Multi criteria analysis for drought assessment using remote sensing and GIS

Abstract

Drought is a disastrous natural phenomenon and 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 groundwater. Existing methods consider only a few factors which are not effective for drought mitigation programmes. The specific objectives are (i) to assess meteorological and agricultural droughts using rainfall and remote sensing data; and (ii) to carry out an integrated drought severity assessment using Analytic Hierarchy Process (AHP) and GIS. Palar Sub basin encompassing Vellore, located in the North-East part of Tamil Nadu State, India, was selected to test the methodology. Paddy is the main crop in the study area and is cultivated in three seasons namely, Sornawari, Samba and Navarai. Thirty five years of monthly rainfall data during 1971 to 2005 were analysed for variation in space and time. The results of IMD method over a period of time will not lead to an overall idea of drought proneness in any area as it gives a mixed bag of different severities of drought. Hence, a frequency based Meteorological Drought Severity Index (MDSI) was formulated and applied. The drought severity values were used to generate drought severity map in GIS environment. The agricultural drought severity assessment was carried out by developing an Agricultural Drought Severity Index (ADSI), which involves crop land and fallow land estimation that were delineated from remote sensing data using NDVI analysis. Integrated Drought Severity Index (IDSI) was developed in GIS environment by combining various parameters affecting drought comprising of spatial and non-spatial data. In this study, a drought assessment procedure which will take into account of all the drought causing factors, is attempted and demonstrated. This might be due to the lack of proper drought assessment procedures which would truly reflect the field situation of drought of an area. This thesis addresses that problem.