Sediment-source data for four basins tributary to Lake Tahoe, California and Nevada; August 1983-June 1988

Hill, B.R.; Hill, J.R.; Nolan, K. Michael

doi:10.3133/ofr89618

Cited by 7 publications

(8 citation statements)

References 3 publications

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“…Sediment budget studies and sediment transport models have identified stream channel erosion in the Tahoe basin as a major source of SS load (Hill et al. , 1990; Nolan and Hill, 1991; Simon et al.…”

Section: Resultsmentioning

confidence: 99%

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada¹

Coats¹,

Larsen²,

Heyvaert³

et al. 2008

J American Water Resour Assoc

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In efforts to control the degradation of water quality in Lake Tahoe, public agencies have monitored surface water discharge and concentrations of nitrogen, phosphorus, and suspended sediment in two separate sampling programs. The first program focuses on 20 watersheds varying in size from 162 to 14,000 ha, with continuous stream gaging and periodic sampling; the second focuses on small urbanized catchments, with automated sampling during runoff events. Using data from both programs, we addressed the questions (1) what are the fluxes and concentrations of nitrogen and phosphorus entering the lake from surface runoff; (2) how do the fluxes and concentrations vary in space and time; and (3) how are they related to land use and watershed characteristics? To answer these questions, we calculated discharge‐weighted average concentrations and annual fluxes and used multiple regression to relate those variable to a suite of GIS‐derived explanatory variables. The final selected regression models explain 47‐62% of the variance in constituent concentrations in the stormwater monitoring catchments, and 45‐72% of the variance in mean annual yields in the larger watersheds. The results emphasize the importance of impervious surface and residential density as factors in water quality degradation, and well‐developed soil as a factor in water quality maintenance.

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Section: Resultsmentioning

confidence: 99%

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada¹

Coats¹,

Larsen²,

Heyvaert³

et al. 2008

J American Water Resour Assoc

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Section: Research Approachmentioning

confidence: 99%

“…Cross sections on Blackwood, General, Logan House, and Edgewood creeks were monumented with metal fence posts and labeled with brass plates (Hill et al. , 1990) by the USGS in 1983 and 1984.…”

Section: Estimates Of Fine‐sediment Contributions From Streambank Eromentioning

confidence: 99%

“…A large amount of useful data on flow, suspended sediment, and channel characteristics were available from previous studies conducted in the Lake Tahoe Basin (Jorgensen et al, 1978;Hill et al, 1990;Nolan and Hill, 1991;Rowe et al, 2002;Simon et al, 2003;Rabidoux, 2005). Still, without resources to conduct detailed numerical simulations of channel processes for each stream as was done for the Upper Truckee River, and Ward and General creeks (Simon et al, 2003), a combination of empirical methods was required to address the study objectives.…”

Section: Research Approachmentioning

confidence: 99%

“…This study also highlighted important distinctions in sediment production from different sides (quadrants) of the basin and from different sources. With extensive reconnaissance‐level field work throughout the basin and by resurveying monumented cross sections originally established in the 1980s (Hill et al. , 1990), streambank erosion was identified as an important source of suspended sediment from several watersheds, including Blackwood and Ward creeks, and the Upper Truckee River.…”

Section: Introductionmentioning

confidence: 99%

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Fine‐Sediment Loadings to Lake Tahoe¹

Simon

2008

J American Water Resour Assoc

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Over the past 35 years, a trend of decreasing water clarity has been documented in Lake Tahoe, attributable in part to the delivery of fine‐grained sediments emanating from upland and channel sources. The overall objective of the research reported here was to determine the amount of fine sediment delivered to Lake Tahoe from each of the 63 contributing watersheds. The research described in this report used combinations of field‐based observations of channel and bank stability with measured and simulated data on fine‐sediment loadings to estimate fine‐sediment loadings from unmonitored basins throughout the Lake Tahoe Basin. Loadings were expressed in the conventional format of mass per unit time but also in the number of particles finer than 20 μm, the latter for future use in a lake‐clarity model. The greatest contributors of fine sediment happened to be those with measured data, not requiring extrapolation. In descending order, they are as follows: Upper Truckee River [1,010 tonnes per year (T/year)], Blackwood Creek (846 T/year), Trout Creek (462 T/year), and Ward Creek (412 T/year). Summing estimated values from the contributing watersheds provided an average, annual estimate of fine‐sediment (<0.063 mm) loadings to the lake of 5,206 T/year. A total of 7.79E + 19 particles in the 5‐20 μm fraction were calculated to enter Lake Tahoe in an average year with the Upper Truckee River accounting for almost 25% of the total. Contributions from Blackwood, Ward, Trout, and Third creeks account for another 23% of these very fine particles. Thus, these five streams making up about 40% of the basin area, account for almost 50% of all fine‐sediment loadings to the lake. Contribution of fine sediment from streambank erosion were estimated by developing empirical relations between measured or simulated bank‐erosion rates with a field‐based measure of the extent of bank instability along given streams. An average, annual fine‐sediment loading from streambank erosion of 1,305 T/year was calculated. This represents about 25% of the average, annual fine‐sediment load delivered to the lake from all sources. The two largest contributors, the Upper Truckee River (639 T/year) and Blackwood Creek (431 T/year), account for slightly more than 80% of all fines emanating from streambanks, representing about 20% of the fine sediment delivered to Lake Tahoe from all sources. Extrapolations of fine‐sediment loadings to the unmonitored watersheds are based on documented empirical relations, yet contain a significant amount of uncertainty. Except for those values derived directly from measured data, reported results should be considered as estimates.

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Analysis of bank erosion on the Merced River, Yosemite Valley, Yosemite National Park, California, USA

Madej¹,

Weaver²,

Hagans³

1994

Environmental Management

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Channel changes from 1919 to 1989 were documented in two study reaches of the Merced River in Yosemite National Park through a review of historical photographs and documents and a comparison of survey data. Bank erosion was prevalent and channel width increased an average of 27% in the upstream reach, where human use was concentrated. Here, trampling of the banks and riparian vegetation was common, and banks eroded on straight stretches as frequently as on meander bends. Six bridges in the upper reach constrict the channel by an average of 38% of the original width, causing severe erosion. In the downstream control reach, where human use was minimal, channel widths both decreased and increased, with a mean increase of only 4% since 1919. Bank erosion in the control reach occurred primarily on meander bends, The control reach also had denser stands of riparian vegetation and a higher frequency of large woody debris in channels. There is only one bridge in the lower reach, located at the downstream end. Since 1919, bank erosion in the impacted upstream reach contributed a significant amount of sediment (74,800 tonnes, equivalent to 2.0 t/km2/yr) to the river. An analysis of 75 years of precipitation and hydrologic records showed no trends responsible for bank erosion in the upper reach. Sediment input to the upper reach has not changed significantly during the study period. Floodplain soils are sandy, with low cohesion and are easily detached by lateral erosion. The degree of channel widening was positively correlated with the percentage of bare ground on the streambanks and low bank stability ratings. Low bank stability ratings were, in turn, strongly associated with high human use areas. Channel widening and bank erosion in the upper reach were due primarily to destruction of riparian vegetation by human trampling and the effect of bridge constrictions on high flow, and secondarily to poorly installed channel revetments. Several specific recommendations for river restoration were provided to park management.

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Sediment-source data for four basins tributary to Lake Tahoe, California and Nevada; August 1983-June 1988

Cited by 7 publications

References 3 publications

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada¹

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada¹

Fine‐Sediment Loadings to Lake Tahoe¹

Analysis of bank erosion on the Merced River, Yosemite Valley, Yosemite National Park, California, USA

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Sediment-source data for four basins tributary to Lake Tahoe, California and Nevada; August 1983-June 1988

Cited by 7 publications

References 3 publications

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada1

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada1

Fine‐Sediment Loadings to Lake Tahoe1

Analysis of bank erosion on the Merced River, Yosemite Valley, Yosemite National Park, California, USA

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Product

Resources

About

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada¹

Nutrient and Sediment Production, Watershed Characteristics, and Land Use in the Tahoe Basin, California‐Nevada¹

Fine‐Sediment Loadings to Lake Tahoe¹