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At least 19 recordsLinked to original sources
USGS2015

Evaluation of mean-monthly streamflow-regression equations for Colorado, 2014

The U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board, evaluated the predictive uncertainty of mean-monthly streamflow-regression equations representative of natural streamflow conditions in Colorado. This study evaluates the predictive uncertainty of mean-monthly streamflow-regression equations developed in a 2009 U.S. Geological Survey study using streamflow data collected over the entire period of record at each streamgage through calendar year 2013. The study area for this report is limited to the Mountain, Northwest, Rio Grande, and Southwest hydrologic regions of Colorado. Data collected from the beginning of the period of record through calendar year 2013 were used to evaluate the mean-monthly streamflow equations using the same basin characteristics as in the 2009 study. U.S. Geological Survey and Colorado Division of Water Resources streamgages with at least 10 years of streamflow record and identified as representative of natural streamflow conditions were selected for this study. During the streamgage selection process, a total of 432 streamgages, composed of 278 from the 2009 study and 154 new streamgages, were identified. The updated standard error of prediction and adjusted coefficient of determination values that correspond to the mean-monthly streamflow equations developed in the 2009 study are in close agreement with the results of this study. The old streamgages performed slightly better than the new streamgages, with approximately 88 and 85 percent of the data within the prediction intervals, respectively. This result was expected because the streamgages used to develop the regression equations should yield a better performance than the new streamgages. For all hydrologic regions, approximately 87 percent of the data are within the 95-percent prediction intervals. The explanation for why fewer than 95 percent of the data are within the prediction intervals is that the data do not conform perfectly to the regression assumptions required to accurately estimate performance metrics. The equations for the Rio Grande hydrologic region had the best fit with the parametric prediction-interval assumptions, with approximately 91.8 percent of the data within the prediction interval (average 12 months). The Mountain, Northwest, and Southwest hydrologic regions had 87.8, 84.9, and 83.5 percent of the data contained within the prediction interval, respectively. Monthly adjusted coefficient of determination values were computed and have the same general pattern for all four hydrologic regions. The largest values usually occur in March or April, and the lowest values usually occur in August or September. Only the Rio Grande hydrologic region deviates from this seasonal pattern, exhibiting a decrease in adjusted coefficient of determination values in August and September, with the lowest values occurring in the winter months (December, January, and February). Generally, the adjusted coefficient of determination values for this report are just slightly less (0.76 compared to 0.79) than the values computed in the 2009 study. The similarity of values, even when tested with data not used to originally develop the mean-monthly streamflow-regression equations, provides confidence that the predictive uncertainty of mean-monthly regression equations in the 2009 study are accurate. The fact that the results for the two datasets are very similar provides assurance that when these equations are applied to locations not used to develop the equations, the standard error of prediction and adjusted-coefficient of determination error metrics should be similar to those established in the 2009 study for locations with natural streamflow. The median absolute differences between the observed and computed mean-monthly streamflow for Mountain, Northwest, and Southwest hydrologic regions are fairly uniform throughout the year, with the exception of late summer and early fall (July, August, and September), when each hydrologic region exhibits a substantial increase in median absolute percent difference. The greatest difference occurs in the Northwest hydrologic region, and the smallest difference occurs in the Mountain hydrologic region. The Rio Grande hydrologic region shows seasonal variation in median absolute percent difference with March, April, August, and September having a median absolute difference near or below 40 percent, and the remaining months of the year having a median absolute difference near or above 50 percent. In the Mountain, Northwest, and Southwest hydrologic regions, the mean-monthly streamflow equations perform the best during spring (March, April, and May). However, in the Rio Grande hydrologic region, the mean-monthly streamflow equations perform the best during late summer and early fall (August and September).

Arizona, Colorado, New Mexico, Utah, Wyoming↗
USGS1981

Summary of U.S. Geological Survey investigations and hydrologic conditions in southwest Florida for 1979

This report summarizes the hydrologic setting and the water-resources investigations in the Southwest Florida Water management District performed by the U.S. Geological Survey, Water Resources Division, for fiscal year 1979. Hydrologic conditions in southwest Florida are described and illustrated by hydrographs of selected surface-water, ground-water, and lake-stage data-collection sites. In addition, summaries of water-use data and data on the regional observation monitor-well program are provided. The investigations are pay of the Federal program of appraising the nation's water resources.l The cooperative program for fiscal year 1979 included 37 investigations. Abstracts of 15 reports released during 1979 are included.

Florida↗
USGS2010

Future dryness in the Southwest US and the hydrology of the early 21st century drought

Recently the Southwest has experienced a spate of dryness, which presents a challenge to the sustainability of current water use by human and natural systems in the region. In the Colorado River Basin, the early 21st century drought has been the most extreme in over a century of Colorado River flows, and might occur in any given century with probability of only 60%. However, hydrological model runs from downscaled Intergovernmental Panel on Climate Change Fourth Assessment climate change simulations suggest that the region is likely to become drier and experience more severe droughts than this. In the latter half of the 21st century the models produced considerably greater drought activity, particularly in the Colorado River Basin, as judged from soil moisture anomalies and other hydrological measures. As in the historical record, most of the simulated extreme droughts build up and persist over many years. Durations of depleted soil moisture over the historical record ranged from 4 to 10 years, but in the 21st century simulations, some of the dry events persisted for 12 years or more. Summers during the observed early 21st century drought were remarkably warm, a feature also evident in many simulated droughts of the 21st century. These severe future droughts are aggravated by enhanced, globally warmed temperatures that reduce spring snowpack and late spring and summer soil moisture. As the climate continues to warm and soil moisture deficits accumulate beyond historical levels, the model simulations suggest that sustaining water supplies in parts of the Southwest will be a challenge.

Proceedings of the National Academy of Sciences of↗
USGS1979

Summary of U.S. Geological Survey investigations and hydrologic conditions in the Southwest Florida Water Management District for 1978

This report summarizes water-resources investigations in the Southwest Florida Water Management District performed by the U.S. Geological Survey, Water Resources Division, for fiscal year 1978. The investigations are part of the Federal program of appraising the nation 's water resources. The cooperative program for fiscal year 1978 included 37 interpretive investigations. Abstracts of 30 reports released during 1978 and a bibliography of reports released since 1933 are included. The hydrologic setting of southwest Florida and discussions of surface-water, ground-water, and quality-of-water conditions are given. Hydrologic conditions in southwest Florida are described and illustrated by hydrographs of selected surface-water, ground-water and lake-stage data collection sites. In addition, summaries of water-use data and data on the regional observation monitor-well program are provided. (Kosco-USGS)

Florida↗
USGS1978

Summary of U.S. Geological Survey investigations and hydrologic conditions in the Southwest Florida Water Management District for 1977

This report summarizes the activities of the Southwest Florida Subdistrict of the U.S. Geological Survey, Water Resources Division for fiscal year 1977. The organization and mission of the subdistrict office are described. The cooperative program for fiscal year 1977 included 41 interpretive investigations. Abstracts of twenty reports released by the subdistrict during 1977 and an extensive bibliography of reports released from 1933 to 1977 are included. The hydrologic setting of southwest Florida is outlined followed by discussions of surface-water, ground-water, and quality-of-water conditions. Hydrologic conditions in southwest Florida in 1977 are shown by the presentation of hydrographs from selected surface-water, ground-water, and lake-stage data collection sites.

Florida↗
USGS2004

Development of a long-term sampling network to monitor restoration success in the southwest coastal Everglades: Vegetation, hydrology, and sediments

Introduction and History Hurricane Andrew, a Category 5 storm, crossed the southern Florida peninsula on the morning of August 24, 1992. Following the storm, the National Park Service conducted an environmental damage assessment to gauge the storm's impacts on the natural resources of south Florida Park Service holdings. Although hurricanes have impacted Park Service lands such as the Everglades in the past, no systematic, permanent sampling scheme has been established to monitor long-term recovery (or lack thereof) following disturbance. In October 1992, vegetation monitoring plots were established in heavily damaged areas of mangrove forest on the southwest coast of the Everlgades, along the Lostmans and Broad Rivers. As the permanent plot network was being established, funding was awarded for the South Florida Global Climate Change project (SOFL-GCC). This led to the establishment of a network of hydrological monitoring stations. Finally, sediment elevation tables (SETs) were installed at many locations. SETs provide the means to measure very small changes (2 mm) in the sediment surface elevation accurately over time. We also set up marker horizons to measure accretion of sediment at each site. Sampling sites were located along three transects extending from upstream freshwater wetlands to downstream saltwater wetlands along the Shark, Lostmans and Chatham Rivers in Everglades National Park. While we were developing our sampling network for basic scientific research needs, concern mounted over the health of the Greater Everglades Ecosystem and in particular over the influence of decreased freshwater flows. Ecosystem restoration planning was begun, resulting in the multi-agency, $8 billion Comprehensive Everglades Restoration Plan (CERP). Our co-located sampling networks allow us to track the interaction of hydrology, sediment, and vegetation over time, and will provide the opportunity to monitor the progress of the Everglades restoration and to gauge its success. Our earlier research questions have been modified over time to place a major emphasis on CERP needs, while still recognizing the importance of other processes, including disturbance and sea-level rise. Our research addresses processes relevant to the following restoration and related questions: * How will increasing freshwater flow affect wetland primary production? * Will increasing freshwater inflow alter nutrient availability? * Does recovery following disturbance in mangroves depend on freshwater inflow? * Will the position of vegetation ecotones change in response to upstream water management? * What will be the influence of global climate change, such as sea-level rise, on the Everglades restoration? * Will processes of wetlands soil formation be altered by sea-level rise and changed freshwater inflow?

Florida↗
USGS1979

Hydrologic data for the southwest subsurface-injection test site, St. Petersburg, Florida

Three injection wells, A1, A2, and A3, and nine observation wells, B1 through B9, were constructed at the Southwest St. Petersburg site to determine the feasibility of injecting wastewater treatment plant effluent into permeable zones containing saline water. Two withdrawal tests and one injection test were performed. Both withdrawal tests ran for about 3 days, one discharging 650 gallons per minute from well B8; the other discharging 6,490 gallons per minute from test well A3. The injection test was run in A3 for 91.1 days at an average rate of 2,830 gallons per minute. Injection well pressure reached a maximum of 48.1 pounds per square inch near the end of the test. Rhodamine WT was used as a tracer during the injection test and was identified in wells B3, B6, and B7. Before the injection test, chloride concentration in well B6, 35 feet distant from the injection well, and in well B3, 733 feet distant, ranged from 19,000 to 21,000 milligrams per liter. At the end of the test, chloride concentration in B6 was 1,800 milligrams per liter and in B3 was 5,400 milligrams per liter. Eleven wells near the site were sampled before the test for water-quality analyses and chlorides ranged from 18 to 1,400 milligrams per liter.

Florida↗
USGS1980

Delineation of ground-water contributing areas of streams of southwest Suffolk County, New York

The hydrologic system of southwest Suffolk County consists of two major components--a deep, southward-flowing ground-water system bounded on the north by Long Islands ' regional ground-water divide and on the south by the south-shore bays and ocean, and an overlying series of shallow ground-water flow systems that are separated from one another by north-south-trending interstream water-table divides. The shallow flow systems are the source of base flow to all streams on the island. The ground-water-contributing areas of southwest Suffolk County 's 21 streams are delineated on a map. The drainage-divide locations were derived from a 1975 water-table map on the assumption that flow in the shallow flow systems is two dimensional (horizontal). This assumption is valid for the southern part of the area (adjacent to flowing streams), but, because the direction of flow in the northern part, near the regional ground-water divide, is mainly downward, the delineations for the northern part are only inferred. (USGS)

Open-File Report↗
USGS1983

Hydrologic data from an area southwest of Tallahassee, Florida, where municipal wastewater effluent is applied by spray irrigation

The effects of spray irrigation using municipal wastewater effluent on a ground-water system (in particular, on the water of the Floridan aquifer) were investigated. The area irrigated was 4 miles southwest of Tallahassee, Florida, on an area covered in part by pine forest and in part by selected grasses and forage crops. Hydrologic and geologic data were collected from 1972 to 1981. Hydrologic data include ground-water levels, water quality, and spray-irrigation rates. Ground-water level measurements were made at 60 wells. Water-quality samples were collected at 1 municipal wastewater effluent site, 3 springs, 17 soil sites, and 64 wells. Water-quality data were obtained from physical, chemical, and bacteriological analyses. Geologic data include geophysical logs and lithologic descriptions of 34 wells. (USGS)

Open-File Report↗
USGS1995

Potentiometric surface of the upper Floridan Aquifer, west-central Florida, May 1995

The Floridan aquifer system consists of the Upper and Lower Floridan aquifers separated by a middle confining unit. The middle confining unit and the Lower Floridan aquifer generally contain highly mineralized water. In most reports on the hydrology of southwest Florida, the term "Floridan aquifer" has been applied to the water-bearing rocks, herin referred to as the Upper Floridan aquifer. The Upper Floridan aquifer is a productive aquifer and supplies more than 10 times the amount of water pumped from either the surfical aquifer system of the intermediate aquifer system in most of the study area (Duerr and other, 1988). This map report depicts the potentiometric surface of the Upper Floridan aquifer in May 1995. The potentipmetric surface represents to the level to which water will rise in tightly cased wells that tap a confined aquifer system. The surface is mapped by determining the altitude of water levels in a network of wells and is represented on maps by contours that connect point of equal altitude. This map represents water-level conditions near the end of the dry season when ground-water withdrawals for agricultural use are usually high. The cumulative rainfall for the study area was 2.98 inches above average for the period from June 1994 through May 1995 (Southwest Florida Water Management District, 1995)

Florida↗
USGS2008

ET–The key to balancing the water budget in the Southwest

Throughout the Southwest, state and federal water-resource managers are becoming increasingly concerned about the impacts of future groundwater development on the region’s limited water resources, environmentally sensitive ecosystems, and rural lifestyle. To address their concerns, scientists and engineers are deploying physically based mathematical models to assess and predict the potential effects of increased groundwater pumping. The accuracy of these predictions is directly related to how well water budgets are quantified and balanced at basin and regional scales.

Nevada↗
USGS2008

Middle to late cenozoic geology, hydrography, and fish evolution in the American Southwest

An evaluation of the poorly understood Cenozoic hydrologic history of the American Southwest using combined geological and biological data yields new insights with implications for tectonic evolution. The Mesozoic Cordilleran orogen next to the continental margin of southwestern North America probably formed the continental divide. Mountain building migrated eastward to cause uplift of the Rocky Mountains during the Late Cretaceous to early Tertiary Laramide orogeny. Closed drainage basins that developed between the two mountain belts trapped lake waters containing fish of Atlantic affinity. Oligocene-Miocene tectonic extension fragmented the western mountain belt and created abundant closed basins that gradually filled with sediments and became conduits for dispersal of fishes of both Pacific and Atlantic affinity. Abrupt arrival of the modern Colorado River to the Mojave-Sonora Desert region at ca. 5 Ma provided a new conduit for fish dispersal. Great dissimilarities in modern fish fauna, including differences in their mitochondrial deoxyribonucleic acid (DNA), indicate that late Miocene runoff from the Colorado Plateau did not flow down the Platte or Rio Grande, or through the Lake Bonneville Basin. Fossil fishes from the upper Miocene part of the Bidahochi Formation on the Colorado Plateau have characteristics that reflect a habitat of large, swift-moving waters, and they are closely related to fossil fishes associated with the Snake and Sacramento Rivers. This evidence suggests that influx of fishes from the ancestral Snake River involved a major drainage, not merely small headwater transfers. ?? 2008 The Geological Society of America.

Conference Paper↗