Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Land use based integrated drought assessment

Auteur : Ravikumar, G

Université de soutenance : Anna University

Grade : Doctor of Philosophy (PhD) 1997

Résumé
Drought is generally viewed as a sustained and regionally extensive occurrence of below average natural water availability either in the form of rainfall, river runoff or ground water. Droughts are defined based on different factors. There is a need to develop a drought assessment procedure which would consider all aspects of drought causing parameters.
The present study developed a methodology to assess the drought in meteorological, hydrological and agricultural contexts independently and to combine them to present an Integrated Drought Severity Index (IDSI). The Integrated Drought Severity Index is applied to identify drought prone areas and to short-term drought prediction. Dharmapuri, a chronic drought prone district, located in the North-West part of Tamil Nadu State, India, was selected to test the methdology. _The assessment of drought severity in the meteorological context was carried out employing Aridity Index, Palmer Drought Severity Index, Herbst and India Meteorological Department methods. The assessment of drought severity in the hydrological context was carried out employing Yeyjevich, Dracup and Herbst methods. An attempt was made in this study to use the water availability data as the basis for hydrological drought assessment. Palmer’s method in meteorological drought calculation and Herbst method in hydrological drought identification emerged to be superior among the respective methods. Rama Prasad method is good in reflecting the reality in the case of agricultural drought.
The meteorological, hydrological and agricultural factors were integrated by using the land use criterion as the basis. The land use map prepared from the Landsat imagery by visual interpretation was used. The area occupied by each of the land use categories was determined using a digital planimeter. Integrated Drought Severity Indices for all the taluks of Dharmapuri district were calculated. For validating the proposed Integrated Drought Severity Indices, they were related with the crop yield values for all the taluks. _The developed Integrated Drought Severity Index was verified for its suitability for early prediction of drought severity in December for the rest of the water year and identification of drought prone areas for Government sponsored alleviation programmes like Drought Prone Areas Programme (DPAP). _The results from the study show that out of 14 blocks covered under Drought Prone Areas Programme in 1995-96, only 8 blocks seem to qualify for inclusion under the programme. Out of 4 blocks which were not covered under DPAP from 1995-96, two blocks might have been included.
Hence, the above analysis suggests that out of the present 18 blocks in Dharmapuri district, only 10 blocks may be included in DPAP from 1995-96 against the current 14 blocks under it. The developed index has been a comprehensive drought assessment procedure that can be confidently used for any drought situation

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