Drought Impact on Industrial Water Discharges in Spain's Agri-Food Sector

Abstract

This study investigates the statistical association between hydroclimatic stress and reported industrial discharge loads from Spain's agri-food industry between 2020 and 2025. Utilizing a panel dataset linked to regulatory and climate data, specifically the Standardized Precipitation Evapotranspiration Index (SPEI) at 6, 12 and 24 month windows, we examine the association between SPEI-based hydroclimatic variability and annual reported loads of Chemical Oxygen Demand (COD), total Nitrogen and total Phosphorus. Results show a statistically significant association between SPEI and reported annual discharge loads. In the aggregate models, higher SPEI values, corresponding to wetter conditions, are associated with higher reported annual discharge totals. Therefore, these estimates should not be interpreted as evidence that drought increases absolute reported loads. Rather, drought is relevant because reduced streamflow can lower the dilution and assimilative capacity of receiving water bodies, increasing environmental pressure for a given discharge load. The response of phosphorus is more variable, influenced by operational decisions and treatment technologies. Spatial analysis identifies provinces exhibiting combined recurrent drought and high discharge loads, creating an operational vulnerability map shaped by local industrial pressure and hydroclimatic conditions. Food and beverage subsectors indicate differing sensitivities to hydroclimatic stress conditions, with the beverage industry showing greater sensitivity in the tested specifications. The findings establish a reproducible empirical basis for operational planning, water risk management and climate resilience strategies in the agri-food sector. This research highlights the importance of integrating regulatory and climate data for effective decision making within Spain's agri-food industry.