Landscape Impacts On Sediment Source and Transport within a Southwestern Oklahoama Watershed.

Agricultural constitutes one of the earth’s major land uses and produces food, fiber, fuel, and other products that sustain life and human economies.  While agricultural productivity increases over the past century constitute one of humanity’s greatest success stories, there have been many unintended effects of agricultural practices and systems on the environment.  Agricultural watersheds are commonly identified as having water quality impairments due to sediment and nutrient loads, along with additional contaminants transported with water and sediment movement.   While there is a large body of knowledge about impacts of agriculture on soil and water resources at the field scale, it remains difficult to quantify such impacts at the watershed scale.  Research was conducted from 2005-2009 in the Fort Cobb Reservoir, where computations estimated an agricultural sediment load to the reservoir of 276,000 metric tons per year and a phosphorus load of 70 metric tons per year, to quantify management impacts, such as cropping pattern, nutrient management, tillage practices, and stream corridor conservation practices on suspended sediment and nutrients in the streams and sediment and nutrient delivery to the reservoir, to target mitigation of negative environmental impacts of agricultural systems in this watershed.  However, to quantify management effects on water quality, it is necessary to quantify impacts of temporal effects such as climate variability over the period of observation and spatial effects, such as basic physiographic variability within the watershed.  Specifically, the objectives are to quantify temperature and precipitation impacts on temporal patterns of suspended sediment over the five-year period, quantify the climate and physiographic properties of the contributing area on spatial autocorrelation patterns of suspended sediment within the watershed, and quantify correlation of suspended sediment to management practices within contributing areas above the sampling sites.