Geology topics

Johnna L. Higgins

Publications and source records attributed to Johnna L. Higgins.

2 recordsLinked to original sources

USGS2009

Estimates of Sediment Load Prior to Dam Removal in the Elwha River, Clallam County, Washington

Years after the removal of the two dams on the Elwha River, the geomorphology and habitat of the lower river will be substantially influenced by the sediment load of the free-flowing river. To estimate the suspended-sediment load prior to removal of the dams, the U.S. Geological Survey collected suspended-sediment samples during water years 2006 and 2007 at streamflow-gaging stations on the Elwha River upstream of Lake Mills and downstream of Glines Canyon Dam at McDonald Bridge. At the gaging station upstream of Lake Mills, discrete samples of suspended sediment were collected over a range of streamflows including a large peak in November 2006 when suspended-sediment concentrations exceeded 7,000 milligrams per liter, the highest concentrations recorded on the river. Based on field measurements in this study and from previous years, regression equations were developed for estimating suspended-sediment and bedload discharge as a function of streamflow. Using a flow duration approach, the average total annual sediment load at the gaging station upstream of Lake Mills was estimated at 327,000 megagrams with a range of uncertainty of +57 to -34 percent (217,000-513,000 megagrams) at the 95 percent confidence level; 77 percent of the total was suspended-sediment load and 23 percent was bedload. At the McDonald Bridge gaging station, daily suspended-sediment samples were obtained using an automated pump sampler, and concentrations were combined with the record of streamflow to calculate daily, monthly, and annual suspended-sediment loads. In water year 2006, an annual suspended-sediment load of 49,300 megagrams was determined at the gaging station at McDonald Bridge, and a load of 186,000 megagrams was determined upstream at the gaging station upstream of Lake Mills. In water year 2007, the suspended-sediment load was 75,200 megagrams at McDonald Bridge and 233,000 megagrams upstream of Lake Mills. The large difference between suspended-sediment loads at both gaging stations shows the extent of sediment trapping by Lake Mills, and a trap efficiency of 0.86 was determined for the reservoir. Pre-dam-removal estimates of suspended-sediment load and sediment-discharge relations will help planners monitor geomorphic and habitat changes in the river as it reaches a dynamic equilibrium following the removal of dams.

Scientific Investigations Report↗

USGS2003

Determination of upstream boundary points on southeastern Washington streams and rivers under the requirements of the Shoreline Management Act of 1971

Regulation of the shorelines of the State of Washington, as mandated by the Shoreline Management Act of 1971, requires knowledge of the locations on streams and river reaches where specific regulatory criteria are satisfied. The U.S. Geological Survey conducted a study in 1971 to determine the upstream boundary points of these reaches for many of the State's streams and rivers. Updated upstream boundary points were determined in the current study for all the streams and rivers in southeastern Washington that fall under the jurisdiction of the Shoreline Management Act of 1971. Upstream boundary point locations where the mean annual discharge equals 20 cubic feet per second were determined for 149 streams. In addition, upstream boundary point locations where the mean annual discharge equals 200 cubic feet per second or the drainage area equals 300 square miles were determined for 22 rivers. Boundary point locations were determined by application of multiple-linear-regression equations that relate mean annual discharge to drainage area and mean annual precipitation. Southeastern Washington was divided into five hydrologically distinct regions, and a separate regression equation was developed for each region. The regression equations are based on data for gaging stations with at least 10 years of record. The number of stations in the regression analysis for each of the five regions ranged from 5 to 33. The coefficient of determination, R2, of the regression equations ranged from 0.953 to 0.997. The equation for the Upper Yakima region had the lowest standard error, ranging from -7 to +9 percent for a regression estimate of 20 cubic feet per second. The equation for the Columbia Basin to Palouse region had the highest standard error, ranging from -36 to +55 percent for a regression estimate of 20 cubic feet per second. The approximate error in the location of an upstream boundary point can be calculated using the variables mean annual precipitation of the basin upstream from a boundary point and average basin width in the vicinity of the boundary point. The calculation gives only a rough estimate of the error of the boundary point location, because of the uncertainty in estimating average basin width.

Water-Resources Investigations Report↗