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Title: DRAINAGE NETWORK CHARACTERISTICS ON ERODING SOIL SURFACES

Author
item HELMING, K - ZALF, GERMANY
item PRASAD, S - UNIV. OF MISSISSIPPI
item Romkens, Mathias

Submitted to: Management of Landscapes Disturbed by Channel Incision Stabilization Rehabi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Surface topography and roughness substantially affects runoff distribution, surface incision and soil loss. Depending on surface flow concentration, incisions may be more or less severe. Accelerated erosion, particularly by rilling and head cuts, take place when flow velocities and concentration increase. This article reports on measurements performed on drainage network development on small plots of upland areas in different initial surface roughness conditions. The study was performed in a 0.6 m by 3.75 flume with simulated rainfall and a highly erodible soil. The results show that drainage network development on the upland areas are similar to those of large river systems, when expressed in terms of commonly used parameters for large river systems, such as Horton's ratio, bifurcation ratios, and length ratio. This information will be helpful in interpreting and predicting runoff and soil losses at the field scale level.

Technical Abstract: Studies were conducted to determine the surface flow pattern during a series of four rainstorm events and one overland flow test on a loess soil packed into a tilted flume of 3.7 m x 0.6 m x 0.3 m. Before and after each rainstorm/overland flow test, digital elevation maps (DEM's) of the cloddy soil surface were made. Runoff pattern and development of flow paths, were calculated from DEM's using Strahler's ordering scheme and Horton's ratios. Results showed interrill surface flow pattern as well organized and described with Horton's ratio. Bifurcation ratios Rb and length ratios R1 were comparable to those for large-scale river systems. Drainage densities Dd were about one order of magnitude larger. Gradients and sinuosity of flow paths decreased with increasing order. The degree of network organization increased with successive rainstorms of decreasing intensity. Changes in energy application from rainfall to overland flow led to a decrease in network organization.