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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Watershed Physical Processes Research » Research » Publications at this Location » Publication #323054
Title: Improving watershed management practices in humid regions

Author
item ZIMALE, FASIKAW - Bahir Dar University
item TILAHUN, SEIFU - Bahir Dar University
item TEBEBU, TIGIST - Cornell University
item GUZMAN, CHRISTIAN - Cornell University
item HOANG, LINH - New York City Department Of Environmental Protection
item SCHNEIDERMAN, ELLIOT - New York City Department Of Environmental Protection
item Langendoen, Eddy
item STEENHUIS, TAMMO - Cornell University

Submitted to: Hydrological Processes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2017
Publication Date: 8/16/2017
Citation: Zimale, F.A., Tilahun, S.A., Tebebu, T.Y., Guzman, C.D., Hoang, L., Schneiderman, E.M., Langendoen, E.J., Steenhuis, T.S. 2017. Improving watershed management practices in humid regions. Hydrological Processes. 31(18): 3294-3301. DOI: 10.1002/hyp.11241.
DOI: https://doi.org/10.1002/hyp.11241

Interpretive Summary: Soil erosion and nutrient management is most effective when conservation practices are applied to runoff source areas. Conventional control practices developed for areas where rainfall intensity exceeds the soil infiltration rate have been unsuccessful in reducing sediment and nutrient concentrations in the (sub)humid region of Ethiopia. In collaboration with researchers of Bahir Dar University, Ethiopia, Cornell University and the New York City Department of Environmental Protection, scientists at the USDA, ARS, Watershed Physical Processes Research Unit conducted watershed studies on three continents (Africa, Central America, and North America) to show the prevalence of runoff generation caused by soil saturation processes in both temperate and (sub) humid monsoonal climates. Watershed runoff was generated at degraded areas with a perched water table over a slowly permeable layer and the bottom lands with a high regional ground water table. The bottom lands are also the source of gullies and dissolved phosphorus in the stream. Thus priority in landscape interventions should focus to re-vegetation of the degraded areas and to gully rehabilitation in the saturated bottom landscape. Finally for nutrient control, application of fertilizers and manure should be avoided on the source areas.

Technical Abstract: Understanding the basic hydrology and erosion is vital for effective management and utilization of water resources and soil conservation planning. To improve the understanding we used watershed studies on three continents. The results show that in well vegetated (sub) humid and temperate watersheds independent of location, the surface soil had generally greater infiltration rates than the prevailing rainfall intensities. This implies that in both temperate and (sub) humid monsoonal climates direct runoff and erosion can only be generated from well vegetated areas when the soil is saturated near the surface. Watershed runoff was generated at degraded areas with a perched water table over a slowly permeable layer and the bottom lands with a high regional ground water table. The bottom lands are also the source of gullies and dissolved phosphorus in the stream. Thus priority in landscape interventions should focus to re-vegetation of the degraded areas and to gully rehabilitation in the saturated bottom landscape. Finally for nutrient control, application of fertilizers and manure should be avoided on the source areas.