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At least 469 records · Page 26Linked to original sources
USGS2009

Introduction to special section on impacts of land use change on water resources

Changes in land use have potentially large impacts on water resources, yet quantifying these impacts remains among the more challenging problems in hydrology. Water, food, energy, and climate are linked through complex webs of direct and indirect effects and feedbacks. Land use is undergoing major changes due not only to pressures for more efficient food, feed, and fiber production to support growing populations but also due to policy shifts that are creating markets for biofuel and agricultural carbon sequestration. Hydrologic systems embody flows of water, solutes, sediments, and energy that vary even in the absence of human activity. Understanding land use impacts thus necessitates integrated scientific approaches. Field measurements, remote sensing, and modeling studies are shedding new light on the modes and mechanisms by which land use changes impact water resources. Such studies can help deconflate the interconnected influences of human actions and natural variations on the quantity and quality of soil water, surface water, and groundwater, past, present, and future.

Water Resources Research↗
USGS2018

Dissolved organic carbon and nitrogen release from boreal Holocene permafrost and seasonally frozen soils of Alaska

Permafrost (perennially frozen) soils store vast amounts of organic carbon (C) and nitrogen (N) that are vulnerable to mobilization as dissolved organic carbon (DOC) and dissolved organic and inorganic nitrogen (DON, DIN) upon thaw. Such releases will affect the biogeochemistry of permafrost regions, yet little is known about the chemical composition and source variability of active-layer (seasonally frozen) and permafrost soil DOC, DON and DIN. We quantified DOC, total dissolved N (TDN), DON, and DIN leachate yields from deep active-layer and near-surface boreal Holocene permafrost soils in interior Alaska varying in soil C and N content and radiocarbon age to determine potential release upon thaw. Soil cores were collected at three sites distributed across the Alaska boreal region in late winter, cut in 15 cm thick sections, and deep active-layer and shallow permafrost sections were thawed and leached. Leachates were analyzed for DOC, TDN, nitrate (NO 3 − ), and ammonium (NH 4 + ) concentrations, dissolved organic matter optical properties, and DOC biodegradability. Soils were analyzed for C, N, and radiocarbon ( 14 C) content. Soil DOC, TDN, DON, and DIN yields increased linearly with soil C and N content, and decreased with increasing radiocarbon age. These relationships were significantly different for active-layer and permafrost soils such that for a given soil C or N content, or radiocarbon age, permafrost soils released more DOC and TDN (mostly as DON) per gram soil than active-layer soils. Permafrost soil DOC biodegradability was significantly correlated with soil Δ 14 C and DOM optical properties. Our results demonstrate that near-surface Holocene permafrost soils preserve greater relative potential DOC and TDN yields than overlying seasonally frozen soils that are exposed to annual leaching and decomposition. While many factors control the fate of DOC and TDN, the greater relative yields from newly thawed Holocene permafrost soils will have the largest potential impact in areas dominated by organic-rich soils.

Alaska↗
USGS2004

Influence of near-surface stratigraphy on coastal landslides at Sleeping Bear Dunes National Lakeshore, Lake Michigan, USA

Lake-level change and landslides are primary controls on the development of coastal environments along the coast of northeastern Lake Michigan. The late Quaternary geology of Sleeping Bear Dunes National Lakeshore was examined with high-resolution seismic reflection profiles, ground-penetrating radar (GPR), and boreholes. Based on sequence-stratigraphic principles, this study recognizes ten stratigraphic units and three major unconformities that were formed by late Pleistocene glaciation and postglacial lake-level changes. Locally high sediment supply, and reworking by two regressions and a transgression have produced a complex stratigraphy that is prone to episodic failure. In 1995, a large landslide deposited approximately 1 million m3 of sediment on the lake floor. The highly deformed landslide deposits, up to 18 m thick, extend 3-4 km offshore and unconformably overlie well-stratified glacial and lacustrine sediment. The landslide-prone bluff is underlain by channel-fill deposits that are oriented nearly perpendicular to the shoreline. The paleochannels are at least 10 m deep and 400 m wide and probably represent stream incision during a lake-level lowstand about 10.3 ka B.P. The channels filled with sediment during the subsequent transgression and lake-level highstand, which climaxed about 4.5 ka B.P. As lake level fell from the highstand, the formation of beach ridges and sand dunes sealed off the channel and isolated a small inland lake (Glen Lake), which lies 5 m above the level of Lake Michigan and may be a source of piped groundwater. Our hypothesis is that the paleochannels act as conduits for pore water flow, and thereby locally reduce soil strength and promote slope failure.

Michigan↗
USGS2013

Scenarios of bioenergy development impacts on regional groundwater withdrawals

Irrigation increases agricultural productivity, but it also stresses water resources (Huffaker and Hamilton 2007). Drought and the potential for drier conditions resulting from climate change could strain water supplies in landscapes where human populations rely on finite groundwater resources for drinking, agriculture, energy, and industry (IPCC 2007). For instance, in the North American Great Plains, rowcrops are utilized for livestock feed, food, and bioenergy production (Cassman and Liska 2007), and a large portion is irrigated with groundwater from the High Plains aquifer system (McGuire 2011). Under projected future climatic conditions, greater crop water use requirements and diminished groundwater recharge rates could make rowcrop irrigation less feasible in some areas (Rosenberg et al. 1999; Sophocleous 2005). The Rainwater Basin region of south central Nebraska, United States, is an intensively farmed and irrigated Great Plains landscape dominated by corn (Zea mays L.) and soybean (Glycine max L.) production (Bishop and Vrtiska 2008). Ten starch-based ethanol plants currently service the region, producing ethanol from corn grain (figure 1). In this study, we explore the potential of switchgrass (Panicum virgatum L.), a drought-tolerant alternative bioenergy feedstock, to impact regional annual groundwater withdrawals for irrigation under warmer and drier future conditions. Although our research context is specific to the Rainwater Basin and surrounding North American Great Plains, we believe the broader research question is internationally pertinent and hope that this study simulates similar research in other areas.

Nebraska↗
USGS1995

Assessment of the subsurface hydrology of the UIC-NARL main camp, near Barrow, Alaska, 1993-94

Imikpuk Lake serves as the drinking-water source for the Ukpeagvik Inupiat Corporation-National Arctic Research Laboratory (UIC-NARL, formerly known as the Naval Arctic Research Laboratory) near Barrow, Alaska. Previously acceptable hazardous-waste disposal practices and accidental releases of various fuels and solvents during the past several decades have resulted in contamination of soil and ground water in the vicinity of the lake. As part of an assessment of the risk that subsurface contamination poses to the quality of water in the lake, the subsurface hydrology of the UIC-NARL main camp was examined. The study area is located approximately 530 kilometers north of the Arctic Circle, on the northern coast of Alaska, and the short annual thaw season and the presence of shallow, areally continuous permafrost restrict hydrologic processes. A transient ground-water system is present within the active layer-the shallow subsurface layer that thaws each summer and refreezes each winter. Water-level and thaw-depth data collected during the summers of 1993 and 1994 show that the configurations of both the water table and the subsurface frost govern the ground- water flow system in the UIC-NARL main camp and indicate that recharge to and discharge from the system are small. Spatial irregularities in the vertical extent of the active layer result from variations in land-surface elevation, variations in soil type, and the presence of buildings and other structures that either act as a heat source or block heat transfer to and from the subsurface. Distinct features in the active-layer hydrologic system in the UIC-NARL main camp include a permafrost ridge, which generally acts as a flow-system divide between the Arctic Ocean and inland water bodies; a mound in the water table, which indicates increased impedance to ground- water flow toward Imikpuk Lake and acts as a flow-system divide between the lake and Middle Salt Lagoon; and a depression in the water table, which suggests a local breach in the permafrost ridge that allows some ground water to flow directly from the main camp to the Arctic Ocean. Similar thaw depths and water-table elevations were measured during the summers of 1993 and 1994, and little change occurred in the thickness of the ground-water zone between mid- and late-thaw- season measurements. These data suggest that the system is in a state of quasi-equilibrium and that ground-water discharge is small. The observed drop in the water table as the active layer develops over the summer is probably largely the result of evapotranspiration losses rather than system outflow.

Open-File Report↗
USGS2024

Digging into detectability: Uncovering how temperature influences detection probability of the fossorial Temblor legless lizard

Knowledge of species distributions is critical for conservation, but surveying for rare, understudied species presents many challenges. A two-phase occupancy study can increase knowledge gained from early occupancy studies of a species by quickly using data from the first survey period to revise the study design for a second period. The Temblor legless lizard Anniella alexanderae is a recently described fossorial species found in the southwestern San Joaquin Valley, California, and its status is currently under review by state and federal wildlife agencies. As a fossorial species that is rarely surface active, Temblor legless lizards might be unavailable for detection at certain times of year or under inhospitable conditions (e.g., hot, dry weather), indicating the importance of accounting for false-negative surveys when determining its distribution. We used a multiscale occupancy model to disentangle detection probability, availability for detection, and occupancy for Temblor legless lizards. Focusing our effort from mid-February to mid-April when temperatures are mild and soil moisture is expected to be higher near the surface, we surveyed a total of 89 sites in 2022 ( n = 60) and 2023 ( n = 68) and detected Temblor legless lizards at 12 sites, including 5 new localities. Detection probability was positively related to temperature during our late winter-early spring survey period, and availability for detection was consistently high with minimal fluctuation within each year. Nevertheless, repeated surveys with nondetection can increase confidence that this fossorial lizard does not occur at a site. Temblor legless lizards were more likely to occur at sites near ephemeral streams and in areas without high clay soil content, but more investigation could help to discern drivers of occurrence. Our study provides valuable information for optimizing surveys for Temblor legless lizards and suggests promising directions for future research on this species’ ecology.

California↗
USGS2015

Observations on the migration of bacillus spores outside a contaminated facility during a decontamination efficacy study

The potential for an intentional wide-area or indoor release of Bacillus anthracis spores remains a concern, but the fate and transport of B. anthracis spores in indoor and outdoor environments are not well understood. Some studies have examined the possibility of spore transport within ventilation systems and in buildings and transport into a building following an outdoor release. Little research exists regarding the potential for spores to migrate to the outside of a building following an indoor release. Bacillus species spores have the potential to remain viable in the soil for many years. Lasting environmental contamination following a release is a possibility, and planning for site characterization and remediation activities should consider both indoor-to-outdoor spore transport and outdoor soil as potential exposure pathways.

Journal of Bioterrorism & Biodefense↗
USGS1997

Recent developments in the reclamation of surface mined lands

A broad review of mine land reclamation problems and challenges in arid lands is presented with special emphasis on work recently completed in India. The economics of mining in the Indian Desert is second only to agriculture in importance. Lands disturbed by mining, however, have only recently been the focus of reclamation attempts. Studies were made and results compiled of problems associated with germplasm selection, soil, plant and overburden characterization and manipulation, plant establishment methods utilized, soil amendment needs, use and conservation of available water and the evaluation of ecosystem sustainability. Emphasis is made of the need for multi-disciplinary approaches to mine land reclamation research and for the long-term monitoring of reclamation success.

Annals of Arid Zone↗
USGS2021

The processes of preferential flow in the unsaturated zone

Preferential flow, a major influence in unsaturated soil and rock almost everywhere, occurs by multiple phenomenologically distinct hydraulic processes. For the mode known as funneled flow, concentrated in particularly conductive portions of the medium, the surface-tension/viscous-flow processes of traditional unsaturated flow theory predominate. Fingered flow, through conductive paths of higher water content than surrounding material, requires amendments to traditional theory concerning instabilities and dynamic flow-regime boundaries. Macropore flow, the most recognized preferential flow mode, poses unanswered questions and major difficulties in practice. Accumulated evidence shows that water flows preferentially mostly through macropores that are (a) only partially filled with water, and (b) surrounded by matrix material that is drier, sometimes much drier, than saturation. With partial filling, geometric characteristics such as aperture have much less influence than was previously thought, and the intra-macropore configuration of the flowing water phase, about which little is conclusively known, is then a dominant controlling influence. With unsaturated surroundings, macropore/matrix exchange interactions control, for given input and medium, the initiating circumstances, conveyed flux, and duration of macropore flow. The multiple processes in play during such interactions have different sensitivities to the matrix water state and different directions of influence. The net influence of matrix water content on macropore flow is thus highly complex and a major research need. Additional high-priority topics are: flowpath connectivity, for watersheds as well as small scales; intra-macropore processes, to discern their importance and possible means of quantification; and the identification of measurable soil and rock properties that can be utilized predictively.

Soil Science Society of America Journal↗
USGS2026

Inverse modeling for post-wildfire hydrologic process understanding over snow-dominated watersheds

Wildfire-induced changes to vegetation and soil properties can alter snowpack dynamics and hydrologic processes in ways that complicate predictions of post-wildfire water availability. To better understand these effects, we coupled the Parameter ESTimation in C++ (PEST++) software with the Weather Research & Forecasting Hydrologic model (WRF-Hydro) across three burned, snow-dominated watersheds in the western United States. We incorporated three burn-severity-based land cover categories into WRF-Hydro and used an iterative Ensemble Smoother (iES) within PEST++ to estimate model parameters controlling snow accumulation and melt, infiltration, and streamflow generation. This framework supported three complementary objectives: (1) assessing parameter sensitivities under pre- and post-wildfire conditions, (2) comparing pre- and post-wildfire parameter ensembles to identify wildfire-driven shifts in hydrologic processes, and (3) using counterfactual simulations to isolate the hydrologic response to wildfire from interannual climate variability. Our findings indicate that model parameter sensitivity varied by domain and shifted following wildfire. Maximum snow albedo and snow albedo decay were most influential in the higher-elevation East Troublesome domain, while the rain-snow partitioning temperature threshold dominated in the lower-elevation Chippy Creek and Las Conchas domains. Following wildfire, streamflow sensitivity shifted away from snowpack parameters toward soil hydraulic parameters, consistent with wildfire-driven reductions in evapotranspiration and increases in soil moisture. Incorporating wildfire effects led to complex changes in simulated snowpack accumulation and streamflow timing, generally leading to earlier snowmelt freshet initiation and cessation and reduced late season flows. Simulations were more sensitive to interannual climate variations than wildfire land cover changes. These results highlight both the potential and challenges of ensemble-based inverse modeling for understanding post-wildfire hydrologic change in snow-dominated watersheds.

Colorado, Montana, New Mexico↗
USGS2016

Summary of SPT based field case history data of CETIN (2016) database

This report provides documentation of the Cetin et al. (2016) field performance case histories, probabilistic maximum likelihood assessment and the sources of differences between the liquefaction triggering resistance estimations (CRR values) of the widely used liquefaction triggering relationships of Seed et al. (1985), Cetin et al. (2004, 2016) and Boulanger and Idriss (2012). Cetin et al. (2016-a) presented a concise summary of the improved database and the updated triggering relationships. For the sake of completeness, as part of Chapter 2 of this report, Cetin et al. (2016-a) manuscript is re-presented, as edited to include the electronic supplements, and a broader and more detailed documentation of all of case histories. This broader and more detailed documentation along with the interpretations of other researchers is presented in Appendix A. Similarly, site response analyses details and results from Cetin (2000) is re-presented in Appendix B. To enable the readers to quickly refer to Cetin and Seed (2004), it is also included in Appendix C. The sources of differences between the liquefaction triggering resistance estimations (CRR values) of the widely used liquefaction triggering relationships of Seed et al. (1985), Cetin et al. (2004) and Boulanger and Idriss (2012) were discussed in Cetin et al. (2016-b). Again, for the sake of completeness, as part of Chapter 3 of this report, Cetin et al. (2016-b) manuscript is re-presented, as edited to the include of electronic supplements, and a detailed response to issues addressed by Idriss and Boulanger (2012). Also, the technical response letter (Cetin, 2014) prepared at the request of the members of the NRC Committee on the State of the Art and Practice in Earthquake Induced Soil Liquefaction Assessment, is given in Appendix D, which is helpful to follow the technical discussions. This report is intended only as a concise summary of a vast amount of data. The interpretations presented are those of the research team. A more detailed description of some of the details of the methods and procedures used to evaluate and analyze these field performance case histories is also presented in Cetin (2000) and Cetin et al. (2000) though the final evaluations presented in this report are the most recent interpretations undertaken under these current studies.

Report↗
USGS2004

Tracing sources of nitrate in snowmelt runoff using a high-resolution isotopic technique

The denitrifier method to determine the dual isotopic composition (??15N and ??18O) of nitrate is well suited for studies of nitrogen contributions to streams during runoff events. This method requires only 70 nmol of NO3- and enables high throughput of samples. We studied nitrate sources to a headwater stream during snowmelt by generating a high-temporal resolution dataset at the Sleepers River Research Watershed in Vermont, USA. In the earliest phase of runoff, stream NO3- concentrations were highest and stream discharge, NO3- concentrations, and ??18O of NO 3- generally tracked one another during diurnal melting. The isotopic composition of stream NO3- varied in-between atmospheric and groundwater NO 3- end members indicating a direct contribution of atmospherically-derived NO3- from the snow pack to the stream. During the middle to late phases of snowmelt, the source shifted toward soil NO3- entering the stream via shallow subsurface flow paths. Copyright 2004 by the American Geophysical Union.

Geophysical Research Letters↗
USGS2014

Natural regeneration processes in big sagebrush ( Artemisia tridentata )

Big sagebrush, Artemisia tridentata Nuttall (Asteraceae), is the dominant plant species of large portions of semiarid western North America. However, much of historical big sagebrush vegetation has been removed or modified. Thus, regeneration is recognized as an important component for land management. Limited knowledge about key regeneration processes, however, represents an obstacle to identifying successful management practices and to gaining greater insight into the consequences of increasing disturbance frequency and global change. Therefore, our objective is to synthesize knowledge about natural big sagebrush regeneration. We identified and characterized the controls of big sagebrush seed production, germination, and establishment. The largest knowledge gaps and associated research needs include quiescence and dormancy of embryos and seedlings; variation in seed production and germination percentages; wet-thermal time model of germination; responses to frost events (including freezing/thawing of soils), CO 2 concentration, and nutrients in combination with water availability; suitability of microsite vs. site conditions; competitive ability as well as seedling growth responses; and differences among subspecies and ecoregions. Potential impacts of climate change on big sagebrush regeneration could include that temperature increases may not have a large direct influence on regeneration due to the broad temperature optimum for regeneration, whereas indirect effects could include selection for populations with less stringent seed dormancy. Drier conditions will have direct negative effects on germination and seedling survival and could also lead to lighter seeds, which lowers germination success further. The short seed dispersal distance of big sagebrush may limit its tracking of suitable climate; whereas, the low competitive ability of big sagebrush seedlings may limit successful competition with species that track climate. An improved understanding of the ecology of big sagebrush regeneration should benefit resource management activities and increase the ability of land managers to anticipate global change impacts.

Rangeland Ecology and Management↗
USGS2011

Assessment of conservation practices in the Fort Cobb Reservoir watershed, southwestern Oklahoma

The Fort Cobb Reservoir watershed encompasses about 813 square kilometers of rural farm land in Caddo, Custer, and Washita Counties in southwestern Oklahoma. The Fort Cobb Reservoir and six stream segments were identified on the Oklahoma 1998 303(d) list as not supporting designated beneficial uses because of impairment by nutrients, suspended solids, sedimentation, pesticides, and unknown toxicity. As a result, State and Federal agencies, in collaboration with conservation districts and landowners, started conservation efforts in 2001 to decrease erosion and transport of sediments and nutrients to the reservoir and improve water quality in tributaries. The U.S. Department of Agriculture selected the Fort Cobb Reservoir watershed in 2003 as 1 of 14 benchmark watersheds under the Conservation Effectiveness Assessment Project with the objective of quantifying the environmental benefits derived from agricultural conservation programs in reducing inflows of sediments and phosphorus to the reservoir. In November 2004, the Biologic, Geographic, Geologic, and Water Disciplines of the U.S. Geological Survey, in collaboration with the Agricultural Research Service, Grazinglands Research Laboratory in El Reno, Oklahoma, began an interdisciplinary investigation to produce an integrated publication to complement this program. This publication is a compilation of 10 report chapters describing land uses, soils, geology, climate, and water quality in streams and the reservoir through results of field and remote sensing investigations from 2004 to 2007. The investigations indicated that targeting best-management practices to small intermittent streams draining to the reservoir and to the Cobb Creek subwatershed may effectively augment efforts to improve eutrophic to hypereutrophic conditions that continue to affect the reservoir. The three major streams flowing into the reservoir contribute nutrients causing eutrophication, but minor streams draining cultivated fields near the reservoir appeared to be disproportionate contributors of nutrients. Increasing conservation practices on small streams may have a greater effect in mitigating eutrophication in the reservoir than additional installation of such measures on the larger creeks.

Oklahoma↗
USGS2023

Attributes of Upper Mississippi River System contiguous forest areas

Floodplain forests are important features of river systems as they create habitat for a variety of wildlife species as well as influence water quality by sequestering nutrients. The ecological conditions found within forested areas can vary greatly from place to place, contributing to spatial variability in species diversity, animal use of the floodplain, and other ecological functions. For this reason, it is important for managers and researchers to identify and map existing forest conditions for use in restoration practices or research studies. A number of forest attributes have been identified as useful in predicting the local ecological conditions found within forested areas. For example, attributes related to the size, shape and configuration of forest patches have been linked to susceptibility to invasion by exotic species, animal and plant dispersal patterns, population distributions, and species diversity (Zuidema and others, 1996; Laurance and others, 2001; Weathers and others, 2001; Lindenmayer and Franklin 2002; Harper and others, 2005; Ramaharitra 2006). In floodplain forests, patterns of inundation have been shown to influence local soil conditions as well as plant species composition and diversity (De Jager and others, 2012). Knowing the land-use history of forest areas has also been shown to be important in understanding present day ecological conditions of forested areas (Turner and others, 2004). To support floodplain forest research and management actions on the Upper Mississippi River System (UMRS), we identified contiguous forested areas (i.e., areas of forest cover that were separated from each other by other land or water cover types) in the floodplain and calculated a wide range of attributes that define basic ecosystem conditions within such forested areas. The data allows users to query on a set of attributes (e.g., size, shape, inundation characteristics, etc.) to visualize the distribution of various ecological conditions. In addition, the data allows for future data analyses of relationships among different ecological conditions and other data, such as animal and plant population distributions.

Upper Mississippi River system↗
USGS2026

Emergent headwater types for watershed monitoring, research, and planning

Headwaters—that is headwater streams and the watersheds they drain—strongly influence water quality, ecosystem services, and hydrologic connectivity, yet remain poorly mapped, monitored, and understood at large spatial scales. Using available spatial data to classify headwater “types” could therefore enhance the utility of sparse monitoring data to advance research and watershed planning—and help update literature-based perceptual models of headwaters as steep, forested, and minimally disturbed watersheds. Here, we analyze headwaters across the contiguous United States to quantify how their attributes (climate, topography, land cover, soils) vary regionally and differ from their downstream watersheds. Our analysis (a) identified seven dominant headwater types with distinct combinations of biophysical and climatic attributes and (b) revealed systematic contrasts with downstream watersheds, with strongest differences in attributes representing potential flowpath depth. Our findings offer a transferable framework for classifying, modeling, and managing these critical yet understudied components of the hydrologic network.

conterminous United States↗
USGS2019

Salinity yield modeling of the Upper Colorado River Basin using 30-meter resolution soil maps and random forests

Salinity loading in the Upper Colorado River Basin (UCRB) costs local economies upwards of $300 million US dollars annually. Salinity source models have generally included coarse spatial data to represent non‐agriculture sources. We developed new predictive soil property and cover maps at 30 m resolution to improve source representation in salinity modeling. Salinity loading erosion risk indices were also created based on soil properties, remotely sensed bare ground exposure, and topographic factors to examine potential surface soil erosion drivers. These new maps and data from previous SPARROW models were related to recently updated records of salinity at 309 stream gauges in the UCRB using random forest regressions. Resulting salinity yield predictions indicate more diffuse salinity sources, with slightly higher yields in more arid portions of the UCRB, and less overall load coming from irrigated agricultural sources. Model simulations still indicate irrigation to be the major human source of salinity (661,000 Mg, or 12%), but also suggest that 75,000 Mg (1.4%) of annual salinity in the UCRB is coming from areas with excessive exposed bare ground in high elevation mountain areas. Model inputs allow for field scale screening of locations that could be targeted for salinity control projects. Results confirm recent studies indicating limited surface erosional influence on salinity loading in UCRB surface waters, but impacts of monsoonal runoff events are still not fully understood, particularly in drylands. The study highlights the utility of new predictive soil maps and machine learning for environmental modeling.

Arizona, Colorado, New Mexico, Utah, Wyoming↗