Research about Linganore Creek Watershed

USGS2015

Sources of fine-grained sediment in the Linganore Creek watershed, Frederick and Carroll Counties, Maryland, 2008-10

Sediment fingerprinting quantifies the delivery of fine-grained sediment from a watershed and sediment-budget measurements quantify the erosion and deposition of fine-grained sediment. Both approaches were used in the agricultural and forested 147-square-kilometer (km 2 ) Linganore Creek watershed in Maryland from August 1, 2008 through December 31, 2010, to determine the sources of fine-grained (less than 63 microns) sediment, and the amount of fine-grained sediment eroded from and deposited on streambanks, flood plains, channel beds, and agricultural and forested uplands. Sediment-weighted results of sediment fingerprinting for 194 suspended-sediment samples collected during 36 storms indicate that streambanks contributed 52 percent of the annual fine-grained suspended-sediment load, agriculture (cropland and pasture) contributed 45 percent, and forests contributed 3 percent. Fifty-four percent of the Linganore Creek watershed is agriculture and 27 percent is forest. Sediment-budget calculations were based on field measurements and photogrammetric analyses and indicated that the highest percentage of fine-grained sediment was eroded from agriculture (86 percent), followed by streambanks (10 percent), forests (3 percent), and the channel bed (less than 1 percent). Results of the sediment budget indicated that the highest percentage of fine-grained sediment was stored in ponds (57 percent), followed by flood plains (32 percent), streambanks (6 percent), and the channel bed (5 percent). Typical of most sediment budgets, the final sediment budget indicated erosion of 4.70 x 10 7 kilograms per year (kg/yr), which is higher than the fine-grained suspended-sediment load leaving the watershed (5.45 x 10 6 kg/yr). The differences in the sediment budget and the measured mass leaving the watershed could be due to an overestimation of erosion using the Cesium-137 method and (or) not adequately defining and measuring storage areas. Management implications of this study indicate that both agriculture and streambanks are important sources of sediment in Linganore Creek where the delivery of agriculture sediment was 4 percent and the delivery of streambank sediment was 44 percent. Fourth order streambanks, on average, had the highest rates of bank erosion. Combining the sediment fingerprinting and sediment budget results indicates that 96 percent of the eroded fine-grained sediment from agriculture went into storage. Flood plains and ponds are effective storage sites of sediment in the Linganore Creek watershed. Flood plains stored 8 percent of all eroded sediment with 4th and 5th order flood plains, on average, storing the most sediment. Small ponds in the Linganore Creek watershed, which drained 16 percent of the total watershed area, stored 15 percent of all eroded sediment. Channel beds were relatively stable with the greatest erosion generally occurring in 4th and 5th order streams.

Maryland↗

USGS2013

Water volume and sediment volume and density in Lake Linganore between Boyers Mill Road Bridge and Bens Branch, Frederick County, Maryland, 2012

To assist in understanding sediment loadings and the management of water resources, a bathymetric survey was conducted in the part of Lake Linganore between Boyers Mill Road Bridge and Bens Branch in Frederick County, Maryland. The bathymetric survey was performed in January 2012 by the U.S. Geological Survey, in cooperation with the City of Frederick and Frederick County. A separate, but related, field effort to collect 18 sediment cores was conducted in March and April 2012. Depth and location data from the bathymetric survey and location data for the sediment cores were compiled and edited by using geographic information system (GIS) software. A three-dimensional triangulated irregular network (TIN) model of the lake bottom was created to calculate the volume of stored water in the reservoir. Large-scale topographic maps of the valley prior to inundation in 1972 were provided by the Frederick County Division of Utilities and Solid Waste Management and digitized for comparison with current (2012) conditions in order to calculate sediment volume. Cartographic representations of both water depth and sediment accumulation were produced, along with an accuracy assessment for the resulting bathymetric model. Vertical accuracies at the 95-percent confidence level for the collected data, the bathymetric surface model, and the bathymetric contour map were calculated to be 0.64 feet (ft), 1.77 ft, and 2.30 ft, respectively. A dry bulk sediment density was calculated for each of the 18 sediment cores collected during March and April 2012, and used to determine accumulated sediment mass. Water-storage capacity in the study area is 110 acre-feet (acre-ft) at a full-pool elevation 308 ft above the National Geodetic Vertical Datum of 1929, whereas total sediment volume in the study area is 202 acre-ft. These totals indicate a loss of about 65 percent of the original water-storage capacity in the 40 years since dam construction. This corresponds to an average rate of sediment accumulation of 5.1 acre-ft per year since Linganore Creek was impounded. Sediment thicknesses ranged from 0 to 16.7 ft. Sediment densities ranged from 0.38 to 1.08 grams per cubic centimeter, and generally decreased in the downstream direction. The total accumulated-sediment mass was 156,000 metric tons between 1972 and 2012.

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