Geology topics

G.C. Bent

Publications and source records attributed to G.C. Bent.

3 recordsLinked to original sources

USGS2001

Effects of forest-management activities on runoff components and ground-water recharge to Quabbin Reservoir, central Massachusetts

The effects of forest-management activities (timber cutting and herbicide application) on runoff components (total streamflow, direct runoff, and base flow) and on ground-water recharge per unit area were evaluated for two separate paired drainage basins of Quabbin Reservoir in central Massachusetts. The Cadwell Creek study area, studied from 1962-1973, included an experimental basin (Upper Cadwell Creek) and a control basin (Lower Cadwell Creek). In the experimental basin, herbicide was applied to mixed oaks, northern hardwoods, and understory vegetation in different riparian zones during the summers of 1967 and 1968, and some pine plantations were thinned or clear-cut during the winter of 1967-1968. These forest-management activities decreased the total basal area by about 34%. The decrease in total basal area resulted in an increase in total streamflow, direct runoff (total streamflow minus base flow), and ground-water recharge for six dormant seasons (October-April) and six growing seasons (May-September) during 1968-1973. Base flow increased for three dormant seasons and two growing seasons during 1968-1970 and the dormant seasons of 1971 and 1973. Base flow accounted for 34% and direct runoff accounted for 66% of the 94 mm (15%) increase in total streamflow during water years 1968-1973. Sixty-one percent of this increase in total streamflow occurred in the dormant seasons. The Dickey Brook study area, studied from 1985-1989, included an experimental basin (Dickey Brook) and a control basin (Dickey Brook Tributary). Some pine plantations were thinned or clear-cut in the headwaters of the experimental basin from October 1986 to March 1987 and October to December 1988. These forest-management activities decreased the total basal area by 24% during 1986-1987 and an additional 8% during 1988. The decrease in total basal area resulted in an increase in total streamflow, base flow, and ground-water recharge for only one dormant season and one growing season in 1987. Direct runoff only increased slightly during the 1987 dormant season. Base flow accounted for 91% and direct runoff accounted for 9% of the 92 mm (21%) increase in total streamflow during water year 1987. Seventy-seven percent of this increase in total streamflow occurred in the dormant season.

Conference Paper↗

USGS1993

Erosion response of a disturbed sagebrush steppe hillslope

Land management activities that disrupt surface vegetation cover pose a serious threat to the long-term stability of buried-waste sites located within the semiarid sagebrush ( Artemisia tridentata Nutt.) steppe region of the northwestern USA. In this study, we evaluated the erosion response of a sagebrush hillslope subjected to three vegetation cover treatments: natural (undisturbed), bare (plant canopy and litter cover removed), and clipped (canopy removed). A rotating boom rainfall simulator was used to apply rain at 60 or 120 mm/h intensities to runoff plots (3.0 m by 10.7 m) with dry, wet, and very wet antecedent moisture conditions, and during two late and one early summer seasons. Supplemental overland flow was added at the upper end of each plot to simulate increased slope length during very wet runs. Maximum soil loss rates on the natural, clipped, and bare treatments were, respectively, 1, 5, and 216 mg/m 2 per s during the 60 mm/h rainfall intensity, and 13, 79, and 1473 mg/m 2 per s during the 120 mm/h rainfall intensity. Cumulative soil loss was typically 100 to 1000 times greater on the bare treatment than on the natural or clipped treatments. Increases in simulated slope length produced a near linear increase in soil loss from the bare treatment plots (about 0.02 g/m 2 per s soil loss per m of slope length) until 30 m, after which the effect of slope length declined. Surface crust development and mound-intermound microtopography played important roles in governing soil detachment and transport on the hillslope. Despite high rainfall intensity and surface runoff rates, rill erosion was negligible on both the undisturbed and disturbed portions of the hillslope.

Journal of Environmental Quality↗

USGS1992

Hydraulic roughness of earth covers at a cold-desert waste burial site

A kinematic wave model of overland flow was used to calculate hydraulic roughness coefficients for earth covers and native hillslope surfaces at a waste burial site. Manning's n roughness coefficients were greater on earth cover plots planted to crested wheatgrass (n = 0.076) than on those planted to streambank wheatgrass (n = 0.030). Mound and intermound microtopography strongly influenced overland flow geometry on the bare native hillslope plots resulting in low apparent roughness values (n = 0.013). Time-related changes in hydraulic roughness appeared to be caused by development of a rain-induced crust on exposed soil surfaces that reduced infiltration and increased plot smoothness. -from Authors

Arid Soil Research and Rehabilitation↗