Runoff Estimation of the Kolong River Basin in Assam, India Using NRCS-Curve Number Method and Geospatial Techniques

Abstract

Rainfall and runoff contribute significantly to the functioning of the hydrological cycle and thus constitute the most integral components of the hydrological environment of a region. The surface runoff generated basically by rainfall is highly responsible for floods in the floodplains of a river basinRiver basin. Therefore, it is very important to find out the complex and intricate rainfall-runoff relationship of a river basin in order to understand its hydrological environment, on the one hand, and to manage the associated fluvio-geomorphic problems on the other. The estimation of runoff also helps in watershed management practices. The present paper is, therefore, an attempt to investigate and estimate the surface runoff of the Kolong river basinKolong river basin in Assam considering the rainfall data series of 2004–2018. An analysis of runoff frequency assessment has been carried out in the study to examine the probabilities of occurrence and their corresponding recurrence intervals attached to the estimated runoff magnitudes of the basin. The Natural Resource Conservation Service Curve Number (NRCS-CN) model has been applied integrating with the Remote Sensing and GISRemote sensing and GIS techniques to estimate and predict the runoff volume based on the rainfall pattern of the given years. The curve number (CN) method, also known as the hydrological soil cover complex, takes into consideration several properties of a basin, like soil permeability, land use, and antecedent moisture conditions (AMCs). In this regard, streamflow, hydrologic soil groups (HSGs), slope, and land use land cover maps have been generated using satellite images in a GISGeographic information systems (GIS) environment. However, the CN parameter values corresponding to various HSGs and land use and land cover conditions of the basin have been selected from the NRCS standard table.