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This article evaluates drought scenarios of the Upper Colorado River basin (UCRB) considering multiple drought variables for the past 500 years and positions the current drought in terms of the magnitude and frequency. Drought characteristics were developed considering water-year data of UCRB’s streamflow, and basin-wide averages of the Palmer Hydrological Drought Index (PHDI) and the Palmer Z Index. Streamflow and drought indices were reconstructed for the last 500 years using a principal component regression model based on tree-ring data. The reconstructed streamflow showed higher variability as compared with reconstructed PHDI and reconstructed Palmer Z Index. The magnitude and severity of all droughts were...
Concentrations of atmospheric CO2 and other radiatively active trace gases have risen since the Industrial Revolution. Such atmospheric modifications can alter the global climate and hydrologic cycle, in turn affecting water resources. The clear physical and biological sensitivities of water resources to climate, the indication that climate change may be occurring, and the substantial social and economic dependencies on water resources have instigated considerable research activity in the area of potential water resource impacts. We discuss how the literature on climate change and water resources responds to three basic research needs: (1) a need for water managers to clearly describe the climatic and hydrologic...
ABSTRACT: As part of a basinwide water-quality study, nitrogen and phosphorus data for the Upper Colorado River Basin from the Colorado-Utah State line to the Continental Divide were analyzed for spatial distributions, concentrations associated with various land uses, and temporal trends. Nitrogen and phosphorus concentrations generally increased in a downstream direction. Some nutrient concentrations were elevated at some sites in the upper parts of the basin in areas influenced by increasing urbanization. Sites were grouped according to land use and site type, and median nutrient concentrations were compared among groups. Sites within the agricultural areas of the basin generally had the highest concentrations...
This article describes the development of a calibrated hydrologic model for the Blue River watershed (867 km2) in Summit County, Colorado. This watershed provides drinking water to over a third of Colorado?s population. However, more research on model calibration and development for small mountain watersheds is needed. This work required integration of subsurface and surface hydrology using GIS data, and included aspects unique to mountain watersheds such as snow hydrology, high ground-water gradients, and large differences in climate between the headwaters and outlet. Given the importance of this particular watershed as a major urban drinking-water source, the rapid development occurring in small mountain watersheds,...
Survey data collected in the San Joaquin Valley of southern California and the Grand Valley of western Colorado reveal that residents of both areas believe that a severe sustained drought is likely to occur within the next 20–25 years and that their communities would be seriously impacted by such an event. Although a severe sustained drought affecting the Colorado River Basin would cause major economic and social disruptions in these and other communities, residents express little support for water management alternatives that would require significant shifts in economic development activities or in water use and allocation patterns. In particular, residents of these areas express little support for strategies...
This paper describes how a hydrologic model proved to be a valuable tool to help interested parties understand impacts to four threatened and endangered fish species in the Upper Colorado River. In 1994, the Ute Water Conservancy District initiated permitting and design of the Plateau Creek pipeline replacement. The project was considered a major Federal action and therefore subject to the National Environmental Policy Act. Under Section 7 of the Endangered Species Act, the U.S. Fish and Wildlife Service (USFWS) entered the process to develop a Biological Opinion (BO) and determined that the project could potentially impact the endangered fish in the 15-mile reach of the Colorado River. The Section 7 consultation...
We review published analyses of the effects of climate change on goods and services provided by freshwater ecosystems in the United States. Climate-induced changes must be assessed in the context of massive anthropogenic changes in water quantity and quality resulting from altered patterns of land use, water withdrawal, and species invasions; these may dwarf or exacerbate climate-induced changes. Water to meet instream needs is competing with other uses of water, and that competition is likely to be increased by climate change. We review recent predictions of the impacts of climate change on aquatic ecosystems in eight regions of North America. Impacts include warmer temperatures that alter lake mixing regimes and...
he Mancos Shale area of the Upper Colorado River basin produces large quantities of solutes. In order to develop an understanding of the mechanism of salt production and to determine the source of salinity, a study of the soluble mineral content (SMC) of Mancos Shale and associated alluvium was undertaken. SMC is highly variable in alluvium and associated surficial Mancos Shale. However, lithomorphological units can be identified in terms of their SMC. Results from this study demonstrate that crusts are leached in deep alluvial fills and they contain somewhat less soluble minerals than underlying Mancos Shale on hillslopes. The crusts are saline, sometimes efflorescent, in shale bedrock channels or where channels...
Observed April 1 snowpack accumulations within and near the Gunnison River basin in southwestern Colorado are compared with simulations from the Rhea-orographic-precipitation model to determine if the model simulates reliable magnitudes and temporal and spatial variability in winter precipitation for the basin. Twenty simulations of the Rhea model were performed using 'optimal' parameter sets determined for 10-kilometer (km) grids (10-km by 10-km grid cells) through stochastic calibration. Comparisons of Rhea-model simulations of winter precipitation with April 1 snowpack accumulations at 32 snowcourse stations were performed for the years 1972-1990. For most stations and most years the Rhea model reliably simulates...
Although our current (1990) knowledge of hydrologic and hydraulic processes is based on many years of study, there are river environments where these processes are complex and poorly understood. One of these environments is in mountainous areas, which cover about 25 percent of the United States. Use of conventional hydrologic and hydraulic techniques in mountain-river environments may produce erroneous results and interpretations in a wide spectrum of water-resources investigations. An ongoing U.S. Geological Survey research project is being conducted to improve the understanding of hydrologic and hydraulic processes of mountainous areas and to improve the results of subsequent hydrologic investigations. Future...
Water resource planning is based primarily on 20th century instrumental records of climate and streamflow. These records are limited in length to approximately 100 years, in the best cases, and can reflect only a portion of the range of natural variability. The instrumental record neither can be used to gage the unusualness of 20th Century extreme low flow events, nor does it allow the detection of low-frequency variability that may underlie short-term variations in flow. In this study, tree rings are used to reconstruct mean annual streamflow for Middle Boulder Creek in the Colorado Front Range, a semi-arid region of rapid growth and development. The reconstruction is based on a stepwise regression equation that...
Two major objectives in operating the multireservoir system of the Upper Colorado River basin are maximization of hydroelectric power production and maximization of the reliability of annual water supply. These two objectives conflict. Optimal operation of the reservoir system to achieve both is unattainable. This paper seeks the best compromise solution for an aggregated reservoir as a surrogate of the multireservoir system by using two methods: the constraint method and the method of combined stochastic and deterministic modeling. Both methods are used to derive the stationary optimal operating policy for the aggregated reservoir by using stochastic dynamic programming but with different objective functions and...
This paper details a case study of economic and natural system responses to alternative water management policies in the Cache La Poudre River basin, Colorado, 1980?1994. The case study is presented to highlight the value and application of a conceptual integration of economic, salmonid population, physical habitat, and water allocation models. Five alternative regimes, all intended to increase low winter flows, were investigated. Habitat enhancements created by alternative regimes were translated to population responses and economic benefits. Analysis concluded that instream flows cannot compete on the northern Colorado water rental market; cooperative agreements offer an economically feasible way to enhance instream...
Relative yields of water, sediment, and salt (as indexed by electrical conductivity) were determined using simulated rainfall plots on three soil landform units on Mancos shale in the Price River Basin, Utah. Final infiltration rates on residual shale derived soils were between 0.13 and 0.50 cm/hr. No runoff was generated on cracked soils derived from aeolian deposits. Suspended sediment concentrations and elehcal conductivities were 180 and 68 times greater, respectively, for a steep dissected Mancos shale upland than for a low relief shale pediment and recent alluvial surface. Riling accounted for approximately 80 percent of the sediment produced on the steep, dissected shale surface. Channel scow and soil creep...
To help meet national energy demands, interest has been focused on the coal, oil shale, and uranium deposits of the Upper Colorado River Basin. Several energy output projections for the basin have been presented based upon water availability. Inherent in all these analyses are estimates as to the rate of water use in each energy development. New energy technologies are characterized by parameters extrapolated from small scale energy facilities. The data provide projected costs, conversion efficiencies, and material inputs and outputs. Alternative techniques for process cooling and solids handling provide variable rates of water use which affect other conversion parameters. Results from a mathematical model are used...
This paper considers the risk of drought and develops drought scenarios for use in the study of severe sustained drought in the Southwestern United States. The focus is on the Colorado River Basin and regions to which Colorado River water is exported, especially southern California, which depends on water from the Colorado River. Drought scenarios are developed using estimates of unimpaired historic streamflow as well as reconstructions of streamflow based on tree ring widths. Drought scenarios in the Colorado River Basin are defined on the basis of annual flow at Lees Ferry. The risk, in terms of return period, of the drought scenarios developed, is assessed using stochastic models. Published in Journal of the...
ABSTRACT: The U.S. Endangered Species Act (ESA) restricts federal agencies from carrying out actions that jeopardize the continued existence of any endangered species. The U.S. Supreme Court has emphasized that the language of the ESA and its amendments permits few exceptions to the requirement to give endangered species the highest priority. This paper estimates economic costs associated with one measure for increasing instream flows to meet critical habitat requirements of the endangered Rio Grande silvery minnow. Impacts are derived from an integrated regional model of the hydrology, economics, and institutions of the upper Rio Grande Basin in Colorado, New Mexico, Texas, and Mexico. One proposal for providing...
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Salinity increases in water in some parts of the Nava-jo aquifer in southeastern Utah have been documented previously. The purpose of this paper is to use bromide, iodide, and chloride concentrations and del oxygen-18 and deuterium values in water from the study area to determine if oil-field brines (OFB) could be the source of increased salinity. Mixing-model results indicate that the bromide-to-chloride X 10,000 weight ratio characteristic of OFB in and outside the study area could not be causing the bromide depletion with increasing salinity in the Navajo aquifer. Mixing-model results indicate that a mixture of one percent OFB with 99 percent Navajo aquifer water would more than double the bromide-to-chloride...
This study emphasized a field investigation of salt release to overland flow from Mancos shale lands of the Price River Basin, Utah. Although a high degree of natural variation existed in the data, which precluded the separation of factors affecting diffuse salt loading that occurs during overland flow, a simplistic nonpoint source loading function developed on empirical concepts was fit to the data. This function was then used to calculate the average annual salt yield to the Price River by overland flow. It was found that even under severe conditions, the salt yields from Mancos shale lands due to overland flow is relatively minor, accounting for less than 1.5 percent of the average annual salt mass transported...
Most southwestern cities were founded along rivers or in areas having springs or readily available ground water. Because of the generally sparse precipitation, the renewable fresh water supply in the Southwest is smaller than most other areas of the United States. Despite the arid climate, water use has increased rapidly, first in the form of irrigation, and more recently the use in cities. This has caused extensive development of local water resources and overdraft of ground water basins in some areas. It is difficult to implement new local supplies and importation projects due to a myriad of environmental and legal constraints and a general shortage of public funds. Various opportunities and plans for water management,...
map background search result map search result map Salinity increases in the Navajo Aquifer in southeastern Utah Salinity increases in the Navajo Aquifer in southeastern Utah