Comparison between Standardized Precipitation Index (SPI) and Standardized Evapotranspiration Index (SPEI) for agricultural drought over Mantaro Valley, Peru

Abstract

Drought is one of the main events associated to climate change that affects water supply and food productions at different locations and time (spatio-temporal) in the Peruvian Tropical Andes (PTA). Furthermore, studies evidenced that drought are causing an enormous damage to social, economic and environmental spheres. Hence, The World Meteorological Organization (WMO) has published a handbook of drought indicators and indices with the most representative methods used in the world to assess drought events, but each index has a different advantage since the requested variable and scope are different. In that sense, this study aims to compare the Standardized Precipitation Index (SPI) and Standardized Evapotranspiration Index (SPEI) for agricultural drought under spatio-temporal consideration in the PTA, Mantaro Valley. Firstly, SPI is based on precipitation data, effectively distinguishes between wet and dry seasons. Secondly, SPEI takes into consideration precipitation and temperature changes which leads to an understanding of global warming. SPI and SPEI were applied to six different meteorological stations within Mantaro Valley with data between 1990-2021 under a spatio-temporal approach. The results mainly show that, 30% reveal characteristics of drought. Also, SPEI was able to identify greater drought events by +-3% for all meteorological stations and applying the Cohen's Kappa statistical analysis, substantial but not perfect agreement can be evidenced with a no agreement value of +-40%. Finally, it is recommended to continue analyzing floods and frosts in the last decades with the purpose of clearly understand the climatic development for an informed decision making in the water management and agricultural activities.