Characterizing meteorological drought using standardized precipitation index for Dehradun, Uttarakhand

Standardized Precipitation Index (SPI) is based on the probability of precipitation for any time scale and it requires less input data and calculation efforts than other methods. The SPI is simply the transformation of the precipitation time series into a standardized normal distribution (−distribution). Among the several proposed drought monitoring indices, the SPI has found a widespread application for describing and comparing droughts at different time periods and regions with different climatic conditions. This paper characterizes the meteorological drought using SPI for Dehradun area located at the foothills of Garhwal Himalayas in Uttarakhand state of India. Monthly SPI values were calculated at the time scales of 1-, 4-, 6-, and 12 months based on the daily rainfall data of 60 years. In monthly analysis, the negative z-values of 2009 indicated that though July and August contributed more in total annual rainfall, they received less rainfall than their average. However, June and September were near normal. On the basis of seasonal and annual rainfalls, 2009 was a severely dry year with z-values-1.84 and-1.826, respectively. As the high rainfall is received in monsoon season (June to September), rain water harvesting and utilization is a way to mitigate drought effect. High water requiring crops can be replaced with low water requiring crops which are efficient to utilize soil moisture through crop replacement practices. The results clearly indicated that there is a need to make and adopt proper drought management plans to mitigate the effect of seasonal and annual drought by way of rainwater harvesting and cultivating low water requiring crops in drought prone areas at watershed scale.