Laserfiche WebLink
t ? <br />Executive Summary <br />Historical and Future Impacts of Vegetation Management <br />and Natural Disturbance on Water Yield from <br />Forest Service Lands in the South Platte River Basin <br />C. A. Troendle, J. M. Nankervis, and A. Peavy <br />This report addresses the prediction, or modeling, of the historical range in variability of <br />water yield and the consequence of present and future National Forest System (NFS) <br />management activities and natural disturbance from fire and insects on water yield from <br />the South Platte River Basin. The vegetation data, activity (management) data, and <br />disturbance data needed for the simulations were provided by staff on the three national <br />forests in the South Platte River Basin. Data acquisition was coordinated by the Forest <br />Service Rocky Mountain Regional Office (R2). <br />Iuitially, the reference (1997) water yield was simulated using current or existing forest <br />condition, other scenarios then were superimposed on current stand conditions and <br />response in water yield was simulated to reflect the following: <br />a) Historical stand conditions and attendant water yield simulations for 1860 to <br />present <br />b) Current forest stand conditions were projected into the future for three 20 year <br />time cycles to evaluate the effect of a no human intervention and no natural <br />clisturbance scenario on future water yield <br />c) Current stands were projected into the future under a no human intervention <br />scenario but allowing stand conditions to be altered to reflect the impact of <br />natural clisturbance on current vegetation. <br />d) The impact of management activities imposed on NFS land in the South Platte <br />River Basin from 1997 to 2005. <br />The updated version of the WRENSS Hydrologic Model was used for the simulations. <br />For this assessment, each Forest provided similar polygon information for lands within <br />the watershed boundary. The result was the development of a GIS database containing <br />stand-level information characterizing specie composition, age class, aspect, elevation, <br />monthly precipitation, and some post-1997 disturbance, or activity, data. Less than 1 <br />percent of the NFS land in the South Platte River Basin is on the MBR National Forest <br />while 53 percent is on the PSI National Forest and 47 percent is on the AR National <br />Forest.