Spatial and Temporal Dynamics of Agricultural Water Footprint in a Changing Climate: A CORDEX-SPARE:WATER Analysis.

The far-reaching impact of climate change on water resources, particularly its intensification of scarcity, poses a substantial threat to the sustainable management of water in agriculture. To enhance cross-sectoral decision-making at various scales, it is vital to quantify both current and future water consumption, employing methodologies that assess the agricultural water footprint (WF).

This study employs the Site-sPecific Agricultural water Requirement and footprint Estimator (SPARE:WATER) to evaluate the susceptibility of green and blue agricultural WF at various scales across Colombia. The assessment is conducted under two CORDEX (Coordinated Regional Climate Downscaling Experiment)-driven climate scenarios, RCP2.6 and RCP8.5. High-resolution (0.22°) CORDEX climate model projections are used to drive the SPARE:WATER model, while historical weather data from fifteen stations (1977-2005) are employed to bias-correct the model's gridded data using the Equal Quantile Matching (EQM) method. This corrected data was spatialized using IDW interpolation. Ten major crops are selected based on their national production significance, based on the National Agricultural Survey. Crop characteristics such as harvested area, yield, and crop coefficients are obtained from local and FAO sources. The analysis focuses on both green and blue WF for the near future (2060) and far future (2099), compared to the present (2020).

Preliminary findings underscore a national WF of 45 km³/yr, with important variations at the departmental level. The spatial variability of WF is influenced by both wet and dry years.  Cocoa, coffee, and palm oil emerge as crops with the most substantial WF, showcasing respective water requirements of 30 k m³/t, 18 k m³/t, and 8 k m³/t nationally. Regional variations reveal the significance of crops such as plantain and banana in the agricultural WF landscape. Under the RCP2.6 scenario, the green and blue WF projections for 2060 and 2099 exhibit marginal changes relative to 2020. Conversely, under the RCP8.5 scenario, a discernible increase, particularly in blue WF, is evident, with a surge of 96% by 2099. This trajectory underscores the heightened water requirements anticipated for pivotal crops like cocoa and coffee in the future agricultural landscape.

These findings underscore the urgent need for informed water management strategies in the future of Colombian agriculture, particularly in the face of a high-emission scenario. The results of this study can inform policy and decision-making aimed at ensuring sustainable water resources management and food security under the evolving climate landscape.