METEREOLOGICAL DROUGHT INSTENSITY ASSESSMENT USING STANDARDIZED PRECIPITATION INDEX

Abstract

Drought is a condition which due to deficiency of moisture in a region due to uneven rainfall, drying up of rivers and loss of ground water. It is estimated that droughts effects around 200 million people are affected from drought every year in India. In 2019 42% of the country’s area is under drought with almost 500 million people severely affected in some ways. Droughts have so far affected the region in study adversely throughout the last century. With increasing global warming and ever-changing trends of monsoon the region has seen worst of the droughts in the last 10 to 20 years. Hence, drought identification, evaluation and mitigation require a solid approach to prepare a suitable and effective management plan. The study focuses on the Uttar Pradesh region of Bundelkhand Plateau, which faces continuous droughts every year. The study is carried out for six districts of Uttar Pradesh viz. Auraiya, Banda, Jalaun, Jhansi, Hamirpur and Lalitpur. To identify drought conditions and classify it Standard Precipitation Index (SPI) was computed. The monthly rainfall data from 1988 to 2018 was collected from various sources. The 3-Month SPI(April-June), 3Month SPI (July-September) and 6-Month SPI (Oct-Mar) were computed using DrinC software and MS excel. The SPI values were used to categorise drought under four groups based on its severity namely mild, moderate, severe and extreme from 1988 to 2018. The IMD classification of rainfall involves categorizing drought by computing the percentage deviation of the current rainfall from normal rainfall. Thus, in this study, the SPI values of different years are analysed with actual rainfall and rainfall deviation from normal in low rainfall and drought prone districts. The objective is to evaluate whether SPI can be used as a better indicator than conventionally adopted rainfall deviation-based approach for drought intensity assessment. The results are represented with the help of bar charts to study the frequency of droughts over the years and categorize it. The SPI vs. Rainfall deviation scatter plots are plotted to examine the validity and relation of SPI with Rainfall deviation method.