during the Ninth Development Plan.
Meeting the water needs of the municipal, industrial, and agricultural sectors in the Kingdom is extremely difficult because of its expanding economy and population [8].More than 80% of the water resources used in the Gulf Cooperation Council (GCC) countries are for agricultural purposes, and groundwater extraction accounts for most of this demand [9].Over the past few years, the groundwater resources in Saudi Arabia have been diminishing more quickly than their recharge rates [8].Due to the massive abstraction of non-renewable water in recent decades, groundwater levels and the quality of the pumping water have sharply decreased.National scientists and water researchers have warned that careless domestic consumption by society and inappropriate agricultural expansion would further exhaust the diminishing water supply provided by the damaged and deteriorated aquifer system [10].Due to issues with inadequate water supply management, unchecked population growth, and careless agriculture policies, Saudi Arabia has a culture of water waste [11].The deposition of salts on agricultural soils as a result of groundwater extraction may increase the cost of production, and expensive technologies would be required to desalinate the salty water for its usage by various sectors [12].Regulatory frameworks must be implemented for agricultural uses, domestic sewage waste disposal, and groundwater pumping to stop groundwater depletion and pollution [10].According to Baig et al. [11], Saudi Arabia's water infrastructure is outdated and deteriorating in some areas.As a result, it is anticipated that up to 20% of the water supply may be lost.Saudi Arabia uses almost 700,000 bbl/day of oil in power generation, of which desalination of water accounts for 60% of the total.Public desalination plants make up 40% of the total, while private sector facilities make up 20% [13].More than half of the country's domestic oil usage is required to keep these desalination facilities operational to ensure enough drinking water is available [14] in the Kingdom.Eke et al. [12] found that the worldwide desalination capacity deployed worldwide increased at a 7 percent annual pace from 2010 to 2019.The Kingdom's water sector is currently dealing with many problems that put the security of water, food, and energy at risk.The distribution of gasoline and desalination of water depletes the nation's energy supplies and raises environmental expenses.Due to rising drinking water expenses, wastewater output subsidized water use, and increased water losses in the water supply network, more salts go into the drainage and wastewater treatment systems [15].The lack of accessible renewable water resources and the rising demand from communities and many economic sectors impede the establishment of a stable society in Saudi Arabia.Due to the Kingdom's significant reliance on desalinated water and increasingly depleting groundwater, the active and ready use of wastewater, Treated Sewerage Effluent, and recycling of clean wastewater for a variety of unusual purposes are required [16].
As agriculture is the sector using the biggest portion of water withdrawals in Saudi Arabia, managing the agricultural water needs is vital to ensure food security in the Kingdom and to make agriculture sustainable.Agriculture needs novel and creative techniques to manage its scarce water resources to be sustainable.This study aims to analyze innovative water management practices to manage water scarcity in the agricultural water management sector in order to ensure sustainable water use in agriculture in Saudi Arabia and to propose viable options and workable solutions to achieve sustainable management of scarce water resources to ensure food security in the Kingdom.
This paper analyzes the water scarcity in Saudi Arabia and its management giving emphasis on sustainable water resources management practices that are being carried out.This paper also evaluates how sustainable and non-sustainable water resource management practices affect water scarcity and food security.It further discusses the challenges and opportunities in achieving food security through sustainable water resource management practices in Saudi Arabia.

Water Resources in Saudi Arabia and Challenges
Only a few regions of Saudi Arabia experience more than 250 mm of annual precipitation due to the country's dry, arid, and hyper-arid environment.Most of the regions receive less than 100 mm of rainfall annually in Saudi Arabia, with a significantly high rate of evaporation.Due to a shortage of renewable water resources, the nation relies mostly on non-renewable "fossil" groundwater supplies and desalinated water from the desalination plants.However, due to issues with location, access, and distance from the site of use, only a small portion of both renewable and non-renewable resources can be economically utilized.The semi-arid environment of the Kingdom exposes a great temperature variation, low annual precipitation, limited groundwater reserves, and a dearth of year-round stream flows and other surface water sources [17].
Water resources in Saudi Arabia can be categorized into four, surface water (accounts for 10% of the water supply, mostly received in the western and southern regions), groundwater from two sources viz.non-renewable from deep fossil aquifers and renewable from shallow alluvial aquifers (makeup 40% of the supply), desalinated water (supply 8% consumable and 50% water for drinking) and reclaimed wastewater (treated) (roughly 1% of water supply).Saudi Arabia produced a volume of water from freshwater by source (surface, underground, desalinated, and treated) of about 17,446 million cubic meters (MCM) in 2010 and 23,933 MCM in 2016 [18] (Figure 1).The consumption of desalinated water consistently between 2010 and 2017.Until 2015, groundwater use increased; however, in 2016 and 2017, it fell.Although the consumed volume of water has changed, the percentage of surface water and treated wastewater used has not changed.Surface, groundwater, desalinated water, and treated wastewater as a proportion of total water use in 2017 were 0.63, 89.0, 9.3, and 1.1, respectively [19,20] (Figure 1).Large groundwater supplies are thus drained as a result of overuse.Figure 1 displays the volume of water consumed in Saudi Arabia from 2010 to 2017 from various sources.It is noted that the over-pumping of water meets the non-sustainable water demands in the Kingdom from non-renewable groundwater sources.Due to Saudi Arabia's inadequate water supply and the rising requirements of water expressed by its urban, industrial, and agricultural sectors on limited national water resources, the International Monetary Fund (IMF) classified Saudi Arabia as an "at-risk" territory [21].The largest consumers of water in Saudi Arabia are the municipal, industrial, and agricultural sectors (see Figure 2).Municipal and industry demands for water have both been rising over time.The municipal sector grew from 4.5 to 14.6 percent between 1990 and 2020.It was noted that groundwater extraction for the agricultural sector decreased from 95% in 1990 to 82.8 percent in 2020.Even though only 1% of Saudi Arabia's land is arable [22], the country still uses a significant amount of water for agriculture.Without question, the country has become one of the leading agricultural producers in the Middle East, using mostly non-renewable aquifers that receive little to no recharge.As a result, the depth of the aquifers is allegedly dropping by 1 to 2 m every year [23].Due to Saudi Arabia's inadequate water supply and the rising requirements of water expressed by its urban, industrial, and agricultural sectors on limited national water resources, the International Monetary Fund (IMF) classified Saudi Arabia as an "at-risk" territory [21].The largest consumers of water in Saudi Arabia are the municipal, industrial, and agricultural sectors (see Figure 2).Municipal and industry demands for water have both been rising over time.The municipal sector grew from 4.5 to 14.6 percent between 1990 and 2020.It was noted that groundwater extraction for the agricultural sector decreased from 95% in 1990 to 82.8 percent in 2020.Even though only 1% of Saudi Arabia's land is arable [22], the country still uses a significant amount of water for agriculture.Without question, the country has become one of the leading agricultural producers in the Middle East, using mostly non-renewable aquifers that receive little to no recharge.As a result, the depth of the aquifers is allegedly dropping by 1 to 2 m every year [23].Due to Saudi Arabia's inadequate water supply and the rising requirements of water expressed by its urban, industrial, and agricultural sectors on limited national water resources, the International Monetary Fund (IMF) classified Saudi Arabia as an "at-risk" territory [21].The largest consumers of water in Saudi Arabia are the municipal, industrial, and agricultural sectors (see Figure 2).Municipal and industry demands for water have both been rising over time.The municipal sector grew from 4.5 to 14.6 percent between 1990 and 2020.It was noted that groundwater extraction for the agricultural sector decreased from 95% in 1990 to 82.8 percent in 2020.Even though only 1% of Saudi Arabia's land is arable [22], the country still uses a significant amount of water for agriculture.Without question, the country has become one of the leading agricultural producers in the Middle East, using mostly non-renewable aquifers that receive little to no recharge.As a result, the depth of the aquifers is allegedly dropping by 1 to 2 m every year [23].

Water for Agriculture and Scarcity Management
In 2015, Saudi Arabia consumed 24.8 BCM of water for domestic, commercial, and agricultural purposes (Figure 1).About 85% or 14.42 BCM of water is used for agriculture.Total water use in Saudi Arabia is estimated to be 17.41 BCM (2.28 BCM for municipal uses, 0.71 BCM for industrial uses).Total renewable sources produce only 5.44 BCM.Hence, the water gap met by the over-exploitation of non-renewable groundwater is 11.98 BCM [24].As agricultural use of water is 85%, it contributes to a major portion of the over-exploited portions via irrigated agriculture.
Sprinkler systems, trickle/drip irrigation systems, and flood irrigation systems are the three primary types of irrigation systems utilized in Saudi Arabia.Some of these systems have high water requirements and relatively poor usage rates.Grain production, mainly wheat production, used a considerable amount of water allocated for agriculture.The Saudi government adopted a policy in 2008 that required farmers to bring less area under domestic wheat production with the prime goal of protecting water resources and asked them to grow vegetables and fruits rather than cultivating field crops [25].Since 2016, the government has stopped buying wheat from local farmers and banned exporting wheat.Having been placed in a situation, the farmers started growing alfalfa using three times more water than wheat; therefore, this policy did not work.In 2015, the Saudi Arabian government ceased cultivating all raw food crops for the next three years [26].However, the farmers were allowed to grow fodder (alfalfa) for the local dairy industry, but this practice was only allowed until 2019 [27].The new policy caused a sharp reduction in the demand for plantations and irrigation water.Two key assumptions-one about supply and the other about demand-would form the basis for the projection of water consumption by the year 2030.Due to the termination of the wheat procurement subsidy in 2016, there will no longer be funds available to farmers, and as a result, production is projected to fall.Demand for fodder will also decline, and the state is promoting subsidies for the importation of feed, so there will be less strain on the local water supplies if there is little or no fodder crop cultivation.As a result, the agriculture sector would use less water, and water from various sources would be successfully saved, helping to at least partially combat scarcity.

Management of Surface Flow, Water Collection Dams and Scarcity Management
Water requirements of different crops significantly vary based on the method of irrigation and can vary from 9100-39,000 m 3 /ha [28].Water for food production is derived from surface water bodies, groundwater aquifers and directly from rainwater.Groundwater is the prioritized source that augments the water demands during dry spells and droughts [29].Agricultural water demand in Saudi Arabia was reported as 1850 MCM/year in 1980 [30], 29,826 MCM/year in 1992 [30], and 19,000 in 2018.The Kingdom introduced several policy measures to conserve water in the agriculture sector, and it reduced the agricultural water demand to 17,530 and 15,464 MCM/year in 2004 and 2009, respectively [31].MOEP planned to reduce the agricultural water demand further to 12,794 MCM/year by 2014 (a 3.7%/reduction per year), implementing policies such as reducing the cultivated area and adopting efficient and advanced irrigation practices [31].
Saudi Arabia receives an overall average annual rainfall of approximately 125 mm [32].The long-term average annual rainfall in the north is 70.1 mm/year (<100 and 200 mm), and in the south, it is 265 mm/year [33].Saudi Arabia has started initiatives to control this water, including building additional dams and developing a "Rainwater Harvesting Program".Occasional intense rainfall events received in the central, north and southwest regions of Saudi Arabia can be harvested and stored to use as a source to meet different demands, including agricultural demand or utilized to recharge renewable groundwater aquifers.Renewable surface and groundwater contribution to water supply in Saudi Arabia increased from 2004 to 2009 by 0.5% per year from 5410 to 5541 MCM [32].Dams contribute to storing surface water and allow the recharge of aquifers that supply renewable groundwater.
The Ninth Development Plan proposed to increase the total surface water dam holding capacity to 2500 MCM and to regulate the captured runoff usage in agriculture.The sustainable groundwater yield is 3850 MCM/y, while the surface-water yield is 1300 MCM/y.The surface-water yield was gradually increased to a capacity of 2400 MCM/y by 2014, based on the Ninth Development Plan [25].According to estimates, 260 irrigation dams in Saudi Arabia held 0.6 BCM of floodwater in 2013 [34].Approximately 1.4 BCM/year of water flowed from 302 dams in 2015 [32].For water collection, storage, recharge, and emergency flood control, there were 449 dams in 2016 [15,35].The amount of water accessible from these dams is around 1.6 BCM per year, following the most recent estimations that have been published [10].Dams in Asir, Mecca, and Jizan supply roughly 73% of the readily available water.The Kingdom has built roughly 535 dams with a storage capacity of more than 2 billion cubic meters to enhance water storage capacity and expand the supply of drinking water resources.More dams are being constructed to accommodate the local residents' agricultural and drinking demands [36].In 2012, a total of 449 dams in the country stored and recharged approximately 2.02 BCM of runoff [37].
Runoff is collected in reservoirs in some parts of Saudi Arabia; however, the possible surface runoff that could be harvested might be significantly higher than the currently collected runoff.The traveling distance of runoff to reach the reservoir in most cases is higher so that more runoff is lost through evaporation and infiltration.This reduces the amount of runoff captured in the reservoir.Furthermore, siltation of the reservoirs due to flood events has reduced the capacity of some of the existing reservoirs limiting the available water for use [37].
Free water surface evaporation from dam reservoirs in Saudi Arabia is in the range of 5-80% on an annual basis [38,39], and the loss of water due to evaporation is, therefore, in the range of 4.7-6.0m per year [40].Climate change-induced increases in temperature will increase the evaporative loss of water from reservoirs and further reduce the availability of surface water sources.Furthermore, an increase in temperature by 1 • C to 5 • C may reduce surface runoff by 115-184 MCM to 600-960 MCM per year, respectively [40,41].This limits the surface water availability that can be captured by dams, and this will also reduce the recharge of shallow aquifers, which supply renewable groundwater sources.The estimated recharge due to the reduction in runoff is estimated to be 91.4MCM to 475 MCM per year.Due to climate change, the overall reduction in water resources will be 241-1435 MCM per year [40,41].The water resources stressed due to the reduction in capacity will be further pressured to supply an increased agricultural water demand of 5-15% in 2050 to maintain the present production levels [42].This is further aggravated by the deterioration of water quality.
Many anthropogenic activities pollute surface and shallow groundwater to levels that could be undesirable for agricultural production [29].Most of the water quality parameters of some dams in the Asir region were satisfactory (magnesium absorption ratio (MAR), magnesium hazard (MH), Kelly's ratio (KR), and soluble sodium percentage (SSP) for irrigation except for sodium percentage (Na%) and sodium adsorption ratio (SAR).Based on the irrigation water quality index (IWQI), 51.6% of samples had a high suitability class, and 11.1% of samples had moderate suitability, whereas the rest (37%) were low suitability for irrigation use [43].
Saudi Arabia faces a huge demand-supply gap in terms of water management.One of the main reasons for this demand-supply gap is the unavailability of surface water resources.Therefore, intensive water demand management measures are necessary to manage agricultural water demand.As the population is growing and as industrial activities are expanding, the water demand of these two sectors is increasing, and the share of water available for the agricultural sector is diminishing.Therefore, the agriculture sector needs to produce with the limited water availability.This can be achieved by prioritizing what to grow as a national policy and by making agricultural systems more input efficient and with higher productivity.Crops that have a lower water demand and methods of irrigation which have higher efficiencies leading to less water use need to be implemented in order to make sure water productivity is improved.A region-specific sustainable water resources management plan needs to be implemented, with interventions such as rainwater harvesting, utilization of treated wastewater to fulfil some portions of the water demand based on the quality of discharged water, introducing water conservation measures and minimizing losses.Surface water conservation could be through dams that store surface runoff.
Construction of new dams to capture more runoff and establishing wells to extract renewable groundwater in appropriate locations is important.This needs to be conducted based on scientific evaluation of the best locations to establish such structures, potential water yields, hydraulic conductivity of soils and structure of the formation, financial viability and feasibility of such interventions are important factors to be considered.Poor quality of water also challenges the supply of agricultural water demand using the limited surface water sources challenging agricultural production.Poor water quality may lead to low yields, deterioration of soil quality and challenges to sustainability.

Management of Subsurface Water Resources and Scarcity Management
Saudi Arabia shares aquifers with the other eight bordering nations.Cross-border groundwater flow is often modest compared with the volume of water used in the Kingdom.It is projected that there are 2175 BCM of deep groundwater reserves in the aquifers in the Arabian Peninsula, with the majority (1919 BCM) being found in Saudi Arabia [44].More than 20 primary and secondary aquifers around the Kingdom contain non-renewable groundwater supplies because of the Arabian Shield's non-porous and stony composition.All aquifers are found on the Arabian Shelf due to the presence of naturally occurring nonmineral rocks, while the Arabian Shield is home to two huge and four small aquifers [10].Shallow alluvial and deep rock aquifers are the two most significant, non-renewable sources of groundwater.The deep rock aquifers contain "fossil" water that is sedimentary in origin [45].The groundwater in the deep sandstone aquifers is non-renewable or "fossil" water, covering thousands of square kilometers with little natural recharge in the mountainous parts [46].Furthermore, limestone and sand strata between 150 and 1500 m below the surface are where fossil water can be found [35]; hence, all the groundwater reserves are not accessible.
The entire amount of water that can be taken from non-renewable groundwater deposits is approximately 1180 billion cubic meters.These non-renewable groundwater reserves have a yearly production capacity of 20.6 billion cubic meters, which satisfies 35% of municipal demands, 6% of industrial needs, and 80% of agricultural needs.The water removal rate from shallow renewable aquifers is larger than the rate of recharge, and they are in danger of running dry.Saudi Arabia uses 10-39 times more water from renewable aquifers than is available.This causes them to dry significantly faster than rainfall replenishes them.
These water supplies may run out in the next 50 years if the high levels of water extraction continue (Jorg et al., 2012) [37].A record 21.2 billion m 3 of abstraction for growing crops is also said to have increased due to the expansion of agriculture [7].A study estimates that 35% of the Kingdom's non-renewable water sources had already been depleted by 1994 [47].The recharging of groundwater will determine whether the groundwater resources can be used in a sustainable manner.
With an active annual recharge of 886 million cubic meters (MCM), their estimations for the non-renewable groundwater reserves ranged from 259.1 to 760.6 billion cubic meters (BCM) with an effective annual recharge of 886 million cubic meters (MCM) [32].According to data from the Ministry of the Environment, some other experts estimate that the Kingdom's non-renewable groundwater reserves could be around 2360 billion cubic meters [10,15].However, it is anticipated that the recharge for all deep aquifers will be extremely constrained, with an estimated value of 2.7 BCM [48].
Groundwater extraction in Saudi Arabia has expanded over the past three decades.Groundwater extraction has now reached 17 BCM/year.Groundwater supplies 80% of the water requirements in Saudi Arabia [49,50].Compared with the annual amounts of water being extracted, groundwater recharge is extremely low.The lowering of groundwater levels can have a negative impact on the quality of the water [50,51], in addition to many other major concerns such as a lowered water level in groundwater wells, reduction of yield, the extra cost needed for pumping, etc., which are leading unsustainable resource use.Increased exploitation of groundwater resources for agriculture leads to a decline in water levels and deterioration of groundwater quality [52]; hence, efficient management options to cater to sustainable agricultural development are needed.
Groundwater supply and quality are two major issues of great importance [53] for Saudi Arabia as a bigger population in the Kingdom rely on groundwater, which is the main water resource for agriculture also.Furthermore, declining water levels in groundwater aquifers due to over-pumping poses a threat to maintaining sustainable utilization of groundwater.Furthermore, the yield and productivity of crops depend on the properties of the soil and the quality of irrigation groundwater.Suitable quantity and quality of groundwater become more crucial factors to be met in the development of the Kingdom, especially the agricultural development [52].Measures need to be implemented to cater to groundwater quality deterioration.
As a result, sustainability in groundwater resource utilization and management has become a priority and a national goal for Saudi Arabia [52].The priority in efficient and concise use of water for agricultural irrigation has become one of the most important factors to be considered in the sustainable management of groundwater resources.On the other hand, many human activities in recent decades have resulted in major pollution of groundwater and deterioration of its quality [50], and climate change has aggravated the management of the resources due to the multiple impacts it causes on the agricultural sector and water resources sector.Due to climate change, Saudi Arabia has experienced losses in dates, wheat, vegetables, and fishing yields, as about 50% of the Kingdom's irrigated farming relies on groundwater [42].Groundwater resources are periodically dried due to high temperatures and low precipitation, and this will be aggravated due to climate change.

Management of Desalinized Water and Scarcity Management
Due to a lack of availability of permanent water sources and rapidly declining groundwater supplies, the Kingdom lacks sufficient freshwater resources to support increasing demands of domestic, industrial and agricultural water requirements.Desalination facilities made drinking water assessable and available to household consumers, greenhouse producers, and farmers for agricultural production.It seems to be the most effective, successful, and finest source for supplying local and national water demands [25,54].The Saudi Arabian government sees desalinated water (DW) as the best solution to address the country's water shortage and meet the rising domestic water demands [25,54].
Saudi Arabia is the world's largest producer of DW and presently produces around one-fifth of the world's DW.The government-owned Saline Water Conversion Corporation (SWCC) manages water production from multifunctional desalination plants in Saudi Arabia.These desalination plants utilize seawater to generate power and provide desalinated water to various Saudi Arabian locations.Water is distributed to consumers in the country's various areas via more than 2500 km of pipelines from these desalination facilities [55].From 200 MCM per year [56] in 1980 to over 1.18 BCM per year in 2016 and 1.2 BCM per year in 2017 [20], the Saline Water Conversion Corporation (SWCC) increased its capacity.In 2019, these facilities were producing 6.28 MCM of desalinated water per day.Saudi Arabian desalination plants had about 1.9 billion cubic meters of water in 2019 [57].In 2020, the Kingdom used 7 MCM of desalinated water per day.Even though desalinated water requires a lot of energy, Saudi Arabia does plan to increase its desalination capacity over the next ten years [14].
With its desalination capacity, Saudi Arabia produced 43% of the GCC's desalinated water and 18% of the world's desalinated water.Saudi Arabia continues to struggle to meet the growing domestic demands of its expanding industries, growing population, and limited groundwater supplies.By installing new desalination facilities in various suitable locations, Saudi Arabia is continuously making concerted attempts to increase its desalination capacity.As shown in Figure 3, Saudi Arabia would produce desalination water from 9.9 to 10.8 MCM per day, with a rise of 3.1 percent per day from the year 2016 to 2030.This is going to reduce the pressure on the limited groundwater resources and may pave the way to sustainable utilization of groundwater water supplies [58].
While the amount of desalinated water utilized is increasing by roughly 14% a year, the amount of water needed to produce electricity rises by 8-9% annually [59].This consumption is six times more than the pace of population growth [14].Saudi Arabia uses twice as much water on average [59] compared with an average country that has much more abundant water resources.Saudi Arabia could supply this much desalinated water together with other sources using its oil resources as the fuel in the desalination process.
Desalination plants, fueled by oil, consume about half of the domestic oil production of the Kingdom [60,61].On the other hand, water demands are increasing with an annual growth rate of 9% at the moment and will be doubled by 2035.Such hikes in water demands could hugely impact the natural economy as it will increase domestic oil consumption accordingly [19].In addition to the high cost and significant energy consumption associated with the desalination process, Saudi Arabia needs a consistent oil supply to keep increasing its desalination capacity [62].Plants for desalination use 10-20% of the energy used in Saudi Arabia [12,14].The cogeneration power desalination plants (CPDP), which use 25% of Saudi Arabia's oil and gas production, provide the residents of the Kingdom with both energy and desalinated water.
It might not be feasible in the long run to rely solely on desalination to produce sufficient water resources at the expense of oil and gas use.The price of producing desalinized water is very high, and Saudi Arabian consumers only pay 1% of the cost of generating desalinated water [62,63]; the rest is covered by the government, which makes the process unsustainable.
inated water requires a lot of energy, Saudi Arabia does plan to increase its desalination capacity over the next ten years [14].
With its desalination capacity, Saudi Arabia produced 43% of the GCC's desalinated water and 18% of the world's desalinated water.Saudi Arabia continues to struggle t meet the growing domestic demands of its expanding industries, growing population and limited groundwater supplies.By installing new desalination facilities in various suit able locations, Saudi Arabia is continuously making concerted attempts to increase its de salination capacity.As shown in Figure 3, Saudi Arabia would produce desalination wate from 9.9 to 10.8 MCM per day, with a rise of 3.1 percent per day from the year 2016 t 2030.This is going to reduce the pressure on the limited groundwater resources and ma pave the way to sustainable utilization of groundwater water supplies [58].
While the amount of desalinated water utilized is increasing by roughly 14% a year the amount of water needed to produce electricity rises by 8-9% annually [59].This con sumption is six times more than the pace of population growth [14].Saudi Arabia use twice as much water on average [59] compared with an average country that has much more abundant water resources.Saudi Arabia could supply this much desalinated wate together with other sources using its oil resources as the fuel in the desalination process.
Desalination plants, fueled by oil, consume about half of the domestic oil production of the Kingdom [60,61].On the other hand, water demands are increasing with an annua growth rate of 9% at the moment and will be doubled by 2035.Such hikes in water de mands could hugely impact the natural economy as it will increase domestic oil consump tion accordingly [19].In addition to the high cost and significant energy consumption as sociated with the desalination process, Saudi Arabia needs a consistent oil supply to keep increasing its desalination capacity [62].Plants for desalination use 10-20% of the energ used in Saudi Arabia [12,14].The cogeneration power desalination plants (CPDP), which use 25% of Saudi Arabia's oil and gas production, provide the residents of the Kingdom with both energy and desalinated water.
It might not be feasible in the long run to rely solely on desalination to produce suf ficient water resources at the expense of oil and gas use.The price of producing desali nized water is very high, and Saudi Arabian consumers only pay 1% of the cost of gener ating desalinated water [62,63]; the rest is covered by the government, which makes th process unsustainable.Adopting a water pricing system increases the value of water, aids in collecting just a portion of the costs associated with producing desalinated water, and encourages consumers to start conserving water.It is expected that assigning a high value to water use will impact behavior and motivate Saudis to use water wisely and sustainably [62,63].Desalination also increases the country's carbon dioxide emissions, contributing to global warming.Additionally, climate change is made worse by pollution from plants that make salt.Furthermore, the health of coastal waters and the oceans can be negatively impacted by the release of chemicals and salts from plants [64,65].Waste from desalination plants is projected to reach 142 million m 3 per day, an increase of around 50% over earlier estimates.Saudi Arabia, the United Arab Emirates, Kuwait, and Qatar produce about 55% of the world's total brine production [66,67].Desalination plants have extremely concentrated salinity, damaging the environment by injecting salts into the drains [45,54].Therefore, in order to sustain the desalination process, many interventions are needed.
Saudi Arabia is now in the process of introducing other options to produce desalinated water.Among the viable options, the use of membrane-based techniques used in modern plants to treat salty saltwater seems appropriate.Saudi Arabia has made significant efforts to replace diesel-based desalination with solar and other renewable energy sources.Another cutting-edge technology is an integrated solar-powered desalination system that uses a membrane immersion system to produce drinking water [64,68].The wind/solar hybrid RO system was shown to be cost-effective [67,69] for desalinating water.Hybrid solar-wind systems to power small-scale Reverse Osmosis (RO) desalination units have distinct low energy requirements at the cost of SAR 1.72 to SAR 1.84 per cubic meter.By harnessing the country's excellent solar and wind resources and implementing renewable energy, Saudi Arabia might, in fact, profitably satisfy its future electricity, water, and gas needs [70,71].Elminshawy et al. [68,72] proposed a desalination system that uses solar energy and low-grade waste heat and can be used to desalinate water with little energy input.Most recent research indicated that one barrel of oil equivalent, which produced 29 m 3 of desalinated water in 2015, shall be capable of producing 86.1 m 3 by the end of 2030 through the process of implementation of more advanced desalination technologies [73].

Managing Treated Wastewater and Its Potential in Water Scarcity Management
Saudi Arabia regards treated domestic wastewater as a significant source of usable water and plans to use all of it (100%) after treatment [69,74].The GCC countries collect over 4.0 BCM of wastewater each year, and 73% of it is treated by the countries' 300 wastewater treatment plants.The nation generates around 1460 MCM of wastewater, of which 671 MCM (or 46%) are collected and processed, according to Ouda and colleagues [75,76].Due to the inadequate coverage, it is required to upgrade and streamline the wastewater collection system.Furthermore, conventional wastewater treatment facilities operate at maximum capacity or more, which reduces the quality of the water they treat [9,10].It is anticipated that 240 MCM, or roughly 38% of the treated wastewater, has been extensively reused in many cities (such as Riyadh, Jeddah, Jubail, Yanbu, etc.) for irrigation of municipal parks and to maintain landscaped beauty of urban areas.
Wastewater that has been treated and recycled is a valuable resource that should be considered in the supply chain in Saudi Arabia, which is striving to address the issue of water scarcity.In 2015, the total amount of treated wastewater that was recycled throughout the Kingdom was 0.61 MCM per day, compared with the 0.40 MCM/per day that agriculture consumed [9,10].
Treated wastewater can be used in construction, forestry, agriculture, landscaping, and gardening.Using cleaned wastewater to rinse food and forage crops is nevertheless prohibited due to health, social, religious, and environmental issues [8,9].Treated wastewater is utilized safely in crop production all over the world; hence, proper management techniques can make treated wastewater safe for agricultural production.
Using treated wastewater may significantly decrease the amount of freshwater needed for agricultural output.According to the National Water Strategy [69,74], the Saudi Arabian government, commercial, industrial, and agricultural sectors anticipate using treated wastewater as a key supply source for non-potable applications.For industrial processes and park watering, treated sewage water is safe.Treated wastewater may be used in various places, depending on the water quality, degree of treatment, and environmental impact.Landscapes, large green spaces, roadside trees and plants, industrial crops, or fodder crops can all be irrigated with treated wastewater depending on the degree of wastewater treatment [70,[77][78][79].Treated wastewater can also be used to irrigate crops for energy production [72,76].
It is estimated that the total treated sewage effluent supply in the six major cities exceeds 4.8 MCM/day [80,81].By 2025, the Kingdom hopes to provide the water demands of all cities with more than 5000 inhabitants [56,60].By investing in the construction of sewage water treatment facilities, treated sewer effluent becomes a resource that can be used to fulfil some of the water demands.
In Saudi Arabia, treated wastewater is used to irrigate trees and plants along streets.This practice has now been extended to include crops on some farms, all under strict government inspection and control [74,78,82,83].In SA, the landscaping in public parks is watered with treated wastewater.While it is possible to use cleaned wastewater for landscaping, it may also contain pathogens, emerging contaminants (drugs and other pharmaceuticals), and excessive sodium levels that make fertile fields salty.Treated wastewater on an alfalfa fodder crop outperformed wastewater in a recent study [10,77].However, they issued a warning that before treated wastewater may be consistently used in irrigation processes, further long-term research is necessary that considers the variations across agricultural sites, changes in the effectiveness of water treatment, and the crop being watered with treated wastewater.
Reusing treated wastewater reduces the need for freshwater resources and relieves pressure on them.Furthermore, it reduces the quantity of treated and untreated effluent released into the environment, depositing organic and inorganic nutrients (like nitrogen and phosphate) into water systems, which can significantly worsen the condition of already existing bodies of water.Reusing treated wastewater minimizes incidents of eutrophication and the growth of blue-green algae [82,84].
It is believed that reusing and recycling water will help with climate change adaptation and mitigation.In 2012, some 146 MCM of wastewater effluents were used to irrigate about 9000 hectares of land supporting date palms and fodder crops in the vicinity of Riyadh.Wastewater is recycled in many cities, including Dhahran, Jeddah, Jubail, Riyadh, and Taif, to irrigate grass, trees, and other landscaped plants in public parks [83].Recycled wastewater is used for irrigation and farming, reducing the water needed for food production and saving money and energy on pumping freshwater.As a result, there may be a decrease in the use of mineral fertilizers due to the availability of nutrients in treated wastewater, which assist in reducing the carbon footprint.It can also provide crops with enough nutrients and fertilizer.Using treated municipal wastewater to irrigate agricultural lands in Saudi Arabia delivered adequate nutrients, decreased the cost of irrigation and fertilization, and increased the yield and profit of wheat and alfalfa crops [74,82].
One of the ambitious long-term goals of the Kingdom is to increase water reuse to more than 65 percent by 2020 and more than 90 percent by 2040.More of the nation's planned and current wastewater treatment assets will be transformed into source water suppliers for all sectors to meet these objectives [10,16,41,75,84].About 50% of Riyadh's cleaned wastewater has been used with tremendous success (about 120 MCM).Given the high price of desalinated water, the city currently uses treated wastewater in many of its industrial and commercial enterprises and in irrigating landscapes.Still, there is space for growth in the future.
The company also revealed that TSE could be typically used in cleaning and washing towns and automobiles, cooling in industrial processes, mixing concrete and other construction materials, irrigation of urban parks and field crops, etc., as depicted in Figure 4.
The company also revealed that TSE could be typically used in cleaning and washing towns and automobiles, cooling in industrial processes, mixing concrete and other construction materials, irrigation of urban parks and field crops, etc., as depicted in Figure 4. Saudi Arabia has started using more reclaimed water to minimize stress and offset the water crisis.The SA is one of the top ten consumer nations in the world for using recycled water.By converting its existing wastewater treatment facility into planned water supply providers across all categories, the nation has strong long-term plans to boost water use by more than 65 percent by 2020 and more than 90 percent by 2040 [10,16,41,75,84].

The Management of Water Resources and Climate Change
Climate change is predicted to result in a 10 mm annual decrease in rainfall in Saudi Arabia's northern region, worsening the country's existing drought conditions [45,54].Precipitation is expected to increase in the central and southern regions by 15 to 25 mm and 109.7 to 130.4 mm yearly by 2050, according to [16,19].Climate change is expected to affect rainfall patterns in different parts of Saudi Arabia differently, impacting the water resources.Furthermore, brief but intense rainfall can cause flash floods and runoff that could jeopardize the quality of the available water sources and introduce contaminants into current water reservoirs [45,54].
Recent rainfall patterns have been unpredictable, with notable increases in the southwest and western regions [35,54].Although certain areas have had more rainfall, evapotranspiration is expected to increase, leaving surface water sources in short supply and less than half of the water being lost through evapotranspiration.Saudi Arabia has experienced a rise in temperature and a decrease in rainfall in several locations [35,54].Based on their prediction models, an increase in temperature and variable rainfall patterns will impact water resources, water quality, agricultural production, and agricultural water demand.It is also pointed out that due to rising temperatures and shifting rainfall patterns, more innovative approaches need to be designed to sustain water resources [35,54] and their management.Climate change-induced changes in weather conditions will alter the quantity of water used and water usage patterns, challenging water resources management.
The amount of water consumed in residential, commercial, and agricultural settings will undoubtedly alter due to climate change.Saudi Arabia is an example of how poor water management can have detrimental repercussions on the water sector, especially considering the pressure that climate change is exerting on the quantity and quality of water resources [45,54].Over-pumping is the primary cause of the loss in groundwater levels, and the marginal reductions in recharge rates brought on by climate change are not important.However, climate changes impact groundwater flow into shallow aquifers.To Cleaning/Washdowns Saudi Arabia has started using more reclaimed water to minimize stress and offset the water crisis.The SA is one of the top ten consumer nations in the world for using recycled water.By converting its existing wastewater treatment facility into planned water supply providers across all categories, the nation has strong long-term plans to boost water use by more than 65 percent by 2020 and more than 90 percent by 2040 [10,16,41,75,84].

The Management of Water Resources and Climate Change
Climate change is predicted to result in a 10 mm annual decrease in rainfall in Saudi Arabia's northern region, worsening the country's existing drought conditions [45,54].Precipitation is expected to increase in the central and southern regions by 15 to 25 mm and 109.7 to 130.4 mm yearly by 2050, according to [16,19].Climate change is expected to affect rainfall patterns in different parts of Saudi Arabia differently, impacting the water resources.Furthermore, brief but intense rainfall can cause flash floods and runoff that could jeopardize the quality of the available water sources and introduce contaminants into current water reservoirs [45,54].
Recent rainfall patterns have been unpredictable, with notable increases in the southwest and western regions [35,54].Although certain areas have had more rainfall, evapotranspiration is expected to increase, leaving surface water sources in short supply and less than half of the water being lost through evapotranspiration.Saudi Arabia has experienced a rise in temperature and a decrease in rainfall in several locations [35,54].Based on their prediction models, an increase in temperature and variable rainfall patterns will impact water resources, water quality, agricultural production, and agricultural water demand.It is also pointed out that due to rising temperatures and shifting rainfall patterns, more innovative approaches need to be designed to sustain water resources [35,54] and their management.Climate change-induced changes in weather conditions will alter the quantity of water used and water usage patterns, challenging water resources management.
The amount of water consumed in residential, commercial, and agricultural settings will undoubtedly alter due to climate change.Saudi Arabia is an example of how poor water management can have detrimental repercussions on the water sector, especially considering the pressure that climate change is exerting on the quantity and quality of water resources [45,54].Over-pumping is the primary cause of the loss in groundwater levels, and the marginal reductions in recharge rates brought on by climate change are not important.However, climate changes impact groundwater flow into shallow aquifers.To alleviate pressure on water supplies brought on by climate change, desalinated water and treated wastewater need to be used during extreme droughts [81].Any extra surface water might be stored in depleted aquifers.The importance of increasing the number of dams used to capture and hold stormwater is also stressed, especially to counteract the negative consequences of climate change [39].

Concluding Statements and the Way Forward
Saudi Arabia is dealing with serious concerns, challenges and problems related to water management.Overuse of surface water sources, renewable and non-renewable groundwater and over-pumping of water resources, declining water quality, and frequently insufficient water supply and irrigation services impact agricultural productivity, the environment, and human health.Recent scientific investigations have shown that the largest problem Saudi Arabia is dealing with is the depletion and degradation of its subsurface water resources.Water resources are located too distant from human facilities or too deep, making it very expensive to utilize them.In some localities, water extracted from deeper horizons is poor in quality.These underground reservoirs are also non-renewable and are rapidly depleting.
To avoid potential financial losses and to address social issues, Saudi Arabia must develop a water policy and should implement it rigidly.To manage its restricted water resources, the Kingdom must make a number of technological and legislative changes.Water resource planning needs to consider both the quantity and quality of water and overall water system improvements.Other steps include promoting service management, taking conservation measures, paying for irrigation, sanitation, and water delivery costs, and strengthening state agencies.Policies and procedures for managing irrigation water should focus on different objectives depending on the sources of water scarcity.
To increase water use efficiency, sensible environmental, economic, and social measures are required.To tackle water scarcity, demand management policies and water resources allocation and management are the two crucial factors that must be addressed.It is projected that by 2030, a creative and workable policy will be fully implemented and operational to address both the demand for water and how services are provided.
Therefore, a holistic approach to the management of scarce water resources through policy and technological means will be an urgent need.Replacing non-renewable and financially nonviable options for water utilization need to be replaced with many different options such as harvesting more rainfall, capturing, treating and using wastewater, introducing and promoting less water-consuming crops and practices for making water use efficient, and using viable and cheaper environmentally friendly technology to produce good quality water and invest in research related to water scarcity management.The holistic approach to water management will facilitate better allocation and use of water in Saudi Arabia so that the Kingdom can march towards achieving food security.

Figure 1 .
Figure 1.Quantity of water used from different sources in Saudi Arabia from 2010 to 2017 and percentage share in 2017 (developed based on stats.gov.sa)(accessed on 25 February 2023) [20].

Figure 2 .
Figure 2. Percentage of water used by different sectors in Saudi Arabia (1990 to 2020).

Figure 2 .
Figure 2. Percentage of water used by different sectors in Saudi Arabia (1990 to 2020).

Figure 2 .
Figure 2. Percentage of water used by different sectors in Saudi Arabia (1990 to 2020).