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Humans have altered nearly every natural disturbance regime on the planet through climate and land-use change, and in many instances, these processes may have interacting effects. For example, projected shifts in temperature and precipitation will likely influence disturbance regimes already affected by anthropogenic fire suppression or river impoundments. Understanding how disturbance-dependent species respond to complex and interacting environmental changes is important for conservation efforts. Using field-based demographic and movement rates, we conducted a metapopulation viability analysis for piping plovers (Charadrius melodus), a threatened disturbance-dependent species, along the Missouri and Platte rivers in the Great Plains of North America. Our aim was to better understand current and projected future metapopulation dynamics given that natural disturbances (flooding or high-flow events) have been greatly reduced by river impoundments and that climate change could further alter the disturbance regime. Although metapopulation abundance has been substantially reduced under the current suppressed disturbance regime (high-flow return interval similar to 20 yr), it could grow if the frequency of high-flow events increases as predicted under likely climate change scenarios. We found that a four-year return interval would maximize metapopulation abundance, and all subpopulations in the metapopulation would act as sources at a return interval of 15 yr or less. Regardless of disturbance frequency, the presence of even a small, stable source subpopulation buffered the metapopulation and sustained a low metapopulation extinction risk. Therefore, climate change could have positive effects in ecosystems where disturbances have been anthropogenically suppressed when climatic shifts move disturbance regimes toward more historical patterns. Furthermore, stable source populations, even if unintentionally maintained through anthropogenic activities, may be critical for the persistence of metapopulations of early-successional species under both suppressed disturbance regimes and disturbance regimes where climate change has further altered disturbance frequency or scope. Nebraska Environmental Trust Nebraska State Wildlife Grant Program Nebraska Wildlife Conservation Fund U.S. Army Corps of Engineers U.S. Fish and Wildlife Service (USFWS) USFWS North Atlantic Landscape Conservation Cooperative Virginia Tech Funding was provided by the Nebraska Environmental Trust, the Nebraska State Wildlife Grant Program, the Nebraska Wildlife Conservation Fund, the U.S. Army Corps of Engineers, the U.S. Fish and Wildlife Service (USFWS), the USFWS North Atlantic Landscape Conservation Cooperative, and Virginia Tech. We thank C. Aron, K. Brennan, R. Cobb, K. Crane, E. Dowd-Stukel, C. Huber, K. Kreil, C. Kruse, G. Pavelka, G. Wagner, W. Werkmeister, S. Wilson, L. Yager, and cooperators from the National Park Service, U.S. Fish and Wildlife Service, South Dakota Department of Game, Fish, and Parks, Nebraska Game and Parks Commission, and the Missouri River Institute for support throughout the project. We would like to thank sand and gravel mining companies and lakeshore housing development communities for access to property. We acknowledge the tireless efforts of our many technicians from 2005 to 2013. We also thank five anonymous reviewers, T. Simmons, and C. McGowan (USGS) for their comments on earlier drafts of this manuscript. This work was conducted under Institutional Animal Care and Use Committee permits 877 and 14-003, and U.S. Fish and Wildlife Service Threatened and Endangered Species Permits TE070027-0 and TE103272-3. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Borehole-geophysical logs can be used to obtain information on water quality and water chemistry. Water quality characteristics that normally are measured directly in water-filled holes or wells include chloride, dissolved oxygen, pH, temperature, and conductivity. In-situ ground water may exist at some distance adjacent to the borehole, and estimates of water quality or water chemistry can be made by measuring the resistivity or specific electrical conductivity of the water in pore spaces. Most geophysical logs, however, are made in test holes filled with drilling fluid. In this environment, logs enabling estimates of water resistivity (Rw) are useful. Relations among Rw and dissolved solids, sodium chloride solutions, and temperature are well established for saline waters; for freshwater, however, the activities of other dissolved ions also need to be considered. The spontaneous potential (SP) is a function of activity of the mud filtrate and water resistivity and, thus, can be used to estimate Rw. Two methods of estimating Rw are useful: the spontaneous potential (SP) method, which uses data from a spontaneous potential log and a resistivity log, and the cross-plot method, which uses log-derived porosity and resistivity-log data. The application of SP logs depends upon the water quality contrast between the water in the pores (Rw) and the mud filtrate on the borehole wall. Both methods estimate Rw to about a half order of magnitude. However, the accuracy of both methods can be greatly improved if additional data, such as a chemical analysis, can be correlated to a log.

Publisher Summary The purposes of outdoor exposure testing (OET) include: (1) obtaining data on material durability and lifetimes at a number of representative locations; (2) understanding why materials degrade at different rates at different test sites; (3) correlating in-service measurements with accelerated life testing results and subsequently making quantitative predictions of material service lifetimes; and (4) validating damage function models derived from accelerated exposure tests. To allow validation, the detailed exposure conditions that candidate sample materials experience must be monitored. For this, test sites must be fully instrumented in terms of monitoring meteorological conditions and solar irradiance. Candidate materials are optically characterized before being subjected to exposure at OET sites. Optical durability is quantified by periodically remeasuring an appropriate response variable as a function of exposure time. By closely monitoring the site- and time-dependent environmental stress conditions experienced by the samples, the actual site dependent loss of performance is obtained. In addition, parallel accelerated exposure testing of these materials in laboratory-controlled conditions permits correlations to be made with in-service results and subsequent prediction of service lifetimes.

Publisher Summary The purpose of this chapter is to outline various ways for quantifying changes in performance. The choice of an appropriate and sensitive measure of degradation is critical to provide a rapid indication of performance loss. By relating such performance indicators to relevant environmental stress parameters, it is possible to derive correlations between outdoor and accelerated exposure test results. Several photometric performance parameters that characterize optical degradation are also discussed.

Intercepted intracell flow, especially if cell includes water table recharge and a stream ((sink), can result in significant model error if not accounted for. A procedure utilizing net flow per cell (Fn) that accounts for intercepted intracell flow can be used for both steady state and transient simulations. Germane to the procedure is the determination of the ratio of area of influence of the interior sink to the area of the cell (Ai/Ac). Ai is the area in which water table recharge has the potential to be intercepted by the sink. Determining Ai/Ac requires either a detailed water table map or observation of stream conditions within the cell. A proportioning parameter M, which is equal to 1 or slightly less and is a function of cell geometry, is used to determine how much of the water that has potential for interception is intercepted by the sink within the cell. Also germane to the procedure is the determination of the flow across the streambed (Fs), which is not directly a function of cell size, due to difference in head between the water level in the stream and the potentiometric surface of the aquifer underlying the streambed. The use of Fn for steady state simulations allows simulation of water levels without utilizing head-dependent or constant head boundary conditions which tend to constrain the model-calculated water levels, an undesirable result if a comparison of measured and calculated water levels is being made. Transient simulations of streams usually utilize a head-dependent boundary condition and a leakance value to model a stream. Leakance values for each model cell can be determined from a steady state simulation, which used the net flow per cell procedure. For transient simulation, Fn would not include Fs. Also, for transient simulation it is necessary to check Fn at different time intervals because M and Ai/Ac are not constant and change with time. The procedure was used successfully in two different models of the aquifer system in the Ozarks. The use of Fn was essential to the two model studies because most model cells in both models contained water table recharge and multiple sinks.

Intracell flow is important in modeling cells that contain both sources and sinks. Special attention is needed if recharge through the water table is a source. One method of modeling multiple sources and sinks is to determine the net recharge per cell. For example, for a model cell containing both a sink and recharge through the water table, the amount of recharge should be reduced by the ratio of the area of influence of the sink within the cell to the area of the cell. The reduction is the intercepted portion of the recharge. In a multilayer model this amount is further reduced by a proportion factor, which is a function of the depth of the flow lines from the water table boundary to the internal sink. A gaining section of a stream is a typical sink. The aquifer contribution to a gaining stream can be conceptualized as having two parts; the first part is the intercepted lateral flow from the water table and the second is the flow across the streambed due to differences in head between the water level in the stream and the aquifer below. The amount intercepted is a function of the geometry of the cell, but the amount due to difference in head across the stream bed is largely independent of cell geometry. A discharging well can intercept recharge through the water table within a model cell. The net recharge to the cell would be reduced in proportion to the area of influence of the well within the cell. The area of influence generally changes with time. Thus the amount of intercepted recharge and net recharge may not be constant with time. During periods when the well is not discharging there will be no intercepted recharge even though the area of influence from previous pumping may still exist. The reduction of net recharge per cell due to internal interception of flow will result in a model-calculated mass balance less than the prototype. Additionally the “effective transmissivity” along the intercell flow paths may be altered when flow paths are occupied by intercepted recharge.

This report covers Investigation No. 29 in the continuing program of coal evaluations for Dofasco Inc., Hamilton, Ontario by the Energy Research Laboratories. The scope of the investigation comprises technical-scale carbonization tests relevant to the understanding of the quality of the coals under review. Purchase Ortler No. T-53509-10 dated August 22, 1983 and No. T-57023 dated August 30, 1983 from the company specified the following mixes must be run in duplicate