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Christopher P. Konrad

Publications and source records attributed to Christopher P. Konrad.

45 records · Page 3Linked 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↗
USGS2008

Bank topography, bathymetry, and current velocity of the lower Elwha River, Clallam County, Washington, May 2006

The removal of two dams from the mainstem of the Elwha River is expected to cause a broad range of changes to the river and nearby coastal ecosystem. The U.S. Geological Survey has documented aspects of the condition of the river to allow analysis of ecological responses to dam removal. This report documents the bank topography, river bathymetry, and current velocity data collected along the lower 0.5 kilometer of the Elwha River, May 15-17, 2006. This information supplements nearshore and beach surveys done in 2006 as part of the U.S. Geological Survey Coastal Habitats in Puget Sound program near the Elwha River delta in the Strait of Juan de Fuca, Washington.

Washington↗
USGS2006

Freshwater and saline loads of dissolved inorganic nitrogen to Hood Canal and Lynch Cove, western Washington

Hood Canal is a long (110 kilometers), deep (175 meters) and narrow (2 to 4 kilometers wide) fjord of Puget Sound in western Washington. The stratification of a less dense, fresh upper layer of the water column causes the cold, saltier lower layer of the water column to be isolated from the atmosphere in the late summer and autumn, which limits reaeration of the lower layer. In the upper layer of Hood Canal, the production of organic matter that settles and consumes dissolved oxygen in the lower layer appears to be limited by the load of dissolved inorganic nitrogen (DIN): nitrate, nitrite, and ammonia. Freshwater and saline loads of DIN to Hood Canal were estimated from available historical data. The freshwater load of DIN to the upper layer of Hood Canal, which could be taken up by phytoplankton, came mostly from surface and ground water from subbasins, which accounts for 92 percent of total load of DIN to the upper layer of Hood Canal. Although DIN in rain falling on land surfaces amounts to about one-half of the DIN entering Hood Canal from subbasins, rain falling directly on the surface of marine waters contributed only 4 percent of the load to the upper layer. Point-source discharges and subsurface flow from shallow shoreline septic systems contributed less than 4 percent of the DIN load to the upper layer. DIN in saline water flowing over the sill into Hood Canal from Admiralty Inlet was at least 17 times the total load to the upper layer of Hood Canal. In September and October 2004, field data were collected to estimate DIN loads to Lynch Cove - the most inland marine waters of Hood Canal that routinely contain low dissolved-oxygen waters. Based on measured streamflow and DIN concentrations, surface discharge was estimated to have contributed about one-fourth of DIN loads to the upper layer of Lynch Cove. Ground-water flow from subbasins was estimated to have contributed about one-half of total DIN loads to the upper layer. In autumn 2004, the relative contribution of DIN from shallow shoreline septic systems to the upper layer was higher in Lynch Cove (23 percent) than in the entire Hood Canal. Net transport of DIN into Lynch Cove by marine currents was measured during August and October 2004-a time of high biological productivity. The net transport of lower-layer water into Lynch Cove was significantly diminished relative to the flow entering Hood Canal at its entrance. Even though the net transport of saline water into the lower layer of Lynch Cove was only 119 cubic meters per second, estuarine currents between 33 and 47 m were estimated to have carried more than 35 times the total freshwater load of DIN to the upper layer from surface and ground water, shallow shoreline septic systems, and direct atmospheric rainfall. The subsurface maximums in measured turbidity, chlorophyll a, particulate organic carbon, and particulate organic nitrogen strongly suggest that the upward mixing of nitrate-rich deeper water is a limiting factor in supplying DIN to the upper layer that enhances marine productivity in Lynch Cove. The presence of phosphate in the upper layer in the absence of dissolved inorganic nitrogen also suggests that the biological productivity that leads to low dissolved-oxygen concentrations in the lower layer of Lynch Cove is limited by the supply of nitrogen rather than by phosphate loads. Although the near-shore zones of the shallow parts of Lynch Cove were sampled, a biogeochemical signal from terrestrial nitrogen was not found. Reversals in the normal estuarine circulation suggest that if the relative importance of the DIN load of freshwater terrestrial and atmospheric sources and the DIN load from transport of saline water by the estuarine circulation in controlling dissolved-oxygen concentrations in Lynch Cove is to be better understood, then the physical forces driving Hood Canal circulation must be better defined.

Scientific Investigations Report↗
USGS2005

Effects of urban development in the Puget Lowland, Washington, on interannual streamflow patterns: Consequences for channel form and streambed disturbance

Recovery and protection of streams in urban areas depend on a comprehensive understanding of how human activities affect stream ecosystems. The hydrologic effects of urban development and the consequences for stream channel form and streambed stability were examined in 16 streams in the Puget Lowland, Washington, using three streamflow metrics that integrate storm‐scale effects of urban development over annual to decadal timescales: the fraction of time that streamflow exceeds the mean streamflow (T Qmean ), the coefficient of variation of annual maximum streamflow (CV AMF ), and the fraction of time that streamflow exceeds the 0.5‐year flood (T 0.5 ). Urban streams had low interannual variability in annual maximum streamflow and brief duration of frequent high flows, as indicated by significant correlations between road density and both CV AMF and T 0.5 . The broader distribution of streamflow indicated by T Qmean may be affected by urban development, but differences in T Qmean between streams are also likely a result of other physiographic factors. The increase in the magnitude of frequent high flows due to urban development but not their cumulative duration has important consequences for channel form and bed stability in gravel bed streams because geomorphic equilibrium depends on moderate duration streamflow (e.g., exceeded 10% of the time). Streams with low values of T Qmean and T 0.5 are narrower than expected from hydraulic geometry. Dimensionless boundary shear stress (t*) for the 0.5‐year flood was inversely related to T 0.5 among the streams, indicating frequent and extensive bed disturbance in streams with low values of T 0.5 . Although stream channels expand and the size of bed material increases in response to urban streamflow patterns, these adjustments may be insufficient to reestablish the disturbance regime in urban streams because of the differential increase in the magnitude of frequent high flows causing disturbance relative to any changes in longer duration, moderate flows that establish a stable channel.

Water Resources Research↗
USGS2004

Simulated Water-Management Alternatives Using the Modular Modeling System for the Methow River Basin, Washington

A precipitation-runoff model for the Methow River Basin was used to simulate six alternatives: (1) baseline of current flow, (2) line irrigation canals to limit seepage losses, (3) increase surface-water diversions through unlined canals for aquifer recharge, (4) convert from surface-water to ground-water resources to supply water for irrigation, and (5) reduce tree density in forested headwater catchments, and (6) natural flow. Daily streamflow from October 1, 1959, to September 30, 2001 (water years 1960?2001) was simulated. Lining irrigation canals (alternative 2) increased flows in the Chewuch, Twisp, and the Methow (upstream and at Twisp) Rivers during September because of lower diversion rates, but not in the Methow River near Pateros. Increasing diversions for aquifer recharge (alternative 3) increased streamflow from September into January, but reduced streamflow earlier in the summer. Conversion of surface-water diversions to ground-water wells (alternative 4) resulted in the largest increase in September streamflow of any alternative, but also marginally lower January flows (at most -8 percent in the 90-percent exceedence value). Forest-cover reduction (alternative 5) produced large increases in streamflow during high-flow periods in May and June and earlier onset of high flows and small increases in January streamflows. September streamflows were largely unaffected by alternative 5. Natural streamflow (alternative 6) was higher in September and lower in January than the baseline alternative.

Open-File Report↗
USGS2003

Hydrogeology of the unconsolidated sediments, water quality, and ground-water/surface-water exchanges in the Methow River Basin, Okanogan County, Washington

The U.S. Geological Survey, in cooperation with Okanogan County, investigated the hydrogeology of the unconsolidated sedimentary deposits in the Methow River Basin, the quality of surface and ground waters, and the exchanges between ground water and surface water. Alluvium (Qa) and glaciofluvial sediments (Qga) deposited during the Quaternary period constitute the primary aquifer in the Methow River Basin, which is used as a source of water for domestic and public-water supplies and for maintaining streamflow during seasonal dry periods. The sediments form a nearly continuous unit along the valley bottom from above the Lost River to the confluence of the Methow and Columbia Rivers, covering more than 45 square miles of the basin?s surface. There are no distinct units within the deposit that can be identified across or along the valley except for fragments of a possible lake bed near the town of Twisp. Ground-water levels in the unconsolidated aquifer are highest during the summer and lowest in the winter and early spring. Ground water and surface water, sampled during June and September 2001, generally were of high quality. Only two samples from domestic and municipal wells indicated the possibility of ground-water contamination from nitrate and arsenic concentrations. In both cases, potential contamination was isolated to an individual well. No trends in water quality were apparent when comparing the results of this investigation with previous studies. The flow of water between rivers and aquifers is important for regulating the availability of water resources for in-stream and out-of-stream uses in the Methow River Basin. Ground-water discharge from the unconsolidated aquifer to the Methow River from Lost River to Pateros ranged from an estimated 153,000 acre-ft in water year 2001 to 157,000 acre-ft in water year 2002. In contrast, ground-water discharge to the lower Twisp River from Newby Creek to near Twisp ranged from 4,700 acre-ft in water year 2001 to 9,200 acre-ft in water year 2002. The Methow and Twisp Rivers, among others in the basin, are major sources of recharge for the unconsolidated aquifer, particularly during high-flow periods in May and June. Aquifer recharge by both rivers increased with streamflow in water year 2002 compared to water year 2001 as indicated by daily losses of streamflow. Aquifer recharge by the Methow River from Lost River to Pateros was estimated to be 82,000 acre-ft in water year 2001 and 137,000 acre-ft in water year 2002. Aquifer recharge by the Twisp River from Newby Creek to near Twisp was estimated to be 2,000 acre-ft in water year 2001 and 6,400 acre-ft in water year 2002. Seepage from unlined irrigation canals also recharges the unconsolidated aquifer during the late spring and summer and may contribute as much 38,000 acre-ft annually to aquifer recharge in the basin. Some portion of this ground water returns to rivers as indicated by a seasonal increase in ground-water discharge in the Methow River from Winthrop to Twisp and in the lower Twisp River during late summer and early autumn. Although the increase is likely due primarily to irrigation canal seepage, however, fluvial recharge during the summer also may have contributed to the increase. The increased rate of ground-water discharge decays by January in both reaches.

Washington↗
USGS2002

Partial entrainment of gravel bars during floods

Spatial patterns of bed material entrainment by floods were documented at seven gravel bars using arrays of metal washers (bed tags) placed in the streambed. The observed patterns were used to test a general stochastic model that bed material entrainment is a spatially independent, random process where the probability of entrainment is uniform over a gravel bar and a function of the peak dimensionless shear stress τ 0 * of the flood. The fraction of tags missing from a gravel bar during a flood, or partial entrainment, had an approximately normal distribution with respect to τ 0 * with a mean value (50% of the tags entrained) of 0.085 and standard deviation of 0.022 (root‐mean‐square error of 0.09). Variation in partial entrainment for a given τ 0 * demonstrated the effects of flow conditioning on bed strength, with lower values of partial entrainment after intermediate magnitude floods (0.065 < τ 0 *< 0.08) than after higher magnitude floods. Although the probability of bed material entrainment was approximately uniform over a gravel bar during individual floods and independent from flood to flood, regions of preferential stability and instability emerged at some bars over the course of a wet season. Deviations from spatially uniform and independent bed material entrainment were most pronounced for reaches with varied flow and in consecutive floods with small to intermediate magnitudes.

Water Resources Research↗