Surface water-ground water interactions along the lower Dungeness River and vertical hydraulic conductivity of streambed sediments, Clallam County, Washington, September 1999-July 2001 (original) (raw)
Related papers
Studies of a regulated dryland river: surfacegroundwater interactions
Unlike rivers in humid regions, dryland rivers typically exhibit reduced flow in the downstream direction as a result of transmission losses, which include seepage of streamflow into the aquifer, evaporation, and transpiration. However, much remains to be learned about the nature of the exchange between surface water and groundwater in these landscapes, especially in terms of spatial and temporal variability. Our study focused on streambank seepage and groundwater flow in the alluvial aquifer, specifically on answering questions such as: Is there seasonal variability in seepage losses? Is seepage permanently lost? Can losses be reduced by killing riparian vegetation? To better understand the magnitude, variability, and fate of streambank seepage, we assessed river stages, groundwater hydraulic gradients, and groundwater flow paths at two sites along a reach of the Pecos River, a dryland perennial river in West Texas. We found that along this reach the river was losing water to the aquifer even under low-flow conditions; but seepage was controlled by a number of different mechanisms. Seepage increased not only during high-flow events but also when the groundwater level was declining owing to long periods of no irrigation release. Tamarix (saltcedar) control did not affect hydraulic gradients nor reduce streambank seepage and given that this reach of the Pecos River is a losing one, streamflow will not be enhanced by controlling saltcedar. These findings can be used to improve basic conceptual models of dryland river systems and to predict hydrologic responses to changes in the timing and magnitude of streamflows and to riparian vegetation management. Figure 2. Monitoring wells and locations of hydraulic heads used to calculate hydraulic gradients in streambank, floodplain and riparian zones at Site B
2006
Construction of flood protection levees in the 1950's resulted in channel incision of 2200 ft of the Jocko River. Resulting floodplain water table lowering is thought to have altered surface water/groundwater interactions, impairing riparian habitat and trout fisheries. The objective of this research was to establish the hydraulic link between the stream and floodplain under pre-restored/re-naturalize conditions; assist the Confederated Salish and Kootenai Tribes in design and implementation efforts to re-naturalize the Jocko River. The Jocko River was instrumented with 11 staff gauges to establish river stage. Monthly water level monitoring of ~50 shallow monitoring and domestic wells along with continuous water level recorders were used to establish the pre-and postrestoration water table position. Grain size analyses, falling head slug tests, seepage runs, mini-piezometers and streambed temperature profiles were used to define the direction and magnitudes of channel-groundwater exchange. Study results show the upper 6400 ft of the river in the study area is primarily a losing reach, whereas the lower portion is a gaining reach throughout the year. Seasonally, the transition point between gaining and losing sections migrates (~3000 ft) upstream. The floodplain aquifer hydraulic conductivities range from 7 to 280 ft/day whereas, riverbed vertical hydraulic conductivities range from 0.1 to 187 ft/day. Initial channel restoration increased the riverbed elevation (~ 3 ft). A correlation exist between river discharge and water table elevation changes near the river whereas, water table elevations further from the river are not correlated. Floodplain water table elevations increased (~0.5 to 1.8 ft) near the restored reach. Streambed vertical hydraulic conductivity and grain size distributions showed minimal changes. Vertical hydraulic gradients in the restored reach showed significant deviations (~0.4) from the pre-restoration established values and patterns. in June 2005, a runoff event exceeded a 20-year flood recurrence interval that may have reduced the ability to measure changes in surface water/groundwater exchange. The transient nature of this river and groundwater system calls setting clear quantitative restoration goals and objectives. Continued long term monitoring will allow for accurate assessment of the overall success of this restoration effort.
An Automated Seepage Meter for Streams and Lakes
Water Resources Research, 2020
We describe a new automatic seepage meter for use in soft bottom streams and lakes. The meter utilizes a thin-walled tube that is inserted into the streambed or lakebed. A hole in the side of the tube is fitted with an electric valve. Prior to the test, the valve is open and the water level inside the tube is the same as the water level outside the tube. The test starts with closure of the valve, and the water level inside the tube changes as it moves toward the equilibrium hydraulic head that exists at the bottom of the tube. The time rate of change of the water level immediately after the valve closes is a direct measure of the seepage rate (q). The meter utilizes a precision linear actuator and a conductance circuit to sense the water level to a precision of about ±0.1 mm. The meter can also provide an estimate of vertical hydraulic conductivity (K v) if data are collected for a characteristic time. The detection limit for q depends on the vertical hydraulic head gradient. For K v = 1 m/day, q of about 2 mm/day can be measured. Results from a laboratory sand tank show excellent agreement between measured and true q, and results from a field site are similar to values from calculations based on independent measurements of K v and vertical head gradients. The meter can provide rapid (30 min) q measurements for both gaining and losing systems and complements other methods for quantifying surface water groundwater interactions.
Transactions of the American Fisheries Society, 2003
Measurements of groundwater-stream water interactions are increasingly recognized as important to understanding the ecology of fishes and other organisms in stream and riparian ecosystems. However, standard measurement techniques are often feasible only at small spatial scales, in areas with easy access, or in systems with relatively fine substrata. We developed simple new techniques for installing minipiezometers and obtaining estimates of vertical hydraulic gradient, hydraulic conductivity, and specific discharge in gravel and cobble streambeds that allowed for large numbers of measurements to be obtained in remote locations. Our approach yielded values comparable to those obtained through more traditional methods. Consequently, these techniques may provide a labor cost-efficient way for detecting groundwaterϪstream water interaction patterns that are critical labor-attributes of stream and riparian systems at multiple scales.
Journal of Hydrology, 2008
The stratification of channel sediments and their vertical hydraulic conductivity (K v ) are important hydrologic information in the analysis of stream-aquifer interactions. This paper describes the use of direct-push technology to generate electrical conductivity (EC) logs and collect continuous sediment cores beneath river channels. The techniques were applied to nine study sites along a 130 km reach of the Platte River in southeast Nebraska. EC logs for the channel surface down to as much as 24 m below the channel surface indicate that the channel sediments in the western part of the reach consist predominantly of sand and gravel; low-K v silt-clay layers occur in the rest of the reach. These silt-clay layers are either interbedded with sand and gravel or occur as a major unit within the channel sediments. As a result, the values of K v , determined from the sediment cores, can vary by four to five orders of magnitude in the same vertical profile of channel sediments at a number of sites. The river channel is not lined by a low-K v layer at the surface. Instead, the K v values for the top part of channel sediments were consistently greater than K v values for sediments in deeper parts. They show a decreasing tendency with the depth. This paper also analyzes the effect of low-K v layers within channel sediments on streamflow depletion induced by groundwater pumping. Simulation results suggest that the effectiveness of low-K v layers on the calculation of streamflow depletion depends on their depth, thickness, vertical permeability, the length along the channel, and the width within the channel, as well as the extension into the aquifer on both sides of the river. A low-K v layer present at the channel surface seems to be the most effective hydrologic feature in reducing the hydrologic connection of stream-aquifer. ª
Journal of Hydrology, 2008
a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j h y d r o l few months of the study. This upstream/downstream difference in K disappeared after the dam collapsed, perhaps in response to re-mobilization of fine sediments or leaf matter that had accumulated in quiet waters ponded on the upstream side of the dam. Temporal variability was significant and followed a variety of different patterns at the 46 measurement locations in the large reach. Temperature data show that variation in streambed and groundwater temperature was not an important cause of the observed temporal variability in K. Measurements of changes in the elevation of the streambed surface suggest erosion and deposition played an important role in causing the observed temporal variability in streambed K (of which the change described above following collapse of the beaver dam was a special case), though other potentially time-varying factors (e.g., gas content, bioturbation, or biofilms in the streambed) were not explicitly addressed and cannot be ruled out as contributors to the temporal variability in streambed K. Temporal variability in streambed K merits additional study as a potentially important control on temporal variability in the magnitudes and spatial patterns of water and solute fluxes between groundwater and surface water. From the data available it seems appropriate to view streambed K as a dynamic attribute, variable in both space and time. ª