Abstract
The 989 square mile Cheney Lake Watershed in Central Kansas serves as the primary water source for the City of Wichita. It is located in South Central Kansas just west of Wichita in Reno County. The Cheney Lake Reservoir is essential for culinary water and recreation activities such as camping, fishing, and water sports. Sediment loads from the contributing watershed catchment have been negatively impacting water quality and causing severe accelerated aggradation of the lake bed. The Cheney Lake catchment area is a designated special emphasis watershed for a Conservation Effects and Assessment Project (CEAP). Five USGS depth integrated samplers were installed in 1996 to determine annual contributions of suspended load. The load data from these samplers are being used to calibrate and validate the USDA AnnAGNPS (Annualized AGricultural Non-Point Source) – CEAP (Conservation Effects Assessment Project) model. Because the ANNAGNPS model accounts for all sources of suspended load including upland, concentrated flow, gullies and others received in the USGS depth integrated sampler, it is essential to have a reliable assessment of the streambank erosion contribution. In 2006, 26 percent of the stream lengths in the watershed were field surveyed and the rest of the watershed stream lengths were assessed using GIS data to determine height and length of eroded sites. Then ten sites were chosen to represent a range of stream bank erosion conditions. The sites rank from slight to extreme rates of erosion. At each site a set of fourteen rebar pins were installed, three sets of 4 pins to define the toe, middle, and top of bank along the erosion site and two benchmarks on either side of the channel. The erosion at each pin has been measured and the pins were reset yearly to measure stream bank recession rates. Field checks and measurements were made in 2006 and 2007 to evaluate the accuracy of using GIS data for stream bank heights and streambank lengths associated with the respective condition class erosion pin site. The USDA Natural Resources Conservation Service Water Quality and Quantity Technology Development Team has developed, and is presently testing, an innovative process using bank-pin erosion data to accurately analyze survey data and calculate the stream bank lateral recession rate. Data has been cooperatively measured and recorded by the Cheney Lake Company, Reno Conservation District, and the Natural Resources Conservation Service for four years. In 2011, five years of data will have been collected from all ten sites. The non-cohesive Ninnescah-Kanza coarse textured soils present on the sites also represent a substantial portion of the Midwestern state soils found on stream banks and floodplains. The results of this streambank lateral recession study can be applied to numerous locations and provide planners access to reliable erosion rates based on a general condition class evaluation sheet such as a Bank Erodibility Index Class. This presentation discusses the results, the utility of this project, and the use of macro-developed software to aid field personnel in appropriately assessing streambank erosion rates in their respective watersheds. The data is being used to develop and test methodologies and protocols by practical field experience and data input requirements.
Published Version
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