How does climate influence evaporation suppression efficiency in shallow water reservoirs covered with floating elements?

Small water reservoirs play a vital role in supplying local water demands, especially in arid and semi-arid regions. However, these reservoirs are highly vulnerable to evaporation losses [1]. Modular floating covers offer a practical and scalable solution to reduce evaporative water losses. While previous studies focused on cover properties and seasonal effects [2,3], the impact of broader climatic variations on evaporation suppression efficiency (ESE) remains understudied. This study uses a validated physically-based model [4] and MERRA-2 meteorological data to showcase the variation of ESE across diverse climatic regions in Iran. Preliminary results show that annual ESE changes between 75 to 81%. We observed a strong negative correlation between potential evaporation (PE) and ESE. While ESE in arid regions with high values of PE remains almost constant during the year, our analysis reveals sharper winter declines in ESE for humid regions with lower values of PE. This study provides a regional assessment of the water-saving potential of evaporation suppression floating elements and enables to identify areas where floating covers can be applied most effectively.