A PHYSICALLY-BASED, MANAGEMENT-ORIENTED, FOREST HYDROLOGY MODEL
Abstract
The past few decades have seen tremendous advances in the area of hydrologic and water quality modeling. The vast majority of the water quality models have emphasized agricultural areas as the major contributors to water pollution. However, forest managers have observed that some forest management practices have a detrimental effect on the quality and quantity of runoff water. Agriculturally based models have been used for forest areas, but the forest hydrologic system is significantly different from agricultural systems. The interflow processes of seepage and pipe flow are the major flow mechanisms in the forest, while overland flow is usually emphasized in agricultural areas. To provide a realistic estimate of the hydrologic and water quality impact of forest management changes, additional hydrologic developments are required. The objectives of this project were to develop and incorporate hydrologic relationships for the forest system into a distributed, watershed model called ANSWERS. This model is to be used for estimating the forest management effects on the hydrology and runoff from forest systems. The developed forest hydrology model utilizes the interflow components of seepage and pipe flow for the majority of the flow processing. The model applies a new seepage element located at the impeding layer in the soil. The model simulates the characteristics of return flow to the surface as in the partial contributing area concept. Validation of the model was done with actual runoff data from five watersheds in northern Mississippi and two watersheds from the mountainous areas of southwestern North Carolina. The model produced reasonable results for many of the events simulated, but not for all events. Peak flow rates were overestimated and runoff volumes were underestimated on watersheds exhibiting large baseflow contributions. Estimates of parameter modifications for different forest management scenarios are discussed. Additional validation of the management practices is required before the model can be utilized as a planning tool.
Degree
Ph.D.
Subject Area
Agricultural engineering
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