Abstract
In this study, a simple travel time-based runoff model was proposed to simulate a runoff hydrograph on soil surfaces with different microtopographies. Three main parameters, i.e., rainfall intensity (I), mean flow velocity (v m) and ponding time of depression (t p), were inputted into this model. The soil surface was divided into numerous grid cells, and the flow length of each grid cell (l i) was then calculated from a digital elevation model (DEM). The flow velocity in each grid cell (v i) was derived from the upstream flow accumulation area using v m. The total flow travel time through each grid cell to the surface outlet was the sum of the sum of flow travel times along the flow path (i.e., the sum of l i/v i) and t p. The runoff rate at the slope outlet for each respective travel time was estimated by finding the sum of the rain rate from all contributing cells for all time intervals. The results show positive agreement between the measured and predicted runoff hydrographs.
Highlights
Surface runoff is an important agent of soil detachment and sediment transportation on hillslopes [1]
In the past several decades, the effect of depression storage on surface runoff has been considered in many laboratory experiments
We define the flow length of rainwater travel within cell i as li, and the amount of time it takes rainwater to travel through cell i is defined as ti. ti can be obtained by dividing li by the flow velocity vi in cell i
Summary
Surface runoff is an important agent of soil detachment and sediment transportation on hillslopes [1]. In the natural environment, runoff generation on hillslopes is a complex process highly affected by many factors, such as soil infiltration, rainfall quantity and timing, and slope and soil properties [4,5,6,7]. Soil surface roughness is another important factor impacting surface runoff generation because it affects depression storage [4]. In the past several decades, the effect of depression storage on surface runoff has been considered in many laboratory experiments. These studies did not take into account the PLOS ONE | DOI:10.1371/journal.pone.0130794. These studies did not take into account the PLOS ONE | DOI:10.1371/journal.pone.0130794 June 23, 2015
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