Abstract:
This paper presents a methodology devised for integrated assessment of vulnerability to drought in spatial and temporal scales using physiographic, meteorological, hydrologic, social and other factors. The physiographic factors are static physical features of basin including topography, slope, land use, soil type, soil depth, proximity to river reach, elevation zones and population density. The meteorological and hydrological factors are monthly rainfall departures from corresponding mean and soil moisture deficit, respectively. The spatial information of multiple factors has been categorized in various sub-classes and maps have been prepared using AreGIS. A differential weighting scheme has been used to integrate different sub-classes of various factors for assessment of vulnerability to drought. The methodology has been applied in the Ken River Basin in Bundelkhand region located in central India. The Soil and Water Assessment Tool (SWAT) model has been applied to demarcate hydrologically homogeneous areas called Hydrologic Response Units (HRUs) in respect of land use, slope and soil type, and for the estimation of spatial and temporal distribution of soil moisture in the study basin. The Soil Moisture Deficit Index (SMDI) has been computed from the soil moisture estimates obtained using SWAT model,. An Integrated Drought Vulnerability Index (IDVI) has been defined as the sum of weights of various factors scored by corresponding IIRU (Hydrologic Response Unit) divided by the sum of the maximum weight value of the factors. The HRUs with higher value of IDVI represents the areas with high degree of vulnerability to drought and vice versa. The maps thus obtained were validated using the documented information and field surveys. The prepared map showed very good agreement with the physical field observations made in the study basin. The methodology presented in this paper puts forward a useful and reliable tool for quantitative assessment and demarcation of zones with different degree of vulnerability to drought in time and space. The proposed methodology can be used for proactive as well as near real time assessment, monitoring and planning of response actions to cope with drought.
