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Drought poses important risks to thermoelectric power production in the United States because of the significant water use in this sector. Here a scoping level analysis is performed to identify the technical tradeoffs and initial cost estimates for retrofitting existing thermoelectric generation to achieve zero freshwater withdrawal and thus reduce drought related vulnerabilities. Specifically, conversion of existing plants to dry cooling or a wet cooling system utilizing non-potable water is considered. The least cost alternative is determined for each of the 1178 freshwater using power plants in the United States. The projected increase in levelized cost of electricity ranges roughly from $0.20 to $20/MW h with a median value of $3.53/MW h. With a wholesale price of electricity running about $35/MW h, many retrofits could be accomplished at levels that would add less than 10% to current power plant generation expenses. Such retrofits would alleviate power plant vulnerabilities to thermal discharge limits in times of drought (particularly in the East) and would save 3.2 Mm 3 /d of freshwater consumption in watersheds with limited water availability (principally in the West). The estimated impact of retrofits on wastewater and brackish water supply is minimal requiring only a fraction of the available resource. Total parasitic energy requirements to achieve zero freshwater withdrawal are estimated at 140 million MW h or roughly 4.5% of the total production from the retrofitted plants. [ABSTRACT FROM AUTHOR]

A significant fraction of our nation's electricity use goes to lift, convey, and treat water, while the resulting expenditures on electricity represent a key budgetary consideration for water service providers. To improve understanding of the electricity-for-water interdependency, electricity used in providing water services is mapped at the regional, state and county level for the 17-conterminous states in the Western U.S. This study is unique in estimating electricity use for large-scale conveyance and agricultural pumping as well as mapping these electricity uses along with that for drinking and wastewater services at a state and county level. Results indicate that drinking and wastewater account for roughly 2% of total West-wide electricity use, while an additional 1.2% is consumed by large-scale conveyance projects and 2.6% is consumed by agricultural pumping. The percent of electricity used for water services varies strongly by state with some as high as 34%, while other states expend less than 1%. Every county in the West uses some electricity for water services; however, there is a large disparity in use ranging from 10 MWh/yr to 5.8 TWh/yr. These results support long-term transmission planning in the Western U.S. by characterizing an important component of the electric load. [ABSTRACT FROM AUTHOR]

Carbon capture and sequestration (CCS) has important implications relative to future thermoelectric water use. A bounding analysis is performed using past greenhouse gas emission policy proposals and assumes either all effected capacity retires (lower water use bound) or is retrofitted (upper bound). The analysis is performed in the context of recent trends in electric power generation expansion, namely high penetration of natural gas and renewables along with constrained cooling system options. Results indicate thermoelectric freshwater withdrawals nationwide could increase by roughly 1% or decrease by up to 60% relative to 2009 levels, while consumption could increase as much as 21% or decrease as much as 28%. To identify where changes in freshwater use might be problematic at a regional level, electric power production has been mapped onto watersheds with limited water availability (where consumption exceeds 70% of gauged streamflow). Results suggest that between 0.44 and 0.96 Mm³/d of new thermoelectric freshwater consumption could occur in watersheds with limited water availability, while power plant retirements in these watersheds could yield 0.90 to 1.0 Mm³/d of water savings. [ABSTRACT FROM AUTHOR]

Large amounts of water are required for electricity generation, and demand for thermoelectric power is predicted to increase significantly over the next several decades. Of concern, is that nearly half of this new demand is in regions currently subject to fresh water shortages due to over-appropriation, drought, and climatic drivers. This study explores the suitability of using non-traditional sources of water, namely wastewater and brackish ground water for future thermoelectric cooling in 22 continental Electricity Market Module Regions. Both sources pose unique financial, technical, and management challenges, but are widely available and in the majority of instances economically feasible. While neither resource can meet all future demand by thermoelectric generation, when added to the existing water supply and management portfolio, they provide significant augmentation to existing traditional water supplies. [ABSTRACT FROM AUTHOR]

In 2005, thermoelectric power accounted for 41% of all freshwater withdrawals and roughly 3% of all consumptive use in the United States. With the demand for electricity projected to increase by 24% by 2035 concerns have been raised as to the availability of water for this growing industry; particularly, as the siting of several new thermoelectric facilities have been challenged on the basis of water supply. To address this concern we estimate the potential impact of water availability on future expansion of the thermoelectric power industry. Specifically, both the extent and location of thermoelectric developments at risk due to limited fresh water supply is estimated for a variety of alternative energy futures that differ according to the assumed mix of fuels utilized in new plant construction. According to the analyzed scenarios water consumption for thermoelectric power generation is projected to increase by 36-43% between 1995 and 2035, with much of this development expected to occur in basins with rapidly growing demands in the nonthermoelectric sectors. To identify where this thermoelectric development might be problematic, projected future thermoelectric production has been mapped onto basins subject to limited water availability. For the purposes of this study, water availability is defined as a local ratio of water demand to physical water supply. Results suggest that 10-19% of all new thermoelectric power production is likely to be sited in watersheds with limited surface and/or groundwater availability. These problematic watersheds are largely located in the West. [ABSTRACT FROM AUTHOR]

Abstract: A dynamic simulation framework is used to compare benefit-cost ratios of riparian restoration investment strategies to pursue ecosystem service benefits. The model is meant to be adaptable to generic restoration planning applications, with the Middle Rio Grande riparian corridor in Albuquerque, New Mexico, U.S.A. presented here as the illustrating case. Model inputs include ecosystem service values from an original choice experiment, values from regional benefit transfer studies, and information from land managers. The model includes three control variable modules: forest management, river restoration, and recreation infrastructure. Investment influences these modules, which in turn affect ecosystem service flows for the region. The model is exercised to compare a “No-Action” alternative with “Optimal Benefit-Cost Ratio” restoration funding. An extended sensitivity analysis explores a range of both physical and economic assumptions. The analysis has two major outcomes. The first is that directed restoration funding yields significant gains as compared with No-Action for all scenarios tested. The second major finding is that although optimized benefit-cost ratios are above unity for all “states of the world” tested, the ratio itself and funding patterns varied widely. These sensitivities underscore the need for a transparent adaptive management decision process supported by tools aimed not at deterministic prediction, but rather at structuring dialogue and inquiry into issues that defy simple intuition. [Copyright &y& Elsevier]

Abstract: Using a slab of Massillon Sandstone, laboratory-scale solute tracer experiments were carried out to test numerical simulations using the Advection–Dispersion Equation (ADE). While studies of a similar nature exist, our work differs in that we combine: (1) experimentation in naturally complex geologic media, (2) X-ray absorption imaging to visualize and quantify two-dimensional solute transport, (3) high resolution transport property characterization, with (4) numerical simulation. The simulations use permeability, porosity, and solute concentration measured to sub-centimeter resolution. While bulk breakthrough curve characteristics were adequately matched, large discrepancies exist between the experimental and simulated solute concentration fields. Investigation of potential experimental errors suggests that the failure to fit solute concentration fields may lie in loss of intricate connectivity within the cross-bedded sandstone occurring at scales finer than our property characterization measurements (i.e., sub-centimeter). [Copyright &y& Elsevier]

Equitable allocation of ground water resources is a growing challenge due to both the increasing demand for water and the competing values placed on its use. While scientists can contribute to a technically defensible basis for water resource planning, this framework must be cast in a broader societal and environmental context. Given the complexity and often contentious nature of resource allocation, success requires a process for inclusive and transparent sharing of ideas complemented by tools to structure, quantify, and visualize the collective understanding and data, providing an informed basis of dialogue, exploration, and decision making. Ideally, a process that promotes shared learning leading to cooperative and adaptive planning decisions. While variously named, mediated modeling, group modeling, cooperative modeling, shared vision planning, or computer-mediated collaborative decision making are similar approaches aimed at meeting these objectives. In this paper, we frame “cooperative modeling” in the context of ground water planning and illustrate the process with two brief examples. [ABSTRACT FROM AUTHOR]

Recent amendments to the Safe Drinking Water Act emphasize efforts toward safeguarding our nation’s water supplies against attack and contamination. Specifically, the Public Health Security and Bioterrorism Preparedness and Response Act of 2002 established requirements for each community water system serving more than 3,300 people to conduct an assessment of the vulnerability of its system to a terrorist attack or other intentional acts. Integral to evaluating system vulnerability is the threat assessment, which is the process by which the credibility of a threat is quantified. Unfortunately, full probabilistic assessment is generally not feasible, since there is insufficient experience and/or data to quantify the associated probabilities. For this reason, an alternative approach is proposed predicated on Markov latent effects (MLE) modeling, which provides a framework for quantifying imprecise subjective metrics through possibilistic or fuzzy mathematics. Here, the MLE approach is introduced and demonstrated within the context of water supply system threat assessment. [ABSTRACT FROM AUTHOR]

The use of capillary barriers as engineered backfill systems to divert water away from radioactive waste potentially stored in a Yucca Mountain emplacement drift is investigated. We designed and conducted a flow visualization experiment to investigate capillary barrier performance in this context. A two-dimensional, thin slab, test system replicated the physical emplacement drift to one-quarter scale (1.4-m diameter) and included the simulated drift wall, waste canister, pedestal, capillary barrier backfill, and host-rock fracture system. Water was supplied at the top of the simulated drift and allowed to discharge by way of wicks located along the left wall of the cell (simulated fractures) or by a gravity drain at the bottom of the right side (simulated impermeable rock with floor drain). Photographs captured the migration of water and a blue dye tracer within the system, analytical balances measured the mass balance of water, while tensiometers measured the capillary pressure at numerous locations. Of particular concern to this test was the drainage of the capillary barrier, which terminates against the drift wall. We found that while the simulated fractures (left side) and drain (right side) each influenced the performance of the capillary barrier at early time, they had little differential affect at later times. Also of concern was the small disparity in capillary properties between the fine and coarse layer (limited by the need of a fine-grained material that would not filter into the coarse layer under dry conditions). While the capillary barrier was able to divert the majority of flow toward the edges of the system and away from the simulated waste canister, the barrier did not preclude flow in the coarse layer, which was noted to be visually wet next to the waste canister on day 92 and was continuing to take on water at termination on day 112. [Copyright &y& Elsevier]

Water is a necessary resource for thermoelectric power generation. Extreme conditions (e.g., droughts and floods) threaten both the quantity and quality of power plant water supply as well as disrupt wastewater discharges back to the environment. Changing climate conditions and water use regimes have prompted numerous assessments exploring the growing threat water poses to the electric power industry. However, lacking from public sources are plant-level data potentially important to such assessments. To better understand this data gap, a semi-structured interview approach was employed with a subset of (coal-fired) power plant owners and operators to characterize the modes by which extreme conditions impact their plant's operations and the measures they have implemented to mitigate water related threats. Interviews engaged 69 power plants, characterized by a range of capacities, cooling types, and water sources. Twenty-five unique modes of impact were identified across the 69 plants, with 96% of plants reported taking some deliberate action to mitigate water-related threats; thirty-four different adaptive measures were recorded. Results here are intended to raise awareness for this potentially important data gap, which could influence the accuracy of projections concerning individual power plant operations under extreme climate conditions supporting grid reliability and long-term system planning exercises. • Conducted interviews with owner-operators of 69 coal-fired power plants. • Acquired plant-level data on water-related threats and mitigation efforts taken. • Twenty-five unique modes of impact were identified from drought and flood. • 96% of plants reported adopting mitigation measures. • 115 individual adaptive measures recorded. [ABSTRACT FROM AUTHOR]

Seasonal runoff from montane uplands is crucial for plant growth in agricultural communities of northern New Mexico. These communities typically employ traditional irrigation systems, called acequias, which rely mainly upon spring snowmelt runoff for irrigation. The trend of the past few decades is an increase in temperature, reduced snow pack, and earlier runoff from snowmelt across much of the western United States. In order to predict the potential impacts of changes in future climate a system dynamics model was constructed to simulate the surface water supplies in a montane upland watershed of a small irrigated community in northern New Mexico through the rest of the 21st century. End‐term simulations of representative concentration pathways (RCP) 4.5 and 8.5 suggest that runoff during the months of April to August could be reduced by 22% and 56%, respectively. End‐term simulations also displayed a shift in the beginning and peak of snowmelt runoff by up to one month earlier than current conditions. Results suggest that rising temperatures will drive reduced runoff in irrigation season and earlier snowmelt runoff in the dry season towards the end of the 21st century. Modeled results suggest that climate change leads to runoff scheme shift and increased frequency of drought; due to the uncontemporaneous of irrigation season and runoff scheme, water shortage will increase. Potential impacts of climate change scenarios and mitigation strategies should be further investigated to ensure the resilience of traditional agricultural communities in New Mexico and similar regions. [ABSTRACT FROM AUTHOR]

Heterogeneous diffusion in different regions of a fractured granodiorite from Japan has been observed and measured through the use of X-ray absorption imaging. These regions include gouge-filled fractures, recrystallized fracture-filling material and hydrothermally altered matrix. With the X-ray absorption imaging technique, porosity, relative concentration, and relative mass of an iodine tracer were imaged in two dimensions with a sub-millimeter pixel size. Because portions of the samples analyzed have relatively low porosity values, imaging errors can potentially impact the results. For this reason, efforts were made to better understand and quantify this error. Based on the X-ray data, pore diffusion coefficients (Dp) for the different regions were estimated assuming a single diffusion rate and a lognormal multirate distribution of Dp. Results show Dp for the gouge-filled fractures are over an order of magnitude greater than those of the recrystallized fracture-filling material, which in turn is approximately two times greater than those for the altered matrix. The recrystallized fracture-filling material was found to exhibit the greatest degree of variability. The results of these experiments also provide evidence that diffusion from advective zones in fractures through the gouge-filled fractures and recrystallized fracture-filling material could increase the pore space available for matrix diffusion. This evidence is important for understanding the performance of potential nuclear waste repositories in crystalline rocks as diffusion is thought to be an important retardation mechanism for radionuclides. [Copyright &y& Elsevier]

This article represents the second report by an ASCE Task Committee “Infrastructure Impacts of Landscape-driven Weather Change” under the ASCE Watershed Management Technical Committee and the ASCE Hydroclimate Technical Committee. Herein, the ‘infrastructure impacts” are referred to as infrastructure-sensitive changes in weather and climate patterns (extremes and non-extremes) that are modulated, among other factors, by changes in landscape, land use and land cover change. In this first report, the article argued for explicitly considering the well-established feedbacks triggered by infrastructure systems to the land-atmosphere system via landscape change. In this report by the ASCE Task Committee (TC), we present the results of this ASCE TC’s survey of a cross section of experienced water managers using a set of carefully crafted questions. These questions covered water resources management, infrastructure resiliency and recommendations for inclusion in education and curriculum. We describe here the specifics of the survey and the results obtained in the form of statistical averages on the ‘perception’ of these managers. Finally, we discuss what these ‘perception’ averages may indicate to the ASCE TC and community as a whole for stewardship of the civil engineering profession. The survey and the responses gathered are not exhaustive nor do they represent the ASCE-endorsed viewpoint. However, the survey provides a critical first step to developing the framework of a research and education plan for ASCE. Given the Water Resources Reform and Development Act passed in 2014, we must now take into account the perceived concerns of the water management community. [ABSTRACT FROM AUTHOR]

In New Mexico, increasing demand for water, combined with limited supplies and periodic drought, is placing additional stress on traditional acequia communities. Research on the hydrology of acequia agriculture in northern New Mexico has been carried out in three communities and their associated watersheds and irrigated valleys. Critical to the effort has been the participation of the acequias and individual farmers, ranchers, and other community member stakeholders. Participation in hydrology research included assistance in altering flows in acequias, and access to private property and wells, critical to obtain ground and surface water measurements. Further research that integrated hydrologic data with ecosystem, land-use, economics, and sociocultural data, via development of a system dynamics model, required community member participation through surveys, interviews, and workshops to develop, calibrate and refine the model. [ABSTRACT FROM AUTHOR]

Hydrologic connectivity can be important when assessing the role of water availability and distribution in sustaining different natural processes and human activities in a given landscape. We present a study that served as one of five case studies for an interdisciplinary modeling course. The main objectives of the study presented are: 1) to characterize the hydrologic connectivity between the uplands and the irrigated valley and; 2) to set the foundations for understanding the connections between hydrology and complementary disciplines of ecology, rangeland management, and system dynamics modeling in a semiarid watershed in the southwestern United States. Study results show a strong hydrologic connectivity between surface and groundwater in the lower agricultural valley that follows a seasonal pattern, driven primarily by irrigation contributions to the shallow aquifer. The interdisciplinary modeling team assigned to this study was able to use data from it and outside sources to create a working model that addressed these interconnections and highlighted the study value of concurrent consideration of multiple components of linked hydrologic, economic, ecological, and social systems. [ABSTRACT FROM AUTHOR]

Storage and release functions of western U.S. traditional river valley irrigation systems may counteract early and rapid spring river runoff associated with climate variation. Along the Rio Grande in northern New Mexico, we instrumented a 20-km-long irrigated valley to measure water balance components from 2005 to 2007. Hydrologic processes of the system were incorporated into a system dynamics model to test scenarios of changed water use. Of river water diverted into an earthen irrigation canal system, some was consumed by crop evapotranspiration (7.4%), the rest returned to the river as surface return flow (59.3%) and shallow groundwater return flow that originated as seepage from canals (12.1%) and fields (21.2%). The modeled simulations showed that the coupled surface water irrigation system and shallow aquifer act together to store water underground and then release it to the river, effectively retransmitting river flow until later in the year. Water use conversion to nonirrigation purposes and reduced seepage from canals and fields will likely result in higher spring runoff and lower fall and winter river flow. [ABSTRACT FROM AUTHOR]

Collaborative modeling offers a novel methodology that integrates core ideals in the policy sciences. The principles behind collaborative modeling enable policy researchers and decision makers to address interdisciplinarity, complex systems, and public input in the policy process. This approach ideally utilizes system dynamics to enable a multidisciplinary group to explore the relationships in a complex system. We propose that there is a spectrum of possibilities for applying collaborative modeling in the policy arena, ranging from the purely academic through full collaboration among subject matter experts, the general public, and decision makers. Likewise, there is a spectrum of options for invoking collaboration within the policy process. Results from our experiences suggest that participants in a collaborative modeling project develop a deeper level of understanding about the complexity in the policy issue being addressed; increase their agreement about root problems; and gain an appreciation for the uncertainty inherent in data and methods in studying complex systems. We conclude that these attributes of collaborative modeling make it an attractive option for improving the decision-making process as well as on-the-ground decisions. [ABSTRACT FROM AUTHOR]

Thermoelectric power plants often depend on multipurpose reservoirs to supply cooling water. Although reservoirs buffer natural hydrologic variability, severe droughts can deplete storage below critical thresholds, or to levels at which the effluent water temperature exceeds the environmental compliance requirement for cooling. This study explores the effects of projected climate change and drought on water storage at 30 major reservoirs in Texas. These reservoirs collectively provide cooling water for about two thirds of thermoelectric power capacity in the Electric Reliability Council of Texas (ERCOT) power grid. Multi-ensemble runoff projections generated from eleven downscaled hydroclimate simulations are mapped to key watersheds to create spatially correlated multi-reservoir inflow sequences. These data are used to drive reservoir storage simulations, which are linked to a metric of "capacity-at-risk" using critical reservoir thresholds. We find that projected impacts of climate change are mixed, with results indicating an increase in the occurrence of thermal disruption under only half of climate models. A critical threshold of 30% storage volume—applied to all reservoirs—results in disruption to about one fifth of ERCOT thermal generation during the most severe projected droughts. The study highlights an important role for detailed reservoir behavior simulations for capturing the effects of drought and climate change on thermoelectric plant performance. • 75% of Texas thermoelectric capacity relies on reservoir water. • We simulate water storage at 30 reservoirs to quantify capacity-at-risk during drought. • Projected extreme droughts disrupt about one fifth of ERCOT thermal generation. • Scenarios of climate change impact on thermal capacity-at-risk diverge. • Known critical storage thresholds would enhance risk assessment to inform planning. [ABSTRACT FROM AUTHOR]

• A coupled Agent-based-Riverware model was applied to assess climate change impact. • Farmers response differently in irrigated area to different climate change impacts. • Basin level's water scarcity metrics cannot reflect farmer level's impacts. Reoccurring drought through the early 2000s has caused a serious water scarcity issue in the Colorado River Basin. Previous modeling studies have focused on the impact of climate change without considering the adaptive behaviors of farmers and under-utilized Indian water rights. In this paper, we use a coupled agent-based water resource model (ABM) to investigate how the adaptive decisions of farmers can affect water resource management under both climate change impacts and fully utilized Indian water right conditions. We used five General Circulation Model projections with RCP8.5 scenarios for the study. The results of farm-level decision-making showed different responses in irrigated areas that were changing due to climate change impact. While winter precipitation changes might partially explain the behavior changes, no specific pattern could be concluded based on their location. Also, farmers' responses about annual water diversion showed more significant inter-year variation compared to irrigated areas. Basin-level metrics showed that climate change impacts will generally worsen water scarcity issues as measured in Navajo Reservoir storage, flow to Lake Powell, and instream flow requirement. But these basin-level water scarcity metrics cannot reflect individual farm-level impacts under climate change, which is why modeling the bottom-up management actions is necessary. When the under-utilized Indian water rights are fully used, it is more likely to trigger the shortage sharing agreement due to the higher tribal water depletion. Evaluation of model uncertainty and a more realistic setup for adaptive actions under drought contingency plans are suggested for future research. [ABSTRACT FROM AUTHOR]