WEAP analysis for enhancing water resource sustainability in Egypt: a dynamic modeling approach for long-term planning and management

ABSTRACT Egypt’s water resources face challenges arising from escalating urban demand, changes in land use, environmental requirements, and the impacts of climate change. To address these challenges, the study develops a dynamic model using WEAP model as a decision support tool for water sector planning and management. By comparing different scenarios, the research examines the benefits of water conservation in terms of cost reduction in supply, wastewater generation, and treatment. Considering the projection period until 2037, it is imperative to carefully examine the research findings and explore opportunities for further optimizing water use efficiency. Based on the model simulation results, it is anticipated that the total water demands in Egypt will rise from 78.40 billion cubic meters (BCM) in 2023 (comprising 61.10 BCM for the agricultural sector, 12.58 BCM for the municipal sector, and 5.73 BCM for the industrial sector) to 81.02 BCM in 2037. The water demand for the agricultural sector is projected to decrease from 61.30 billion cubic meters (BCM) in 2023 to 60.14 BCM in 2037 as a result of the implementation of modern and smart irrigation systems. Conversely, the municipal sector is expected to experience an increase from 12.58 BCM in 2023 to 14.88 BCM in 2037. Furthermore, for the industrial sector, the water demand is anticipated to rise from 5.73 BCM in 2023 to 6.00 BCM in 2037.


Introduction
Freshwater resources are crucial natural resources, and in Egypt, a country characterized by a dry climate and desert landscape, water resources are limited.Conventional sources such as the Nile River inflow, groundwater, and rainfall, along with non-conventional sources like seawater desalination and wastewater, contribute to Egypt's water resources (Table 1).Nevertheless, the obstacle resides in effectively addressing the expanding disparity between the finite water resources and the escalating requirement for potable water [1].
The per capita availability of freshwater in Egypt has been experiencing a continuous decline, dropping below the water scarcity threshold set by the World Bank.Between 1959 and 2012, the per capita availability diminished from 1,893 m 3 to 700 m 3 , with a projected additional decrease to 505 m 3 by the year 2025 [3].This decline is coupled with a projected population increase to around 110 million by 2025, intensifying competition for water across domestic, agricultural, and industrial sectors [4].Developments in the countries on the Nile basin like Ethiopia are also pose potential impacts on Egypt's water availability.The utilization of inefficient flood irrigation techniques by agricultural practitioners contributes to the loss through evaporation, excessive irrigation, soil degradation, and the elevation of groundwater tables.Moreover, industrial chemicals, excessive fertilizer and pesticide use contaminate shallow groundwater.Egypt already utilizes 127 percent of its water resources and will require an additional 20% by 2025, leading to a significant dependence on imported water through virtual water embedded in food and other products, potentially reaching 47% by 2025 [5].
The United Nations predicts water scarcity in Egypt by 2025 (El-Behary, 2017), considering continued population growth, land reclamation projects, and heavy reliance on Nile water for irrigation.Moreover, it is anticipated that surface water evaporation in Lake Nasser will surpass previous estimations, further aggravating the existing water supply predicament [6].A deficit of over 20 BCM (billion cubic meters) per year in the national water budget compounds the situation [5], with climate change impacts and upstream economic developments adding further pressure on the Nile flow to Egypt.The Nile's low runoff/rainfall ratio of 4% makes it highly sensitive to temperature and precipitation changes.
This research aims to develop a dynamic mathematical model representing and simulating the water sector in Egypt to be used as a planning tool for the evaluation of the water sector performance and the sustainability management under various future scenarios to the year 2037.The model will evaluate strategic options under various future scenarios, contributing to long-term planning and sustainability of water resources.Enhancing irrigation efficiency in the agricultural sector, the primary water consumer, will reduce water demand and alleviate pressure on resources, supporting sustainable water resource management [7].The WEAP model functions as a decision support system, facilitating integrated management of water resources and policy analysis.It enables the simulation of water demand, supply, crop water requirements [8], and various other parameters, enabling a comprehensive analysis of the water system across different scales within Egypt [9].

Research methodology
This study employs a descriptive analytical approach to fulfill its research objectives.The methodology used is outlined below:

Situation analysis
To begin, we conducted a comprehensive review of existing literature pertaining to Egypt's water sector.This step aimed to assess and analyze the current conditions within the sector, identifying its most pressing problems and challenges.Data were gathered from various sources, including governmental and non-governmental publications and reports spanning the last decade.This thorough literature survey ensured the availability of representative data concerning Egyptian water sources, utilization, and management issues.Furthermore, changing trends were examined over time to provide an up-to-date assessment of the water situation in Egypt.

Mathematical modeling
The next phase involved the development of a dynamic mathematical model using the WEAP software.This model serves as a critical tool for evaluating the water management system in Egypt.It simulates the water sector in Egypt, allowing to calculate both current and future water supply and demand under existing policies.Additionally, it aids in estimating and describing available water data in Egypt.

Nile River
The Nile River is the world's second longest river, spanning 6,695 km and covering an area of 2.9 million square kilometers [10].It begins in Africa and travels through Tanzania, Burundi, Rwanda, Kenya, Congo, Uganda, Ethiopia, Eritrea, South Sudan, Sudan, and eventually reaches Egypt.Notably, the Ethiopian Plateau accounts for around 86% of the Nile's flow, including key tributaries like as the Blue Nile (59%), Sobat (14%), and Atbara (13%), while the Equatorial Lakes region accounts for only 14% (the White Nile).Given Egypt's restricted precipitation levels, the Nile River plays an important role in satisfying the water demands of the Egyptian population, which is especially concentrated around the Nile River [6].However, as the Nile's sources lie beyond the borders of Egypt, the Nile River and its surrounding territories face heightened susceptibility to changing climatic conditions, leading to instances of both floods and droughts within Egypt.

Groundwater
Groundwater, Egypt's second primary source of freshwater, accounts for around 12% of total water supply [6].It is divided into two types: renewable groundwater resources in the Nile Valley and Delta, and nonrenewable groundwater resources in the Western Desert's Nubian Sandstone Aquifer.Egypt has various subsurface reservoirs, including the Nile aquifer, the Nubian Sandstone aquifer, the Moghra aquifer, the coastal aquifer, the fissured carbonate aquifer, the Pre-Cambrian fissured and weathered hard rock aquifer, Sinai groundwater, and groundwater in the Western Nile Delta aquifers [11].Annual groundwater extraction from the Nile aquifer system amounts to roughly 4.6 billion cubic meters (BCM), with a total groundwater abstraction of 5.1 BCM/year estimated in the Delta, Sinai, and New Valley areas.Furthermore, an extra 0.5 BCM/year is removed from the western desert aquifers [12].The Nile Valley aquifer is the greatest in volume, followed by the Nubian and Moghra aquifers, while the Sinai aquifer is very tiny [13].Annual groundwater use in Egypt's valley and delta areas is estimated to be over 6 billion cubic meters, with a predicted increase to 7.5 billion cubic meters [14].Nonetheless, groundwater in Egypt faces issues such as exceeding the safe yield and overexploitation of aquifer systems due to excessive use [11].
Because of factors such as surface activity, rainy seepage, irrigation water, drainage water, and other effluents, groundwater has distinct physical and chemical properties than surface water.The coastal aquifers of northern Egypt are particularly vulnerable to seawater intrusion and saltwater seepage.Climate change has a direct impact on groundwater recharge rates, which can decrease when precipitation decreases [6].

Rainwater
Egypt, a hyper-arid country, experiences minimal rainfall, with most of it concentrated along the coastal strip and gradually decreasing southward.Rainfall occurs only in winter as scattered showers.The average annual precipitation varies across different regions, ranging from 0 mm in the desert areas to approximately 200 mm in the northern coastal region.On average, the annual rainfall is approximately 20 mm.The total volume of rainwater amounts to approximately one billion cubic meters per year.However, rainwater cannot be relied upon as a consistent water resource due to regional and temporal variations.Furthermore, predictions indicate a decrease in annual rainfall for Mediterranean African countries, including Egypt's northern Sahara region [6].
Non-conventional water resources in Egypt contribute 21% of the total available water resources [6].These resources include agriculture drainage water reuse (13.5 BCM), desalinated water (0.35 BCM), and treated wastewater reuse (2.9 BCM).They are primarily utilized in agriculture, landscaping, and industry.Egypt utilizes seawater desalination methods, especially along the Red Sea and Mediterranean coastlines.Furthermore, Egypt has significant deposits of brackish groundwater and significant potential for cost-effective desalination.Water quality, technical developments, energy expenses, and plant capacity are all cost considerations impacting desalination.Since 1920, Egypt has been at the forefront of wastewater reuse practices.In Upper Egypt, drainage water is indirectly reused by returning it to the Nile, whereas reused water in the Delta area comes from agricultural fields.Future plans are for increasing water supply by three billion cubic meters per year through projects such as the Al-Salam Canal Project and the Nubaria Canal.At the moment, treated sewage and industrial wastewater provide about three billion cubic meters of water every year.However, issues such as salt buildup, toxic contamination, and chemical constituents hazardous to aquifers as a result of excessive drainage water reuse pose obstacles.

Water desalination
Desalination operations encompass three primary categories: seawater desalination, groundwater desalination, and wastewater desalination.As mentioned earlier, Egypt possesses extensive coastlines along both the Red Sea and the Mediterranean Sea.It stands as one of the pioneering nations in utilizing saltwater desalination for water provision.In terms of saltwater desalination, there are existing technological approaches proposed for implementation in Egypt.This field holds crucial importance for various industries such as tourism, petroleum, urban coastal communities, and industrial sectors, as they heavily rely on this water source.Egypt boasts substantial reserves of brackish groundwater and exhibits significant potential for costeffective water desalination, thereby providing a viable alternative for water supply.In the presence of plentiful electricity, desalination is regarded as one of the options for generating freshwater.

Reuse of drainage wastewater
As Egypt's water demand surpasses its conventional water supply, the utilization of non-conventional water resources has become of utmost importance.Egypt has been a pioneer in water reuse, with the practice commencing as early as 1920.In Upper Egypt, drainage water is indirectly reused when it flows back into the Nile.In the Delta region, reused water is derived from agricultural land.Egypt has future plans to further increase water reuse by an additional three billion cubic meters per year for the Al-Salam Canal Project and the Nubaria Canal.Currently, treated sewage and industrial effluent contribute up to three billion cubic meters of water annually.Despite the necessity of recycling drainage water, agricultural drainage reuse factors are restricted.Excessive reuse results in salt buildup on agricultural land.Drainage water seepage may contain harmful contaminants and chemical components that affect aquifers

Current and future challenges of water resources in Egypt
Today, the primary issue in determining future orientations is to examine water resource concerns attentively.Although the primary freshwater concerns in Egypt are increased urban demand, land-use changes, and environmental needs, climate change is occurring with severe and diverse consequences, with the Ethiopian Renaissance Dam being the most conspicuous.Climate change is unavoidable at the moment, and the water sector is the most exposed to it.Egypt is one of the countries affected by climate change, both within and outside its boundaries, throughout the Nile Basin.The Nile River 's levels are expected to plummet dramatically [12].
There is no clear indication of how climate change may affect Nile River flow.The Nile water, on the other hand, would be reduced by 20% during the next 50 years [6].Meanwhile, rising temperatures will accelerate the evaporation process in natural ecosystems, resulting in increased water demand.As a result, lower rainfall and increased evaporation result in decreased groundwater recharge.Such dry weather and decreased rainfall are likely to place further strain on limited water supplies.Furthermore, rising temperatures and, as a result, sea level rise will cause seawater intrusion into coastal groundwater aquifers [1].

Literature review conclusion
The overall conclusion from the literature review is that the water sector conditions in Egypt are facing major challenges in the areas of water sources and water uses.First, groundwater resources are being depleted and their quality is deteriorating by their unregulated utilization, mainly by the agricultural sector; second, Desalination is associated with major financial, economic and environmental costs; and third, treated wastewater, though available at large quantities is not being utilized effectively.
On the user's side, in the municipal sector, per capita water consumption is relatively high and the irrigation efficiencies in the agricultural sector are low.Data and information on the industrial sectors are not detailed.Moreover, the water sector is fragmented institutionally, leading to sectoral water planning and management with minimum coordination among the various water agencies as well as between the water sector and other water-related sectors such as energy and food.Clearly, the efficiency of the water management sector is not high, and its sustainability is at question under the current conditions.
There is a need for a systematic and quantitative evaluation and assessment of the water sector performance and its sustainability.The management interventions of the system can be proposed and their effectiveness in improving the water management system in Egypt on a long-term base can be assessed.Due to the many interactions of the water sector, this can be made by using dynamic simulation models, such as WEAP.Therefore, WEAP can be used to simulate water demand, supply, and storage on a long-term projection for the water system in Egypt.In addition, WEAP will be used to project future water demand and evaluate sustainable management scenarios.
This research marks the first attempt to build a dynamic mathematical model using the WEAP software to simulate and predict the water budget in Egypt up to the year 2037.The model will help assess and manage the water sector in Egypt, providing valuable insights into future water supply and demand dynamics.

Water Evaluation and Planning (WEAP) model studies
The Water Evaluation and Planning (WEAP) is a comprehensive software tool developed by the U.S. Center of the Stockholm Environmental Institute.It addresses the challenges of freshwater management by integrating supply and demand, water quality, and ecological considerations for effective water resource planning [15].Since its introduction in 1989, WEAP has been widely used as a water balance database, scenario generator, and policy analysis tool.It can be adapted to suit data availability and analytical objectives, including climate change vulnerability assessment and studying the waterenergy nexus by integrating with the Low Emissions Analysis Platform (LEAP) software.WEAP facilitates the exploration of various strategies for allocating water supplies to meet multiple demands under different future scenarios [16].

Using Water Evaluation and Planning System (WEAP) model in Egypt
The Water Evaluation and Planning System (WEAP) is a versatile and integrated water resource management modeling platform used in Egypt.It is a generic, object-oriented, and programmable software that allows for datadriven application and graphical representation of water systems.WEAP incorporates various modules and can be linked to external software, making it an integrated tool for water resource modeling.The platform enables users to explore different strategies for allocating water supplies to meet diverse demands under different scenarios.It offers flexibility in representing system components, allowing for aggregation or disaggregation based on data availability and analytical objectives.The key elements of the WEAPanalysis are shown in Figure 1.

Application of the WEAP model
The WEAP model is applied in Egypt to enhance water resource efficiency, particularly in the agricultural, municipal, and industrial sectors.It considers the utilization of Treated Sewage Effluent (TSE) for irrigation purposes.The model development process involves building a dynamic model using relevant data, simulating the water system through calibration, selecting indicators for different sectors, projecting the system's future with population growth, and suggesting future scenarios for improved performance and sustainable management.In the WEAP model, the primary water sources that are encompassed include Nile water, deep groundwater, rainfall and flash floods, seawater desalination, shallow groundwater in the Delta region, and the reuse of agricultural drainage water.The three sectors considered are the municipal, industrial, and agricultural sectors.The conceptual dynamics diagram in Figure 2 illustrates the water system, with demand sites represented by red dots, desalination plant by a green diamond, groundwater resource by a green square, discharge to the sea by a blue line, and treatment plant by a violet brown circle.Green and red links represent the flow from water resources to user sites and returned flows from users to wastewater treatment plants, respectively.

Model data and model assumptions
The amount of water resources in Egypt 2017 was used in the modeling process to build and calibrate the WEAP model in the period 2017-2023 (Table 2).
The model development incorporates the following key data and assumptions: The actual leakage of the drinking water network, as reported by the  3).Available desalination yearly inflow to local supply and waste-water treatment plants daily capacity data were conducted from the national desalination plan 2050 and the Water consumption in the agricultural sector is based on the cultivated area.The water demand was used as follows: agriculture sector: 61.26 billion cubic meter, industrial sector: 5.65 billion cubic meter and, municipal sector: 11.9 billion cubic meters [14].
The significant population growth in Egypt is recognized as the primary factor influencing water demand within the municipal sector.Additionally, the extent of agricultural lands serves as the principal driver for water demand in the agricultural sector.In the modeling process, a 60% irrigation efficiency is employed for the business-asusual scenario.The amount of water used in the industrial sector in Egypt for the period (2020-2037) based on the second national water resources plan (2021) for the modeling process in the business-as-usual scenario (Table 3).

Population projection
The population growth is the main driving force in water demand and wastewater generation; population projections naturally follow statistical analysis and other assessments.Basically, the population projections are based on provided historical data and collected development data.It must be noted that all future population projections are made based on the socio-economic information and data available at a particular moment in time (Table 3) and the World Bank projections (https://data.albankaldawli.org/indicator/SP.POP.GROW?locations=EG).By considering historical population data, studying previous reports on population growth, analyzing current government policy relating to socio-economic activity and applying sound judgment, population projections can be made.In time as market forces change, government policy shifts and the general populace adapts to a changing social, economic and environmental climate, the accuracy of these population projections will diminish.Regional and International circumstances will affect future trends in Egyptian's population growth.The actual population data was used based on governmental data [14].For the purposes of the study, the projected forward to 2037 have been used to assess the requirements of the modeling process and were assumed to represent the business-as-usual scenario (Figure 3).

Model calibration
To build a representative dynamic modeling of the actual water system in Egypt, model calibration by using historical observations was performed first.Available data for the period 2017-2037 were used for the calibration.The calibration is made using the actual and observed and projected [14] water data [17][18][19].The calibration was made using the WEAP model to calculate the water consumption for the period 2020-2037, where the model calculated results were compared with the actual observed values for the same years.The parameters used for the calibration of the municipal water demand are the per capita water rate and the agricultural water consumption.Figures (4, 5 and 6) represent the measured/projected and simulated agricultural, municipal and industrial water requirements respectively for the period 2020-2037.The Figures show the calibrated agricultural, municipal and industrial water requirements with R-square of 0.980, 0.982 and 0.985 respectively, which means good results for both agricultural and total water supply requirements.Figure 7 shows the measured and simulated total water requirements, showing the relation between the two values with a R-square of 0.983.

Business as usual (BaU) scenario
The reference model for the water sector in Egypt is built to represent the continuity of the current situation of the water management system and continuation of the current water policies [20], which are focused on the demand side management instead of supply side management.The  business -as -usual (BaU) scenario assumes that future plans for seawater desalination, wastewater treatment, and agricultural development will be implemented according to the present Egyptian plans and periods.The reference model assumes no climate change impacts on consumption.The result of this model will be used for comparison with the other developed scenarios.After model calibration against the measured data, the model was used to simulate a number of management intervention options to measure their performance and their effectiveness in meeting the objectives of sustainability for water resources system in Egypt.The actual population data was used based on governmental.This research estimates Egypt population to be about 94.80, 101.79, 128.09 and 147.14 million by the years 2017, 2020, 2030 and 2037 respectively.These estimates are based on recorded and predicted population for the period 2017-2037 data [14].Figure 8) shows the development of future total water demand for all sectors under the BaU scenario, which represents current management and policies trends with no management interventions.The model simulation results indicate that the total water demands in Egypt will increase from 78.60 BCM (61.38.BCM for agricultural sector, 11.65 BCM for   municipal sector, 5.57 BCM for industrial sector) in 2020 to 81.25 BCM in 2037.The calculation is based on the forecasted population and water activity increases in the sectors.Similarly, under the same assumptions, water demand for agricultural sector is expected to decrease from 61.38 BCM in 2020 to 60.08 BCM in 2037 due to using modern and smart irrigation systems (Figure 9).The municipal sector is expected to increase from 11.65 BCM in 2020 to 15.13 BCM in 2037 (Figure 10); and for the industrial sector is expected to increase from 5.57 BCM in 2020 to 6.04 BCM in 2037 (Figure 11), respectively, during the simulation period 2020-2037.Evidently, the agricultural sector is the largest consumer of water resources in Egypt.Figure 9 shows the total water demands in the agricultural sector with no management intervention.
Figure 9 shows that total agriculture water demand will decrease from 61.38 BCM in 2020 to 60.08 BCM in 2037.This will enhance the water use efficiency by implementing management intervention by using modern and smart irrigation systems in the agricultural sector because of its high-water consumption rate with low water use efficiency.In the municipal sector, where the per capita water consumption is considered to be high, there exists an opportunity to reduce it by a number of management intervention options (e.g.block tariff, public awareness, water saving devices, and building codes).Water demand inflows and outflows in the period 2017-2037 is shown in Figure 12.The Egyptian Water Strategy (2037) document provides a detailed information on the development and implementation plan for the Egyptian water budget.This document highlights the significance and purpose of the water sectors and the process followed in its development.The targets are to reduce the per capita water consumption, the collection rate of the municipal sector to be increased 65% by the year 2037; and the average irrigation efficiency to be increased to 75% by the year 2037.Those three indicators were the main scenario options to reduce the pressure on water resources in Egypt.The next section will represent the future options scenario as the main target is to reduce the water demand by reducing the per capita   consumption, enhancing the irrigation efficiency, increasing the collection wastewater rate from the municipal sector and, utilization of the generated Treated Sewage Effluent (TSE) from the municipal sector.Return inflows and outflows for BaU scenario in the period 2023-2037 are show in Figure 13.

Ministry of Water Resources and Irrigation (MWRI) business scenario
This scenario is based on the second national water resources plan, 2021.The state of water in 2020, 2030 and 2037 has been assessed on the assumption that investments in water resources management would continue at the present level and as currently intended, but with population growth projections taken into account.This forecast provides the base case to evaluate the NWRI scenario [14].Table (3) shows that despite the modest increase in available freshwater resources, the availability of renewable freshwater would drop to 386 m 3 /capita/year, well below the threshold value for absolute scarcity 500 m 3 /capita/year.The driving factor is the population growth.

Agriculture water supply and use
By the year 2037, according to the MWRI scenario, the available water for agricultural purposes is projected to decrease to 60.14 billion cubic meters (BCM).This decline is primarily attributed to the increased allocation of freshwater to domestic and industrial sectors, which offsets the gains in overall freshwater availability.Although additional lands have been reclaimed for agriculture, the net increase in agricultural area is limited due to the loss of existing lands to urbanization.As a result, the irrigated area will remain relatively similar to that of 2017 [21].Consequently, the water allocation per feddan (approximately 1.038 acres) will experience a reduction of approximately 8% from 6,752 to 6,137 cubic meters per feddan per year.This will necessitate farm households and agricultural enterprises to cope with a 9% decrease in the available water for their crops.The situation is further compounded by the expected rise in temperatures due to climate change, which will increase the potential crop evapotranspiration.In response, farmers will need to make choices such as opting for crops or cultivation systems with lower water requirements, reducing cropping intensity, or accepting sub-optimal production conditions [21].

Domestic and industrial water supply and use
In MWRI scenario, the amount of water allocated to domestic water supply is gradually increasing, in response to the trend in population growth.The increase in per capita allocation for years 2020 and 2030 reflect that in this period the planned increase in production of drinking water exceeds the effects of any measures at reducing unaccounted for water and water supply system loss.The consumptive use per capita reflects the same trend.Growth projection for industrial water use is harder to make and historic data hard to obtain, but seems valid to say that a likely growth in consumption will partially the offset by higher efficiency of industrial water usage.
Figure 14 provides a comparison between theBusiness-as-Usual (BaU) scenario and the Ministry of Water Resources andIrrigation (MWRI) scenario for the period spanning from 2023 to 2037.The Figure illustrates the projected future total water demand for the MWRI scenario, which reflects the existing management and policy trends along with the management interventions implemented by the Ministry of Water Resources andIrrigation.Based on the model simulation results, it is anticipated that the total water demands in Egypt will rise from 78.40 billion cubic meters (BCM) in 2023 (comprising 61.10 BCM for the agricultural sector, 12.58 BCM for the municipal sector, and 5.73 BCM for the industrial sector) to 81.02 BCM in 2037.The calculation is based on the forecasted population and water activityincreases in the sectors [14].
In a similar vein, assuming the same conditions, the water demand for the agricultural sector is projected to decrease from 61.30 billion cubic meters (BCM) in 2023 to 60.14 BCM in 2037 as a result of the implementation of modern and smart irrigation systems (Figure 15).Conversely, the municipal sector is expected to experience an increase from 12.58 BCM in 2023 to 14  BCM in 2037 (Figure 16) [22].Furthermore, for the industrial sector, the water demand is anticipated to rise from 5.73 BCM in 2023 to 6.00 BCM in 2037 (Figure 17).These projections pertain to the simulation period from 2023 to 2037.While, water inflows and outflows for MWRI scenario in the period 2023-2037 is shown in Figure 18 and, return inflow and outflow for MWRI scenario in the period 2023-2037 is shown in Figure 19.Egypt's agricultural sector is a major water consumer, driven in part by the widespread use of traditional irrigation methods with low efficiency and high water losses.To align with the strategic objectives of the Ministry of Water Resources and Irrigation, we aim to increase irrigation efficiency to approximately 75% by 2035.Our proposed strategies for achieving this goal include altering crop patterns, adopting modern irrigation methods, regulating groundwater usage through water charges, introducing advanced agricultural systems (such as soilless agriculture), implementing volumetric water metering and pricing, and promoting effective water conservation tools for farmers, such as water recycling and drought-resistant landscaping.Additionally, we emphasize the reuse of treated wastewater as a sustainable resource within the agricultural sector.The study built a dynamic model for simulation of the water system in Egypt using WEAP modeling system, which can be used as a decision support tool in the planning and management of the water sector in Egypt.As the water management system in Egypt is assessed using a dynamic   mathematical model representing the water sector, which was used in the evaluation of the water sector performance in terms of water demand without changes (reference model, business as usual scenario) and with management intervention tools impact (Ministry of Water Resources and Irrigation scenario).Analysis of the results indicates clearly that every cubic meter of water saved in the water sector results in a multitude of benefits for the country.

Conclusion
Egypt's water resources system is facing significant challenges, including a rapid increase in sectorial water demands and inadequate wastewater reuse plans.This situation has substantial financial, economic, and environmental costs, posing a threat to the country's future development and economic achievements.Unsustainable water uses, such as escalating water demands, per capita water consumption, and increasing volumes of wastewater discharge, further exacerbate the problem and impact human and ecological health.Population growth in the next 30 years is expected to worsen the situation.Thus, optimizing water use and enhancing water efficiency are vital for reducing costs and achieving water sustainability in Egypt.To support water sector planning and management in Egypt, a dynamic model utilizing the WEAP modeling system was developed.This model serves as a decision support tool for simulating the water system and evaluating performance.By analyzing different scenarios, including a reference model without changes and a model incorporating management intervention tools, the research demonstrated that saving each cubic meter of water in the sector yields numerous benefits.These include financial savings in water supply and wastewater treatment costs.The study relied on the Ministry of Water Resources and Irrigation scenario 2037 for the agricultural, municipal, and industrial sectors.Simulations were conducted for the period 2023-2037.However, due to insufficient information on leakage percentage, it is crucial to enhance water management practices and monitoring efforts to obtain accurate data.This improved understanding of water-related impacts and management strategies will contribute to more effective decision-making.Furthermore, it is recommended to enhance the current management model by incorporating additional information about the agricultural and industrial sectors.This will result in a more comprehensive and appropriate water management plan.Additionally, since the research projected outcomes until 2037 based on the National Water Resources Plan 2037, there is a need for further examination of water use efficiency and potential management interventions within an integrated water resources management approach.

Figure 2 .
Figure 2. Conceptual dynamic diagram of the water system in Egypt.

Figure 3 .
Figure 3. Actual governmental population and population projection.

Figure 5 .
Figure 5. Measured/Projected and simulated municipal water requirements.

Figure 6 .
Figure 6.Measured/Projected and simulated industrial water requirements.

Figure 7 .
Figure 7. Measured/Projected and simulated total water requirements.

Figure
Figure BaU scenario: industrial water demand for the period 2017-2037.

Figure 12 .
Figure 12.Water inflows and outflows for BaU scenario in the period 2017-2037.

Figure 13 .
Figure 13.Return inflows and outflows for BaU scenario in the period 2017-2037.

Figure 14 .
Figure 14.Comparison between BaU scenario and MWRI scenario: total water demand for the period 2023 to 2037.

Figure 15 .
Figure 15.Comparison between BaU scenario and MWRI scenario: agricultural water demand for the period 2023 to 2037.

Figure 16 .
Figure 16.Comparison BaU scenario and MWRI scenario: municipal demand for the period 2023 to 2037.

Figure 17 .
Figure 17.Comparison between BaU scenario and MWRI scenario: industrial demand for the period 2023 to 2037.

Figure
Figure Water inflows and outflows for MWRI scenario in the period 2023-2037.

Figure 19 .
Figure 19.Return inflow and outflow for MWRI scenario in the period 2023-2037.
*The year 2017 was explicitly used to determine Egypt's water resources based on the second national water resources plan.