Thursday, November 16, 2006 - 9:30 AM

Runoff Prediction in Harvested Pine Stands in Central and Lower Alabama.

Emily Carter1, J.P. Fulton2, Christian Brodbeck2, and Brian Burton2. (1) USDA, Forest Service, USDA - Forest Service, 520 Devall Dr., Auburn, AL 36849, (2) Auburn Univ, 200 Corley Bldg, Biosystesm Engineering Dept, Auburn, AL 36849

Harvested landscapes are prone to erosional processes that result in soil and nutrient losses and redistribution that can alter site productivity. Previous studies have relied on installation of bound plots to isolate a portion of the harvest tract to determine erosion rates and nutrient loss. The question arises as to the utility of the installation of bound plots in providing relevant erosional information. Highly accurate spatial data, especially with vertical or elevation measurements, can be used to construct digital elevation models (DEMs). The application of DEMs to harvested stands has the potential to determine runoff flow paths to identify accumulation points and contributing areas to better evaluate erosion on a landscape basis. Two studies were initiated in central and lower Alabama to evaluate soil response to harvesting/thinning operations and evaluate the erosion potential by construction of DEMs. One meter DEMs were generated by Real-Time Kinematic (RTK) GPS derived elevation data to model flow paths of water movement developed by Topogrid and ArcHydro. This process was initially tested by constructing silt fences in five locations of similar length and steepness on a site restored to longleaf pine (Pinus palustris Mill.) after removal of slash pine (P. elliotti Engelm.) in the Conecuh National Forest, Alabama. Flow paths were observed to intersect silt fence locations in all locations with Topogrid. One meter DEMs were constructed from RTK derived elevation data in a thinned loblolly pine (P. taeda L.) stand near Lake Martin, Alabama and placement of silt fences at pour points determined from flow paths predicted by Topogrid and ArcHydro. Both spatial analysis processes identified similar pour points on the landscape. Results have indicated that DEMs can be used to optimize installation of collection systems through identification of collection points and contributing areas.