Search USGS⌕ Search
Home/Archive/USGS

USGS · pp1441

Runoff characteristics and washoff loads from rainfall-simulation experiments on a street surface and a native pasture in the Denver metropolitan area, Colorado

Martha H. Mustard·Sherman R. Ellis·Johnnie W. Gibbs
View original source ↗Read source document ↗Export metadata ↓

Abstract

Rainfall simulation studies were conducted in conjunction with the Denver Regional Urban Runoff Program to: (1) Compare runoff quantity and quality from two different intensities of rainfall on impervious plots having identical antecedent conditions, (2) document a first flush of constituent loads in runoff from l,000-square-foot street-surface plots, (3) compare runoff characteristics from a street surface subjected to simulated rainfall with those from a 69-acre urban basin of mixed land use subjected to natural rainfall, (4) perform statistical analysis of constituent loads in the runoff with several independent variables, and (5) compare the quantity and quality of runoff from 400-square-foot plots of native grasses used for pasture and subjected to simulated rainfall with that from a 405-acre basin covered with native grasses used for pasture and subjected to natural rainfall. The rainfall simulations conducted on the street surface showed that higher intensity simulated rainfall produced a higher percentage of runoff than lower intensity rainfall. A first flush of constituent loads occurred for most constituents in the runoff from most rainfall simulations on the street surface; however, a first flush did not occur in the runoff from simulated rainfall on the pasture. The event mean concentrations of constituents in the runoff from simulated storms on the street surface were generally much smaller than the event mean concentrations of constituents in the runoff from an adjacent urban basin. Analysis of the data from the rainfall simulations on a street surface indicates that intensity of rainfall and total rainfall are important variables determining constituent loads. The design of the experiment was such that intensity of rainfall and total rainfall were highly correlated, thus precluding the development of useful regression equations to predict washoff loads. The quality of runoff from the simulated rainfall on the pasture was influenced by the disturbed perimeters of the plots; however, the runoff-to-rainfall ratios for the simulated storms fell within the range of ratios measured for natural storms over the adjacent 405-acre basin.

Explore related subjects

Professional PaperReport

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Martha H. Mustard, Sherman R. Ellis, Johnnie W. Gibbs. 1987. Runoff characteristics and washoff loads from rainfall-simulation experiments on a street surface and a native pasture in the Denver metropolitan area, Colorado. https://doi.org/10.3133/pp1441

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Resurvey of the Marble Canyon and Bridge Canyon dam sites in Grand Canyon National Park—Changes in sediment storage and evidence supporting the occurrence of bedrock incision through the mid-20th century

The Bureau of Reclamation developed an extensive plan for a network of dams, water tunnels, and hydropower plants in and around Grand Canyon, Arizona, in the 1940s through 1960s. The two largest of these planned dams were the Marble Canyon and Bridge Canyon Dams on the Colorado River. Though these dams were ultimately never built, Reclamation conducted extensive topographic, bathymetric, and subsurface exploration work at the sites proposed for these dams in the 1940s and 1950s. Resurveys of these dam sites were conducted between 1998 and 2021 to determine the changes in sediment storage at these dam sites caused by the upstream construction and operation of Glen Canyon Dam and by the recession of Lake Mead, the reservoir impounded by Hoover Dam. The resurveys of the Marble Canyon dam sites indicate that the post-1950s changes in sediment storage at these dam sites are broadly consistent with flux-based estimates of voluminous sand erosion from Marble Canyon since the 1963 closure of Glen Canyon Dam. These resurveys also suggest that the pre-dam longitudinal variation in sediment thickness over bedrock played a key role in determining the locations of the sand erosion induced by Glen Canyon Dam; more sand eroded from locations where more sand was present in the 1950s. The resurvey of the Bridge Canyon dam sites indicates that the Colorado River’s incision of the Lake Mead delta is regulated both by bed-sediment grain size and downstream hydraulic controls. Finally, analyses of bed-sediment thickness and sedimentological data at the dam sites, and observations of bed scour and gravel transport, suggest that sufficient bedrock was exposed to allow bedrock incision during commonly recurring pre-dam snowmelt floods that entrained small boulders into transport.

Arizona↗
USGS2026

The eruptive behavior of distributed volcanism forming low shield edifices—A case study of Sentinel-Arlington volcanic field, U.S.A.

Distributed volcanic fields are present in various tectonic settings worldwide, and their characteristics reflect differing influences from magmatic and tectonic processes. In the southwestern United States alone, there are 37 Quaternary distributed volcanic fields. After the primary period of extensional tectonics in the southern Basin and Range 15–5 million years ago, the Sentinel-Arlington volcanic field developed in southwestern Arizona between 4 and 1 million years ago. The Sentinel-Arlington volcanic field consists primarily of low relief shield volcanoes, a type of distributed volcanism with poorly understood temporal evolution. The Sentinel-Arlington volcanic field is less than 200 kilometers (km) from the Colorado Plateau, Gulf of California, and southern San Andreas Fault system. This work identifies and examines controls on the emplacement of the Sentinel-Arlington volcanic field by documenting shallow and surficial structures as well as eruption characteristics and style through time. The Sentinel-Arlington volcanic field consists of 21 volcanoes with a total of 33 vents over an area of about 770 square kilometers (km 2 ). The prominence of low relief shield volcanoes may be explained by ascent of basaltic magmas through thin Basin and Range crust, without much crustal contamination, and low viscosities common to mafic compositions. Typical eruption characteristics involve the construction of low relief shield volcanoes followed by Strombolian fissure eruptions at the summits or near-summit medial areas that produce scoria lapilli, which may weld to form agglomerate. The total lifetime erupted volume of about 4.3 cubic kilometers (km 3 ) represents an average eruptive flux of approximately 2x10 -3 km 3 per thousand years (k.y.). This erupted volume is low relative to Neogene basaltic intraplate distributed volcanic fields worldwide, which typically range from 10 -3 to 1 km 3 k.y. -1 . Sentinel-Arlington volcanic field eruptions were likely triggered by intermittent rejuvenation of transient magmatic zones that exist in thinned crust. Instantaneous flux from point sources feeding the lava flows is estimated to be on the order of 10 -1 to 10 cubic meters per second.

Arizona↗
USGS2026

Capitalization of positional (Lower/Middle/Upper) and temporal (Early/Middle/Late) adjectives in the names of formal chronostratigraphic and geochronologic units of the Phanerozoic

Many authors are understandably confused about the capitalization of the words “lower,” “middle,” “upper,” “early,” and “late.” Where these words are used simply as descriptive adjectives, they should be in lowercase; where they form the first word of a formal chronostratigraphic or geochronologic unit name, they should be in uppercase.

Professional Paper↗