On VASAT’s invitation, Prof. R. Nagarajan of the Center of Studies in Resource Engineering, Indian Institute of Technology, Bombay agreed to spend some of his project resources to develop this study.

A drought or an extreme dry periodic climate is an extended period where water availability falls below the statistical requirements for a region. Drought is not a purely physical phenomenon, but rather an interplay between natural water availability and human demands for water supply.

Many regions of India and Sub-saharan Africa are mercilessly exposed to severe bouts of drought. Hence, information is the backbone to drought preparedness.

The project is to develop a micro-level drought vulnerability forecast and analysis method that can be used by trained community members. The absence of such a tool is well known.

Remote Sensing and GIS tools and techniques were employed to assess the avaibale surface water bodies in the Adakkal region to suggest a plan for combating drought.

  In total 62 such water bodies that are connected to a group, their degradation status, and feasibility of restoration and benefit of restoration were assessed in Addakkal region. Status of degradation in terms of surface area, silt thickness, encroachments on the reservoir bed and blockage/impediments alongwith the inward channels was assessed. Thematic maps (survey of India) prepared during 1966, 1987 & 2000 and Indian Remote Sensing satellite data of 1992 and 2003 were used for this purpose (in addition site verification was carried out in March 2005). Status of outward channels and the probable areas for rainfed agriculture was estimated by calculating the restoration benefits. Annual (40 years), monthly (10years) and daily (5 years) rainfall records were used in understanding the rainfall intensity and time series pattern. Further, run-off from the tank catchment for a range of rainfall scenarios was calculated in meeting the human, animal and crop-irrigational requirements of villages that are located in the vicinity. Deficiency of water availability from the tanks towards the winter and summer crops and ground water extraction requirements were estimated.

This information was collated in the preparation of tank improvement scheme as a macro level drought management program (asset generation). This map indicates the Degradation status – low (<10%), Moderate (10-30%), High (30-50%) and Very High (>50%); restoration benefit that was calculated based on the quantity of silt to be removed from the lake bed, length of in-ward and outward channel to be restored etc. and grouped into 3 categories. This information could form the basis for micro level planning in combating drought. Based on this model, a range of vulnerability scenarios for different rainfall regimes have been developed as color-coded maps (see an example in Figure above). The usefulness of such maps has been discussed with the communities to assess their response to the interpretation of experts. Initial responses have been positive, and the testing process continues. In the mean time, a group of researchers of the Indian National Remote Sensing Agency (NRSA), an institute having mandate to apply space technology and remote sensing information for natural resource management, has come forward to join such a study.