Geology topics

M.G. Rupert

Publications and source records attributed to M.G. Rupert.

5 recordsLinked to original sources

USGS2009

Predicting the probability and volume of postwildfire debris flows in the intermountain western United States

Empirical models to estimate the probability of occurrence and volume of postwildfire debris flows can be quickly implemented in a geographic information system (GIS) to generate debris-flow hazard maps either before or immediately following wildfires. Models that can be used to calculate the probability of debris-flow production from individual drainage basins in response to a given storm were developed using logistic regression analyses of a database from 388 basins located in 15 burned areas located throughout the U.S. Intermountain West. The models describe debris-flow probability as a function of readily obtained measures of areal burned extent, soil properties, basin morphology, and rainfall from short-duration and low-recurrence-interval convective rainstorms. A model for estimating the volume of material that may issue from a basin mouth in response to a given storm was developed using multiple linear regression analysis of a database from 56 basins burned by eight fires. This model describes debris-flow volume as a function of the basin gradient, aerial burned extent, and storm rainfall. Applications of a probability model and the volume model for hazard assessments are illustrated using information from the 2003 Hot Creek fire in central Idaho. The predictive strength of the approach in this setting is evaluated using information on the response of this fire to a localized thunderstorm in August 2003. The mapping approach presented here identifies those basins that are most prone to the largest debris-flow events and thus provides information necessary to prioritize areas for postfire erosion mitigation, warnings, and prefire management efforts throughout the Intermountain West.

Geological Society of America Bulletin↗

USGS2008

Post-Wildfire Hydrologic Hazards in the Wildland Urban Interface of Colorado and the Western United States

Following a wildfire, such as the 2002 Missionary Ridge fire, a number of hydrologic hazards may develop that can have an important impact on water resources, businesses, homes, reservoirs, roads, and utilities in the wildland urban interface (areas where homes and commercial developments are interspersed with wildlands) in mountainous areas of the Western United States. This fact sheet describes these hazards and identifies approaches to quantify them, thus enabling land and resource managers to plan for and mitigate the effects of these hazards. The fact sheet has been produced in association with the U.S. Geological Survey (USGS) Fire Science Thrust program and the Colorado Front Range Demonstration Project (CFRDP). The current (2007) focus of the CFRDP is on the Three Lakes watershed in Grand County, Colorado, which has applicability to many similar forested, mountain areas in the Western United States.

Fact Sheet↗

USGS2005

Calibration of the DRASTIC ground water vulnerability mapping method

Ground water vulnerability maps developed using the DRASTIC method have been produced in many parts of the world. Comparisons of those maps with actual ground water quality data have shown that the DRASTIC method is typically a poor predictor of ground water contamination. This study significantly improved the effectiveness of a modified DRASTIC ground water vulnerability map by calibrating the point rating schemes to actual ground water quality data by using nonparametric statistical techniques and a geographic information system. Calibration was performed by comparing data on nitrite plus nitrate as nitrogen (NO 2 + NO 3 -N) concentrations in ground water to land-use, soils, and depth to first-encountered ground water data. These comparisons showed clear statistical differences between NO 2 + NO 3 -N concentrations and the various categories. Ground water probability point ratings for NO 2 + NO 3 -N contamination were developed from the results of these comparisons, and a probability map was produced. This ground water probability map was then correlated with an independent set of NO 2 + NO 3 -N data to demonstrate its effectiveness in predicting elevated NO 2 + NO 3 -N concentrations in ground water. This correlation demonstrated that the probability map was effective, but a vulnerability map produced with the uncalibrated DRASTIC method in the same area and using the same data layers was not effective. Considerable time and expense have been outlaid to develop ground water vulnerability maps with the DRASTIC method. This study demonstrates a cost-effective method to improve and verify the effectiveness of ground water vulnerability maps.

Idaho, Wyoming↗

USGS2005

Age of irrigation water in ground water from the Eastern Snake River Plain Aquifer, south-central Idaho

Stable isotope data ( 2 H and 18 O) were used in conjunction with chlorofluorocarbon (CFC) and tritium/helium-3 ( 3 H/ 3 He) data to determine the fraction and age of irrigation water in ground water mixtures from farmed parts of the Eastern Snake River Plain (ESRP) Aquifer in south-central Idaho. Two groups of waters were recognized: (1) regional background water, unaffected by irrigation and fertilizer application, and (2) mixtures of irrigation water from the Snake River with regional background water. New data are presented comparing CFC and 3 H/ 3 He dating of water recharged through deep fractured basalt, and dating of young fractions in ground water mixtures. The 3 H/ 3 He ages of irrigation water in most mixtures ranged from about zero to eight years. The CFC ages of irrigation water in mixtures ranged from values near those based on 3 H/ 3 He dating to values biased older than the 3 H/ 3 He ages by as much as eight to 10 years. Unsaturated zone air had CFC-12 and CFC-113 concentrations that were 60% to 95%, and 50% to 90%, respectively, of modern air concentrations and were consistently contaminated with CFC-11. Irrigation water diverted from the Snake River was contaminated with CFC-11 but near solubility equilibrium with CFC-12 and CFC-113. The dating indicates ground water velocities of 5 to 8 m/d for water along the top of the ESRP Aquifer near the southwestern boundary of the Idaho National Engineering and Environmental Laboratory (INEEL). Many of the regional background waters contain excess terrigenic helium with a 3 He/ 4 He isotope ratio of 7 x 10-6 to 11 x 10-6 (R/R a = 5 to 8) and could not be dated. Ratios of CFC data indicate that some rangeland water may contain as much as 5% to 30% young water (ages of less than or equal to two to 11.5 years) mixed with old regional background water. The relatively low residence times of ground water in irrigated parts of the ESRP Aquifer and the dilution with low-NO 3 irrigation water from the Snake River lower the potential for NO 3 contamination in agricultural areas.

Ground Water↗

USGS1998

Water quality in the upper Snake River basin, Idaho and Wyoming, 1992-95

This report is intended to summarize major findings that emerged between 1992 and 1995 from the water-quality assessment of the Upper Snake River Basin Study Unit and to relate these findings to water-quality issues of regional and national concern. This information is primarily intended for those who are involved in water-resource management. Yet, the information contained here may also interest those who simply wish to know more about the quality of water in the rivers and aquifers in the area where they live.

Idaho;Wyoming↗