Water resources in Saudi Arabia: trends in rainfall, water consumption, and analysis of agricultural water footprint

Saudi Arabia’s rapid population growth and economic development are driving up freshwater demand in one of the most arid regions globally. Permanent surface water bodies are absent, replenishable reservoirs are small, and freshwater production is energy-intensive, relying heavily on fossil-fuel-powered desalination and deep aquifer pumping. Government subsidies have historically made water relatively cheap for municipal and agricultural users, enabling a sizable agricultural sector but often without sustainable practices. Non-renewable fossil groundwater is being depleted while water demand increases and climate change intensifies heat extremes, raising irrigation needs and reducing crop yields. Prior studies documented that agriculture dominated national water use (e.g., 87% in 2010) with substantial shares for forage crops, but Saudi Arabia’s nearly fully irrigated agriculture and dependence on desalinated municipal supplies limit comparability with other countries. Public data gaps further complicate assessments. An updated, national-level analysis is needed to reflect recent policy incentives, newly available datasets on precipitation and water use, and to focus on the agricultural sector that currently accounts for about two-thirds of freshwater consumption. The study aims to quantify precipitation trends, sectoral water use, and agricultural water footprint and efficiency, and to discuss implications for food supply and security.

Previous national assessments highlighted Saudi Arabia’s unique water sector characterized by near-total irrigation and large-scale desalination, with agriculture historically accounting for the vast majority of water use and a significant portion devoted to forage. Numerous local studies have evaluated crop evapotranspiration and water requirements, especially for date palms, with estimates varying widely by region (e.g., ~35 m³/tree/year in Qatif to ~195 m³/tree/year in central regions) and irrigation method (surface vs. subsurface drip). Seasonal variability is substantial, with higher needs in summer. However, comprehensive, up-to-date, countrywide data on agricultural water intensity and per-crop water use were lacking, and public datasets are sparse or inconsistent across sources. These gaps motivate the present work to synthesize available statistics and infer agricultural water footprints using global benchmarks adjusted to Saudi conditions.

Data sources and climate reanalysis: The study used ERA5/ERAS reanalysis datasets (global, 0.25° grid) to construct consistent, spatially complete precipitation statistics for Saudi Arabia over 1950–2021. Reanalysis blends observations with model forecasts to fill observational gaps. ERA data were compared with Ministry of Environment, Water and Agriculture (MEWA) and General Authority of Statistics (GASTAT) data for 2010–2019 to assess discrepancies due to methodology and station coverage. Crop production data: Historical crop production statistics were obtained from MEWA (reports in 2018 and 2020) for 2015–2020 (excluding 2019 due to missing data) and from FAO (1961–2020). MEWA and FAO totals differ, notably because MEWA includes forage crops (42% of mass production in 2020) not fully represented in FAO time series. For calculations, MEWA 2015–2020 data were used as the primary source. Water footprint estimation: - Theoretical water footprint: For each crop, the theoretical (global-average) water footprint was calculated by multiplying MEWA-reported production by global average total water footprint coefficients (green + blue + grey) from Mekonnen and Hoekstra (2010). - Actual water footprint for Saudi Arabia: Total agricultural water use was compiled from MEWA (2010–2019) and 2020 reports. Because MEWA 2010–2019 reports provide only non-renewable water, total agricultural water use was estimated by adding regenerated water, assumed to be 20% of total agricultural agricultural water use (based on 2020 data). Water used for non-crop agricultural activities (fish, meat, dairy, eggs) was subtracted, assumed to be 6% of total agricultural water use based on a 2012 KAPSARC estimate (held constant for subsequent years due to lack of newer data). The resulting total water used for crop cultivation was then divided by total agricultural production mass to obtain liters/kg. - Efficiency factor X: The ratio X = (actual agricultural water use for crop production in Saudi Arabia) / (theoretical water footprint for the same crop mix). X captures how many times more water is used in Saudi Arabia relative to global average footprints. For 2015–2018, X was found to be approximately 2.6–2.9. Application: Theoretical water use and footprints for the top crops (including forage aggregated as one category) were computed; actual values for a given year are obtained by multiplying theoretical values by X. Special handling was needed for forage due to limited per-crop footprint coefficients. Uncertainty and data gaps: 2019 data were unavailable; 2020 actual agricultural water consumption may be underestimated in MEWA reports. ERA reanalysis and MEWA precipitation differ due to coverage and methodology; station networks are sparse and urban-centered.

- Climate and precipitation: Average annual precipitation across Saudi Arabia is very low, with long-term mean reported as approximately 65 mm/year (1950–2021 ERA data; mean 65 mm/year, SD 21.6 mm/year). Spatially, most of the country receives <100 mm/year, with as little as ~20 mm/year in the Empty Quarter and up to ~50+ mm/year in southern mountains. ERA vs MEWA precipitation for 2010–2019 differ (ERA: ~40–90 mm/year; MEWA: ~60–130 mm/year) due to methodology and spatial coverage. - Sectoral water consumption: With negligible rainfall-runoff, desalination supplies about two thirds of municipal freshwater demand; agriculture is predominantly supplied by non-renewable groundwater (about 80% of agricultural water). Total water use rose sharply to a peak in 2015 of 24.8 billion m³ (about 30 billion m³ including regenerated water), ~150% higher than in 2010, then declined due to reductions in agricultural use following forage cultivation controls (especially after 2019). Municipal water use continues to grow at ~4.5%/year; the share of municipal water treated increased from 45% (2010) to 52% (2020), but only about 18% of treated wastewater is reused (~10% of total municipal supply). - Agricultural water use and composition (circa 2020): Agriculture accounted for ~67% of total national water use (or ~62% excluding regenerated water). Approximately 5.5 billion m³/year came from non-renewable groundwater, and ~20% (~2.2 billion m³/year) was regenerated water. Forage crops made up ~42% of production mass but only ~12% of agricultural water use; dates and cereals dominated water use, consuming ~38% and ~24% of agricultural water, respectively, while contributing ~14% and ~12% of mass. - Production trends: Non-forage production peaked at 8.2 Mt in 1994, with another peak (~7 Mt) in the mid-2000s. In 2020, non-forage production reached ~6.1 Mt (highest since 2005), with vegetables leading by mass, followed by dates, cereals, and other fruits, even as agricultural water use declined. - Water footprint and efficiency: The theoretical (global-average) agricultural water footprint was ~600 L/kg during 2015–2018, increasing to ~860 L/kg in 2020 due to a higher share of water-intensive fruits and vegetables. Actual water use for crops was ~1450–1650 L/kg during 2015–2018, implying X ≈ 2.6–3.0. 2020 actual footprint likely dropped in reported data due to underestimation; projecting using 2016–2018 average X gives ~2265 L/kg for 2020. For cereals, the global average footprint is ~1644 m³/ton, Middle East average ~2991 m³/ton, and estimated Saudi Arabia ~4274–4884 m³/ton (2.6–3× global). Higher local water use reflects environmental conditions, conveyance losses, and slower adoption of efficient irrigation. - Food security metrics: Domestic production supplies about 33% of the food balance by mass; domestic supply for local consumption is ~89% with ~11% exported. Food availability is ~3308 kcal/person/day versus a theoretical requirement of ~2139 kcal/person/day, equating to ~483 kg/person/year and implying about 35% food waste or misuse.

The analysis addresses national-scale water supply and demand, documenting extreme aridity, heavy reliance on desalination and non-renewable groundwater, and the dominant role of agriculture in total water use despite providing only about one-third of the food supply by mass. The comparison of ERA reanalysis and MEWA precipitation underscores uncertainty in hydroclimate metrics but affirms persistently low rainfall and vulnerability to climate variability and change. The agricultural water footprint analysis shows that producing Saudi Arabia’s crop mix requires roughly 2.6–3 times the global-average water, reflecting harsh climatic conditions, high evaporative demand, and system inefficiencies (e.g., losses in transport, limited penetration of advanced irrigation). Policy actions to curb forage cultivation have measurably reduced non-renewable groundwater extraction since 2015, demonstrating the effectiveness of targeted interventions. However, growing municipal and industrial demands, limited wastewater reuse, and climate-driven heat stress elevate future risks to water and food security. The findings emphasize trade-offs between conserving finite groundwater via food imports and maintaining resilience against global supply disruptions. Improving irrigation efficiency, expanding controlled-environment agriculture (e.g., greenhouses), increasing safe wastewater reuse, and reducing food waste (particularly animal-origin products) are critical levers to enhance sustainability and security. These measures directly address the identified inefficiencies and could narrow the gap between actual and theoretical water footprints.

This study provides an overarching assessment of Saudi Arabia’s water resources, sectoral consumption, and agricultural water footprint using ERA reanalysis, national statistics, and a novel method to infer actual water use for crops from global footprints. Key contributions include: (i) documenting long-term precipitation patterns and their spatial variation; (ii) quantifying sectoral water use trends and the impacts of policy on agricultural withdrawals; and (iii) estimating that Saudi crop production requires about 2–3 times more water than global averages, with dates and cereals dominating agricultural water use while forage dominates production mass. The work highlights critical gaps in wastewater reuse (only about one-tenth of municipal supply when normalized) and the growing municipal and industrial demands. It underscores that water sustainability depends not only on supply-side measures but also on curbing food waste and optimizing agricultural practices. Future research should improve national water-use accounting (particularly for 2020 and beyond), refine per-crop local water footprints (especially forage), evaluate irrigation technology penetration and conveyance losses, and assess the potential of expanded wastewater reuse and controlled-environment agriculture to reduce blue-water dependence.

- Data gaps and inconsistencies: 2019 crop production data are missing; discrepancies exist between MEWA and FAO statistics (notably for forage). MEWA 2010–2019 agricultural water reports exclude regenerated water; totals were inferred using a 20% regenerated fraction based on 2020. - Assumptions: A constant 6% of agricultural water allocated to fish/meat/dairy/eggs (from a 2012 estimate) was assumed due to lack of recent data; 20% regenerated water share was assumed for years prior to 2020. These assumptions introduce uncertainty into actual water use and footprint estimates. - Potential underestimation: MEWA’s 2020 actual agricultural water use may be underestimated, affecting calculated footprints for that year. - Methodological differences: ERA reanalysis vs. station-based MEWA precipitation datasets yield different national means due to spatial coverage and methodology. - Forage crop footprints: Limited availability of crop-specific forage footprint coefficients required aggregation, reducing resolution. - Industrial water use: Limited public data restricted analysis of industrial sector consumption and trends.