Evaluation of hydro-meteorological drought indices for characterizing historical and future droughts and their impact on groundwater

Abstract

The effect of meteorological and hydrological droughts is very important in arid and semi-arid regions. Analyzing these effects on groundwater supplies plays an important role for water management in those regions. This paper aims to characterize droughts in the Isfahan-Borkhar basin, an arid area of Iran. The observed hydro-climatic data (for the period of 1971-2005) were used for hydro-meteorological projections (for the period of 2006-2040). Meteorological and surface hydrological drought evaluated by Standardized Precipitation Index (SPI), Standardized Runoff Index (SRI), and the effect of hydro-meteorological droughts on groundwater was investigated by Groundwater Resources Index (GRI). Results showed that dry and wet conditions would occur in the region in the initial and subsequent decades, based on the three indices. There was a significant association between SPI, SRI, and GRI at the time scale of 12 months. The SPI estimated using only meteorological variables alone and it is useful for estimating meteorological drought forecasts. However, SRI and GRI can represent hydrological drought that computed using catchment discharge, soil moisture and groundwater level. Results showed a considerable alteration in time of drought outlines across the area and association between the variables of predicted precipitation, temperature and the kind of indices. The projection of all three drought indices indicated drier conditions in the future period (2006-2042). The results provide reasonable management strategy for management of water resources in arid coastal plains.