Geology topics

S. R. Ellis

Publications and source records attributed to S. R. Ellis.

4 recordsLinked to original sources

USGS1985

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

Rainfall-runoff simulation studies were conducted in conjunction with the Denver Regional Urban Runoff Program to: (1) Compare runoff characteristics from two different intensities of simulated rainfall on street-surface plots, (2) document a first flush of constituent washoff loads in runoff from 1,000-sq-ft street-surface plots, (3) compare runoff characteristics from the street surface plots with those from a 69-acre urban mixed land use subjected to natural rainfall, (4) perform statistical analysis of washoff loads, and (5) compare quantity and quality of runoff from 400-sq-ft plots of native pasture subjected to simulated rainfall and from a 405-acre basin of native pasture subjected to natural rainfall. Experiments on the street surface showed that higher intensity simulated rainfall produced a higher percentage of runoff than lower intensity rainfall, and a first flush of constituent loads occurred for most constituents. The event mean constituent concentrations in the street-surface runoff from simulated storms were generally much smaller than those in the runoff from an adjacent urban basin. Simulated rainfall in small native pasture plots produced runoff-to-rainfall ratios similar to runoff-to-rainfall ratios from a larger native pasture subject to natural rainfall. (USGS)

Colorado↗

USGS1985

A summary of urban runoff studies in the Denver Metropolitan area, Colorado

The Denver metropolitan area has been the subject of urban-runoff studies for several years. The first studies, started in about 1968, usually were concerned only with the quantity of urban runoff. In 1974, studies were begun that included both quantity and quality of urban runoff. In 1979, Denver was selected as one of the cities to be included in the Nationwide Urban Runoff Program. The Denver study was called the Denver Regional Urban Runoff Program and was a cooperative study between the Denver Regional Council of Governments and the U.S. Geological Survey. This report presents the major conclusions of the pre-Denver Regional Urban Runoff Program studies and a summary of the various elements of the Denver Regional Urban Runoff Program. The report summarizes and references urban-runoff studies in the Denver metropolitan area and is a reference guide for planners and other persons interested in urban runoff.

Colorado↗

USGS1983

Hydrologic characteristics of lagoons at San Juan, Puerto Rico, during an October 1974 tidal cycle

Flow and water-quality changes were studied during a period of intense rainfall in the San Juan Lagoon system. The study covered a 25-hour period beginning 0900 hours 22 October, 1974. Precipitation during the study period averaged 70 millimeters. Sampling stations were located at Boca de Cangrejos, the main ocean outlet; Canal Pinones between Laguna de Pinones and Laguna La Torrecilla; Canal Suarez between Laguna San Jose, connects to Laguna La Torrecilla; and Cano de Martin Pena between Laguna San Jose and Bahia de San Juan. In addition water-elevation recording gages were installed at each lagoon. Water samples from the canal stations were analyzed for organic carbon, nitrogen and phosphorus species, and suspended sediment. Specific-conductance measurements were used with the chemical data to estimate the runoff contributions of nutrients. Runoff into the lagoon, system during the study period was about 2.8 million cubic meters, or about 70 percent of the average precipitation. The runoff contributed chemical loadings to the lagoons of 95,000 kilograms total-organic carbon; 2,700 kilograms of total phosphorus; and 10,000 kilograms of total Khjeldhal nitrogen. A comparison with a prior study during which there was no significant rain, show that dry-period loadings are less than 10 percent of the wet-period loadings. At the end of the study period the system had not reached equilibrium, and the lagoons retained 80 percent of the water inflows from 50 to 90 percent of the chemical loads. Nearly 95 percent of the water outflows occurred at the Boca de Cangrejos sea outlet. The three lagoons and interconnecting canals form a very complex hydraulic system that is difficult to study using traditional techniques. A model of the system will facilitate management to improve the quality of water in the lagoons.

Open-File Report↗

USGS1976

History of dredging and filling of lagoons in the San Juan area, Puerto Rico

Laguna La Torrecilla, Laguna de Pinones, Laguna San Jose, and Laguna del Condado, in the San Juan, Puerto Rico area, are located within a metropolitan area of more than 1 million people. Bathymetric maps made during the study, in 1973, showed that Lagunas La Torrecilla, San Jose, and del Condado have been modified by dredging and filling; whereas, Laguna de Pinones has remained in a near natural state. Laguna La Torrecilla has been dredged to a depth, in places, of about 18 meters, and Lagunas San Jose and del Condado, in places to about 11 meters. Dredging in the San Juan lagoons has been harmful, beneficial, and in a few instances has had little or no noticeable effect on the water quality. Usually, dredging in the connecting canals has been beneficial if the water entering the lagoons through the canals was of better quality than the water in the lagoon. Dredging in the mouths of lagoons has been beneficial; whereas, filling or blocking the mouths has been harmful.

Puerto Rico↗