Development of Dynamic Non-Hortonian Watershed Models for Steeply Sloping Forested Watersheds: Application to Eastern Kentucky

A comprehensive conceptual watershed model is developed to simulate the hydrologic response of steeply sloping forested watersheds. Two non-Hortonian and two Hortonian models were first tested with data from selected watersheds in West Virginia and eastern Kentucky in order to understand the different mechanisms of flow responsible for storm hydrograph generation in this type of watersheds. The two non-Hortonian models tested were the kinematic storage model (Sloan et al. 1983) and the saturation deficit model (Beven and Wood, 1983). Both models were unable to adequately reproduce the observed hydrographs in the four forested watersheds considered in this research. The two Hortonian models tested were Clark\u27s unit hydrograph model and Snyder\u27s unit hydrograph model. These two models were able to reproduce the observed hydrographs only through model calibration with unrealistic parameter values. Based on the conclusions from the testing of the two non-Hortonian and the two Hortonian models, a simple conceptual comprehensive watershed model was developed for predicting storm hydrograph from small, steeply sloping forested watersheds. The conceptual model incorporates all types of flow processes including macropore flow (quick response subsurface flow). An evaluation of the resulting model was made using the data from the previously mentioned four watersheds in West Virginia and eastern Kentucky. The model predicted with reasonable accuracy the response of these watersheds to precipitation. The results indicate that the model is capable of simulating the hydrologic response of this type of watersheds while at the same time depicting the actual flow mechanism in play