HYDROLOGICAL RESPONSE CHARACTERIZATION OF THE SUBSURFACE FLOW IN HILLSLOPE: A REVIEW

The article explores the concepts and techniques of hillslope hydrology, various pathways that water travels in a hillslope to the stream networks. Topographic characteristics such as elevation, gradient, orientation, hillslope length, longitudinal and transverse curvatures play an important role for enrouting water. These characters not only influence the volume and time of water runoff but influence its quality through control of flow patterns and water travel time distributions across the hillslope. Tracer studies estimate the velocity of the flow, which can present the information about the paths of the underground flow. However, it is observed that physical measurement of these flow paths is complicated and need more time besides difficult to collect data, since the soil parameters vary spatially, initial moisture varies and usually, the datasets available exclude extreme hydrological events. Computational modeling then appears quite worthwhile asset in this regard as it allows simulating and studying hydrological responses, which does not need a substantial amount of empirical data. Hydrological catchment modeling has changed over the past decades, at least when it comes to understanding watershed behaviour, which was formerly an engineer-bound solution and now a scientific process of hypothesis testing and understanding.