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Watershed Management using GRDSS

T V Ramachandra
Centre for Ecological Sciences
Indian Institute of Science, Bangalore, India
[email protected]

Uttam Kumar
Centre for Ecological Sciences,
Indian Institute of Science, Bangalore, India

The dimensions of watershed management can be easily understood and improved by applications involving innovative information management technologies. This paper discusses the capability of Geographic Resources Decision Support System in watershed planning and management

Watershed is a region (or area) delineated with a well-defined topographic boundary and water outlet. It is a geographic region within which hydrological conditions are such that water becomes concentrated within a particular location, for example, a river or a reservoir, by which the watershed is drained. Within the topographic boundary or a water divide, watershed comprises a complex of soils, landforms, vegetation, and land uses. The terms watershed, catchment, and basins are often used interchangeably (Rattan Lal, et al, 2000). They have long been recognised as desirable units for planning and implementing developmental programmes.

Watershed management encompasses the simultaneous consideration of hydrological, pedological, and biological resources, necessitating the need for making better use of analytical tools and approaches, which address spatial and temporal variability, is critical. The cumulative impacts of human activities, which threaten the ecological, economic, and aesthetic integrity of many drainage systems and the strategies to mitigate these impacts, have explicit spatial dimensions (Morgan and Nyborg, 1995). Watershed approaches in resource planning require timely and accurate data with spatial as well as statistical aspects. In this regard, GIS holds great promise with a provision to handle spatial and temporal data and aid as an integrative planning tool for watershed management.

GIS has options to store and create spatial maps with a potential for performing multiple analyses or evaluations of scenarios such as model simulations of physical, chemical, and biological processes, which support the applications of watershed. Multi spectral space borne remote sensors (such as LISS3 in IRS 1C, etc.) provide spatial and temporal data (at 24 days interval) at various spectral (G, R, IR) and spatial resolutions (23.5 m for MSS data and 5.8 m for Panchromatic data). This is helpful in analyzing the dynamic changes associated with the earth resources such as land and water. Thus, spatial and temporal analysis technologies such as GIS and Remote Sensing are very useful in generating scientifically based statistical spatial data for understanding the land ecosystem dynamics. GRDSS (Geographic Resources Decision Support System) has the functionality to carry out spatial raster and vector analyses and also aids as a Decision Support System that helps in analysing and visualising the decisions.

GRDSS is a GRASS (Geographic Resources Analysis Support System, . in/grass) based GIS. GRASS is an open source GIS that works on Linux platform (freeware), but most of the applications are in command line arguments. The command line syntax for GRASS was time consuming for individuals with limited programming skills. In order to overcome this, a user friendly graphical user interface (GRDSS) for GRASS GIS was developed with all functionality of GIS and image processing (Figure 1). It aids decision-makers and planners as a decision support system to visualise the decisions with spatial and temporal dimensions along with capabilities to capture, store, process, display, organize, and prioritize spatial and temporal data.

Natural resource management for watershed requires collating and analyzing detailed land resource data. GRDSS was used to identify potential development sites by comparing actual sites for watershed management through digital elevation models (DEM). DEM is a representation of the continuous variation of relief over space that helps in assessing landscape characteristics along with topography and has a wide application in hydrological modeling. These characteristics help to determine slope steepness, slope length, flow directions, areas, boundaries and outlets of watersheds.