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TERI University (2017)

A study of drought occurrences and forecasting of drought events in the Indian subcontinent

Shrivastava, Sourabh

Titre : A study of drought occurrences and forecasting of drought events in the Indian subcontinent

Auteur : Shrivastava, Sourabh

Université de soutenance : TERI University

Grade : Doctor of Philosophy (PhD) 2017

Résumé partiel
Rainfall over the Indian subcontinent, especially Madhya Pradesh in central India and Myanmar has large Intra-seasonal and interannual variability causing droughts and floods in many years. The main objectives of the present research are to (i) examine the intra-seasonal ad interannual variability of the summer monsoon over central India and Myanmar and look for any predictive signal for drought ; (ii) examine the potential of extended-range and seasonal predictions from dynamic models for drought prediction and (iii) examine the suitability of crop yield models to provide indication of droughts through modeling. Additional objectives include prediction of several drought indices to identify and predict droughts. In this study, rainfall variability in daily and monthly scale over central India as Madhya Pradesh (MP) and Myanmar has been examined using observed rainfall (GPCP and IMD gridded) data. Skill of an extended range forecast system has been evaluated for identifying droughts over central India and Myanmar up to 20-days in advance. Moreover, skill of seasonal forecast using 11 different handcast model data is also studied. Performance of the crop simulation model DSSATv4.5 is also evaluated over four district of Madhya Pradesh. In addition, the soil moisture and evapotranspiration relationship with rainfall is also studied so that drought can be monitored. Consistencies among various datasets such as rainfall, surface temperature, soil moisture and evapotranspiration have been examined. These parameters are from various different sources and critical for drought monitoring and prediction. It is found that during weak phases of monsoon, central India receives deficit rainfall with weaker monsoon circulation and this phase is characterized by an anticyclonic circulation anomaly at 850hPa centred on MP. The EOF analysis of daily rainfall suggests that the two leading modes explain about 23.7 % of rainfall variability in intraseasonal timescale. These two modes represent drought/flood conditions over MP. Relationships of weak phases of rainfall over central India with real time multivariate (RMM) indices of MJO have been examined. It is found that RMM-6, RMM-7, RMM-1 and RMM-2 describe the drought conditions over central India. However, frequency of drought occurrence over MP is more during RMM-7 phase. Surface temperature increases by about 0.5 to 1 degree during weak phases of rainfall over this region.

Mots clés : Drought forecasting Ecology and Environment Environmental Sciences Life Sciences Weather forecasting

Présentation et version intégrale (Shodhganga)

Page publiée le 19 avril 2021