Rainfall-Runoff Simulation in Cache River Basin, Illinois, Using HEC-HMS

Rainfall-runoff simulation is an essential step in analyzing the impacts of extreme flood events. This can aid in water resource management and planning. In areas that are prone to floods, it becomes necessary to perform an extensive hydrological study. Cache River watershed is one of the flood prone watersheds in Illinois, mainly due to the confluence of two large rivers Mississippi and Ohio, in southern Illinois. This study utilizes hydrological modeling system (HEC-HMS) for simulation of Cache River watershed to analyze the response of rainfall and runoff. Rainfall-runoff modelling helps in estimating peak flows which is very essential to strategize water resources management. This model also incorporates ArcGIS extension HEC-GEOHMS, which performs geospatial analysis and generates the hydrologic modeling inputs for the HEC-HMS model. SCS unit hydrograph method was used for runoff estimation depending on the available parameters to be estimated. Daily precipitation data, elevation data, percentage of impervious, and curve number, which takes into account the land use and soil characteristics of the watershed was used as model inputs for the HEC-HMS model. The model was then calibrated by taking a set of storm events occurring in the catchment from 2010 to 2015. Another set of storm events was used for validation of the model. The model performance was evaluated by using various statistical indices. The model, thus developed, can be used to manage different flood evens and adopt effective decision and warning systems.