Towards a framework for quantifying water resources in india
D. Shankar
e-mail: shankar@darya.nio.org
Vidya Kotamraju
e-mail:vidyakr@darya.nio.org
S. R. Shetye
Physical Oceanography Division, National Institute of Oceanography
Dona Paula, Goa 403004, India.
Abstract
While issues related to water attract considerable attention in India, very little quantitative information is available on the water budget of the country. There are two reasons for this lacuna: the dearth of information on hydrological variables and the absence of an easily accessible quantitative framework to put these variables in perspective. In this paper, we assemble a framework to address both issues. At its core is a hydrological routing model (HYDRA) that has been used to study the water balance of basins on scales ranging from a few square kilometres to continents. The basic data needed for implementing the framework are a suitable digital elevation model (DEM) and data on precipitation and evapotranspiration; the freely available GIS, GRASS, is used for manipulating the DEM. Available discharge data can be used to validate the model.
We demonstrate the viability of the framework by applying it to the hydrology of the Mandovi river; it is typical of the rivers along the Indian west coast that flow down from the Sahyadris into the Arabian Sea. Most of the catchment area of the river is in Goa, but parts of the river also flow through Karnataka and Maharashtra. We use a 30" (~ 1 km) resolution DEM (GLOBE) and HYDRA to show that the model output mimics the observed discharge well, providing indirect validation for the surface runoff and sub-surface drainage values on which no data are available.