HR: 0800h
AN: H11F-0357    [Abstracts]
TI: Rainfall-Runoff Interaction in Shallow Flows and Its Effect on Rill Erosion
AU: * Ventura, E
EM: eventura@uaq.mx
AF: University of Queretaro, School of Engineering C.U. Cerro de las Campanas, Queretaro, QRO 76010 Mexico
AU: Nearing, M A
EM: mnearing@tucson.ars.ag.gov
AF: Southwest Watershed Research Center, 2000 E. Allen Road , Tucson, AZ 85719 United States
AU: Dominguez, M A
EM: migueld@uaq.mx
AF: University of Queretaro, School of Engineering C.U. Cerro de las Campanas, Queretaro, QRO 76010 Mexico
AU: Mobayed, N
EM: nabil@uaq.mx
AF: University of Queretaro, School of Engineering C.U. Cerro de las Campanas, Queretaro, QRO 76010 Mexico
AB: Rill erosion is a dynamic process consisting of the detachment and transport of soil materials by concentrated flow. A considerable amount of soil is lost in this form in many parts of the world, causing both on-site and off-site problems. Rill erosion does not occur as an isolated process in nature. In fact, while detaching and transporting soil, raindrops impact the flow causing some of the flow characteristics to change. However, the information on this interaction is not well known or not readily available. The objective of this study was to evaluate the rain-runoff interaction and its effect on the process of rill erosion. The methodology included the evaluation of two rainfall intensities, three different slopes and four different inflow rates, with three replicates, in a simulated rill. Rainfall was applied with a Norton type rainfall simulator. In general, it was observed that rill erosion detachment rate due to runoff alone was greater for increasing values of rainfall intensity, slope and discharge. Rill erosion factor, Kr, defined as the rate of soil detachment per unit of hydraulic shear stress, tau, was greater for the rain-runoff interaction than it was for the runoff alone. Critical shear stress, tau-c, or the value at which initiation of detachment occurs was greater for higher intensities and slopes and for the interaction of rain-runoff. The Mean Weigh Diameter (MWD) of sediments was only significantly different for the interaction rain-runoff for the 16 percent slope and inflow rates of 6 liters per minute (lpm). No significant differences were found for the rest of the treatments. Most of the sediments under low rain intesities and gentle slopes had an average MWD of 0.13 mm. This value increased up 1.50 mm for the high inflow rate and slope. In conclusion, rill erosion increased significantly due to the interaction of rain and runoff and the effect was greater for steeper slopes and higher rainfall intensities. This interaction must be considered in soil erosion models to make a better prediction of this water erosion process.
DE: 1894 Instruments and techniques
DE: 1815 Erosion and sedimentation
DE: 1854 Precipitation (3354)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting