English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Movement of sediment during a period of intensive highway construction was studied in the Scott Run basin, Fairfax County, Va., from 1961 to 1964. The 4.54-square-mile drainage basin, which empties into the Potomac River about 6 miles above the head of the Potomac Estuary, was the scene of highway construction covering 11 percent of the basin; other types of urban construction in the basin during this time were minor. Sediment that moved with the flow was measured at the gaging station by a system of representative samples. These samples made it possible to document the sediment yield for 88 storm events representing the overland runoff. Analysis of streamflow and sediment transport during the period showed that (1) the 88 events accounted for 37 percent of the runoff and 99 percent of the sediment movement in 3 percent of the time; (2) the highway construction areas, varying from less than 1 to more than 10 percent of the basin at a given time, contributed 85 percent of the sediment; (3) 38 percent of the sediment movement occurred during April, May, and June, and only 11 percent occurred during July, August, and September; and (4) on the basis of residual soil and streamsediment particle sizes, the amount of sediment eroded from areas of construction was about twice that transported from the basin. Precipitation during the study was about 12 percent less than the long-term average. If normal precipitation had prevailed, the estimated gross erosion in the construction area would have been about 20 percent more than actually occurred, giving an average of 151 tons per acre per year, about 76 tons of which would be transported from the basin. This amount is about 10 times that normally expected from cultivated land, 200 times that expected from grassland, and 2,000 times that expected from forest land. INTRODUCTION This report shows the extent to which earth materials may be eroded by rainfall and carried by stream systems during a period of disturbance of surface materials common to highway construction. The study El E2 HYDROLOGIC EFFECTS OF URBAN GROWTH was made in a drainage basin of 4.54 square miles in the northwestern part of Fairfax County near McLean, Va., during 1961 to 1964. The basin is drained by Scott Kun which empties into the Potomac River 5.9 miles above the head of the Potomac Estuary at Washington, D.C. The project was inspired by earlier studies (Guy and Ferguson, 1962; Guy, 1964,1965) of the effects of urbanization on sedimentation in the suburban area of Washington, D.C. These investigations measured the large quantities of earth materials eroded at commercial and residential construction sites and carried by the stream systems during storm events. These studies also described the manner in which sediments of larger sizes were deposited in or below drainage facilities and in reservoirs, as well as the tendency of the finer materials to remain longer in suspension and cause turbidity in downstream water bodies, such as the Potomac Estuary. These studies, and others begun more recently (Wolman, 1964; Dawdy, 1967), provide some insight that may assist public officials and construction organizations in devising practices to minimize the movement of soil materials from construction sites. The significant and impressive findings about fluvial sediments associated with building sites induced the authors to seek comparable information about sedimentation from highway construction where large areas of land are denuded and great quantities of soil and rock are excavated, transported, and placed. Moreover, new highways and streets occupy a sizable segment of the land under development in suburban areas. Scott Run basin was chosen for the study site for several reasons. 1. The area under highway construction, constituting about 11 percent of the 4.54-square-mile drainage area, assured a source of streamborne sediments that could be measured effectively and that could be reasonably well identified with the sources. The construction area as it relates to the Scott Run stream system is shown in figure 1. 2. Nonhighway types of construction were expected to be minor during the study period so that most of the expected sediment would come from highway construction. Figure 2 is from an aerial photograph taken in March 1963 showing the extent of the highways and the nature of the land use at that time. 3. The study site was but a few miles from the residences of the authors, permitting them to reach the primary measuring site in time to make vital observations and measurements within the 2 hours or less between the period of concentrated rainfall and the passage of the sediment-laden flood waters past the measurement sites. SCOTT RUN BASIN, FAIRFAX COUNTY, VIRGINIA E3

Sediment movement in an area of suburban highway construction, Scott Run Basin, Fairfax County Virginia, 1961-64