Submitted to: Shuili Xueabao
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2001
Publication Date: N/A
Interpretive Summary: Laboratory experiments were performed to better understand the development and geometry of eroding soil. Most severe erosion of soil by water occurs as rills, or small channels within fields, that are cut by water running off the land during rainstorms. These experiments were conducted so that we can better understand the basic process of how these small channels develop, and specifically, how they change in shape over time during a rain. We ran experiments using several levels of water flow rates and slopes of the soil surface. We observed in the results some specific patterns of alternation between wide flows and narrow flows, which we believe develop as a function of the basic physics of the flow system. These results have important implications for helping us to understand, quantify, and ultimately control erosion on agricultural and other disturbed lands. The impact of this work will be better methods of controlling erosion on agricultural lands, and hence, increased long-term productivity of American agriculture.
Technical Abstract: A series of flume experiments were conducted to understand shallow water hydraulics, erosion in rills, as well as morphological patterns of a rill as effected by rill bed slopes and inflow rates. The soil used was Cecil soil, a sandy loamy soil. Four flow rates: 3.8, 7.6, 11.4 and 15.2 l/min and 4 slopes: 1 percent, 3 percent, 5 percent and 7 percent were adopted in the experiments. The velocities, rill widths and sediment concentrations at the outlet were recorded and analyzed with multi-variable regression method as functions of slopes, inflow rate and/or their interactive terms. Rill widths changing along the rill with certain periodical patterns were visually observed. A mathematical model was advanced to describe these changing patterns of rill width. Sampling length for transport capacity was determined with the analysis of both sediment yields and width patterns.