Water scarcity has been a persistent challenge for Israel. Early strategies included technological innovation, conservation, and policy measures such as wastewater recycling and drip irrigation. Despite these efforts, water levels in the Sea of Galilee remained critically low. This led to the adoption of desalination as a major strategy in 1999. By 2020, desalination supplied about 50% of Israel's domestic water needs. However, Israel's high population growth rate (averaging over 2.1% for 30 years) poses a significant threat to the sustainability of this approach. The Central Bureau of Statistics projects a population increase to 15-25 million by 2065. This study analyzes the impact of three population growth scenarios (low, medium, high) on Israel's water system from 2020 to 2065. The analysis is based on historical water production and consumption data, assuming stable per capita consumption rates. The study aims to demonstrate the impact of population growth on water demand, desalination capacity, treated wastewater production, and natural water supplies. The findings will highlight the potential consequences of relying on desalination and offer crucial lessons for other water-stressed regions experiencing rapid population growth.

The introduction adequately sets the stage by reviewing Israel’s historical water management strategies and the shift towards desalination. It cites relevant statistics on population growth and projections, establishing the context for the study's focus on the interplay between population growth and water demand. The paper also briefly touches upon existing literature concerning climate change and its anticipated impact on water availability in Israel. However, a more extensive literature review, possibly detailing studies on the environmental and economic aspects of large-scale desalination, the impact of treated wastewater reuse on soil and human health, and comparative studies of water management strategies in other water-scarce regions, would have strengthened the paper’s foundation.

The study uses a modeling approach to project Israel's future water demand and supply under three distinct population growth scenarios: low (0.8% annual growth by 2065), medium (gradually decreasing to 1.6% by 2065), and high (over 2% annual growth). Population projections are sourced from Israel's Central Bureau of Statistics. The model relies on historical water production and consumption data (1992-2020) from the Israel Central Bureau of Statistics, assuming relatively stable per capita consumption rates. Future water demand is calculated as a product of projected population and average per capita consumption. The model incorporates anticipated declines in natural water sources due to climate change (a 20% reduction by 2065), consistent with the Israel Water Authority's projections. It also accounts for the continued use of 60% of domestic wastewater for agricultural purposes, reflecting current practices. The authors clearly state assumptions made regarding per capita water consumption and future water production from natural sources, ensuring transparency and allowing for critical evaluation of the results. Data sources are clearly cited, and simulation codes are available online, enhancing the study's reproducibility. The analysis integrates projections for total water consumption, required desalination capacity (measured in 100 million m³ units), treated wastewater production, and the declining role of natural water resources. The use of different population growth scenarios provides a range of potential outcomes, acknowledging uncertainties inherent in long-term projections. A detailed explanation of the model’s structure and the assumptions used would have further improved the methodological section.

The study projects a dramatic increase in Israel's total water needs by 2065, ranging from 3.8 billion m³ (low growth) to 6.2 billion m³ (high growth) compared to 2.4 billion m³ in 2020. This signifies a substantial increase in desalination requirements. Under the high-growth scenario, desalination production would need to increase from 0.5 billion m³ in 2020 to 3.75 billion m³ in 2065, a 650% increase. Meeting this demand would necessitate the construction of approximately 30 new desalination units (each with an average capacity of 100 million m³). The rate of new desalination unit construction will scale with the population growth rate, requiring significantly more units in the latter half of the projected period, particularly under the high-growth scenario. The projections show that treated wastewater production will also rise substantially, potentially exceeding agricultural demand in most scenarios. Even under the low-growth scenario, treated wastewater production is predicted to more than double by 2065. Agricultural capacity to absorb this excess wastewater is anticipated to be limited due to factors such as land use restrictions and environmental concerns. The study also highlights a significant decrease in per capita natural water availability, highlighting Israel's increasing reliance on non-natural water sources. This decrease is projected to be more pronounced under higher population growth scenarios, with per capita natural water availability potentially dropping below 40 m³ per year under the high-growth scenario.

The findings demonstrate that population growth, rather than climate change, will be the dominant driver of water stress in Israel. The projected reliance on desalination to meet increased water demand would have substantial environmental implications, including a significant increase in electricity demand (up to 11 TWh annually under the high-growth scenario) and potential negative impacts on coastal ecosystems due to brine discharge and infrastructure development. The study also underscores potential health concerns associated with desalination (mineral deficiencies in desalinated water) and the environmental and health risks of using treated wastewater for irrigation. While the study acknowledges technological advancements that could reduce energy consumption in desalination and increase water reuse efficiency, the projected increases in water demand remain substantial even under optimistic assumptions. Addressing water scarcity will require significant investment in infrastructure, careful management of wastewater, and a strategic approach to energy production and consumption. The study emphasizes the need for greater regional cooperation to address shared water challenges and manage transboundary water resources.

This study underscores the critical role of population growth in shaping Israel's future water security. The projected substantial increase in desalination needs, coupled with the limitations of wastewater reuse and the shrinking availability of natural water resources, presents a considerable challenge. The environmental and health implications of meeting this increased demand must be carefully considered. Future research could explore in more detail the potential of improved water management practices, including further advancements in desalination technology, more efficient wastewater treatment and reuse, and innovative approaches to water conservation. Investigating policy options that manage population growth and encourage regional cooperation could also enhance Israel's water security.

The study's projections rely on several key assumptions, such as stable per capita water consumption and a consistent rate of wastewater reuse for agriculture. Changes in these assumptions could significantly affect the projected water demand. The model does not explicitly incorporate potential technological advancements in water conservation or desalination beyond the already accounted-for efficiency improvements and assumes a constant level of agricultural efficiency. Further research is needed to assess the potential impact of technological advancements and policy interventions in reducing water demand and ensuring sustainable water management.