ASSESSMENT OF RUNOFF POTENTIAL OF JHAL WATERSHED IN BEMETARA DISTRICT FOR IDENTIFICATION OF SUITABLE SITES FOR RAINWATER HARVESTING STRUCTURES
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Date
2020
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Indira Gandhi Krishi Vishwavidyalaya, Raipur (C.G.)
Abstract
Appropriate planning and management of natural resources like land and water on watershed basis is of outmost necessity for sustainable agricultural development. Knowledge of hydrological response for planning and effective utilization of water resources is important. Based on above fact a research study has been carried out on estimation of runoff volume and point out suitable sites for water conservation measures in a watershed.
The present investigation dealt with the use of geo-spatial techniques assessment of runoff potential based on SCS-CN model and identification of site suitable for rain water harvesting structures in the Jhal watershed of Bemetara district of Chhattisgarh state. The total area of watershed is 3250 ha and receives average annual rainfall of 1200-1500 mm. Various maps like watershed boundary, DEM, aspect, contour, slope, HSG, CN, drainage and land use/ cove were generated. The majority of the watershed area has very gently sloping (0-3%) lands. Morphometric parameters indicate that watershed has less distortion in drainage pattern. The circulation ratio and elongation ratio was found to be 0.52 and 0.66, respectively indicating that the watershed is elongated with low relief and has gentle slope. More than 80% area of the watershed is under agricultural land (2698 ha) and paddy is cultivated as a major kharif crop. More than 75% area of the watershed (2510 ha) has very deep clayey soils occurring on the very gentle to gentle sloping land (< 5% slope) with low permeability or infiltration rate with C and D (2510 ha) type of Hydrological Soil Groups.
Results revealed that for the period of 2014-2018, the year 2018 had the highest annual rainfall of 1398.8 mm with coefficient of variance of 112.2 % for the monthly rainfall. The runoff potential of the watershed was estimated by using SCS-CN method and geospatial techniques of RS and GIS for the period of 2014-2018. The year of 2018 was a rainfall excess (15%) year whereas the year of 2015 was a deficit year as it received rainfall less than 75% of normal rainfall. The year of 2018 contributed the highest runoff volume of 28.27 Mm3 and the year of 2015 contributed the lowest runoff volume of 15.39 Mm3.
Five thematic layers, viz., land use/cover, slope, HSG, soil texture and soil depth were considered for identification of appropriate places for conservation measures. Weights were also considered which has been determined by using AHP and Satty’s criteria along with weighted linear combination 0.41, 0.25, 0.16, 0.13 and 0.05 were assigned to each layers, such as land use/cover, slope, HSG, soil texture and soil depth respectively. The assignment of relative ranking was found to be consistent as CR is 6%, which is less than 10%. The entire area of the Jhal watershed was delineated into four suitability classes for rainwater harvesting structures. It was observed that the maximum area of watershed belongs to highly suitable class (8.0 – 9.0) for rainwater harvesting with an area about 2311 ha.
Based on the IMSD guidelines, two types of rainwater harvesting structures namely check dam and farm ponds has been proposed other than existing structure 6 sites for check dam and 30 sites for farm ponds were identified for the Jhal watershed.
On the basis of this study, it can be concluded that the excess runoff from a watershed can be utilized more effectively by providing water harvesting structures.
Description
ASSESSMENT OF RUNOFF POTENTIAL OF JHAL WATERSHED IN BEMETARA DISTRICT FOR IDENTIFICATION OF SUITABLE SITES FOR RAINWATER HARVESTING STRUCTURES