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At least 685 records · Page 38Linked to original sources
USGS2013

Wetland Reserve Program enhances site occupancy and species richness in assemblages of anuran amphibians in the Mississippi Alluvial Valley, USA

We measured amphibian habitat use to quantify the effectiveness of conservation practices implemented under the Wetland Reserve Program (WRP), an initiative of the U.S. Department of Agriculture’s Natural Resources Conservation Service. From February to June 2007, we quantified calling male anurans in cultivated cropland, former cultivated cropland restored through the WRP, and mature bottomland hardwood forest. Sites were located in two watersheds within the Mississippi Alluvial Valley of Arkansas and Louisiana, USA. We estimated detection probability and site occupancy within each land use category using a Bayesian hierarchical model of community species occurrence, and derived an estimate of species richness at each site. Relative to sites in cultivated cropland, nine of 1 l species detected were significantly more likely to occur at WRP sites and six were more likely to occur at forested sites. Species richness estimates were also higher for WRP and forested sites, compared to those in cultivated cropland. Almost half (45 %) of the species responded positively to both WRP and forested sites, indicating that patches undergoing restoration may be important transitional habitats. Wetland Reserve Program conservation practices are successful in restoring suitable habitat and reducing the impact of cultivation-induced habitat loss on amphibians in the Mississippi Alluvial Valley.

Arkansas;Louisiana↗
USGS2025

A comparison of deep-sea coral and sponge species distribution models and the impact of ocean currents in the Southern California Bight

Deep-sea corals and sponges (DSCS) are signature taxa of deep-water habitats, but ecological mechanisms that drive their geographic distributions can be difficult to uncover due to the challenges of surveying deep-water ecosystems and limited oceanographic data. A comparison of species distribution models was made for three DSCS ( Antipathes dendochristos, Plumarella longispina, and an unidentified sponge morphotype known as Porifera #2), two of which are associated with young-of-the-year and adult rockfish taxa ( Sebastes spp.). Models were built using generalized additive models (GAMs) that accounted for spatial autocorrelation. These models were compared to Maxent models, a commonly used method. All models utilized bathymetrically derived variables (including depth, slope, and Bathymetric Position Index) and output from a coupled physical-biogeochemical ocean model (including current direction and magnitude, food abundance, and dissolved oxygen). Direction of benthic ocean currents played an important role in predictions, pointing to large-scale ecological processes that may determine presence of DSCS. GAMs outperformed Maxent models and predicted more ecologically interpretable patterns. Additionally we quantified the predicted amount of suitable habitat that is currently located within some protected areas of the Southern California Bight and show that many hot spots occur outside protected areas. Given the importance of DSCS for multiple demersal fish species of commercial or conservation concerns, this research provides valuable information that natural resource managers can use as a tool in the Southern California Bight.

California↗
USGS2013

Spatial extent and dynamics of dam impacts on tropical island freshwater fish assemblages

Habitat connectivity is vital to the persistence of migratory fishes. Native tropical island stream fish assemblages composed of diadromous species require intact corridors between ocean and riverine habitats. High dams block fish migration, but low-head artificial barriers are more widespread and are rarely assessed for impacts. Among all 46 drainages in Puerto Rico, we identified and surveyed 335 artificial barriers that hinder fish migration to 74.5% of the upstream habitat. We also surveyed occupancy of native diadromous fishes (Anguillidae, Eleotridae, Gobiidae, and Mugilidae) in 118 river reaches. Occupancy models demonstrated that barriers 2 meters (m) high restricted nongoby fish migration and extirpated those fish upstream of 4-m barriers. Gobies are adapted to climbing and are restricted by 12-m barriers and extirpated upstream of 32-m barriers. Our findings quantitatively illustrate the extensive impact of low-head structures on island stream fauna and provide guidance for natural resource management, habitat restoration, and water development strategies.

BioScience↗
USGS2006

Knowledge and Understanding of the Hydrogeology of the Salt Basin in South-Central New Mexico and Future Study Needs

The Salt Basin covers about 2,400 square miles of south-central New Mexico and extends across the State line into Texas. As much as 57 million acre-feet of ground water may be stored within the New Mexico part of the Salt Basin of which 15 million acre-feet are potentially potable and recoverable. Recent work suggests that the volume of ground water in storage within the New Mexico portion of the Salt Basin may be substantially greater than 57 million acre-feet. In this report, aquifers contained in the San Andres, Bone Spring, and Victorio Peak Limestones and in the Yeso, Hueco, and Abo Formations are collectively referred to as the carbonate aquifer. Porosity and permeability of the major aquifer are primarily determined by the density and interconnectedness of fractures and karstic solution channels. The spatial variability of these fractures and karstic features leads to a large spatial variability in hydraulic properties in the carbonate aquifer. Ground water generally moves southward away from recharge areas along the northern border of the Salt Basin and generally moves eastward to southeastward away from areas of distributed recharge on the Otero Mesa and the Diablo Plateau. Ground water originating from these recharge areas generally moves toward the central valley. Present day discharge is mostly through ground-water withdrawal for agricultural irrigation. A zone of relatively low hydraulic gradient, corresponding to the location of the Otero Break, extends from near the Sacramento River watershed southward toward Dell City, Texas. Ground water in the carbonate aquifer generally is very hard and has dissolved-solids concentrations ranging from 500 to 6,500 milligrams per liter. Substantial variability exists in current estimates of (1) ground-water recharge, (2) natural ground-water discharge, (3) the volume of ground water in storage, (4) the volume of recoverable ground water, (5) the conceptual model of ground-water flow, (6) the distribution of ground-water quality, and (7) the distribution of hydraulic characteristics. Future study could reduce uncertainty in these estimates and allow for better management of ground-water resources in the Salt Basin.

Open-File Report↗
USGS2002

Integrated management of waterbirds: Beyond the conventional

Integrated waterbird management over the past few decades has implicitly referred to methods for managing wetlands that usually attempt to enhance habitat for taxonomic groups such as shorebirds and wading birds, in addition to waterfowl, the traditional focus group. Here I describe five elements of integration in management: taxonomic, spatial, temporal, population and habitat, and multiple-use management objectives. Spatial integration simply expands the scale of management concern. Rather than emphasizing management on a very limited number of impoundments or wetlands in small refuges or wildlife management areas, the vision is beginning to shift to connectivity within larger landscapes on the order of many square kilometers as telemetry data on daily and seasonal movements for many species become available. Temporal integration refers to the potential for either simultaneous management for waterbirds and commercial 'crops' (e.g., crayfish and rice) or for temporally-staggered management such as row crop production in spring-summer growing seasons and waterbird management on fallow fields in the non-growing (winter) season. Integrating population dynamics with habitats has become a major research focus over the past decade. Identifying which wetlands are ?sources? or ?sinks? for specific populations provides managers with critical information about effective management. Further, the applications of spatially explicit population models place heavy demands on researchers to identify use patterns for breeding and dispersing individuals by age, sex, and reproductive class. Population viability analysis models require much the same information. Finally, multiple-use management integration refers to trying to optimize the uses of wetlands, when only one (perhaps secondary) use may include waterbird management. Depending upon the ownership and primary land use of a particular parcel of land containing wetlands and/or water bodies, managing for waterbirds may be an ?easy sell? (e.g., public natural resource lands) or a very contentious one, where wetlands are created for industrial, aquaculture or urban uses. In the latter case, careful planning and implementation require broad stakeholder participation and education.

Book chapter↗
USGS2023

Sharing land via keystone structure: Retaining naturally regenerated trees may efficiently benefit birds in plantations

Meeting food/wood demands with increasing human population and per-capita consumption is a pressing conservation issue, and is often framed as a choice between land sparing and land sharing. Although most empirical studies comparing the efficacy of land sparing and sharing supported land sparing, land sharing may be more efficient if its performance is tested by rigorous experimental design and habitat structures providing crucial resources for various species––keystone structures––are clearly involved. We launched a manipulative experiment to retain naturally regenerated broad-leaved trees when harvesting conifer plantations in central Hokkaido, northern Japan. We surveyed birds in harvested treatments, unharvested plantation controls and natural forest references one-year before the harvest and for three consecutive post-harvest years. We developed a hierarchical community model separating abundance and space-use (territorial proportion overlapping treatment plots) subject to imperfect detection to assess population consequences of retention harvesting. Application of the model to our data showed that retaining some broad-leaved trees increased total abundance of forest birds over the harvest rotation cycle. Specifically, pre-harvest survey showed that the amount of broad-leaved trees increased forest bird abundance in a concave manner (i.e., in a form of diminishing-return). After harvesting, a small amount of retained broad-leaved trees mitigated negative harvesting impacts on abundance though retention harvesting reduced the space-use. Nevertheless, positive retention effects on the post-harvest bird density as the product of abundance and space-use exhibited a concave form. Thus, small profit reductions were shown to yield large increases in forest bird abundance. The difference in bird abundance between clear-cutting and low amounts of broad-leaved tree retention increased slightly from the first to second post-harvesting years. We conclude that retaining a small amount of broad-leaved trees may be a cost-effective on-site conservation approach for the management of conifer plantations. Retention of 20-30 broad-leaved trees per ha may be sufficient to maintain higher forest bird abundance than clear-cutting over the rotation cycle. Retention approaches can be incorporated into management systems using certification schemes and best management practices. Developing an awareness of the roles and values of naturally regenerated trees is needed to diversify plantations.

Ecological Applications↗
USGS2010

A consumer-resource approach to the density-dependent population dynamics of mutualism

Like predation and competition, mutualism is now recognized as a consumer resource (C-R) interaction, including, in particular, bi-directional (e.g., coral, plant- mycorrhizae) and uni-directional (e.g., ant-plant defense, plant-pollinator) C-R mutualisms. Here, we develop general theory for the density-dependent population dynamics of mutualism based on the C-R mechanism of interspecific interaction. To test the influence of C-R interactions on the dynamics and stability of bi- and uni-directional C-R mutualisms, we developed simple models that link consumer functional response of one mutualistic species with the resources supplied by another. Phase-plane analyses show that the ecological dynamics of C-R mutualisms are stable in general. Most transient behavior leads to an equilibrium of mutualistic coexistence, at which both species densities are greater than in the absence of interactions. However, due to the basic nature of C-R interactions, certain density-dependent conditions can lead to C-R dynamics characteristic of predator-prey interactions, in which one species overexploits and causes the other to go extinct. Consistent with empirical phenomena, these results suggest that the C-R interaction can provide a broad mechanism for understanding density-dependent population dynamics of mutualism. By unifying predation, competition, and mutualism under the common ecological framework of consumer-resource theory, we may also gain a better understanding of the universal features of interspecific interactions in general.

Ecology↗
USGS2024

The 3D Elevation Program—Supporting the Texas economy

Introduction High-resolution elevation data for Texas inform decision making to improve the State’s economy. Existing elevation data coverage is used to improve resiliency to natural disasters, manage energy infrastructure, and assess natural resources. The expanding availability of current and more accurate elevation data helps better support natural resources conservation, agriculture and precision farming, flood risk management, infrastructure and construction management, geologic resource assessment and hazard mitigation, coastal zone management, and identification of features of interest or concern, such as archaeological and historic sites. Critical applications that meet the State’s management needs depend on light detection and ranging (lidar) data that provide a highly detailed three-dimensional (3D) model of the Earth’s surface and aboveground features. The 3D Elevation Program (3DEP) is managed by the U.S. Geological Survey (USGS) in partnership with Federal, State, Tribal, U.S. territorial, and local agencies to acquire consistent lidar coverage at quality level 2 or better to meet the many needs of the Nation and Texas. The status of available and in-progress 3DEP baseline lidar data in Texas is shown in figure 1. 3DEP baseline lidar data include quality level 2 or better, 1-meter or better digital elevation models, and lidar point clouds, and must meet the Lidar Base Specification version 1.2 ( https://www.usgs.gov/3dep/lidarspec ) or newer requirements. The National Enhanced Elevation Assessment identified user requirements and conservatively estimated that availability of lidar data would result in at least $53.1 million in new benefits annually to the State. The top 10 Texas business uses for 3D elevation data, which are based on the estimated annual conservative benefits of 3DEP, are shown in table 2.

Texas↗
USGS2002

U.S. Geological Survey spatial data access

The U.S. Geological Survey (USGS) has done a progress review on improving access to its spatial data holdings over the Web. The USGS EROS Data Center has created three major Web-based interfaces to deliver spatial data to the general public; they are Earth Explorer, the Seamless Data Distribution System (SDDS), and the USGS Web Mapping Portal. Lessons were learned in developing these systems, and various resources were needed for their implementation. The USGS serves as a fact-finding agency in the U.S. Government that collects, monitors, analyzes, and provides scientific information about natural resource conditions and issues. To carry out its mission, the USGS has created and managed spatial data since its inception. Originally relying on paper maps, the USGS now uses advanced technology to produce digital representations of the Earth’s features. The spatial products of the USGS include both source and derivative data. Derivative datasets include Digital Orthophoto Quadrangles (DOQ), Digital Elevation Models, Digital Line Graphs, land-cover Digital Raster Graphics, and the seamless National Elevation Dataset. These products, created with automated processes, use aerial photographs, satellite images, or other cartographic information such as scanned paper maps as source data. With Earth Explorer, users can search multiple inventories through metadata queries and can browse satellite and DOQ imagery. They can place orders and make payment through secure credit card transactions. Some USGS spatial data can be accessed with SDDS. The SDDS uses an ArcIMS map service interface to identify the user’s areas of interest and determine the output format; it allows the user to either download the actual spatial data directly for small areas or place orders for larger areas to be delivered on media. The USGS Web Mapping Portal provides views of national and international datasets through an ArcIMS map service interface. In addition, the map portal posts news about new map services available from the USGS, many simultaneously published on the Environmental Systems Research Institute Geography Network. These three information systems use new software tools and expanded hardware to meet the requirements of the users. The systems are designed to handle the required workload and are relatively easy to enhance and maintain. The software tools give users a high level of functionality and help the system conform to industry standards. The hardware and software architecture is designed to handle the large amounts of spatial data and Internet traffic required by the information systems. Last, customer support was needed to answer questions, monitor e-mail, and report customer problems.

Journal of Geospatial Engineering↗
USGS1988

Regionalization of peak discharges for streams in Kentucky

Multiple regression analysis was used to delineate hydrologically distinct regions in Kentucky, and to develop regression models for estimating peak discharge for unregulated streams in these regions. The regression models provide estimates of flood quantiles with associated average recurrence intervals of 2, 5, 10, 25, 50, and 100 years. The data base used in the analysis included annual peak discharge records (through water year 1985) at 266 continuous- and partial-record gaging stations in, and adjacent to, Kentucky. Selected drainage basin characteristics upstream of each gaging station were used to develop the regression equations. Flood quantiles at the gaged stations were estimated on the basis of log-Pearson Type III distribution and the methodology recommended by the U.S. Water Resources Council. Seven hydrologic regions were delineated in Kentucky on the basis of analysis of residuals from statewide and regional regression models. Regression models for estimating flood quantiles in the hydrologic regions are based on measurements of contributing drainage area, main channel slope, basin shape index, and main channel sinuosity. The regression coefficients indicated an increase in flood discharge with increasing drainage area and channel slope, and a decrease in discharge with increasing channel sinuosity and basin elongation. Accuracy of the discharge estimates from the regression models as measured by the standard error of the estimate ranged from 21 to 52%. The procedures for estimating flood quantiles vary depending on whether the estimate is for an ungaged site, an ungaged site near a gaged site on the same stream, or a gaged site. Also considered is whether the drainage area crosses hydrologic region boundaries or state lines. The methods apply only to natural flow streams drainage areas < 1 ,000 sq mi.

Kentucky↗
USGS2014

Hydrologic models and analysis of water availability in Cuyama Valley, California

Changes in population, agricultural development practices (including shifts to more water-intensive crops), and climate variability are placing increasingly larger demands on available water resources, particularly groundwater, in the Cuyama Valley, one of the most productive agricultural regions in Santa Barbara County. The goal of this study was to produce a model capable of being accurate at scales relevant to water management decisions that could be considered in the evaluation of the sustainable water supply. The Cuyama Valley Hydrologic Model (CUVHM) was designed to simulate the most important natural and human components of the hydrologic system, including components dependent on variations in climate, thereby providing a reliable assessment of groundwater conditions and processes that can inform water users and help to improve planning for future conditions. Model development included a revision of the conceptual model of the flow system, construction of a precipitation-runoff model using the Basin Characterization Model (BCM), and construction of an integrated hydrologic flow model with MODFLOW-One-Water Hydrologic Flow Model (MF-OWHM). The hydrologic models were calibrated to historical conditions of water and land use and, then, used to assess the use and movement of water throughout the Valley. These tools provide a means to understand the evolution of water use in the Valley, its availability, and the limits of sustainability. The conceptual model identified inflows and outflows that include the movement and use of water in both natural and anthropogenic systems. The groundwater flow system is characterized by a layered geologic sedimentary sequence that—in combination with the effects of groundwater pumping, natural recharge, and the application of irrigation water at the land surface—displays vertical hydraulic-head gradients. Overall, most of the agricultural demand for water in the Cuyama Valley in the initial part of the growing season is supplied by groundwater, which is augmented by precipitation during wet winter and spring seasons. In addition, the amount of groundwater used for irrigation varies from year to year in response to climate variation and can increase dramatically in dry years. Model simulation results, however, also indicated that irrigation may have been less efficient during wet years. Agricultural pumpage is a major component to simulated outflow that is often poorly recorded. Therefore, an integrated, coupled farm-process model is used to estimate historical pumpage for water-balance subregions that evolved with the development of groundwater in the Valley from 1949 through 2010. The integrated hydrologic model includes these water-balance subregions and delineates natural, municipal, and agricultural land use; streamflow networks; and groundwater flow systems. The redefinition of the geohydrologic framework (including the internal architecture of the sedimentary units) and incorporation of these units into the simulation of the regional groundwater flow system indicated that faults have compartmentalized the alluvial deposits into subregions, which have responded differently to regional groundwater flow, locations of recharge, and the effects of development. The Cuyama Valley comprises nine subregions grouped into three regional zones, the Main, Ventucopa Uplands, and Sierra Madre Foothills, which are fault bounded, represent different proportions of the three alluvial aquifers, and have different water quality. The CUVHM uses MF-OWHM to simulate and assess the use and movement of water, including the evolution of land use and related water-balance regions. The model is capable of being accurate at annual to interannual time frames and at subregional to valley-wide spatial scales, which allows for analysis of the groundwater hydrologic budget for the water years 1950–2010, as well as potential assessment of the sustainable use of groundwater. Simulated changes in storage over time showed that significant withdrawals from storage generally occurred not only during drought years (1976–77 and 1988–92) but also during the early stages of industrial agriculture, which was initially dominated by alfalfa production. Since the 1990s, agriculture has shifted to more water-intensive crops. Measured and simulated groundwater levels indicated substantial declines in selected subregions, mining of groundwater that is thousands to tens of thousands of years old, increased groundwater storage depletion, and land subsidence. Most of the recharge occurs in the upland regions of Ventucopa and Sierra Madre Foothills, and the largest fractions of pumpage and storage depletion occur in the Main subregion. The long-term imbalance between inflows and outflows resulted in simulated overdraft (groundwater withdrawals in excess of natural recharge) of the groundwater basin over the 61-year period of 1949–2010. Changes in storage varied considerably from year to year, depending on land use, pumpage, and climate conditions. Climatically driven factors can greatly affect inflows, outflows, and water use by more than a factor of two between wet and dry years. Although precipitation during inter-decadal wet years previously replenished the basin, the water use and storage depletion have lessened the effects of these major recharge events. Simulated and measured water-level altitudes indicated the presence of large areas where depressed water levels have resulted in large desaturated zones in the younger and Older Alluvium layers in the Main-zone subregions. The results of modeled projection of the base-case scenario 61 years into the future indicated that current supply-and-demand are unsustainable and will result in additional groundwater-level declines and related storage depletion and land subsidence. The reduced-supply and reduced-demand projections reduced groundwater storage depletion but may not allow for sustainable agriculture under current demands, agricultural practices, and land use.

California↗
USGS2003

Statistical, economic and other tools for assessing natural aggregate

Quantitative aggregate resource assessment provides resource estimates useful for explorationists, land managers and those who make decisions about land allocation, which may have long-term implications concerning cost and the availability of aggregate resources. Aggregate assessment needs to be systematic and consistent, yet flexible enough to allow updating without invalidating other parts of the assessment. Evaluators need to use standard or consistent aggregate classification and statistic distributions or, in other words, models with geological, geotechnical and economic variables or interrelationships between these variables. These models can be used with subjective estimates, if needed, to estimate how much aggregate may be present in a region or country using distributions generated by Monte Carlo computer simulations.

Bulletin of Engineering Geology and the Environmen↗
USGS2020

Decision analysis for greater insights into the development and evaluation of Chinook salmon restoration strategies in California’s Central Valley

Considerable amounts of resources have been invested in ecological restoration projects across the globe to restore ecosystem integrity. Restoration strategies are often diverse and have been met with mixed success. In this paper, we describe the Chinook salmon (Oncorhynchus tshawytscha) decision-support models developed by the Central Valley Project Improvement Act Science Integration Team as part of a larger structured decision making effort aimed at maximizing natural adult production of Chinook salmon in California’s Central Valley, USA. We then describe the decision analytic tools the stakeholder group used to solve the models and explore model results, including stochastic dynamic programming, forward simulation, proportional scoring, relative loss, expected value of perfect information, response profile analyses, and indifference curves. Using these tools, the stakeholder group was able to develop and evaluate restoration strategies for multiple Chinook salmon runs simultaneously, a first for the restoration program. We found that actions targeted at one run were detrimental to others, which was unexpected. Furthermore, information uncovered during this process was used to direct efforts towards targeted research/monitoring to reduce critical uncertainties in salmon demographic rates and make better restoration decisions moving forward. The decision sciences have established a wide range of analytical tools and approaches to simplify complex problems into key components, and we believe the concepts described in this paper are of great interest and can be applied by many restoration practitioners that undoubtedly face similar difficulties when implementing restoration strategies for complex systems.

California↗
USGS2004

Simulated Water-Management Alternatives Using the Modular Modeling System for the Methow River Basin, Washington

A precipitation-runoff model for the Methow River Basin was used to simulate six alternatives: (1) baseline of current flow, (2) line irrigation canals to limit seepage losses, (3) increase surface-water diversions through unlined canals for aquifer recharge, (4) convert from surface-water to ground-water resources to supply water for irrigation, and (5) reduce tree density in forested headwater catchments, and (6) natural flow. Daily streamflow from October 1, 1959, to September 30, 2001 (water years 1960?2001) was simulated. Lining irrigation canals (alternative 2) increased flows in the Chewuch, Twisp, and the Methow (upstream and at Twisp) Rivers during September because of lower diversion rates, but not in the Methow River near Pateros. Increasing diversions for aquifer recharge (alternative 3) increased streamflow from September into January, but reduced streamflow earlier in the summer. Conversion of surface-water diversions to ground-water wells (alternative 4) resulted in the largest increase in September streamflow of any alternative, but also marginally lower January flows (at most -8 percent in the 90-percent exceedence value). Forest-cover reduction (alternative 5) produced large increases in streamflow during high-flow periods in May and June and earlier onset of high flows and small increases in January streamflows. September streamflows were largely unaffected by alternative 5. Natural streamflow (alternative 6) was higher in September and lower in January than the baseline alternative.

Open-File Report↗
USGS2018

Land subsidence along the California Aqueduct in west-central San Joaquin Valley, California, 2003–10

Extensive groundwater withdrawal from the unconsolidated deposits in the San Joaquin Valley caused widespread aquifer-system compaction and resultant land subsidence from 1926 to 1970—locally exceeding 8.5 meters. The importation of surface water beginning in the early 1950s through the Delta-Mendota Canal and in the early 1970s through the California Aqueduct resulted in decreased groundwater pumping, recovery of water levels, and a reduced rate of compaction in some areas of the San Joaquin Valley. However, drought conditions during 1976–77, 1987–92, and drought conditions and operational reductions in surface-water deliveries during 2007–10 decreased surface-water availability, causing pumping to increase, water levels to decline, and renewed compaction. Land subsidence from this compaction has reduced freeboard and flow capacity of the California Aqueduct, Delta-Mendota Canal, and other canals that deliver irrigation water and transport floodwater. The U.S. Geological Survey, in cooperation with the California Department of Water Resources, assessed more recent land subsidence near a 145-kilometer reach of the California Aqueduct in the west-central part of the San Joaquin Valley as part of an effort to minimize future subsidence-related damages to the California Aqueduct. The location, magnitude, and stress regime of land-surface deformation during 2003–10 were determined by using data and analyses associated with extensometers, Global Positioning System surveys, Interferometric Synthetic Aperture Radar, spirit-leveling surveys, and groundwater wells. Comparison of continuous Global Positioning System, shallow-extensometer, and groundwater-level data indicated that most of the compaction in this area took place beneath the Corcoran Clay, the primary regional confining unit. The integration of measurements strengthens confidence in individual measurement methods and provides the information at spatial and temporal scales that water managers need to design and implement groundwater sustainability plans in compliance with California’s Sustainable Groundwater Management Act. Measurements of land-surface deformation during 2003–10 indicated that the parts of the California Aqueduct closest to the Coast Ranges in the west-central part of the San Joaquin Valley were fairly stable or minimally subsiding on an annual basis; some areas show seasonal periods of subsidence and uplift that resulted in little or no longer-term elevation loss. Many groundwater levels in these areas did not reach historical lows during 2003–10, indicating that deformation nearest the Coast Ranges was likely primarily elastic. Land-surface deformation measurements indicated that some parts of the California Aqueduct that traverse farther from the Coast Ranges toward the valley center subsided. Some parts of the California Aqueduct subsided locally, but generally the California Aqueduct is within part of a 12,000-square-kilometer area affected by 25 millimeters or more of subsidence during 2008–10, with maxima in Madera County, south of the town of El Nido near the San Joaquin River and the Eastside Bypass (540 millimeters), and in Tulare County, west of the town of Pixley (345 millimeters). Interferometric Synthetic Aperture Radar-derived subsidence maps for various periods during 2003–10 show that the area of maximum active subsidence (that is, the largest rates of subsidence) shifted from its historical (1926–70) location southwest of the town of Mendota to these areas nearer the valley center. Calculations indicated that the subsidence rate doubled in 2008 in parts of the study area. Water levels declined during 2007–10 in many shallow and deep wells in the most rapidly subsiding areas, where water levels in many deep wells reached their historical lows, indicating that subsidence measured during this period was largely inelastic. Continued groundwater-level and land-subsidence monitoring in the San Joaquin Valley is important because (1) operational- and drought-related reductions in surface-water deliveries since 1976 have resulted in increased groundwater pumping and associated water-level declines and land subsidence, (2) land use and associated pumping continue to change throughout the valley, and (3) subsidence management is stipulated in the Sustainable Groundwater Management Act. The availability of surface water remains uncertain; even during record-setting precipitation years, such as 2010–11, water deliveries fell short of requests and groundwater pumping was required to meet the irrigation demand. In some areas, the infrastructure is not available to supply surface water, and groundwater is the only source of water. Because of the expected continued demand for water and the limitations and uncertainty of surface-water supplies, groundwater pumping and associated land subsidence remains a concern. Spatially detailed information on land subsidence is needed to minimize future subsidence-related damages to the California Aqueduct and other infrastructure in the San Joaquin Valley, as well as alterations to natural resources such as stream gradients, water depths, and water temperatures. The integration of data on land-surface elevation, subsurface deformation, and water levels—particularly continuous measurements—enables the analysis of aquifer-system response to groundwater pumping, which in turn, enables estimation of the preconsolidation head and calculation of aquifer-system storage properties. This information can be used to improve numerical model simulations of groundwater flow and aquifer-system compaction and allow for consideration of land subsidence in the evaluation of water resource management alternatives and compliance with the Sustainable Groundwater Management Act.

California↗
USGS2009

Toward production from gas hydrates: Current status, assessment of resources, and simulation-based evaluation of technology and potential

Gas hydrates (GHs) are a vast energy resource with global distribution in the permafrost and in the oceans. Even if conservative estimates are considered and only a small fraction is recoverable, the sheer size of the resource is so large that it demands evaluation as a potential energy source. In this review paper, we discuss the distribution of natural GH accumulations, the status of the primary international research and development (R&D) programs, and the remaining science and technological challenges facing the commercialization of production. After a brief examination of GH accumulations that are well characterized and appear to be models for future development and gas production, we analyze the role of numerical simulation in the assessment of the hydrate-production potential, identify the data needs for reliable predictions, evaluate the status of knowledge with regard to these needs, discuss knowledge gaps and their impact, and reach the conclusion that the numerical-simulation capabilities are quite advanced and that the related gaps either are not significant or are being addressed. We review the current body of literature relevant to potential productivity from different types of GH deposits and determine that there are consistent indications of a large production potential at high rates across long periods from a wide variety of hydrate deposits. Finally, we identify (a) features, conditions, geology and techniques that are desirable in potential production targets; (b) methods to maximize production; and (c) some of the conditions and characteristics that render certain GH deposits undesirable for production. Copyright ?? 2009 Society of Petroleum Engineers.

Conference Paper↗
USGS2021

Cloud water interception in Hawai‘i: Developing capacity to characterize the spatial patterns and effects on water and ecological processes responses in Hawai‘i

Cloud-water interception (CWI) is the process by which fog or cloud water droplets are captured and accumulate on the leaves and branches of plants, some of which drips to the ground. Prior studies in Hawai'i indicate that CWI is highly variable and can contribute substantially to total precipitation. In this study, we monitored CWI and other processes at five mountain field sites on the Islands of Oʻahu, Maui, and Hawaiʻi to explore how CWI (1) varies with different climate and vegetation characteristics, (2) affects plant water use and growth, and (3) contributes to water resources. Results show that annual CWI varied from 158 to 910 mm, accounting for 3-34% of total water input at individual sites. This large variation was caused by differences in the quantity of cloud water, wind speed, and vegetation structure between sites. We developed a model to predict CWI using both climatic and forest canopy characteristics. On average, the model underestimated annual CWI by 18%, but reproduced the site differences relatively well. Plant water use decreased during periods of fog events mainly because of associated higher humidity. This new CWI model can be used to assess impacts of climate and land cover change on CWI and provide valuable information for resource management in Hawai‘i, which was not previously possible. At one field site, we explored the impacts of fog water on hydrological and ecological processes. Fog effects on native plant growth were indirect, primarily buffering effects of solar radiation. Removal of grass allowed natural regeneration of seedlings but did not alter soil moisture values. A soil data-collection program was initiated to help evaluate the role CWI has in providing moisture for plants, reducing wildfire risk within the fog zone, and contributing to groundwater recharge to aquifers that supply drinking water and groundwater discharge to streams.

Hawaii↗
USGS2022

Characterizing mauka-to-makai connections for aquatic ecosystem conservation on Maui, Hawaiʻi

Mauka-to-makai (mountain to sea in the Hawaiian language) hydrologic connectivity – commonly referred to as ridge-to-reef – directly affects biogeochemical processes and socioecological functions across terrestrial, freshwater, and marine systems. The supply of freshwater to estuarine and nearshore environments in a ridge-to-reef system supports the food, water, and habitats utilized by marine fauna . In addition, the ecosystem services derived from this land-to-sea connectivity support social and cultural practices (hereafter referred to as socio-cultural) including fishing, aquaculture, wetland agriculture, religious ceremonies, and recreational activities. To effectively guide island resource management, a better understanding of the linkages from ridge-to-reef across natural and social usages is critical, particularly in the context of climate change, with anticipated increasing temperature and shifting precipitation patterns. The objective of this study was to identify spatial linkages that promote multiple and diverse uses, following the ridge-to-reef concept, at an island-wide scale to identify regions of high conservation importance for aquatic resources. We selected the Island of Maui as a study representative of many Pacific islands. Diverse datasets, including agricultural lands within watersheds, wetland locations, presence of stream species, indicators of freshwater input from streams, coral cover, nearshore fish biomass, socio-cultural data such as fishpond locations, wetland taro cultivation, beach recreation use, and lastly the dynamically downscaled Coupled Model Intercomparison Project Phase (CMIP5) future climate projections scenarios (Representative Concentration Pathway (RCP) 4.5 & 8.5) were used to examine the spatial linkages through hydrological connectivity from land to the sea. Zonation spatial planning software was used to prioritize areas of high management and conservation value and to help inform aquatic resources management. The resulting prioritized areas included many minimally disturbed watersheds in east Maui and western nearshore and coastal zones that are adjacent to diverse coral reefs. These results are driven by the importance of fish biomass and coral reef distribution as well as traditional wetland taro cultivation and coastal access points for recreation. These results underline the importance of examining ridge-to-reef systems for aquatic resource management and including important social and cultural values in resource management upon planning adaptation strategies for climate change. Improving our understanding of diverse natural and socio-cultural influences on habitat conditions and their values in these areas provides an opportunity to strategically plan future management and conservation actions.

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