Current and future water availability in the context of water insecurity in the Parón catchment, Santa River basin

Abstract

Water security in Andean watersheds depends on adaptive water management in the face of glaciohydrological and socioeconomic impacts. The Parón sub-basin in the Santa River basin (Ancash, Peru) is a suitable case in this respect. Water is regulated by a floodgate in the Parón lake, which has become a focal point of social conflict. This study analyzes the water balance of this sub-basin using a semi-distributed hydrological model for the present (2006-2016) and future (2030-2050), considering different scenarios of precipitation variation, glacial melting, and increased water demand. Without regulation of the lake, the sub-basin would enter into a strong water deficit in the dry months (June-August). Until 2030 (2050), assuming a maximum regulation of 2.6 m³/s, a 15% (35%) increase in precipitation, and a 10% (26%) decrease in the glacier contribution to the annual flow, water availability would be reduced by 37% (35%). In a pessimistic scenario with a 15% (35%) decrease in precipitation, water availability would still be reduced by 47% (56%) annually. These results highlight the need to keep a socially acceptable minimum water flow (>2 m³/s) to avoid critical levels of water scarcity in the dry months and to address the needs of local water users.