An investigation of the effect of drainage density on hydrologic response

The sensitivity of streamflow simulations to the drainage density of river basins was investigated. A physically based spatially distibuted hydrologic model was used in the model experiments. The hydrologic model was applied to the Monongahela river basin in the United States of America for the simulation of 1988 and 1993 hydrologic regimes for selected periods between April and July. Model simulations of streamflows for 3 different drainage density scenarios (0.2, 0.24 and 0.38 km-1) were compared against the observations. Evaluation of the model results indicated that the hydrologic model response changes significantly for the prescribed drainage densities. In general, the hydrologic model overestimated the stream discharges in response to an increase in drainage density. This outcome was attributed to an increase in the number of channel pixels, and thus an increase in the subsurface flow contribution to the total streamflow. © TÜBITAK