Estimation of Surface Runoff using Rainfall – Runoff Modeling of Warasgaon Dam Catchment

Estimation of Surface Runoff using Rainfall – Runoff Modeling of Warasgaon Dam Catchment - a geospatial approach

A. A. Kulkarni, S. P.Aggarwal & K.K.Das
Indian Institute of Remote Sensing,
4, Kalidas Road, Dehradun.
E- Mail: amol1_k@rediffmail.com

Introduction:
The term ‘precipitaion’denotes all forms of the water that reach the earth from the atmosphere, and runoff means the draining or flowing off of precipitation from a catchment area though a surface channel after satisfying all surface and sub surface losses. (Dubayah, R., et al, 1997) Establishing a mathematical relationship between the rainfall and runoff events.

Prediction of surface runoff is one of the most useful hydrological capabilities of a GIS. system. The prediction may be used to assess or predict aspects of flooding, aid in reservoir operation, or be used in the prediction of the transport of water born contamination (Jain, M.K., 1996). The type of models that have been applied with a GIS will be classified as lumped parameters, Physical based or some combination of the two. There has been a growing need to study, understand and quantify the impact of major land use changes on hydrologic regime, both water quantity and quality (Engman, E.T., et al, 1991). This is necessary to anticipate and minimize potential environmental detriment and to satisfy water resources requirements. Hydrological modeling is a powerful technique of hydrologic system investigation for both the research hydrologists and the practicing water resources engineers involved in the planning and development of integrated approach for management of water resources (Schultz, G.A., 1993). Hydrologic models are symbolic or mathematical representation of known or assumed functions expressing the various components of a hydrologic cycle. (Beven, K.J. et al., 1979).

The modified SCS model enables the hydrologist to simulates various designs alternatives and compare the results. The expression used in Modified SCS method is given as following Eq.s 1,2 & 3. Using the Land use/Land cover and Hydrologic Soil Group (HSG) map Curve Number (weighted CN) value has been calculated and further CNI and CNII values are calculated by following equations as,

CNI = (4.2*CNII)/(10 – 0.058*CNII) ----------- Eq.1

CNIII = (23*CNII)/(10 + 0.13*CNII) -----------Eq.2

For, daily rainfall S values are derived from the CN values using the following formula as

S = (25400 /CN) – 254 -----------Eq.3

Where CN is function of watershed hydrologic land use/land cover units, hydrologic soil groups and antecedent moisture conditions (USDA, 1972).

Study Area:
The proposed Warasgaon Catchment is located in the Pune district of Maharashtra state in the scenic surrounding of the Western Ghats. There are three dams and back water lakes in the surrounding vicinity namely Panshet, Warasgaon and Temghar. The backwater helps in maintaining the surrounding pleasant and cool. The area is approximately 20 km in length and about 5 km wide forming a beautiful valley, through which Mose river traverse in East – West direction. One end of the valley borders the coastal area of Konkan and other end extends up to the Warasgaon dam. The study area lies between the geocoordinates 18°21'00" to 18°25'48" North latitude and 73°25'12" to 73°37'12" East longitude. (Fig.1).

Fig. 1. Location Map

Page 1 of 5
| Next |