What solutions are there for water shortages in rural and agricultural areas in arid and semi-arid regions? Can water shortages be helped in foothill areas through aqueducts and karez?

Arid and semiarid regions are defined as areas where precipitation is less than the amount of water lost through evaporation and transpiration. Semiarid regions, where annual precipitation ranges between 250 mm and 500 mm, have slightly more water than arid areas, but water management is critical for agricultural production (FAO, 2017). Arid regions, on the other hand, receive less than 250 mm of precipitation annually and water resources are extremely limited (UNEP, 2021). Globally, arid and semiarid regions cover approximately 41% of the Earth’s land surface, and more than 2 billion people live in these areas. Farming in such regions presents significant challenges due to natural water scarcity and erratic rainfall. Water scarcity has encouraged the development of innovative irrigation strategies to increase agricultural productivity (WWAP, 2019). Water management in arid and semiarid regions is vital not only for the sustainability of agricultural output, but also for maintaining ecosystems and improving the quality of life of local communities. Effective water resource management in these areas increases agricultural productivity and enables more efficient water use (Kang et al., 2017). Climate change is increasing the pressure on water resources in arid and semiarid regions. Rising temperatures, changing precipitation patterns, and extreme weather events negatively affect the availability and quality of water resources. Therefore, developing flexible and sustainable irrigation strategies that can adapt to climate change is vital for the continuity of agriculture in these regions (IPCC, 2022). Effective water management in arid and semiarid regions requires the development of resilient strategies that integrate agricultural production systems with irrigation technologies and address future threats such as climate change and diminishing water resources (Kinzelbach et al., 2010). In this context, formulation of water management policies at regional and national levels plays a critical role in long-term water conservation and sustainable agriculture. Widespread adoption of modern irrigation methods, smart agricultural technologies, and water harvesting systems can be key solutions to future water scarcity challenges facing the agricultural sector in these regions Efficient water management in arid and semiarid regions is important not only to increase agricultural productivity, but also to maintain soil health, ensure sustainability of water resources, and maintain environmental balance. Another important aspect of water management in these regions is to balance crop production and water conservation by providing the right amount of water at the right time (Wang et al., 2021). Accurately determining the water needs of plants and precisely planning the duration and amount of irrigation are among the key strategies that increase water use efficiency (Gu et al., 2020). These strategies also minimize water losses, allowing water to reach larger agricultural areas.Nowadays, modern irrigation techniques and water management practices enable more efficient use of water resources and minimize water losses. Innovative methods such as drip irrigation, sprinkler irrigation, and smart irrigation systems increase water use efficiency and reduce water stress in plants. In this section, various irrigation strategies that can be applied to arid and semiarid regions, their advantages and disadvantages, and successful application examples will be discussed. CHALLENGES OF WATER RESOURCES MANAGEMENT IN ARID AND SEMI-ARID REGIONS Water management in arid and semi-arid regions poses significant challenges due to a combination of environmental, social, and economic factors. These areas, characterized by low and highly variable rainfall, high evaporation rates, and frequent droughts, are particularly vulnerable to water scarcity. The growing impacts of climate change exacerbate these challenges, leading to increased temperatures, altered precipitation patterns, and prolonged drought periods, further stressing already limited water resources (Garrido et al., 2010). This creates a pressing need for effective water management strategies to ensure the sustainability of agricultural production and water supply in these regions. One of the most critical issues in water management is the over-extraction of groundwater resources, which is often the primary source of irrigation in arid and semi-arid areas. Overextraction leads to a decline in groundwater levels, land subsidence, and the degradation of water quality due to salinization and the intrusion of seawater in coastal areas (Khorrami and Malekmohammadi, 2021). As groundwater reserves are depleted, the long-term sustainability of agriculture and other water-dependent activities becomes uncertain. Moreover, the reliance on fossil groundwater—water that has accumulated over thousands of years—makes replenishment through natural means impossible within human timescales (Wada et al., 2011). This unsustainable water use threatens the agricultural economy and food security in these regions. Figure 1 illustrates the projected impact of current water consumption on future water resources. According to the World Resources Institute (WRI), this scenario represents a "business as usual" future, with global temperatures rising between 2.8 and 4.6 degrees Celsius by 2100, while inequality persists worldwide. In this scenario, countries such as Iran, India, and the entire Arabian Peninsula, along with most North African nations including Algeria, Egypt, and Libya, are expected to use at least 80% of their available water resources by 2050.Compounding these environmental issues are the social and economic challenges. Rapid population growth, urbanization, and increasing demand for water-intensive crops place additional pressure on scarce water resources (Fader et al., 2016). Conflicts over water use between agriculture, urban needs, and industry are intensifying, leading to competition and inefficiencies in water allocation. This scenario highlights the necessity of integrated water resource management (IWRM) approaches that take into account the multiple uses of water while prioritizing sustainable practices. The inadequacy of infrastructure and outdated irrigation techniques also contributes to inefficient water use. Traditional methods like flood irrigation, which is still widely used in many arid regions, result in high water losses through evaporation and runoff. According to Oweis and Hachum (2006), modernizing irrigation systems—such as adopting drip or sprinkler irrigation—can significantly reduce water losses and enhance water-use efficiency. However, the implementation of these technologies is often limited by financial constraints, lack of technical knowledge, and insufficient policy support. In conclusion, the challenges of water management in arid and semi-arid regions are multifaceted, involving environmental degradation, unsustainable water extraction, population pressures, and infrastructural limitations. Addressing these challenges requires an integrated approach that combines modern technologies, sustainable practices, and supportive policy frameworks to mitigate water scarcity and ensure long-term resilience in these vulnerable regions.SOIL MANAGEMENT AND INCREASING WATER RETENTION CAPACITY :The sustainability of agricultural production in arid and semi-arid regions heavily depends on the effectiveness of soil management strategies. Given the limited water resources in these areas, enhancing the soil's water retention capacity plays a crucial role in improving water efficiency and plant growth (Lal and Stewart, 2013). Water retention capacity varies depending on soil structure, organic matter content, soil texture, and local climatic conditions. Methods employed to increase soil water retention not only ensure efficient water use but also help plant roots remain moist for longer periods under drought conditions (Gupta et al., 2020). One of the most effective ways to improve water retention capacity in soil management is by increasing the organic matter content. Organic matter improves soil structure, thus enhancing the soil's ability to retain water. Soils enriched with organic matter hold water for extended periods, making it accessible to plant roots. Additionally, organic matter promotes the formation of soil aggregates, which improves water infiltration (Yang et al., 2022). Incorporating compost, green manure, and plant residues into the soil are primary methods for increasing organic matter levels. These practices are key components that support both soil health and water management strategies.Another important soil management strategy is the optimization of tillage techniques. Minimal tillage methods help preserve soil structure, allowing water to remain in the soil for a longer period. While conventional deep tillage techniques can lead to water loss, minimum tillage strategies aid in retaining surface moisture in the soil (Lv et al., 2023). Additionally, surface covering techniques such as mulching reduce water loss through evaporation by conserving soil moisture and regulating soil temperature. Mulching contributes to the successful implementation of water management strategies by enhancing the soil's water retention capacity (El-Beltagi et al., 2022). Controlling soil salinity is another crucial soil management strategy that enhances water retention capacity. In arid and semi-arid regions, excessive irrigation and poor drainage conditions can lead to salt accumulation in the soil. Soil salinity restricts the ability of plant roots to access water, thereby increasing water stress. To prevent salinization, it is essential to establish proper drainage systems and implement controlled irrigation techniques (Singh, 2021). These strategies support the more efficient use of water in the soil and ensure suitable moisture conditions for plant growth.Furrow irrigation, on the other hand, involves directing water through furrows dug along the field, allowing the water to reach the plant's root zone more directly. While this method can still lead to water losses, it improves water use efficiency by 30% compared to flood irrigation (Fahong et al., 2004). Traditional irrigation methods are advantageous due to their low investment costs and ease of implementation. However, they also have drawbacks such as soil salinization, unequal water distribution, and water waste. • Modern irrigation methods In order to maximize water efficiency and reduce water loss, modern irrigation techniques are developed. Drip irrigation systems, which deliver water directly to the plant’s root zone in the form of droplets, can achieve water use efficiencies of 90-95% (Capra & Scicolone, 2008). This method prevents water wastage and reduces water stress in plants. As of 2020, approximately 10% of agricultural areas globally that use modern irrigation methods are irrigated with drip irrigation systems (FAO, 2017). Sprinkler irrigation involves applying water to plant surfaces through pressurized pipes and sprinklers, ensuring even distribution across a wider area. This method is suitable for various plant species and soil conditions, maintaining water use efficiency between 70-85% (Evans and Sadler, 2008).Modern irrigation techniques have been developed to maximize water efficiency and reduce water loss. • Subsurface drip irrigation Subsurface drip irrigation systems involve delivering water directly to the plant’s root zone through underground pipes. This method prevents water loss through evaporation and allows plants to utilize water more efficiently. Subsurface irrigation systems can achieve water use efficiencies of up to 95%, offering the highest efficiency compared to other irrigation methods (Ayars et al., 1999). However, the installation and maintenance of subsurface irrigation systems are more expensive and complex than other methods. The applicability of subsurface irrigation systems depends on soil characteristics, plant species, and water availability. When properly managed, subsurface irrigation systems increase water use efficiency and support the sustainability of agricultural production. Globally, only 1-2% of agricultural areas are irrigated using subsurface systems, but this figure is increasing due to climate change and water scarcity (Skaggs et al., 2010). 4.4. Irrigation Management • Determining irrigation amounts Accurately determining irrigation amounts is critical to meet the optimal water needs of plants. Various methods and formulas are used to calculate irrigation water amounts. These methods include calculations based on soil moisture content, meteorological data (ET0), and other empirical approaches.CONCLUSION The continuous evolution of technology significantly impacts agricultural practices. Various applications, including chemical fertilizers, hormones, soil amendments, and pesticides, are widely used, along with the application of sludge and wastewater for irrigation. In addition to these agricultural practices, heavy metal contamination from factories and mining activities directly or indirectly pollutes water sources. Phytoremediation emerges as a primary method for addressing water pollution. However, there is a need for expanded research on hyperaccumulator plants suitable for this approach, particularly those effective in water remediation. It is essential to prioritize studies that create an inventory of plants suited to specific regions and climates, as water sources are increasingly threatened by environmental pollution. Consequently, focusing on hyperaccumulator plants in relation to heavy metal pollutants is crucial for mitigating water pollution and enabling the reuse of wastewater after remediation.