Downstream effects of impounding a natural lake: the Snake River downstream from Jackson Lake Dam, Wyoming, USA

Abstract

A sediment mass balance constructed for a 16-km reach of the Snake River downstream from Jackson Lake Dam (JLD) indicates that river regulation has reduced the magnitude of sediment mass balance deficit that would naturally exist in the absence of the dam. The sediment budget was constructed from calibrated bed load transport relations, which were used to model sediment flux into and through the study reach. Calibration of the transport relations was based on bed load transport data collected over a wide range of flows on the Snake River and its two major tributaries within the study area in 2006 and 2007. Comparison of actual flows with unregulated flows for the period since 1957 shows that operations of JLD have reduced annual peak flows and increased late summer flows. Painted tracer stones placed at five locations during the 2005 spring flood demonstrate that despite the reduction in flood magnitudes, common floods are capable of mobilizing the bed material. The sediment mass balance demonstrates that more sediment exits the study reach than is being supplied by tributaries. However, the volume of sediment exported using estimated unregulated hydrology indicates that the magnitude of the deficit would be greater in the absence of JLD. Calculations suggest that the Snake River was not in equilibrium before construction of JLD, but was naturally in sediment deficit. The conclusion that impoundment lessened a natural sediment deficit condition rather than causing sediment surplus could not have been predicted in the absence of sediment transport data, and highlights the value of transport data and calculation of sediment mass balance in informing dam operations.

Sediment supply and channel morphology in mountain river systems: 2. Single thread to braided transitions

“…[]; 2 = Erwin et al . []; 3 = Jones and Seitz []; 4 = Ryan and Emmett []; 5 = Hortness and Berenbrock []; 6 = Clark and Woods []; 7 = Williams and Krupin []; 8 = USGS National Water Information System accessed between 1/2008 and 7/2011; 9 = determined from field measurements by the authors; 10 = Berenbrock and Tranmer []; 11 = Kondolf et al . []; 12 = bankfull discharge estimated from a regional relationship as Q = a DA b , where Q is discharge, DA is drainage area, and a and b are empirical power law parameters; 13 = Miller []; 14 = Holnbeck []; 15 = Curran et al .…”

Evaluating the capabilities of the CASI hyperspectral imaging system and Aquarius bathymetric LiDAR for measuring channel morphology in two distinct river environments

“…The Snake River is regulated by Jackson Lake Dam, but wood and coarse bed material delivered from tributaries produce a wandering, frequently changing channel (Erwin et al. ; Nelson et al. ).…”

Bayesian sediment transport model for unisize bed load

“… Mueller et al [2005], however, noted that uncertainties in specifying a single critical shear can lead to large errors since the process is nonlinear. This estimate can be made using statistical methods, but it is not uncommon to adjust it by eye [ Erwin et al , 2011; Gaeuman et al , 2009; Wilcock et al , 2003; Mueller et al , 2005; Wilcock et al , 2009; Wilcock , 1988] because of some nonlinear regression techniques giving too much weight to observations far from critical (see Wilcock [1988] for a discussion on this). Additionally, Buffington and Montgomery [1997] compiled data from eight decades of incipient motion studies and created lists of reported critical shear values.…”