USE OF .GIS .& REMOTE SENSING TECHNIQUES FOR ASSESSING RAINWATER HARVESTING POTENTIAL

Abstract

Assessing, managing and planning of water resources for sustainable use has become a crucial issue in recent times. There is an obvious need for proper understanding of the hydrological processes in the watershed. Rainfall-runoff relationship plays an important role in understanding the dynamic aspects of the hydrological processes that take place in any region. Harvesting of available runoff at a micro-level for storage and recycling is necessary for better utilization of rainfall, control of erosion and providing life saving irrigation to crops during dry spells in the monsoon season and also for growing a second crop in the Rabi season. In areas under rain fed agriculture, a small additional increment of harvesting water can dramatically increase crop yields and lower the risk of crop failure. Sometimes, it can make a difference between crop and no crop in drought prone areas. The objective and technologies of rain water harvesting are highly location specific and an appropriate technology developed for a particular region cannot be used as such for other areas due to physiographic, environmental, technical and socio-economic reasons. As far as water harvesting is concerned, technologies are not based on annual rainfall only, but terrain, soil permeability, landuse and its variation in space and time also play an important role in determining the sites. Integration of Remote Sensing and Geographical Information System (GIS) Techniques provides reliable, accurate and up-to-date database on land and water resources, which is a pre-requisite for an integrated approach in identifying potential runoff zones and suitable sites for water harvesting structures such as check dams, farm ponds, percolation tanks and bandies etc Hydrologic information is needed for watershed management planning, analysis and design of water resource projects and for making landuse impact assessment. Sometimes adequate hydrologic, meteorological and biophysical data are not available at locations of interest and even when data are available, deciding the most appropriate method to use can be difficult. Selecting the appropriate hydrological method requires careful consideration of following: 1. The type and accuracy of information and data available 2. The physical and bio-geological characteristics of watershed. 3. The technical capabilities of the individual performing the study