Rain Fall Run Off Estimation In a Small Watershed Using Satellite Data And GIS Technique.
LECTURER, GEOLOGY DEPT.
V. HARI PRASAD
IIRS DEHRADUN, India
Hydro logical models are divided in two groups mainly 1. Stochastic 2. Deterministic model . In this deterministic model system is spatially arranged as a single point in space without dimensions. Mainly rainfall run off models like HEC-1, SCS -CN, AGNPS, SCS. In present studies SCS model has been used to stimulate. The main rainfall events and direct run off stimulate. The main study area is in darer watershed covering the part of Doon valley (western portion of Dehradun west of 15km from main Hathi Barkla area), extend from Lat. 30° 20' to 30°25'5.8''N and Long. 77°56' 20" to 77°57'53.0" E., using SOl Topo sheet No.53F/15, Geocoded imagery of two different dates IRS-IC Liss - iii 19th october 1997, digital data of 9th Feb. 1997, FCC and total work has been canied out in GIS and GPS environment, to create a data base for the watershed. IL WIS, SURFUR, IDRS, MS-office software has been used to generate data base.
The prime objective of this study is to create spatial watershed database such as LU/LC classification, HSG for estimation of surface run off with the help of SCS method, for estimating floods on small to medium sized ungauged drainage basins in rural as well as in urban area which is mostly use full in rainfall run off modeling. Magellan GPS has been used in the field area in the prediction of exact pin pointed outlet boundary of watershed and LU/LC classes their changes and difference in soil classes (A BCD ).
The rainfall run off relationship for four months is established. The percentage of run off is varying from 5% to 28% with minimum in Sept. to maximum in Aug. The average percentage of run off is estimated as 21 %. The regression model is developed between rainfall and run off is Y=0.00048 x2 0.139*+0.3342 in broader sense.it could be concluded that model can be applied for estimating run off and evaluating. on struvtures the darer watershed area. Recharge structures are also suggested to villagers and .farmers during the field work and also checking of GCP check work.