Peak-flow characteristics of Virginia streams

Austin, Samuel H.; Krstolic, Jennifer L.; Wiegand, Ute

doi:10.3133/sir20115144

Cited by 7 publications

(6 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Chow, ). Using the flow regression equations provided in Austin et al (), we calculated the 10‐year and 50‐year recurrence interval flows ( Q 10 and Q 50 ) in each sampled cross‐section by using drainage area to scale flows from a gaging station on Difficult Run. The discharges estimated from the regression equations were then used in conjunction with the rating curve to approximate the flow depth and width at the 10‐year and 50‐year flows.…”

Section: Methodsmentioning

confidence: 99%

Field evidence for the influence of weathering on rock erodibility and channel form in bedrock rivers

Shobe

Hancock

Eppes

et al. 2017

Earth Surf Processes Landf

View full text Add to dashboard Cite

Erosion processes in bedrock-floored rivers shape channel cross-sectional geometry and the broader landscape. However, the influence of weathering on channel slope and geometry is not well understood. Weathering can produce variation in rock erodibility within channel cross-sections. Recent numerical modeling results suggest that weathering may preferentially weaken rock on channel banks relative to the thalweg, strongly influencing channel form. Here, we present the first quantitative field study of differential weathering across channel cross-sections. We hypothesize that average cross-section erosion rate controls the magnitude of this contrast in weathering between the banks and the thalweg. Erosion rate, in turn, is moderated by the extent to which weathering processes increase bedrock erodibility. We test these hypotheses on tributaries to the Potomac River, Virginia, with inferred erosion rates from~0.1 m/kyr to >0.8 m/kyr, with higher rates in knickpoints spawned by the migratory Great Falls knickzone. We selected nine channel cross-sections on three tributaries spanning the full range of erosion rates, and at multiple flow heights we measured (1) rock compressive strength using a Schmidt hammer, (2) rock surface roughness using a contour gage combined with automated photograph analysis, and (3) crack density (crack length/area) at three cross-sections on one channel. All cross-sections showed significant (p < 0.01 for strength, p < 0.05 for roughness) increases in weathering by at least one metric with height above the thalweg. These results, assuming that the weathered state of rock is a proxy for erodibility, indicate that rock erodibility varies inversely with bedrock inundation frequency. Differences in weathering between the thalweg and the channel margins tend to decrease as inferred erosion rates increase, leading to variations in channel form related to the interplay of weathering and erosion rate. This observation is consistent with numerical modeling that predicts a strong influence of weathering-related erodibility on channel morphology.

show abstract

Section: Methodsmentioning

confidence: 99%

Field evidence for the influence of weathering on rock erodibility and channel form in bedrock rivers

Shobe

Hancock

Eppes

et al. 2017

Earth Surf Processes Landf

View full text Add to dashboard Cite

show abstract

“…The USGS streamflow gage located downstream from UDR on Difficult Run near Great Falls, VA ( Fig. 1; USGS station ID 01646000), which has a longer period of record going back to 1935, recorded a peak flow of 481 m 3 /s; estimated to be an event with a recurrence interval between 100 and 200 years (Austin et al, 2011).…”

Section: Tropical Storm Lee and Super Storm Sandymentioning

confidence: 99%

“…Rainfall total for Fairfax County, VA, was 6.25 inches (159 mm; Blake et al, 2013). Difficult Run at Fox Lake recorded a peak flow of 44.5 m 3 /s, and Difficult Run near Great Falls recorded a peak flow of 75.0 m 3 /s -estimated to be an event at Great Falls with a recurrence interval between 2 and 5 years (Austin et al, 2011).…”

Section: Tropical Storm Lee and Super Storm Sandymentioning

confidence: 99%

Storms, channel changes, and a sediment budget for an urban-suburban stream, Difficult Run, Virginia, USA

et al. 2017

View full text Add to dashboard Cite

Determining erosion and deposition rates in urban-suburban settings and how these processes are affected by large storms is important to understanding geomorphic processes in these landscapes. Sediment yields in the suburban and urban Upper Difficult Run are among the highest ever recorded in the Chesapeake Bay watershed, ranging from 161 to 376 Mg/km 2 /y. Erosion and deposition of streambanks, channel bed, and bars and deposition of floodplains were monitored between 1 March 2010 and 18 January 2013 in Upper Difficult Run, Virginia, USA. We documented the effects of two large storms, Tropical Storm Lee (September 2011), a 100-year event, and Super Storm Sandy (October 2012) a 5-year event, on channel erosion and deposition. Variability in erosion and deposition rates for all geomorphic features, temporally and spatially, are important conclusions of this study. Tropical Storm Lee was an erosive event, where erosion occurred on 82% of all streambanks and where 88% of streambanks that were aggrading before Tropical Storm Lee became erosional. Statistical analysis indicated that drainage area explains linear changes (cm/y) in eroding streambanks and that channel top width explains cross-sectional area changes (cm 2 /y) in eroding streambanks and floodplain deposition (mm/y). A quasi-sediment budget constructed for the study period using the streambanks, channel bed, channel bars, and floodplain measurements underestimated the measured suspended-sediment load by 61% (2130 Mg/y). Underestimation of the sediment load may be caused by measurement errors and to contributions from upland sediment sources, which were not measured but estimated at 36% of the gross input of sediment. Eroding streambanks contributed 42% of the gross input of sediment and accounted for 70% of the measured suspended-sediment load. Similar to other urban watersheds, the large percentage of impervious area in Difficult Run and direct runoff of precipitation leads to increased streamflow and streambank erosion. This study emphasizes the importance of streambanks in urban-suburban sediment budgets but also suggests that other sediment sources, such as upland sources, which were not measured in this study, can be an important source of sediment.

show abstract

“…The USGS StreamStats service for estimating peak flow rates in Virginia is based on two separate USGS reports. The first report (Austin et al, 2011) contains regression equations for estimating the peak flow rate of a stream obtained by analyzing stream gage records from 1895 to 2007. The second report (Austin, 2014) includes methods and equations for estimating peak streamflow in Virginia's urban basins.…”

Section: Study Areamentioning

confidence: 99%

Method for Rapidly Assessing the Overtopping Risk of Bridges Due to Flooding over a Large Geographic Region

Shen

Goodall

Chase

2017

J American Water Resour Assoc

View full text Add to dashboard Cite

Hydraulic events are a leading cause of bridge failures. While these hydraulic events are accounted for in bridge design, changing environmental and land use conditions require continual updating of this risk. For example, after a bridge has been constructed, streamflow can change in unanticipated ways as a result of land use changes, geomorphic changes, and climate change. The objective of this research was to create a screening method able to quickly and inexpensively estimate overtopping risk across a collection of bridges based on the current streamflow conditions. The method uses a geographic information system, nationally available and standardized datasets, and recent regression equations to quantify bridge vulnerability to overtopping for flooding with varying return periods. This screening method could also be used to assist decision makers in updating the Waterway Adequacy field in the National Bridge Inventory, which indicates the overtopping risk of bridges. The method was applied to a portion of the Hampton Roads region of Virginia, United States that includes 475 bridges. The results of the analysis, when combined with transportation data for bridges, aid decision makers to assign further resources to complete more detailed analyses of bridges identified as being at risk for overtopping.(KEY TERMS: bridge; vulnerability; overtopping; flooding; transportation infrastructure.)

show abstract

Peak-flow characteristics of Virginia streams

Cited by 7 publications

References 17 publications

Field evidence for the influence of weathering on rock erodibility and channel form in bedrock rivers

Field evidence for the influence of weathering on rock erodibility and channel form in bedrock rivers

Storms, channel changes, and a sediment budget for an urban-suburban stream, Difficult Run, Virginia, USA

Method for Rapidly Assessing the Overtopping Risk of Bridges Due to Flooding over a Large Geographic Region

Contact Info

Product

Resources

About