Abstract
Present study uses decision support system “WARIS” for identification of suitable sites for water harvesting structures. The study has been conducted for upper Betwa watershed of Betwa basin, which covers 1385.61 sq km area. Theme layers viz , landuse / landcover, soil, slope, hydrogeomorphology etc which affect the identification of suitable sites were generated in Arc/INFO environment. The themes were then integrated to generate a composite coverage. A buffer of 1 km around second and third order drainage was constructed. Suitable weights were given to all the categories in each theme. The cumulative weighted values were calculated for each polygon of the composite theme map falling within buffer area. Three suitability zones viz most suitable, more suitable and suitable were generated from cumulative weighted value. Lineament map was also superimposed over the suitability zones. Various water harvesting structures like nala bund, anicuts, farm ponds etc were suggested in the area. WARIS has provided a guided flexible approach for identification of suitable sites making it versatile for any type of terrain.
Introduction
Water harvesting has to be done on watershed basis, as watersheds are natural hydrologic units. Management of water resource done in this way is more effective. Watershed is characterisied by many parameters like land use, soil, hydrogeomorphology, morphometric characteristics etc. Output from similar watershed is often similar. With a suitable structure it is possible to harness maximum amount of water from the watershed. Location and type of structures depend upon soil, land use / landcover, drainage pattern, geomorphology etc.
To analyse all the affecting themes and come up with a solution for water harvesting, resource information and decision support systems are need of the time. Water Resources Information and Decision Support System package (WARIS) is designed as a system that uses geographic data, with associated ancillary data to derive information required by resource managers in a time effective manner. WARIS is intended to provide data to resource managers, in a way that allows the manager to understand data and its implications so as to construct a tactical knowledge model before making a management decision. WARIS has various analysis facilities and identification of water harvesting sites is one of them. Present study analyses upper Betwa watershed for identification of water harvesting sites using package WARIS developed over Arc/INFO GIS.
Study Area
The study area covers 1385.61 sq km and falls in parts of Bhopal and Raisen districts in Madhya Pradesh. Agricultural land use covers 38.57% of the study area. Notified forest covers 26.07% of the area. Nearly 10.85% area is in forest category but falling outside notified forest. Land with scrub category covers 14.01% of the area. Water bodies cover 1.88% area under study. Watershed is mostly level plain with 37.15% area under 0 – 1 percent slope category. Around 12.77 % area is under 5 – 10 percent slope category. Higher slopes occupy around 10% of the watershed. Around 85% of the area falls under slope categories less than 10%. Hydrogeomorphically area is dominated by ridge type structural hills, which cover 44.79 %. Dissected lower plateau covers 51.54% of the area. 13 different soil units are also found in the area. Ground water prospect map shows that 51.53% area is under good to moderate category and 44.78% is under poor to nil categories. There is hardly any area under excellent category. Total length of drainage is 2377.61 km with order of drainage being 6 in the area. General elevation in the area varies from 660 m to 420 m.
Data Used
IRS LISS III data for August 1999 and March 2000 were used for generation of resource themes. Collateral data from various other sources were also utilized in the analysis.
Analysis
For identification of water harvesting sites following analysis was done:
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Generation of various theme maps
- Customization of maps in WARIS
- Analysis through WARIS for identification of structures
Generation of various Theme Maps
Various theme maps, which affect the water harvesting in any area, were generated either through satellite data or through other sources. The coverage’s were generated in Arc/INFO as per standard NRIS format.
Customisation of Maps in Waris
WARIS is a generalized package, which accepts data for any area. A WARISCUSTOM file integrates all the themes with the package WARIS. The package has many analysis facilities out of which generation of water resources development plan is one.