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USGS2024

Peak streamflow trends in South Dakota and their relation to changes in climate, water years 1921–2020

Peak-flow (flood) frequency analysis is essential to water-resources management applications, including the design of critical infrastructure such as bridges and culverts, and floodplain mapping. Federal guidelines for performing peak-flow flood frequency analyses are presented in a U.S. Geological Survey Techniques and Methods Report known as Bulletin 17C. A basic assumption within Bulletin 17C, which documents the guidelines for determining annual peak streamflow frequency, is that, for basins without major hydrologic alterations (for example, regulation, diversion, and urbanization), statistical properties of the distribution of annual peak streamflows are stationary; that is, the mean, variance, and skew are constant through time. Nonstationarity is a statistical property of a peak-flow series such that the long-term (on the order of decades) distributional properties change one or more times either gradually or abruptly through time. Individual nonstationarities may be attributed to one source such as flow regulation, land-use change, or climate but are often the result of a combination of sources, making detection and attribution of nonstationarities challenging. In response to a growing concern regarding nonstationarity in peak streamflows in the region, the U.S. Geological Survey, in cooperation with the Departments of Transportation of Illinois, Iowa, Michigan, Minnesota, Missouri, South Dakota, and Wisconsin; the Montana Department of Natural Resources and Conservation; and the North Dakota Department of Water Resources, assessed the potential nonstationarity in peak streamflows in the north-central United States. This chapter characterizes the effects of natural hydroclimatic shifts and potential climate change on annual peak streamflows in the State of South Dakota. Annual peak and daily streamflow as well as model-simulated gridded climatic data were examined for temporal monotonic trends, change points, and other statistical properties indicative of changing climatic and environmental conditions. Changes in annual peak and daily flows were evaluated among 13, 35, and 81 qualifying U.S. Geological Survey streamgages for the 75-, 50-, and 30-year trend periods through water year 2020 (the period from October 1, 2019, to September 30, 2020) in South Dakota, respectively. No qualifying streamgages were in the 100-year trend period in the State. Statistical tests for autocorrelation (independent and identically distributed assumption), monotonic trends, and change points in the median and scale are analyzed to evaluate potential stationarity violations (nonstationarity) for performing at-site peak-flow flood-frequency analysis. The trends are reported using a likelihood approach as an alternative to simply reporting significant trends with an arbitrary p -value cutoff point. A distinct east-west spatial pattern of likely upward and downward monotonic trends and change points, respectively, was detected in 75- and 50-year trend periods, but an inconsistent spatial pattern was detected in the 30-year trend period. Additionally, change points in the median annual peak streamflows were detected in the late 1970s and early 1980s in the western part of the State, but in the east, the change point was more commonly detected in 1992–93. A similar east-west spatial pattern of likely upward and downward trends was detected in the annual peak-flow timing, the day of the year of the annal peak streamflow. In the western part of the State, the annual peak streamflows are arriving earlier, but in the east, the annual peak streamflows are arriving later. A peaks-over-threshold (POT) analysis where, on average, there are two events per year (POT2) and four events per year (POT4) was also used to evaluate changes in the frequency (count) of daily streamflows exceeding the threshold. Similar to detected changes in the annual peak streamflow, an east-west likely upward or downward change corresponding to an increase or decrease, respectively, in the frequency of daily streamflow greater than a POT2 and POT4 threshold was detected. A monthly water-balance model was used to evaluate hydroclimatic variation in annual and seasonal precipitation, snowfall, potential evapotranspiration, and soil moisture storage for all qualifying streamgages in the 75-, 50-, and 30-year trend periods. Detected trends in the annual hydroclimatic metrics for the 75- and 50-year trend periods indicate a spatially consistent statewide increase in precipitation, decrease in snowfall, increase in potential evapotranspiration, and increase in soil moisture storage. Furthermore, detected trends in seasonal precipitation in the 75- and 50-year trend periods highlight a pronounced change in precipitation in winter and later into the summer season, especially in the 50-year trend period in the eastern part of the State. Statewide increases in seasonal soil moisture storage were also detected, highlighting year-round increasing flood magnitudes, particularly in the eastern part of the State. Based on the results of these stationarity tests for the qualifying streamgages in South Dakota among the 75-, 50-, and 30-year trend periods, consistent temporal and spatial patterns of nonstationarity were detected among the 75- and 50-year trend periods. Furthermore, when nonstationarity is detected in daily streamflow, increased streamflow and volume (increasing frequency in POT), as well as potentially bridge scour, may have implications on culvert and highway design in the eastern part of South Dakota. Thus, when performing at-site peak-flow flood-frequency analyses in South Dakota, potential nonstationarities and alternative approaches are important considerations.

South Dakota↗
USGS2018

Characterization of peak streamflows and flood inundation of selected areas in southeastern Texas and southwestern Louisiana from the August and September 2017 flood resulting from Hurricane Harvey

Hurricane Harvey made landfall near Rockport, Texas, on August 25, 2017, as a Category 4 hurricane with wind gusts exceeding 150 miles per hour. As Harvey moved inland, the forward motion of the storm slowed down and produced tremendous rainfall amounts over southeastern Texas, with 8-day rainfall amounts exceeding 60 inches in some locations, which is about 15 inches more than average annual amounts of rainfall for eastern Texas and the Texas coast. Historic flooding occurred in Texas as a result of the widespread, heavy rainfall; wind and flood damages were estimated to be $125 billion, and the storm resulted in at least 68 direct fatalities. In the immediate aftermath of the Harvey-related flood event, the U.S. Geological Survey (USGS) and the Federal Emergency Management Agency initiated a cooperative study to evaluate the magnitude of the flood, determine the probability of occurrence, and map the extent of the flood in Texas. Seventy-four USGS streamflow-gaging stations in Texas with at least 15 years of record and no large data gaps in the period of record had a 2017 annual peak streamflow related to Harvey ranking in the top five of all annual peaks for each given station. New peaks of record streamflow were recorded at 40 of the 74 USGS streamflow-gaging stations. The number of years of peak streamflow record for the 74 analyzed streamflow-gaging stations ranged from 18 to 105, with a mean number of 55 years. The annual exceedance probability estimates for the analyzed streamflow-gaging stations ranged from less than 0.2 to 14.0 percent. USGS field crews surveyed 2,123 high-water marks to obtain water-surface elevations, in feet above the North American Vertical Datum of 1988. In some locations, several water-surface elevations were averaged to obtain 1 water-surface elevation, resulting in 1,258 water-surface elevations. Some of these high-water marks were used, along with peak-stage data from USGS streamflow-gaging stations, to create 19 inundation maps to document the areal extent of the maximum depth of the flooding. Digital datasets of the inundation area, modeling boundary, water-depth rasters, and final map products are available from the USGS data release associated with this report ( https://doi.org/10.5066/F7VH5N3N ).

Arkansas, Louisiana, Texas↗
USGS1985

Compilation of water resources development and hydrologic data of Saipan, Mariana Islands

Saipan is the largest island of the Northern Mariana Islands, a chain of 14 islands north of Guam. Saipan comprises one third of the land area of the islands. No long-term rainfall record is available at any location, but some rainfall records are for periods up to 16 years, some of which began in 1901. Average annual rainfall for the island is 81 inches, with the southern end receiving about 10 inches less annually than the rest of the island. The amount of rainfall which runs off in northeast Saipan ranges from 23 to 64 percent and averages about 40 percent. Runoff on the rest of the island is from springs or occurs only during heavy rainfall. Surface-water development appears impractical. Ground water is the main source of water for the island and production was almost 4 million gallons per day in 1982. However, chloride concentration in ground water exceeds 1,000 milligrams per liter in many locations. The average chloride concentration of the domestic water stays near the maximum permissible level (600 milligrams per liter). This report summarizes the history of the water-resources development and presents all available hydrologic data, including rainfall records since 1901, streamflow records since 1968, and drilling logs, pumping tests, chemical analyses, and production figures from 180 testholes and wells drilled on Saipan. (USGS)

Water-Resources Investigations Report↗
USGS2022

Effect of repeated fire on annual brome invasion at Badlands National Park

Prescribed fire is used to combat exotic plant species in mixed-grass prairie of Northern Great Plains parks. However, prescribed fires rarely occur at a frequency likely to maintain any gains against exotic species. The unusual circumstance of experimental plots being burned twice in 2 years provides a unique opportunity to investigate the effect of more frequent fire on invasive annual brome grasses. I established 40 plots on Sheep Mountain Table at Badlands National Park in 2015 to examine the relative effectiveness of prescribed fire alone or in combination with imazapic (an herbicide) application or with native seeding. Ten of the 40 plots were controls, with no experimental treatment; the remainder were burned with a prescribed fire in November 2016, and the herbicide and seeding treatments were applied soon thereafter to 10 plots each. In the 2018 growing season, annual brome abundance remained lower in the burned plots than in the controls, but monitoring by the National Park Service’s Northern Great Plains Fire Effects programs suggests that, by 5 years (or perhaps earlier) following a prescribed fire, annual brome abundance will return to its pre-fire level. Repeated fires may prevent this return if they sufficiently reduce the annual brome seedbank or produce conditions less conducive to annual brome growth (reduced litter layer or increased competition, for example). All plots in this experiment burned as part of a larger prescribed fire in fall 2018. This extension of the original study measures plant community composition (to species level) in the experimental plots (original control and burn only) after the 2018 prescribed fire; this report provides the results from the fourth growing season after that fire.

South Dakota↗
USGS2018

Discharge, sediment, and water chemistry in Clear Creek, western Nevada, water years 2013–16

Clear Creek is a small stream that drains the eastern Carson Range near Lake Tahoe, flows roughly parallel to the Highway 50 corridor, and discharges to the Carson River near Carson City, Nevada. Historical and ongoing development in the drainage basin is thought to be affecting Clear Creek and its sediment-transport characteristics. Previous studies from water years (WYs) 2004 to 2007 and from 2010 to 2012 evaluated discharge, selected water-quality parameters, and suspended-sediment concentrations, loads, and yields at three Clear Creek sampling sites. This report serves as a continuation of the data collection and analyses of the Clear Creek discharge regime and associated water-chemistry and sediment concentrations and loads during WYs 2013–16. Total annual sediment loads ranged from 870 to 5,300 tons during WYs 2004–07, from 320 to 1,770 tons during WYs 2010–12, and from 50 to 200 tons during WYs 2013–16. Ranges in annual loads during the three study periods were not significantly different; however, total loads were greater during 2004–07 than they were during 2013–16. Annual suspended-sediment loads in WYs 2013–16 showed no significant change since WYs 2010–12 at sites 1 (U.S. Geological Survey reference site 10310485; Clear Creek above Highway 50, near Spooner Summit, Nevada) or 2 (U.S. Geological Survey streamgage 10310500; Clear Creek above Highway 50, near Spooner Summit, Nevada), but significantly lower loads at site 3 (U.S. Geological Survey site 10310518; Clear Creek at Fuji Park, at Carson City, Nevada), supporting the theory of sediment deposition between sites 2 and 3 where the stream gradient becomes more gradual. Currently, a threshold discharge of about 3.3 cubic feet per second is required to mobilize streambed sediment (bedload) from site 2 in Clear Creek. Mean daily discharge was significantly lower in 2010–12 than in 2004–07 and also significantly lower in 2013–16 than in 2010–12. During this study, lower bedload, and therefore lower total sediment load in Clear Creek was primarily due to significantly lower discharge and cannot be directly attributed to sediment mitigation work in the basin. Water chemistry in Clear Creek shows that the general water type of the creek under base-flow conditions in autumn is a dilute calcium bicarbonate. During winter and spring, the chemistry shifts toward a slightly more sodium and chloride character. Though the chemical characteristics show seasonal change, the water chemistries examined as part of this investigation remain within ecological criteria as adopted by the Nevada Division of Environmental Protection. There was no evidence of aqueous polynuclear aromatic hydrocarbons (PAHs) present in Clear Creek water during this study. Concentrations of PAHs, as determined in one bed-sediment sample and multiple semi-permeable membrane device extracts, were either less than quantifiable limits of analysis or were found at similar concentrations as blank samples. In July 2014, a 250–300-acre fire burned in the Clear Creek drainage basin. One day after the fire was extinguished, a thunderstorm washed sediment into the creek. A water chemistry sample collected as part of the post-fire storm event showed that the stormwater entering the creek had increased the concentrations of ammonium and organic nitrogen, phosphorus, manganese, and potassium; a similar finding of many other studies evaluating the effects of fires in small drainage basins. Subsequent chemical analyses of Clear Creek water in August 2014 (one month later) showed that these constituents had returned to pre-fire concentrations.

Nevada↗
USGS1972

Suspended sediment yield of New Jersey coastal plain streams draining into the Delaware estuary

An investigation was begun in 1965 by the U.S. Geological Survey in cooperation with the U.S. Army Corps of Engineers, Philadelphia District to meet the Corps’ need for information on sediment transport in the Delaware River basin in relation to the maintenance of navigable channels in the river 's estuarine areas. Sediment records were needed by the Corps to identify the principal sources and amounts of suspended sediment transported by New Jersey tributary streams into these estuarine areas. In order to meet the project's objective, a daily sediment sampling program at streamflow- gaging stations on Crosswicks Creek, Cooper River, Maurice River, and Raccoon Creek was established. Because of protracted drought, which resulted in unusually low sediment discharges, the period of data collection at these daily stations was extended. Upon reviewing these records, three partial-record stations were established on the Pennsauken, Big Timber, and Mantua Creeks in 1970 to complete the areal coverage. Records at two additional stations, Delaware River at Trenton and McDonalds Branch in Lebanon State Forest, collected as part of other cooperative projects were available also for use in this study. The purpose of this report is to summarize sediment data collected at selected stream-sampling sites in southern New Jersey. Computations of excepted average annual yields at each sampling site were made and utilized to estimate the annual yield at ungaged sites. Similar data currently are being compiled for streams draining Pennsylvania and Delaware. It is planned to report on the combined information at a later date in the Geological Survey's Water-Supply Paper series.

New Jersey↗
USGS2012

Anaerobic oxidation of arsenite by autotrophic bacteria: The view from Mono Lake, California

Introduction The phenomenon of arsenite [As(III)] oxidation by aerobic bacteria was first reported by Green (1918), and the many subsequent discoveries made in this realm, most occurring over the past three decades, are the primary focus of this book. In contrast, the fact that select anaerobes can also achieve this feat was an entirely serendipitous discovery. As often occurs in science, the intended path leading towards a stated goal can take an unexpected turn, ultimately leading to greater rewards than those originally anticipated. The intellectual freedom to meander such a path of curiosity-driven research is a great gift especially when one arrives at an unexpected revelation. It is perhaps the most rewarding aspect of a scientist's career. Such was the case when we first uncovered the phenomenon of anaerobic As(III) oxidation. Our arsenic-related field work focused on Mono Lake, California because of its exceptionally high levels of dissolved inorganic arsenic (~200 μM), and the fact that we had previously isolated two novel species of arsenate [As(V)]-respiring bacteria, Bacillus arseniciselenatis and B. selenitireducens from its bottom sediments(Switzer Blum et al. , 1998). Radiotracer investigations employing 73 As(V) measured high As(V) reductase activity in the anoxic water column of the lake, yielding an estimate that this electron sink could mineralize approximately 8-14% of annual phytoplankton productivity (Oremland et al. , 2000), a value confirmed independently on the basis of mass balance considerations (Hollibaugh et al. , 2005). In both studies both groups also used cultivation-based methods (Most-Probable-Numbers) to estimate the densities of As(V)-respiring bacteria in the anoxic water column, and arrived at similar low but detectable values (e.g. 10 2 -10 3 ml -1 ). The next goal was to determine what taxa of As(V)-respiring prokaryotes were involved in these water-column transformations, using culture-independent analyses (Denaturing Gradient Gel Electrophoresis) of As(V)-amended anoxic bottom water. We had expected to find 16S rRNA gene amplicon sequences similar to those from the bacilli we isolated from the sediments, but instead found a few rather unremarkable amplicons in the Epsilon, Gamma and Delta proteobacteria; yet these incubations showed a complete reduction of the added As(V), caused by sulfide-linked oxidation by resident chemoautotrophs of the Delta-proteobacteria (Hoeft et al. , 2004; Hollibaugh et al. , 2006). This As(V) reductase activity was inhibited by nitrate, while addition of As(III) to nitrate-amended waters resulted in the formation of As(V). This observation led us to conclude that there was anaerobic biological oxidation of As(III) to As(V), linked to the provided nitrate ions (Hoeft et al. , 2002).

California↗
USGS2004

Phosphorus and suspended sediment load estimates for the Lower Boise River, Idaho, 1994-2002

The U.S. Geological Survey used LOADEST, newly developed load estimation software, to develop regression equations and estimate loads of total phosphorus (TP), dissolved orthophosphorus (OP), and suspended sediment (SS) from January 1994 through September 2002 at four sites on the lower Boise River: Boise River below Diversion Dam near Boise, Boise River at Glenwood Bridge at Boise, Boise River near Middleton, and Boise River near Parma. The objective was to help the Idaho Department of Environmental Quality develop and implement total maximum daily loads (TMDLs) by providing spatial and temporal resolution for phosphorus and sediment loads and enabling load estimates made by mass balance calculations to be refined and validated. Regression models for TP and OP generally were well fit on the basis of regression coefficients of determination (R2), but results varied in quality from site to site. The TP and OP results for Glenwood probably were affected by the upstream wastewater-treatment plant outlet, which provides a variable phosphorus input that is unrelated to river discharge. Regression models for SS generally were statistically well fit. Regression models for Middleton for all constituents, although statistically acceptable, were of limited usefulness because sparse and intermittent discharge data at that site caused many gaps in the resulting estimates. Although the models successfully simulated measured loads under predominant flow conditions, errors in TP and SS estimates at Middleton and in TP estimates at Parma were larger during high- and low-flow conditions. This shortcoming might be improved if additional concentration data for a wider range of flow conditions were available for calibrating the model. The average estimated daily TP load ranged from less than 250 pounds per day (lb/d) at Diversion to nearly 2,200 lb/d at Parma. Estimated TP loads at all four sites displayed cyclical variations coinciding with seasonal fluctuations in discharge. Estimated annual loads of TP ranged from less than 8 tons at Diversion to 570 tons at Parma. Annual loads of dissolved OP peaked in 1997 at all sites and were consistently higher at Parma than at the other sites. The ratio of OP to TP varied considerably throughout the year at all sites. Peaks in the OP:TP ratio occurred primarily when flows were at their lowest annual stages; estimated seasonal OP:TP ratios were highest in autumn at all sites. Conversely, when flows were high, the ratio was low, reflecting increased TP associated with particulate matter during high flows. Parma exhibited the highest OP:TP ratio during all seasons, at least 0.60 in spring and nearly 0.90 in autumn. Similar OP:TP ratios were estimated at Glenwood. Whereas the OP:TP ratio for Parma and Glenwood peaked in November or December, decreased from January through May, and increased again after June, estimates for Diversion showed nearly the opposite pattern ? ratios were highest in July and lowest in January and February. This difference might reflect complex biological and geochemical processes involving nutrient cycling in Lucky Peak Lake, but further data are needed to substantiate this hypothesis. Estimated monthly average SS loads were highest at Diversion, about 400 tons per day (ton/d). Average annual loads from 1994 through 2002 were 144,000 tons at Diversion, 33,000 tons at Glenwood, and 88,000 tons at Parma. Estimated SS loads peaked in the spring at all sites, coinciding with high flows. Increases in TP in the reach from Diversion to Glenwood ranged from 200 to 350 lb/d. Decreases in TP were small in this reach only during high flows in January and February 1997. Decreases in SS, were large during high-flow conditions indicating sediment deposition in the reach. Intermittent data at Middleton indicated that increases and decreases in TP in the reach from Glenwood to Middleton were during low- and high-flow conditions, respectively. All constituents increased in the r

Scientific Investigations Report↗
USGS2010

Simulation of streamflow and suspended-sediment concentrations and loads in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary, South Texas, 1958-2008

The U.S. Geological Survey (USGS), in cooperation with the U.S. Army Corps of Engineers-Fort Worth District, City of Corpus Christi, Guadalupe-Blanco River Authority, San Antonio River Authority, and San Antonio Water System, developed, calibrated, and tested a Hydrological Simulation Program ? FORTRAN (HSPF) watershed model to simulate streamflow and suspended-sediment concentrations and loads during 1958-2008 in the lower Nueces River watershed, downstream from Lake Corpus Christi to the Nueces Estuary in South Texas. Data available to simulate suspended-sediment concentrations and loads consisted of historical sediment data collected during 1942-82 in the study area and suspended-sediment concentration data collected periodically by the USGS during 2006-07 at three USGS streamflow-gaging stations, Nueces River near Mathis, Nueces River at Bluntzer, and Nueces River at Calallen. The Nueces River near Mathis station is downstream from Wesley E. Seale Dam, completed in 1958 to impound Lake Corpus Christi. Suspended-sediment data collected before and after completion of Wesley E. Seale Dam provide insights to the effects of the dam and reservoir on suspended-sediment loads transported by the lower Nueces River from downstream of the dam to the Nueces Estuary. Annual suspended-sediment loads at a site near the Nueces River at Mathis station were considerably lower, for a given annual mean discharge, after the dam was completed than before the dam was completed. Most of the suspended sediment transported by the Nueces River downstream from Wesley E. Seale Dam occurred during high-flow releases from the dam or during floods. During October 1964-September 1971, about 532,000 tons of suspended sediment were transported by the Nueces River near Mathis. Of this amount, about 473,000 tons, or about 89 percent, were transported by large runoff events (mean streamflow exceeding 1,000 cubic feet per second). To develop the watershed model to simulate suspended-sediment concentrations and loads in the lower Nueces River watershed during 1958-2008, streamflow simulations were calibrated and tested with available data for 2001-08 from the Nueces River at Bluntzer and Nueces River at Calallen stations. Streamflow data from the Nueces River near Mathis station were used as input to the model at the upstream boundary of the model. Simulated streamflow volumes for the Bluntzer and Calallen stations showed good agreement (within 6 percent) with measured streamflow volumes. The HSPF model was calibrated to simulate suspended sediment using suspended-sediment data collected at the Mathis, Bluntzer, and Calallen stations during 2006-07. The calibrated watershed model was used to estimate streamflow and suspended-sediment loads for 1958-2008, including loads transported to the Nueces Estuary. During 1958-2008, on average, an estimated 307 tons per day of suspended sediment were delivered to the lower Nueces River; an estimated 297 tons per day were delivered to the estuary. The annual suspended-sediment load was highly variable, depending on the occurrence of storm events and high streamflows. During 1958-2008, the annual total sediment loads to the estuary varied from an estimated 3.8 to 2,490 tons per day. On average, 117 tons per day, or about 38 percent of the estimated annual suspended-sediment contribution, originated from cropland in the study watershed. Releases from Lake Corpus Christi delivered an estimated 98 tons per day of suspended sediment or about 32 percent of the 307 tons per day estimated to have been delivered to the lower Nueces River. Erosion of stream-channel bed and banks accounted for 55 tons per day or about 18 percent of the estimated total suspended-sediment load. All other land categories, except cropland, accounted for an estimated 37 tons per day, or about 12 percent of the total. An estimated 9.6 tons per day of suspended sediment or about 3 percent of the suspended-sediment load delivered to the lower Nueces River

Scientific Investigations Report↗
USGS2015

Hydrology of the middle San Pedro area, southeastern Arizona

In the middle San Pedro Watershed in southeastern Arizona, groundwater is the primary source of water supply for municipal, domestic, industrial, and agricultural use. The watershed comprises two smaller subareas, the Benson subarea and the Narrows-Redington subarea. Early 21st century projections for heavy population growth in the watershed have not yet become a reality, but increased groundwater withdrawals could have undesired consequences - such as decreased base flow to the San Pedro River, and groundwater-level declines - that would lead to the need to deepen existing wells. This report describes the hydrology, hydrochemistry, water quality, and development of a groundwater budget for the middle San Pedro Watershed, focusing primarily on the elements of groundwater movement that could be most useful for the development of a groundwater model Precipitation data from Tombstone, Arizona, and base flow at the stream-gaging station on the San Pedro River at Charleston both show relatively dry periods during the 1960s through the mid-1980s and in the mid-1990s to 2009, and wetter periods from the mid-1980s through the mid-1990s. Water levels in four out of five wells near the mountain fronts show cyclical patterns of recharge, with rates of recharge greatest in the early 1980s through the mid-1990s. Three wells near the San Pedro River recorded their lowest levels during the 1950s to the mid-1960s. The water-level record from one well, completed in the confined part of the coarse-grained lower basin fill, showed a decline of approximately 21 meters. Annual flow of the San Pedro River, measured at the Charleston and Redington gages, has decreased since the 1940s. The median annual streamflow and base flow at the gaging station on the river near Tombstone has decreased by 50 percent between the periods 1968–1986 and 1997–2009. Estimates of streamflow infiltration along the San Pedro River during 1914–2009 have decreased 44 percent, with the largest decreases in the months June–October in the Benson subarea. In the Narrows-Redington subarea, streamflow infiltration has decreased about 65 percent during 1914–2009. The average annual outflow (27.6 hm 3 /year [cubic hectometers per year]) from the Benson subarea aquifer for water years 2001 through 2009 exceeded the inflows (20.0 hm 3 / yr) by 7.60 hm 3 /yr. In the Narrows-Redington subarea for the same period, the average annual outflow (15.7 hm 3 /yr) from the aquifer system exceeded the inflows (13.8 hm 3 /yr) by nearly 2 hm 3 /yr. The largest withdrawals of groundwater in both subareas are for irrigation; these withdrawals peaked in 1973 and have been steadily decreasing since then. Recharge from streamflow infiltration exceeded recharge from the mountain-front and from ephemeral channels in the Benson subarea. In the Narrows-Redington subarea, however, recharge from mountain-front and ephemeral channel recharge exceeded recharge from streamflow infiltration. Evapotranspiration by phreatophytes accounts for the largest outflow of groundwater for both subareas—78 percent of the outflow in the Narrows-Redington subarea and 62 percent of the outflow in the Benson subarea. Precipitation, surface-water, and groundwater chemistry and isotope data indicated the relative age and residence time of groundwater, the amount of interaction between geologic sources and groundwater, and how recharge elevation and season were related to the presence of modern water. The bedrock aquifer receives modern recharge (

Arizona↗
USGS2022

Development of continuous bathymetry and two-dimensional hydraulic models for the Willamette River, Oregon

The Willamette River is home to at least 69 species of fish, 33 of which are native, including Chinook salmon ( Oncorhynchus tshawytscha ) and steelhead ( Oncorhynchus mykiss ). These fish need suitable hydraulic conditions, such as water depth and velocity, to fulfill various stages of their life. Hydraulic conditions are driven by interactions between channel morphology and streamflow, which throughout the Willamette River are strongly influenced by the operation of flood-control dams in upstream tributaries. To assess how streamflow management at these dams affects downstream fish habitat, the U.S. Geological Survey has developed high-resolution bathymetric datasets to support the development of two-dimensional hydraulic models. The datasets were created by combining data collected by airborne topo-bathymetric Light Detection and Ranging with boat-based sonar to create a seamless modeling surface over which a computational mesh with a resolution of roughly 5 by 5 meters was overlaid using the U.S. Army Corps of Engineers Hydraulic Engineering Center’s River Analysis System 5.0.7 hydraulic modeling software. Models were developed for about 200 river kilometers, separated into five modeling reaches, and hydraulic conditions were simulated at flows ranging from extremely low values to annual peak flows. Results of the simulations highlight distinct patterns of inundation extents, water depths, and velocities that vary longitudinally along the Willamette River. In the two farthest upstream model reaches, from Eugene to Corvallis, the river is slower, shallower, and inundates more area at similar seasonal flows than in reaches downstream from Corvallis, where the river generally is deeper and faster. These findings align with previous geomorphic analysis of the Willamette River showing the upper reaches of the river to be geomorphically more dynamic compared to the largely single-thread channel farther downstream. Results of simulations made with these hydraulic models can be used to drive fish-habitat models to further inform flow-management decisions.

Oregon↗
USGS2003

Sedimentation Survey of Lago El Guineo, Puerto Rico, October 2001

Lago El Guineo has lost about 17.5 percent of its original storage capacity in 70 years because of sediment accumulation. The water volume has been reduced from 2.29 million cubic meters in 1931, to 2.03 million cubic meters in 1986, and to 1.89 million cubic meters in 2001. The average annual storage-capacity loss (equal to the sedimentation rate) of Lago El Guineo was 4,727 cubic meters for the period of 1931 to July 1986 (or 0.21 percent per year), increasing to 5,714 cubic meters for the period of 1931 to October 2001 (or 0.25 percent per year). Discrepancies that could lead to substantial errors in volume calculations in a small reservoir like Lago El Guineo, were found when transferring the field-collected data into the geographic information system data base 1:20,000 U.S. Geological Survey Jayuya, Puerto Rico quadrangle. After verification and validation of field data, the Lago El Guineo shoreline was rectified using digital aerial photographs and differential global positioning data.

Water-Resources Investigations Report↗
USGS1989

Estimation of the recharge area of a pumped, stratified-drift aquifer in Connecticut by simulation modeling

Groundwater quality management plans in Connecticut require information about the size and shape of recharge areas that contribute flow to pumping centers in extensive, stratified-drift aquifers. Flow models of a hypothetical aquifer , and a stratified-drift aquifer in Farmington are used to evaluate how contributing areas change in response to variations in recharge and hydraulic conductivity. A series of simulations of a hypothetical aquifer model were made during which average annual recharge rates of 0, 15, 25, and 35 inches were combined with aquifer hydraulic conductivity values of 25, 75, and 225 ft/day. Under steady-state conditions, and a withdrawal rate of 1.2 million gal/day, the size of the contributing recharge area ranges from 0.16 to 0.75 sq mi as recharge from precipitation and average aquifer hydraulic conductivity range from highest to lowest values. Three simulations of the Farmington aquifer model were made: they assumed steady-state conditions, a withdrawal rate of 2.8 million gal/day, and combinations of recharge and aquifer hydraulic conductivity that represented highest, average and lowest rates. The size of the contributing recharge area, under these conditions, ranges from 0.89 to 1.94 sq mi. (USGS)

Water-Resources Investigations Report↗
USGS1987

Geohydrology and simulated effects of withdrawals on the Miocene aquifer system in the Mississippi Gulf Coast area

Intense development of the Miocene aquifer system for water supplies along the Mississippi Gulf Coast has resulted in large water level declines that have altered the groundwater flow pattern in the area. Water levels in some Miocene aquifers have declined about 2 ft/year since 1940; declines exceed 100 ft (80 ft sea level) in large areas along the coast. Water levels in the surficial aquifer system, generally less than 20 ft below land surface, have not declined. The Miocene and younger interbedded and lenticular sands and clays crop out in southern Mississippi and dip to the south and southwest. These sediments have large vertical variations in head and locally respond to stresses as separate aquifers. Freshwater recharge to the Miocene aquifer system primarily is from rainfall on the surficial aquifers. The water generally moves to the south and southeast along the bedding planes toward the Mississippi Gulf Coast where the water is either withdrawn by wells, discharges to the ocean, or gradually percolates upward into overlying aquifers. Drawdowns caused by large groundwater withdrawals along the coast probably have resulted in the gradual movement of the saltwater toward the pumping centers. In parts of the Miocene aquifer system commonly used for water supplies, the water generally is a sodium bicarbonate type. Increasing chloride concentrations in a few wells indicate that saline water is migrating into parts of all layers in the Pascagoula area. A quasi three-dimensional numerical model of the groundwater flow system was constructed and calibrated on the basis of the both pre- and post-development conditions. The effects of an expected 1.5% annual increase in groundwater withdrawals during the period 1985-2005 were evaluated by the flow model. Additional water level declines expected by the year 2005 in response to estimated pumpage are as follows: Gulfport, 135 ft in layer 4; Biloxi-Gulfport area, 100 ft in layer 5 and 50 ft in layer 3; Pascagoula area, 40 ft in layer 6 and 30 ft in layer 4. The most serious threats of saltwater encroachment occur in layers 4, 5, and 6 (the 800-, 600- and 400-ft sands) in the Pascagoula area where contamination of the southern edges of the production areas is expected to occur in less than 10 years. (Author 's abstract)

Water-Resources Investigations Report↗
USGS1996

Hydrogeology of the Quitobaquito Springs and La Abra Plain area, Organ Pipe Cactus National Monument, Arizona, and Sonora, Mexico

Quitobaquito Springs, in Organ Pipe Cactus National Monument near the south end of the northwestward-trending Quitobaquito Hills, are less than 0.25 mile north of the international boundary between the United States and Mexico. The National Park Service is concerned that the natural flow from Quitobaquito Springs might be reduced by ground-water withdrawals in the adjacent State of Sonora, Mexico. Quitobaquito and other nearby springs flow from a highly fractured granite that forms the Quitobaquito Hills. Fractures in the granitic intrusive rocks provide conduits for ground water to flow from an alluvial flow system along Aguajita Wash to a line of springs on the southwest side of Quitobaquito Hills. The chemical composition of water from all the springs is similar. Carbon-14 analysis of water from Quitobaquito Springs indicates that the spring water probably is between 500 and several thousand years old. Discharge at Quitobaquito Springs averaged 28 gallons per minute and ranged from 15 to 40 gallons per minute for 1981-92. Rainfall at two gages in the area of recharge to the northeast of Quitobaquito Hills averaged 6.6 inches per year during the 11-year monitoring program ending in September 1992. The lack of correlation between spring discharge and local rainfall indicates that local annual recharge may be small relative to the total quantity of ground water in storage. Surface-geophysical data indicate that a thin alluvial aquifer overlies the shallow crystalline rocks northeast of Quitobaquito Hills along Aguajita Wash. Results of the study indicate that the ground-water flow system along Aguajita Wash provides a source of water to the springs and may be hydraulically connected to the ground-water system that is pumped for agricultural purposes in Mexico. The altitude and low permeability of the granite bedrock near the international boundary, however, may provide a barrier to and (or) delay the effect of a northwestward propagation of water- level declines caused by pumping near the Rio Sonoyta in Mexico.

Water-Resources Investigations Report↗
USGS1956

Sedimentation and chemical quality of surface waters in the Wind River basin, Wyoming

This report gives results of an investigation by the U. S. Geological Survey of chemical quality of surface waters and sedimentation in the Wind River Basin, Wyo. The sedimentation study was begun in 1946 to determine the quantity of sediment that is transported by the streams in the basin; the probable sources of the sediment; the effect of large irrigation projects on sediment yield, particularly along Fivemile Creek; and the probable specific weight of the sediment when initially deposited in a reservoir. The study of the chemical quality of the water was begun in 1945 to obtain information on the sources, nature, and amounts of dissolved material that is transported by streams and on the suitability of the waters for different uses. Phases of geology and hydrology pertinent to the sedimentation and chemical quality were studied. Results of the investigation through September 30, 1952, and some special studies that were made during the 1953 and 1954 water years are reported. The rocks in the Wind River Basin are granite, schist, and gneiss of Precambrian age and a thick series of sedimentary strata that range in age from Cambrian to Recent. Rocks of Precambrian and Paleozoic age are confined to the mountains, rocks of Mesozoic age crop out along the flank of the Wind River and Owl Creek Mountains and in denuded anticlines in the floor of the basin, and rocks of Tertiary age cover the greater part of the floor of the basin. Deposits of debris from glaciers are in the mountains, and remnants of gravel-capped terraces of Pleistocene age are on the floor of the basin. The lateral extent and depth of alluvial deposits of Recent age along all the streams are highly variable. The climate of the floor of the basin is arid. The foothills probably receive a greater amount of intense rainfall than the areas at lower altitudes. Most precipitation in the Wind River Mountains falls as snow. The foothill sections, in general, are transitional zones between the cold, humid climate of the high mountains and the warmer, drier climate of the basin floor. Average annual runoff in the basin is about 3.6 inches on the basis of adjusted streamflow records for the Bighorn River near Thermopolis. Runoff from the mountains is high and is mostly from melting of snow and from spring and early summer rains. It does not vary greatly from year to year because annual water losses are small in comparison to annual precipitation. In the areas on the floor of the basin, where runoff is low, the runoff is mostly the result of storms in late spring and early summer. The annual water losses nearly equal the annual precipitation; therefore, runoff is extremely variable, in terms of percentage changes, from year to year and from point to point during any 1 year.

Water Supply Paper↗
USGS2019

Flood-frequency comparison from 1995 to 2016 and trends in peak streamflow in Arkansas, water years 1930–2016

In 2016, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers and the Federal Emergency Management Agency, began a study in Arkansas to investigate possible increasing trends in annual peak streamflow data and the possible resulting increase in the annual exceedance probability flood (AEPF) predictions. Temporal trends of peak streamflow were investigated at 15 selected streamgages on unregulated streams in Arkansas having 30 or more years of peak streamflow data through the 2016 water year. For the period of record at each streamgage, the Mann-Kendall trend test indicated that 14 of the 15 streamgages had no statistically significant peak streamflow trends and 1 streamgage had a statistically significant decreasing peak streamflow trend. Visual examination of the locally estimated scatterplot smoothing technique trend lines of the peak streamflow data indicated a possible increasing peak streamflow trend at 8 of the 15 streamgages since the 1990s. A sequential series analysis of the 1-percent AEPF at each of the 15 selected streamgages was completed by selecting an initial subset of the oldest peak streamflow data from each site to estimate the initial 1-percent AEPF. This initial peak streamflow data subset was subsequently appended with 10-year increments of additional peak streamflow data until the full period of peak streamflow data was analyzed. The maximum increase in the 1-percent AEPF was 113 percent, and the maximum decrease was 31.9 percent. Percentage differences between the AEPFs derived from regional regression equations presented in the 1995 and 2016 Arkansas flood-frequency reports were compared. The average percentage differences for the 74 selected locations indicate that the 4-, 2-, 1-, and 0.2-percent AEPFs computed using the 2016 regional regression equations were higher by 3.52, 5.10, 8.59, and 13.31 percent, respectively (25-, 50-, 100-, and 500-year recurrence interval floods), than the same percentage AEPFs computed using the 1995 regional regression equations. The average percentage differences between the 1995 and 2016 AEPFs for the 10-percent AEPF (10-year recurrence interval flood) resulted in 2016 AEPF predictions being 0.41 percent higher. For the 50- and 20-percent AEPFs (2- and 5-year recurrence interval floods), the 2016 AEPFs were less than the 1995 AEPFs by 2.53 and 0.31 percent, respectively.

Arkansas↗
USGS2004

Riverbed elevations and water quality of the Missouri River at Sioux City, Iowa, 2002-03

The U.S. Geological Survey, in cooperation with the City of Sioux City, Iowa, conducted an investigation of the Missouri River, during 2002-2003, to assess changes in riverbed elevations from its confluence with the Big Sioux River, downstream to the area of the Sioux City municipal well field. Water-quality samples also were collected across the Missouri River to provide additional information on the differences between the water quality of the Missouri River and Big Sioux River in the well field area. The water supply at Sioux City, Iowa, is withdrawn from fourteen vertical wells and one horizontal collector well. Twelve vertical wells and the collector well are completed in the alluvial sand and gravel aquifer adjacent to the Missouri River at Sioux City. The well field is located on the left bank (looking downstream) of the Missouri River about 0.5 mile upstream from USGS streamflow gage 06486000, and approximately 5,000 feet downstream from the confluence with the Big Sioux River. The Missouri River, adjacent to the Sioux City alluvial well field, consists of the combined streamflows from the Missouri and the Big Sioux Rivers. The streamflows do not appear to be well mixed downstream from the confluence, and the streamflow directly adjacent to the well field could be predominately from the Big Sioux River. The U.S. Geological Survey measures streamflow on the Missouri River at Sioux City, Iowa (USGS streamflow gage 06486000). The riverbed of the Missouri River at Sioux City consists of a sequence of sands and gravels. The surface of the riverbed is undulatory, with continuously migrating riverbed forms, 5 to 8 feet in relief, of sand and gravel. Measurements of riverbed elevations from October 1, 2002, to September 30, 2003, showed an annual change of as much as 8 feet with the majority of the riverbed change closer to 5 feet. The largest change occurred near a wing dike on the Nebraska side of the Missouri River. On the Iowa side, the annual change was close to 5 feet. The results showed that channel fill occurred in the winter months and scour occurred during the summer months. Results of analyses of water samples collected at five locations across the Missouri River, near the municipal well field, were similar for most samples. Higher values of specific conductance and turbidity were recorded on the Iowa side of the Missouri River, the side from which the Big Sioux River enters upstream. Higher concentrations of chloride, ammonia nitrogen, nitrate nitrogen, and atrazine also were detected on the Iowa side of the Missouri River. Based on these results, there does not appear to be complete mixing of water from the Missouri and Big Sioux Rivers near the municipal well field.

Iowa↗