Modeling the impact of land use change on the hydrology of a rural watershed

Land use dynamics can have a significant impact on watershed hydrology. In this study, we develop a land use dynamics model coupled with a spatially distributed three-dimensional surface-subsurface hydrologic model. The coupled model is applied to the Bartin spring watershed, a rural watershed located in the northwestern Turkey. The land use dynamics model considers natural and anthropogenic transformations between land use categories classified as coniferous forests, deciduous forests, agriculture and settlement. The processes considered in the hydrodynamic model are evapotranspiration, overland flow, river channel flow, and saturated/unsaturated subsurface flow. The link between the land use model and the hydrodynamic model is through the vegetation parameters: leaf area index (LAI) and root depth (RD). The land use and hydrologic models were calibrated using satellite maps and daily flow and meteorological data, respectively. The correlation coefficient between the simulated and observed daily discharges for the considered watershed was about 0.72, indicating good agreement with observed data. The coupled model was used to simulate the water budget based on alternative land use and forest management scenarios. Results show that the water budget is most sensitive to variations in precipitation and conversion between forest and agricultural lands but is less sensitive to the type of forest stands. Overall, it is shown that the coupled model is a useful tool for assessing the impact of land use change on the watershed hydrological processes. (C) 2013 Elsevier B.V. All rights reserved.