Drought analysis using different indices for Pantnagar and Dehradun areas of Uttarakhand
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Date
2013-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
In this present study, the annual and seasonal rainfall series of Pantnagar and Dehradun areas were analyzed using India Meteorological Department (IMD) classification of drought as mild, moderate, severe and extreme drought as per percentage rainfall deviation. Based on the drought analysis using the SPI criteria, appropriate crop planning and design of rainwater harvesting and storage structures in the drought affected areas can be proposed in drought affected areas. Standardized Precipitation Index (SPI) was calculated at different time scales (1, 3, 6, 12, and 24 months). The SPI is a drought index based on the probability of an observed precipitation deficit occurring over a given prior time period. The assessment periods considered range from 1 to 36 months. The monthly data were converted into seasonal rainfall of four month period as pre-monsoon (February to May), monsoon (June to September) and post-monsoon (October to January) and multi-temporal rainfall series with running sum for 1-month, 3-month, 6-month, 12-month and 24-month durations for both the locations. The SPI, calculated for a desired period at any location, are based on the long term precipitation record (30 years or more). The positive SPI values show greater than medium precipitation, while negative SPI values indicate less than medium precipitation.
The results shows that the SPI can be used for better assessment of drought as it considers larger range of moving sums of rainfall data. Since SPI uses for the running sum of rainfall values at multi-time scales (1 to 24 months) and more variables depending on the statistical distributions used, it gives better assessment of meteorological drought at multitime scales. The 3-month SPI can be used for short term drought monitoring and agricultural crop planning and 12-month SPI can be used for long term drought monitoring and water resource planning.
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