Influence of Geomorphology on Runoff Characteristics of A Catchment

Abstract

Morphometric analysis for deriving the geomorphological parameters of the Thuthapuzha river basin was performed using GIS platform. GIS is proven to be an efficient tool for hydro-geomorphological studies. The geomorphological parameters and the processes associated with geomorphology gives a better understanding of the hydrological processes within the basin. The derived Geomorphological parameters for Thuthapuzha river basin show a dendritic type of drainage network with elongated basin. As the Thuthapuzha river basin exhibits higher stream velocity, the basin is highly prone to soil erosion and the stream erosion is more predominant than sheet erosion. The total percentage variance explained by all the factors is about 83.9%, when the factor analysis which is a good approach for finding the significant parameters is conducted. Among the percentage variance explained by each factor, the runoff factor exhibits the highest percentage variance of about 37%. The highest correlation coefficient is obtained between runoff and the length of overland flow, and the constant of channel maintenance which are more significant. Factor analysis shows that the form factor, elongation ratio, and circulatory ratio, exhibits shape characteristics which are more important after the runoff factor. Factor analysis eliminates the insignificant parameters which may be discarded in the regression model with least loss of accuracy. The variables with large values of factor score from the factor analysis is considered as the independent variables in the regression analysis. The length of overland flow, constant of channel maintenance, elongation ratio and rainfall are used as the independent variables for estimating the runoff. R 2 obtained through the regression analysis is 97.85%, a statistically significant value indicating the goodness of fit for the regression equation. Regression analysis revealed that the constant of channel maintenance has a positive impact on the runoff whereas the elongation ratio revealed a negative impact on the runoff. The regression analysis show that the rainfall exhibit more contribution to the runoff, as expected.