Characterization of Drought under Dry Sub-Humid Saurashta Zone Of Gujarat
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Date
2019
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MPUT, UDAIPUR
Abstract
Drought characterization study is one of the most important aspects in the rainfed farming as well as in planning of various water resources, management and allocation of irrigation water. The present study was undertaken to characterize drought in dry sub-humid Saurashtra zone of Gujarat with the help of analyzing rainfall characteristics, estimating dry spells and water deficits, computing different water balance components, study of drought duration, drought severity and determining suitable frequency distributions for extreme water deficit data. Weekly meteorological data (1997-2017) and soil data were collected from Rajkot (Targhdia) and Junagadh stations.
Weekly rainfall data was analyzed for determination of onset and withdrawal of monsoon season and determination of dry spells for using Morris and Zandestra (1979) method. Annual, seasonal and weekly rainfall analysis of dry sub-humid Saurashtra zone of Gujarat indicates that coefficient of variation at Rajkot (Taraghdia) was higher. Onset of effective monsoon starts from around 26th (July 9-15) week and was terminated on 40th (October 1-7) week. Length of rainy season was observed 15 weeks during study period. Initial and conditional probabilities of dry and wet spells and two consecutive dry and wet week probability were determined by Markov-Chain model. Dry spells analysis indicated that probability of dry weeks was high during first two weeks of onset of monsoon and it remained less during monsoon season.
For determination of weekly reference evapotranspiration CROPWET 8.0 (Penman-Monteith method) was used. It was observed that annual and seasonal reference evapotranspiration of Rajkot (Taraghdia) was higher as compared to Junagadh. Different water balance components were determined with the help of annual reference evapotranspiration and Rainfall. It was identify that under normal condition moisture status was sufficient for satisfactory growth of rainfed crops. Using water balance components different indices aridity index (Ia), moisture adequacy index (Ima), humidity index (Ih) and moisture index (Im) were estimated. Climatic shift studies revealed that major climatic shift of Rajkot (Taraghdia) and Junagadh was falling between semi-arid to dry sub-humid type. Drought identification study indicated that there is frequency of one drought year
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occurs in around every two years. It is also found that there is one disastrous drought (2002) was found in Rajkot (Targhdia). It was observed that there is 12(57.14 %) drought year found during the study period. Frequency analysis of weekly maximum water deficit during crop growing season indicated that Log Pearson type –III was best fit probability distribution for Junagadh and Gumbel Max. was best fit probability distribution for Rajkot(Junagadh) under dry sub-humid Saurashtra zone of Gujarat.
Description
Characterization of Drought under Dry Sub-Humid Saurashta Zone Of Gujarat
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Citation
Gordhanbhai H.J. And Singh P.K.