ABSTRACT

Long-term droughts significantly impact surface and groundwater resources in India, however, observed changes in major river basins have not been well explored. Here we use Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) at three different time scales (24, 48, and 60 months) to identify long-term droughts in India for the observed record of 1951–2015. Drought characteristics (extent, events, frequency, and intensity) are analyzed for different river basins in India. Increasing trend in the areal extent of droughts is observed in two methods with three time scales in the maximum area (63.66%) in India. We use the data from the Gravity Recovery and Climate Experiment (GRACE) to estimate the changes in the terrestrial water storage (TWS) during the period 2002–2015. We identify that major long-term droughts in India occurred from 1966 to 1969, 1972, 1986–1987, and 2002–2004. The all-India average TWS shows a negative trend from 2002 to 2015 with prominent decline in north Indian river basins and positive trend in south Indian river basins. SPI and SPEI at longer time scales are positively associated with TWS indicating the adverse impacts of droughts on surface and groundwater resources in such a populated region.

摘要

长期干旱严重影响了印度的地表和地下水资源，然而，主要河流流域的观察变化尚未得到很好的探索。在这里，我们使用三个不同时间尺度（24、48 和 60 个月）的标准化降水指数 (SPI) 和标准化降水蒸散指数 (SPEI) 来确定印度 1951-2015 年观测记录的长期干旱。分析了印度不同流域的干旱特征（程度、事件、频率和强度）。在印度的最大面积（63.66%），用两种方法和三个时间尺度观察到干旱面积的增加趋势。我们使用重力恢复和气候实验 (GRACE) 的数据来估计 2002-2015 年期间陆地储水量 (TWS) 的变化。我们确定印度的主要长期干旱发生在 1966 年至 1969 年、1972 年、1986 年至 1987 年和 2002 年至 2004 年。2002 年至 2015 年，全印度平均 TWS 呈负趋势，北印度河流域下降显着，南印度河流域呈上升趋势。较长时间尺度上的 SPI 和 SPEI 与 TWS 呈正相关，表明干旱对这样一个人口稠密地区的地表和地下水资源的不利影响。