Geology topics

Research about Kansas

Source-linked reports with geographic coverage including Kansas.

At least 181 records · Page 10Linked to original sources

USGS2009

Transport and sources of suspended sediment in the Mill Creek Watershed, Johnson County, Northeast Kansas, 2006-07

The U.S. Geological Survey, in cooperation with the Johnson County Stormwater Management Program, evaluated suspended-sediment transport and sources in the urbanizing, 57.4 mi2 Mill Creek watershed from February 2006 through June 2007. Sediment transport and sources were assessed spatially by continuous monitoring of streamflow and turbidity as well as sampling of suspended sediment at nine sites in the watershed. Within Mill Creek subwatersheds (2.8-16.9 mi2), sediment loads at sites downstream from increased construction activity were substantially larger (per unit area) than those at sites downstream from mature urban areas or less-developed watersheds. Sediment transport downstream from construction sites primarily was limited by transport capacity (streamflow), whereas availability of sediment supplies primarily influenced transport downstream from mature urban areas. Downstream sampling sites typically had smaller sediment loads (per unit area) than headwater sites, likely because of sediment deposition in larger, less sloping stream channels. Among similarly sized storms, those with increased precipitation intensity transported more sediment at eight of the nine monitoring sites. Storms following periods of increased sediment loading transported less sediment at two of the nine monitoring sites. In addition to monitoring performed in the Mill Creek watershed, sediment loads were computed for the four other largest watersheds (48.6-65.7 mi2) in Johnson County (Blue River, Cedar, Indian, and Kill Creeks) during the study period. In contrast with results from smaller watersheds in Mill Creek, sediment load (per unit area) from the most urbanized watershed in Johnson County (Indian Creek) was more than double that of other large watersheds. Potential sources of this sediment include legacy sediment from earlier urban construction, accelerated stream-channel erosion, or erosion from specific construction sites, such as stream-channel disturbance during bridge renovation. The implication of this finding is that sediment yields from larger watersheds may remain elevated after the majority of urban development is complete. Surface soil, channel-bank, suspended-sediment, and streambed-sediment samples were analyzed for grain size, nutrients, trace elements, and radionuclides in the Mill Creek watershed to characterize suspended sediment between surface or channel-bank sources. Although concentrations and activities of cobalt, nitrogen, selenium, total organic carbon, cesium-137, and excess lead-210 had significant differences between surface and channel-bank samples, biases resulting from urban construction, additional sorption of constituents during sediment transport, and inability to accurately represent erosion from rills and gullies precluded accurate characterization of suspended-sediment source.

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USGS2008

Continuous water-quality monitoring of streams in Johnson County, Kansas 2002-06

Water quality in Johnson County, Kansas was characterized on the basis of continuous, in-stream monitoring. The results summarized in this fact sheet may be used to better understand concentration and load variability during changing seasonal and streamflow conditions and to assess water-quality conditions relative to water-quality standards and management goals. The baseline information also will be useful for evaluating future changes in land use and effectiveness of implemented best management practices.

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USGS2008

Hydrologic droughts in Kansas— Are they becoming worse?

Multi-year droughts have been a recurrent feature of the climate and hydrology of Kansas since at least the 1930s. Streamflow records collected by the U.S. Geological Survey (USGS) indicate that water years 2000 to 2006 (October 1, 1999, through September 30, 2006) represent the sixth hydrologic drought during the past eight decades, and that corresponding streamflow levels in some parts of Kansas were lower than those during historic droughts of the 1930s and 1950s, even though the precipitation deficit was not as severe. Record-low streamflows in water year 2006 were recorded at USGS streamgages on the Republican, Smoky Hill, Solomon, Saline, upper Kansas, middle Arkansas, and Little Arkansas Rivers, as well as many tributary sites, and one tributary site of the Neosho River (fig. 1, table 1). Low streamflows during the hydrologic drought also resulted in record low levels at three Federal reservoirs in Kansas (fig. 1, table 2). An unprecedented number of administrative decisions were made by the Division of Water Resources, Kansas Department of Agriculture to curtail water diversions from rivers to maintain minimum desirable streamflows, and low flows on the lower Republican River in Kansas created concerns that Colorado and Nebraska were not complying with the terms of the 1943 Republican River Compact.

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USGS2008

Sedimentation and occurrence and trends of selected nutrients, other chemical constituents, and diatoms in bottom sediment, Fall River Lake, southeast Kansas, 1948-2006

A combination of available bathymetric-survey information and bottom-sediment coring was used to investigate sedimentation and the occurrence of selected nutrients (total nitrogen and total phosphorus), organic and total carbon, 25 trace elements, diatoms, and the radionuclide cesium-137 in the bottom sediment of Fall River Lake, southeast Kansas. The total estimated volume and mass of bottom sediment deposited from 1948 through 2006 in the original conservation pool of the reservoir was 470 million cubic feet and 18.8 billion pounds, respectively. The estimated sediment volume occupied about 36 percent of the original conservation-pool, water-storage capacity of the reservoir. Mean annual net sediment deposition since 1948 in the original conservation pool of the reservoir was estimated to be 324 million pounds per year. Mean annual net sediment yield from the Fall River Lake Basin was estimated to be 585,000 pounds per square mile per year. The mean annual net loads of total nitrogen and total phosphorus deposited in the bottom sediment of Fall River Lake were estimated to be 648,000 pounds per year and 267,000 pounds per year, respectively. The estimated mean annual net yields of total nitrogen and total phosphorus from the Fall River Lake Basin were 1,170 pounds per square mile per year and 480 pounds per square mile per year, respectively. Throughout the history of Fall River Lake, total nitrogen and total phosphorus concentrations in the deposited sediment were relatively uniform. Trace element concentrations in the bottom sediment of Fall River Lake generally were uniform over time. Arsenic, chromium, nickel, and zinc concentrations typically exceeded the threshold-effects guidelines, which represent the concentrations above which toxic biological effects occasionally occur. Trace element concentrations did not exceed the probable-effects guidelines (available for eight trace elements), which represent the concentrations above which toxic biological effects usually or frequently occur. Diatom occurrence in the bottom sediment of Fall River Lake was dominated by the species Aulacoseira granulata , which is an indicator of eutrophic (nutrient-rich) conditions. The abundance of the diatom Aulacoseira granulata , combined with cyanobacteria evidence and historical water-quality data, indicated that Fall River Lake likely has been eutrophic throughout much of its history.

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USGS2007

Velocity control as a tool for optimal plume containment in the Equus Beds aquifer, Kansas

A ground-water-management model was developed to investigate the best management options for the containment of an oil-field-brine plume in the Equus Beds aquifer in south-central Kansas. The main purpose of the management model was to find the optimal locations and minimum rates of pumpage of a set of plume-interception wells, to successfully reverse the velocity vectors at observation wells located along the plume front, and also to satisfy freshwater demands from supply wells. The effects of the calculated minimum withdrawals from the interception wells on the migration of contaminants throughout the ground-water system were evaluated utilizing a solute-transport model. This latter analysis was carried out to ensure the containment of the plume. Whereas application of the management model to the study area achieves the management objectives, the implementation of the results is believed to be impractical and expensive. This is because a considerable amount of water must be pumped out to reverse the velocity vectors in the vicinity of the plume. In general, the proposed technique of pollutant containment may be effective when applied to aquifers having low hydraulic gradients and/or to aquifers with hazardous plumes whose containment is not subject to economic constraints.

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USGS2007

Channel stability downstream from a dam assessed using aerial photographs and stream-gage information

The stability of the Neosho River channel downstream from John Redmond Dam, in southeast Kansas, was investigated using multiple-date aerial photographs and stream-gage information. Bankfull channel width was used as the primary indicator variable to assess pre- and post-dam channel change. Five six-mile river reaches and four stream gages were used in the analysis. Results indicated that, aside from some localized channel widening, the overall channel change has been minor with little post-dam change in bankfull channel width. The lack of a pronounced postdam channel change may be attributed to a substantial reduction in the magnitude of the post-dam annual peak discharges in combination with the resistance to erosion of the bed and bank materials. Also, the channel may have been overwidened by a series of large floods that predated construction of the dam, including one with an estimated 500-year recurrence interval.

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USGS2007

Significant findings from a water-quality study on Prairie Band Potawatomi Reservation, northeastern Kansas, June 1996 through August 2006

Water-quality samples were collected from surface- (stream-) and ground-water sites on and near the Prairie Band Potawatomi Reservation in northeastern Kansas (fig. 1) from June 1996 through August 2006 as part of a cooperative study between the U.S. Geological Survey (USGS) and the Prairie Band Potawatomi Nation (Schmidt and others, 2007). Surface- and ground-water quality were evaluated using applicable drinking-water standards to consider whether these resources can be used in the future to supply drinking water for the reservation. Presently (2007), drinking water on the reservation is purchased from Rural Water District #3 in Jackson County (Sharon Bosse, Prairie Band Potawatomi Nation Department of Planning and Environmental Protection, oral commun., 2007). Results of water-quality analyses are summarized in the following sections. Water-quality activities for this study are documented in several reports (Trombley, 1999, 2001; Schmidt, 2004; Schmidt and others, 2007).

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USGS2007

Status of ground-water levels and storage volume in the Equus Beds aquifer Near Wichita, Kansas, January 2003-January 2006

The Equus Beds aquifer northwest of Wichita, Kansas, was developed to supply water to Wichita residents and for irrigation in south-central Kansas. Ground-water pumping for city and agricultural use from the aquifer caused water levels to decline in a large part of the aquifer northwest of Wichita. Irrigation pumpage in the area increased substantially during the 1970s and 1980s and accelerated water-level declines. A period of water-level rises associated with greater-than-average precipitation and decreased city pumpage from the area began in 1993. An important factor in the decreased city pumpage was increased use of Cheney Reservoir as a water-supply source by the city of Wichita; as a result, city pumpage from the Equus Beds aquifer during 1993-2005 decreased to quantities similar to those pumped in the 1940s and went from being about 60 percent to about 40 percent of Wichita's water usage. Since 1995, the city also has been investigating the use of artificial recharge in the study area to meet future water-supply needs and to protect the aquifer from the intrusion of saltwater from sources to the west. During January 2006, the direction of ground-water flow in the Equus Beds aquifer in the area was generally from west to east, similar to the direction prior to development of the aquifer. Water-level changes since 1940 for the period January 2003-January 2006 ranged from a decline of more than 36 feet to a rise of more than 2 feet. Almost all wells in the area had small cumulative water-level rises from January 2003 to January 2006 and larger rises from October 1992 (period of maximum storage loss) to January 2006. The water-level rises from October 1992 to January 2006 probably are due principally to decreases in city pumpage, with increases in recharge due to increased precipitation during the period also a contributing factor. Irrigation pumpage increased during the period, so irrigation did not contribute to the rises in water levels between the beginning and end of the period. The storage volume change from October 1992 to January 2006 represents a recovery of about 55 percent of the storage volume previously lost between August 1940 and October 1992.

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USGS2007

Geochemical effects of induced stream-water and artificial recharge on the Equus Beds Aquifer, South-Central Kansas, 1995-2004

Artificial recharge of the Equus Beds aquifer is part of a strategy implemented by the city of Wichita, Kansas, to preserve future water supply and address declining water levels in the aquifer of as much as 30 feet caused by withdrawals for water supply and irrigation since the 1940s. Water-level declines represent a diminished water supply and also may accelerate migration of saltwater from the Burrton oil field to the northwest and the Arkansas River to the southwest into the freshwater of the Equus Beds aquifer. Artificial recharge, as a part of the Equus Beds Ground-Water Recharge Project, involves capturing flows larger than base flow from the Little Arkansas River and recharging the water to the Equus Beds aquifer by means of infiltration or injection. The geochemical effects on the Equus Beds aquifer of induced stream-water and artificial recharge at the Halstead and Sedgwick sites were determined through collection and analysis of hydrologic and water-quality data and the application of statistical, mixing, flow and solute-transport, and geochemical model simulations. Chloride and atrazine concentrations in the Little Arkansas River and arsenic concentrations in ground water at the Halstead recharge site frequently exceeded regulatory criteria. During 30 percent of the time from 1999 through 2004, continuous estimated chloride concentrations in the Little Arkansas River at Highway 50 near Halstead exceeded the Secondary Drinking-Water Regulation of 250 milligrams per liter established by the U.S. Environmental Protection Agency. Chloride concentrations in shallow monitoring wells located adjacent to the stream exceeded the drinking-water criterion five times from 1995 through 2004. Atrazine concentrations in water sampled from the Little Arkansas River had large variability and were at or near the drinking-water Maximum Contaminant Level of 3.0 micrograms per liter as an annual average established by the U.S. Environmental Protection Agency. Atrazine concentrations were much smaller than the drinking-water criterion and were detected at much smaller concentrations in shallow monitoring wells and diversion well water located adjacent to the stream probably because of sorption on aquifer sediment. Before and after artificial recharge, large, naturally occurring arsenic concentrations in the recharge water for the Halstead diversion well and recharge site exceeded the Maximum Contaminant Level of 10 micrograms per liter established by the U.S. Environmental Protection Agency for drinking water. Arsenic and iron concentrations decreased when water was recharged through recharge basins or a trench; however, chemical precipitation and potential biofouling eventually may decrease the artificial recharge efficiency through basins and trenches. At the Sedgwick site, chloride concentrations infrequently exceeded regulatory criteria. Large concentrations of atrazine were treated to decrease concentrations to less than regulatory criteria. Recharge of treated stream water through recharge basins avoids potentially large concentrations of arsenic and iron that exist at the Halstead diversion site. Results from a simple mixing model using chloride as a tracer indicated that the water chemistry in shallow monitoring well located adjacent to the Little Arkansas River was 80 percent of stream water, demonstrating effective recharge of the alluvial aquifer by the stream. Results also indicated that about 25 percent of the water chemistry of the diversion well water was from the shallow part of the aquifer. Additionally, diverting water through a diversion well located adjacent to the stream removed about 75 percent of the atrazine, probably through sorption to aquifer sediment, and decreased the need for additional water treatment to remove atrazine.

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USGS2007

Water quality on the Prairie Band Potawatomi Reservation, northeastern Kansas, June 1996 through August 2006

This report describes surface- and ground-water-quality data collected on the Prairie Band Potawatomi Reservation in northeastern Kansas from November 2003 through August 2006 (hereinafter referred to as the "current study period"). Data from this study period are compared to results from June 1996 through August 2003, which are published in previous reports as part of a multiyear cooperative study with the Prairie Band Potawatomi Nation. Surface and ground water are valuable resources to the Prairie Band Potawatomi Nation as tribal members currently (2007) use area streams to fulfill subsistence hunting and fishing needs and because ground water potentially could support expanding commercial enterprise and development. Surface-water-quality samples collected from November 2003 through August 2006 were analyzed for physical properties, dissolved solids, major ions, nutrients, trace elements, pesticides, fecal-indicator bacteria, suspended-sediment concentration, and total suspended solids. Ground-water samples were analyzed for physical properties, dissolved solids, major ions, nutrients, trace elements, pesticides, and fecal-indicator bacteria. Chemical oxygen demand and volatile organic compounds were analyzed in all three samples from one monitoring well located near a construction and demolition landfill on the reservation, and in one sample from another well in the Soldier Creek drainage basin. Previous reports published as a part of this ongoing study identified total phosphorus, triazine herbicides, and fecal coliform bacteria as exceeding their respective water-quality criteria in surface water on the reservation. Previous ground-water assessments identified occasional sample concentrations of dissolved solids, sodium, sulfate, boron, iron, and manganese as exceeding their respective water-quality criteria. Fifty-six percent of the 55 surface-water samples collected during the current study period and analyzed for total phosphorus exceeded the goal of 0.1 mg/L (milligram per liter) established by the U.S. Environmental Protection Agency (USEPA) to limit cultural eutrophication in flowing water. Concentrations of dissolved solids frequently exceeded the USEPA Secondary Drinking-Water Regulation (SDWR) of 500 mg/L in samples from two sites. Concentrations of sodium exceeded the Drinking-Water Advisory of 20 mg/L set by USEPA in almost 50 percent of the surface-water samples. All four samples analyzed for atrazine concentrations showed some concentration of the pesticide, but none exceeded the Maximum Contaminant Level (MCL) established for drinking water by USEPA of 3.0 µg/L (micrograms per liter) as an annual average. A triazine herbicide screen was used on 55 surface-water samples, and triazine compounds were frequently detected. Triazine herbicides and their degradates are listed on the USEPA Contaminant Candidate List. In 41 percent of surface-water samples, densities of Escherichia coli ( E. coli ) bacteria exceeded the primary contact, single-sample maximum in public-access bodies of water (1,198 colonies per 100 milliliters of water for samples collected between April 1 and October 31) set by the Kansas Department of Health and Environment (KDHE). Nitrite plus nitrate concentrations in all three water samples from 1 of 10 monitoring wells exceeded the MCL of 10 mg/L established by USEPA for drinking water. Arsenic concentrations in all three samples from one well exceeded the proposed MCL of 10 µg/L established by USEPA for drinking water. Boron also exceeded the drinking-water advisory in three samples from one well, and iron concentrations were higher than the SDWR in water from four wells. There was some detection of pesticides in ground-water samples from three of the wells, and one detection of the volatile organic compound diethyl ether in one well. Concentrations of dissolved solids exceeded the SDWR in 20 percent of ground-water samples collected during the current study period, and concentrations of sulfate and chloride exceeded their respective SDWR in 10 percent of the ground-water samples. Concentrations exceeded the Drinking-Water Advisory Level set by USEPA for sodium in 50 percent of the ground-water samples. Results from the current study period remained similar to results from previous study periods. The median triazine herbicide concentration (triazine screen by ELISA) for the current study period decreased slightly compared to past study periods. In the event that ground water on the reservation is to be used as a drinking-water source, additional treatment may be necessary to remove excess dissolved solids, sulfate, sodium, and chloride.

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USGS2007

Northeast Kansas well tests oil, gas possibilities in Precambrian rocks

Tests for oil and gas prospects in Precambrian rocks in Northeast Kansas is currently being undertaken by WTW Operating LLC. It drilled in late 2005 the no.1 Wilson well with a depth of 5,772ft, 1,826ft into the Precambrian basement on a venture testing the possibility of oil and gas in the crystalline rocks. The basin extends northeast into Nebraska and Iowa and is a shallow cratonic basin filled with Paleozoic segments. The rocks have been previously though as not a potential for oil and gas due to the rocks' crystalline and nonporous character with the exception of the Midcontinent rift system (MRS). Later, though, small quantities of oil have been produced on the Central Kansas uplift from granite wash while the wells also produced low-Btu with swabbing operations. The recovered gas contained considerable nonflammable components of nitrogen, carbon dioxide and helium which equates to a low btu content of 283.

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USGS2006

Habitat use by a Midwestern U.S.A. riverine fish assemblage: effects of season, water temperature and river discharge

The hypothesis that temperate stream fishes alter habitat use in response to changing water temperature and stream discharge was evaluated over a 1 year period in the Neosho River, Kansas, U.S.A. at two spatial scales. Winter patterns differed from those of all other seasons, with shallower water used less frequently, and low-flow habitat more frequently, than at other times. Non-random habitat use was more frequent at the point scale (4.5 m2) than at the larger reach scale (20-40 m), although patterns at both scales were similar. Relative to available habitats, assemblages used shallower, swifter-flowing water as temperature increased, and shallower, slower-flowing water as river discharge increased. River discharge had a stronger effect on assemblage habitat use than water temperature. Proportion of juveniles in the assemblage did not have a significant effect. This study suggests that many riverine fishes shift habitats in response to changing environmental conditions, and supports, at the assemblage level, the paradigm of lotic fishes switching from shallower, high-velocity habitats in summer to deeper, low-velocity habitats in winter, and of using shallower, low-velocity habitats during periods of high discharge. Results also indicate that different species within temperate river fish assemblages show similar habitat use patterns at multiple scales in response to environmental gradients, but that non-random use of available habitats is more frequent at small scales. ?? 2006 The Fisheries Society of the British Isles.

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USGS2006

Remote sensing and geophysical investigations of glacial buried valleys in northeastern Kansas

Aquifers found in glacial buried valleys are a major source of good-quality ground water in northeastern Kansas. The extent and character of many of these deposits are not precisely known, so a detailed study of the buried valleys was undertaken. Test drilling, Landsat imagery, shallow-earth temperature measurements, seismic refraction, surface electrical resistivity, and gravity data were used to evaluate two sites in Nemaha and Jefferson Counties. Tonal patterns on springtime Landsat imagery and winter/summer anomalies in shallow-earth temperatures were quick and inexpensive methods for locating some glacial buried aquifers and suggested areas for more intensive field studies. Reversed seismic refraction and resistivity surveys were generally reliable indicators of the presence or absence of glacial buried valleys, with most depth determinations being within 25% of test-drilling results. The effectiveness of expensive test-hole drilling was greatly increased by integrating remote sensing, shallow-earth temperature, seismic, and resistivity techniques in the two buried valley test areas. A gravity profile allowed precise definition of the extent of one of the channels after the other techniques had been used for general information.

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USGS2006

Water quality and relation to taste-and-odor compounds in the North Fork Ninnescah River and Cheney Reservoir, south-central Kansas, 1997-2003

Cheney Reservoir, the primary water supply for the city of Wichita in south-central Kansas, and its main source of inflow, the North Fork Ninnescah River, were sampled between 1997 and 2003 for sediment, nutrients, and the taste-and-odor-causing compounds geosmin and 2-methylisoborneol (MIB). It is believed that objectionable tastes and odors in Cheney Reservoir result from cyanobacteria (blue-green algae), and there is concern with proliferation of algal growth. Both nutrients and suspended solids affect algal growth and may be a concern for taste-and-odor issues. The transport of nutrients and suspended solids from the North Fork Ninnescah River to Cheney Reservoir was monitored as part of an effort to understand and thereby mitigate algal proliferation. The regression-estimated concentrations of total phosphorus in water entering the reservoir from the North Fork Ninnescah River during 2001–03 exceeded the base-flow, runoff, and long-term goals established by the Cheney Reservoir Task Force. Total suspended-solids concentrations in water from the North Fork Ninnescah River during 2001–03 generally exceeded long-term goals only during periods of runoff. Water samples from Cheney Reservoir were analyzed for geosmin and MIB, the two most common taste-and-odor causing compounds produced by cyanobacteria. MIB was rarely detected in samples, indicating that geosmin is likely the primary source of objectionable tastes and odors. Anabaena, a cyanobacterial genera often linked to taste-and-odor occurrences, was not statistically related to geosmin in Cheney Reservoir, which indicates that Anabaena abundance is not linearly related to geosmin concentration or that other cyanobacteria are producing geosmin. Regression models were developed between geosmin and the physical property measurements continuously recorded by water-quality monitors at each site. The geosmin regression model was applied to water-quality monitor measurements, providing a continuous estimate of geosmin for 2003. The city of Wichita will be able to use this type of analysis to determine the probability of when concentrations of geosmin are likely to be at or above the human detection level of 0.01 microgram per liter.

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USGS2005

Effects of lowhead dams on the ephemeropterans, plecopterans, and trichopterans group in a north American River

We assessed the effects of lowhead dams on the EPT group (ephemeropterans, plecopterans, and trichopterans) by sampling habitat and macroinvertebiates monthly from November 2000 to October 2001 at eight gravel bars centered around two lowhead dams on the Neosho River, Lyon County, Kansas. Sites included a reference and treatment site upstream and downstream from each dam. Percent EFT was greater at reference sites than upstream treatment sites, and was positively correlated with stream velocity and %gravel in the substrate, but negatively correlated with substrate compaction and %boulder in the substrate. These results are similar to those for large dams and suggest that differences in habitat around these lowhead dams are unfavorable for EPT taxa, a finding important to the conservation and restoration of biotic integrity in riverine ecosystems.

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USGS2005

4D seismic to image a thin carbonate reservoir during a miscible CO2 flood: Hall-Gurney Field, Kansas, USA

Time-lapse (TL) seismic monitoring has proven a valuable tool for reservoir management. If available in a timely and cost-effective manner, it can be incorporated into a dynamic reservoir management approach, spec-ifically in terms of assessing sweep efficiency through constraining reservoir simulations, quantifying compartmentalization, and enhancing the placement of infill wells. Thus, cost-effectiveness, rapid turnaround time, and sensitivity of the seismic response to subtle changes in reservoir properties evident in production data are critical assets of a robust and economic TL application. Successful applications of TL monitoring have been predominantly offshore—Gulf of Mexico and North Sea—in thick clastic reservoirs characterized as low technical risk. Changes in TL seismic images as a direct result of enhanced oil recovery operations in low compressibility, “stiff” carbonate reservoirs are so small that distinguishing reservoir fluid changes from background noise on seismic attribute maps is challenging at best and many times impossible. Consequently, reservoirs predicted to produce weak TL anomalies associated with enhanced oil recovery (EOR) operations are classified as high-risk cases and languish in what has been designated the “stretch portfolio” of time-lapse application in reservoir management.

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USGS2005

Markov Chain Monte Carlo estimation of species distributions: A case study of the swift fox in western Kansas

Accurate maps of species distributions are essential tools for wildlife research and conservation. Unfortunately, biologists often are forced to rely on maps derived from observed occurrences recorded opportunistically during observation periods of variable length. Spurious inferences are likely to result because such maps are profoundly affected by the duration and intensity of observation and by methods used to delineate distributions, especially when detection is uncertain. We conducted a systematic survey of swift fox ( Vulpes velox ) distribution in western Kansas, USA, and used Markov chain Monte Carlo (MCMC) image restoration to rectify these problems. During 1997–1999, we searched 355 townships (ca. 93 km 2 ) 1–3 times each for an average cost of $7,315 per year and achieved a detection rate (probability of detecting swift foxes, if present, during a single search) of θ̂ = 0.69 (95% Bayesian confidence interval [BCI] = [0.60, 0.77]). Our analysis produced an estimate of the underlying distribution, rather than a map of observed occurrences, that reflected the uncertainty associated with estimates of model parameters. To evaluate our results, we analyzed simulated data with similar properties. Results of our simulations suggest negligible bias and god good precision when probabilities of detection on ≥1 survey occasions (cumulative probabilities of detection) exceed 0.65. Although the use of MCMC image restoration has been limited by theoretical and computational complexities, alternatives do not possess the same advantages. Image models accommodate uncertain detection, do not require spatially independent data or a census of map units, and can be used to estimate species distributions directly from observations without relying on habitat covariates or parameters that must be estimated subjectively. These features facilitate economical surveys of large regions, the detection of temporal trends in distribution, and assessments of landscape-level relations between species and habitats. Requirements for the use of MCMC image restoration include study areas that can be partitioned into regular grids of mapping units, spatially contagious species distributions, reliable methods for identifying target species, and cumulative probabilities of detection ≥0.65.

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USGS2005

Scat removal: A source of bias in feces-related studies

Consumption of feces (coprophagy) may alter findings of dietary studies and population estimates based on fecal analyses, but its magnitude is poorly understood. We investigated seasonal incidence of scat removal on Fort Riley, Kansas, from January through December 2000. We placed feces from captive bobcats ( Lynx rufus ), captive coyotes ( Canis latrans ), and free-ranging coyotes randomly on tracking stations in forest and prairie landscapes to determine rates of scat removal by local wildlife. Rates of removal of feces from captive bobcats, captive coyotes, and free-ranging coyotes varied from 7% during spring to 50% during summer. We identified opossums ( Didelphis virginiana ) as the most common species present at stations where scat removal occurred. Feces may be an important seasonal source of food for opossums and may provide seasonal dietary supplements for other species. Other factors responsible for disturbance of feces included a woodrat ( Neotoma floridana ) caching coyote feces, removal of captive coyote feces by free-ranging coyotes accompanied by deposition of fresh feces, a bobcat burying a captive bobcat sample and depositing fresh feces, and rain storms. Dietary studies based on fecal analyses could be biased by scat removal, assuming that contents in feces are representative of the proportion of foods consumed.

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