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ARS Home » Midwest Area » Columbia, Missouri » Cropping Systems and Water Quality Research » Research » Publications at this Location » Publication #319734

Title: A process-based algorithm for simulating terraces in SWAT

item SHAO, HUI - University Of Guelph
item GAO, JIANEN - Northwest Agricultural & Forestry University
item Baffaut, Claire

Submitted to: Annual International SWAT Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/8/2015
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Terraces in crop fields are one of the most important soil and water conservation measures that affect runoff and erosion processes in a watershed. In large hydrological programs such as the Soil and Water Assessment Tool (SWAT), terrace effects are simulated by adjusting the slope length and the USLE P-factor. A process-based terrace algorithm, activated at the hydrological response unit (HRU) level, was developed and incorporated into SWAT (version 2009) to simulate the environmental effects of different kinds of terraces, i.e., normal and bench terraces. Normal terraces are common in the US and are designed to hold water no longer than 24 or 48 hours. Bench terraces are more common in Asia, on steeper slopes, and they can hold water for longer periods. The modified SWAT model was evaluated in both field and watershed scales using runoff, sediment, nutrients, and plant yield data in China and the US. Terrace effects on soil erosion and sediment transport in the upstream and middle sections of the Weihe River basin in the Loess Plateau were further analysed using this new tool. Results indicated a 10.6 percent (28 million tons) sediment reduction in the upstream and middle sections of the Weihe River because of terrace installation. Terraces were also estimated to have decreased sediment transport at the outlet of the watershed by 16.2 million tons per year. The unit area sediment reduction from terrace installation was 3000 t/km2. Scientists, water resources managers and conservationists will benefit from this process-based algorithm. Future development of a GIS powered integrated modelling user interface will facilitate decision makers in evaluating and optimizing terraces from both environmental and economic perspectives.