Saudi Arabia faces a critical challenge: balancing rapid population growth and economic development with the scarcity of freshwater resources in its arid environment. The country's reliance on energy-intensive desalination and non-renewable groundwater is unsustainable in the long term. While government subsidies make water readily accessible, this abundance masks underlying vulnerabilities. Climate change exacerbates the situation, leading to increased temperatures and higher water demands for irrigation, impacting crop yields. Existing studies on Saudi Arabia's water resources are limited by data availability and do not reflect recent changes in government policies and resource use. This study aims to address these gaps by providing an updated analysis of water consumption across sectors, focusing on the agricultural sector's water footprint and its impact on food security. The authors developed a novel method to estimate water consumption associated with crop production at a national scale to better understand the efficiency of water use in the agricultural sector. The paper also analyzes precipitation trends using ERA5 data, considering its implications for water supply.

Previous research has documented water resource trends and consumption patterns in Saudi Arabia, highlighting the need for improved water resource management practices, particularly within the agricultural sector which historically consumed a significant portion of the country's water resources. The studies noted that improvements are needed, particularly in agricultural water use efficiency which accounted for 87% of the country’s water use in 2010, with 31% dedicated to forage crop cultivation. However, these studies were limited by a lack of publicly available data and did not reflect recent changes in government incentives and policies. Furthermore, most studies focused on specific crops, particularly date palms, but lacked comprehensive data on the overall agricultural water intensity and water use per crop type. This study addresses this gap by providing a countrywide analysis, focusing on the agricultural sector's water consumption and its impact on food security. The authors leverage recently released datasets on precipitation and water use to present a more complete and up-to-date picture of water resource management in the Kingdom.

The study utilized a multi-faceted approach, integrating various datasets and developing a novel methodology. Precipitation data were obtained from ERA5, a high-resolution global climate reanalysis dataset spanning 1950-2021. The ERA5 data were compared with data from the Ministry of Environment, Water, and Agriculture (MEWA) for the period 2010-2019. Historical crop production data were sourced from MEWA's statistical reports (2015-2020, excluding 2019 due to data unavailability) and the Food and Agriculture Organization of the United Nations (FAO). To estimate the water footprint of crops, a two-pronged approach was employed. First, a theoretical water consumption was calculated using MEWA crop production data and global average water footprint values (including green, blue, and grey footprints) from Mekonnen and Hoekstra (2010). Second, actual water footprint was determined by considering local conditions and agricultural water use, incorporating estimates for regenerated water (assumed to be 20% of total agricultural water use based on 2020 data) and water used for non-crop agricultural production (assumed to be 6%, based on a 2012 estimate). The ratio of actual to theoretical water consumption (X) was calculated to quantify the difference between the global average and Saudi Arabia's water use efficiency. This involved comparing the actual agricultural water use for crop production with the calculated theoretical water footprint. This ratio (X) varied between 2.6 and 2.9 for the years 2015–2018. The methodology also included analyzing the distribution of water use across various sectors and correlating it with crop production and overall food security. The authors used equations to calculate the theoretical and actual water footprint based on available data and relevant assumptions.

The analysis revealed several key findings: 1. **Precipitation:** Average annual precipitation in Saudi Arabia is extremely low, less than 100 mm/year across most of the country, insufficient to meet water demands. Discrepancies between ERA5 and MEWA data highlight the challenges of data collection in arid regions. 2. **Water Consumption:** Total freshwater use peaked in 2015 and has since declined, primarily due to a reduction in agricultural water consumption. However, the agricultural sector remains the largest consumer (67% of total water use), highlighting the importance of improving efficiency in this sector. Municipal and industrial water demand continues to increase. 3. **Agricultural Water Use:** The study's novel methodology revealed that agricultural water requirements in Saudi Arabia are up to three times the global average. Dates and cereals account for a substantial portion of agricultural water consumption, while forage crops, despite comprising a large share of mass production, have a relatively smaller water footprint. 4. **Water Footprint of Crops:** The calculated theoretical water footprint for the agricultural sector (based on global averages) was around 600 liters/kg of produce (2015-2018), while the actual water consumption ranged from 1450 to 1650 liters/kg, indicating significant inefficiency. 5. **Food Security:** While Saudi Arabia has a significant agricultural sector, domestic production only satisfies about one-third of the national food demand. This reliance on imports poses food security risks. A substantial amount of food (35%) is wasted or misused. The country produces 33% of its food needs while the remainder is imported, this highlights the reliance of Saudi Arabia on food imports.

The findings highlight the critical need for sustainable water management strategies in Saudi Arabia. The significantly higher actual water consumption compared to the global average underscores the inefficiencies in the agricultural sector. The reliance on non-renewable groundwater resources for agriculture is unsustainable, emphasizing the urgency of transitioning towards more efficient irrigation techniques and diversifying crop production to reduce water demand. The high rate of food waste also presents an opportunity for improving resource management. The study's emphasis on both production and consumption sides of the water-food nexus offers a comprehensive framework for policy interventions. The study's findings underscore the complex interplay between water resources, agricultural practices, and food security in arid regions, providing valuable insights for developing sustainable water management policies.

This study offers a comprehensive assessment of water resource management in Saudi Arabia, emphasizing the unsustainable reliance on non-renewable resources and the high water footprint of the agricultural sector. The findings highlight the need for improved irrigation techniques, diversification of crops, and reduction of food waste to enhance water efficiency and ensure food security. Future research could focus on the cost-effectiveness of different water conservation methods, and the impact of specific policy interventions on agricultural water use and food security. Further investigation into industrial water consumption, constrained by limited data availability, is also warranted.

The study's findings are subject to certain limitations. Data availability presented challenges, particularly regarding comprehensive and consistent data on agricultural water use and crop production across all years. Assumptions were made regarding the proportions of regenerated water and water used for non-crop agricultural production, which could slightly affect the accuracy of the water footprint estimations. The study relied on existing data sources and thus could not fully address current changes in the water sector. Future research with more updated data would help to refine these estimations and enhance the robustness of the findings.