Surface Water Withdrawal Research Articles

Agricultural Water Policy during Drought: A Strategy for Including Groundwater Permits in Future Irrigation Buyout Auctions in the Flint River Basin

Georgia’s Flint River Basin has water management challenges from extensive groundwater pumping for agriculture and in-stream flow requirements. The state has experimented with buying out irrigation permits through auctions. Past auctions were relegated to surface water permits. Recently, the state has allowed groundwater permit holders to participate in future auctions. The Flow-Impact Offer (FIO) developed in this paper provides a way to reconcile the disparate impacts of groundwater and surface water withdrawals on in-stream flows when comparing offers in a buyout auction. The techniques suggested here to operationalize the FIO are applicable to other regions of the world as well.

PCR-GLOBWB 2: a 5 arcmin global hydrological and water resources model

Abstract. We present PCR-GLOBWB 2, a global hydrology and water resources model. Compared to previous versions of PCR-GLOBWB, this version fully integrates water use. Sector-specific water demand, groundwater and surface water withdrawal, water consumption, and return flows are dynamically calculated at every time step and interact directly with the simulated hydrology. PCR-GLOBWB 2 has been fully rewritten in Python and PCRaster Python and has a modular structure, allowing easier replacement, maintenance, and development of model components. PCR-GLOBWB 2 has been implemented at 5 arcmin resolution, but a version parameterized at 30 arcmin resolution is also available. Both versions are available as open-source codes on https://github.com/UU-Hydro/PCR-GLOBWB_model (Sutanudjaja et al., 2017a). PCR-GLOBWB 2 has its own routines for groundwater dynamics and surface water routing. These relatively simple routines can alternatively be replaced by dynamically coupling PCR-GLOBWB 2 to a global two-layer groundwater model and 1-D–2-D hydrodynamic models. Here, we describe the main components of the model, compare results of the 30 and 5 arcmin versions, and evaluate their model performance using Global Runoff Data Centre discharge data. Results show that model performance of the 5 arcmin version is notably better than that of the 30 arcmin version. Furthermore, we compare simulated time series of total water storage (TWS) of the 5 arcmin model with those observed with GRACE, showing similar negative trends in areas of prevalent groundwater depletion. Also, we find that simulated total water withdrawal matches reasonably well with reported water withdrawal from AQUASTAT, while water withdrawal by source and sector provide mixed results.

Developing a methodology for real-time trading of water withdrawal and waste load discharge permits in rivers

In this paper, a new methodology is proposed for the real-time trading of water withdrawal and waste load discharge permits in agricultural areas along the rivers. Total Dissolved Solids (TDS) is chosen as an indicator of river water quality and the TDS load that agricultural water users discharge to the river are controlled by storing a part of return flows in some evaporation ponds. Available surface water withdrawal and waste load discharge permits are determined using a non-linear multi-objective optimization model. Total available permits are then fairly reallocated among agricultural water users, proportional to their arable lands. Water users can trade their water withdrawal and waste load discharge permits simultaneously, in a bilateral, step by step framework, which takes advantage of differences in their water use efficiencies and agricultural return flow rates. A trade that would take place at each time step results in either more benefit or less diverted return flow. The Nucleolus cooperative game is used to redistribute the benefits generated through trades in different time steps. The proposed methodology is applied to PayePol region in the Karkheh River catchment, southwest Iran. Predicting that 1922.7 Million Cubic Meters (MCM) of annual flow is available to agricultural lands at the beginning of the cultivation year, the real-time optimization model estimates the total annual benefit to reach 46.07 million US Dollars (USD), which requires 6.31 MCM of return flow to be diverted to the evaporation ponds. Fair reallocation of the permits, changes these values to 35.38 million USD and 13.69 MCM, respectively. Results illustrate the effectiveness of the proposed methodology in the real-time water and waste load allocation and simultaneous trading of permits.

The environmental cost of a reference withdrawal from surface waters: Definition and geography

Abstract World freshwater ecosystems are significantly deteriorating at a faster rate than other ecosystems. Water withdrawals are recognized as one of the main drivers of growing water stress in river basins worldwide. Over the years, much effort has been devoted to quantify water withdrawals at a global scale; however, comparisons are not simple because the uneven spatiotemporal distribution of surface water resources entails that the same amount of consumed water does not have the same environmental cost in different times or places. In order to account for this spatiotemporal heterogeneity, this work proposes a novel index to assess the environmental cost of a withdrawal from a generic river section. The index depends on (i) the environmental relevance of the impacted fluvial ecosystem (e.g., bed-load transport capacity, width of the riparian belt, biodiversity richness) and (ii) the downstream river network affected by the water withdrawal. The environmental cost has been estimated in each and every river section worldwide considering a reference withdrawal. Being referred to a unitary reference withdrawal that can occur in any river section worldwide, our results can be suitably arranged for describing any scenario of surface water consumption (i.e., as the superposition of the actual pattern of withdrawals). The index aims to support the interpretation of the volumetric measure of surface water withdrawal with a perspective that takes into account the fluvial system where the withdrawal actually occurs. The application of the index highlights the river regions where withdrawals can cause higher environmental costs, with the challenge of weighting each water withdrawal considering the responsibilities that it has on downstream freshwater ecosystems.

Significant impacts of irrigation water sources and methods on modeling irrigation effects in the ACMELand Model

AbstractAn irrigation module considering irrigation water source and irrigation method has been incorporated into the ACME Land Model (ALM). Global numerical experiments were conducted to investigate irrigation effects and their sensitivity to irrigation water sources and irrigation methods. All simulations shared the same irrigation soil moisture target constrained by a global census data set of irrigation amounts. Irrigation has large impacts on terrestrial water balances especially in regions with extensive irrigation. Such effects depend on the irrigation water source: surface water‐fed irrigation decreases runoff and water table depth, while groundwater‐fed irrigation increases water table depth, and increases or decreases runoff depending on the pumping intensity. Irrigation effects also depend significantly on the irrigation method. Flood irrigation applies water in large volumes within short durations, resulting in much larger impacts on runoff and water table depth than drip and sprinkler irrigation. Differentiating the irrigation water source and method is important not only for representing the distinct pathways of how irrigation influences the terrestrial water balances, but also for estimating irrigation water use efficiency. Specifically, groundwater pumping has lower irrigation water use efficiency than irrigation relying on surface water withdrawal only due to enhanced recharge rates. Different irrigation methods also affect water use efficiency, with drip irrigation being the most efficient followed by sprinkler and flood irrigation. Our results highlight the importance of explicitly accounting for irrigation source and irrigation method, which are the least understood and constrained aspects in modeling irrigation water demand, water scarcity, and irrigation effects in Earth System Models.

Environmental flows in the context of unconventional natural gas development in the Marcellus Shale.

Quantitative flow-ecology relationships are needed to evaluate how water withdrawals for unconventional natural gas development may impact aquatic ecosystems. Addressing this need, we studied current patterns of hydrologic alteration in the Marcellus Shale region and related the estimated flow alteration to fish community measures. We then used these empirical flow-ecology relationships to evaluate alternative surface water withdrawals and environmental flow rules. Reduced high-flow magnitude, dampened rates of change, and increased low-flow magnitudes were apparent regionally, but changes in many of the flow metrics likely to be sensitive to withdrawals also showed substantial regional variation. Fish community measures were significantly related to flow alteration, including declines in species richness with diminished annual runoff, winter low-flow, and summer median-flow. In addition, the relative abundance of intolerant taxa decreased with reduced winter high-flow and increased flow constancy, while fluvial specialist species decreased with reduced winter and annual flows. Stream size strongly mediated both the impact of withdrawal scenarios and the protection afforded by environmental flow standards. Under the most intense withdrawal scenario, 75% of reference headwaters and creeks (drainage areas <99km2 ) experienced at least 78% reduction in summer flow, whereas little change was predicted for larger rivers. Moreover, the least intense withdrawal scenario still reduced summer flows by at least 21% for 50% of headwaters and creeks. The observed 90th quantile flow-ecology relationships indicate that such alteration could reduce species richness by 23% or more. Seasonally varying environmental flow standards and high fixed minimum flows protected the most streams from hydrologic alteration, but common minimum flow standards left numerous locations vulnerable to substantial flow alteration. This study clarifies how additional water demands in the region may adversely affect freshwater biological integrity. The results make clear that policies to limit or prevent water withdrawals from smaller streams can reduce the risk of ecosystem impairment.

Water permit integration in the Paraguaçu River Watershed (Bahia)

ABSTRACT In Brazil, water regulatory agencies adopt two different methodologies of equating water balance for the purposes of water permits: one that considers the uses for surface water withdrawal and waste water discharge in an integrated way, and one that analyses these two uses as demands that do not relate with each other. In the state of Bahia, this analysis disregards the integration of quantitative and qualitative uses. Furthermore, at the moment, there are not internal procedures that enable the integration of the water permit with other water resources management instruments. In this context, the aim of this work consists of analysing the advantages and limitations of the implementation of the equating methodology that integrates the quali-quantitative analysis of the water balance for purposes of water permit, compared with current procedures in the state of Bahia. For this analysis, a diagnosis of use of the Paraguaçu River Watershed (BHRP) was developed through the Water Balance Control System (SCBH), simulating the two methodologies and comparing potential water use index. The results reinforce that the methodology of equating the quali-quantitative water balance does not represent an advance for water resources management when the other instruments, present in the State Water Resources Policy, are not integrated with the water permit.

Small-scale catchment analysis of water stress in wet regions of the U.S.: an example from Louisiana

Groundwater is increasingly being overdrafted in the Southeastern U.S., despite abundant rainfall and the apparent availability of surface water. Using the state of Louisiana as an example, the current study quantifies the stresses on water resources and investigates the potential for opportunities to use surface water in lieu of groundwater pumping. The assessment is based on a fine watershed scale (12-digit Hydrological Unit Code [HUC] boundaries) water balance between the availability of surface and groundwater and surface water and groundwater demand. Water demand includes environmental flows, as well as public supply, rural domestic, industrial, power generation, agricultural, and aquaculture sectors. The seasonality of water stress is also addressed by incorporating monthly variations in surface water supply and irrigation demands. We develop several new weighting schemes to disaggregate the water withdrawals, provided by the U.S. Geological Survey on a county scale, to the HUC12 scale. The analysis on the smaller HUC12 scale is important for identifying areas with high water stress that would otherwise be masked at a larger scale (e.g. the county or HUC8 watershed scales). The results indicate that the annual water stress in Louisiana is below one (i.e. there is more water available than is used) for most watersheds; however, some watersheds (15 of the HUC12 units) show stresses greater than one, indicating an insufficient water supply to meet existing demands. The areas of the highest water stress are largely attributable to water consumption for power generating plants or irrigation. Moreover, estimating the stresses on surface water and groundwater sources separately confirms our speculation of abundant surface water and demonstrates a significant over-drafting/deficit of groundwater in many of the states aquifer systems. These results have implications for identifying new opportunities for reallocation of surface water use to reduce groundwater pumping and improve water sustainability in the region. Seasonal fluctuations in surface water supply and water withdrawals for irrigation highlight the fact that the water system is under more stress during the summer season. This observation underscores the need for infrastructure for short-term surface water storage in agricultural regions. The water budget analysis presented here can be useful for stakeholders in developing water management plans and can also help to inform the development of a water code that will enable Louisiana to successfully manage and conserve its water resources for the future.

Effects of anthropogenic water regulation and groundwater lateral flow on land processes

AbstractBoth anthropogenic water regulation and groundwater lateral flow essentially affect groundwater table patterns. Their relationship is close because lateral flow recharges the groundwater depletion cone, which is induced by over‐exploitation. In this study, schemes describing groundwater lateral flow and human water regulation were developed and incorporated into the Community Land Model 4.5. To investigate the effects of human water regulation and groundwater lateral flow on land processes as well as the relationship between the two processes, three simulations using the model were conducted for the years 2003–2013 over the Heihe River Basin in northwestern China. Simulations showed that groundwater lateral flow driven by changes in water heads can essentially change the groundwater table pattern with the deeper water table appearing in the hillslope regions and shallower water table appearing in valley bottom regions and plains. Over the last decade, anthropogenic groundwater exploitation deepened the water table by approximately 2 m in the middle reaches of the Heihe River Basin and rapidly reduced the terrestrial water storage, while irrigation increased soil moisture by approximately 0.1 m3 m−3. The water stored in the mainstream of the Heihe River was also reduced by human surface water withdrawal. The latent heat flux was increased by 30 W m−2 over the irrigated region, with an identical decrease in sensible heat flux. The simulated groundwater lateral flow was shown to effectively recharge the groundwater depletion cone caused by over‐exploitation. The offset rate is higher in plains than mountainous regions.

Private rights, public interests and water use conflicts: evolving water law and policy in Michigan

Water conflicts are rare across Michigan's history. As a result, water rights have received little attention by courts or the legislature. Traditionally, the common law of water rights in Michigan embraces the riparian doctrine for surface water and provides landowners with the right to use groundwater. However, two recent changes in common and statutory law significantly modify the legal relations among water users and others with a stake in water use decisions. A 2005 Michigan Court of Appeals decision created a new legal relation among riparian and groundwater rights holders. In 2008, Michigan's legislature passed laws aimed at regulating surface water and groundwater withdrawals. As an exercise of police power intended to protect public rights in water and associated environmental quality, the 2008 laws cap total water withdrawals. This program of restricting water withdrawals coexists with the state's common law which provides for reasonable use of surface water by riparian landowners and groundwater by owners of the overlying land. The result is a new set of legal relations, an uncertain legal environment, and a growing likelihood of water use conflicts. Because Michigan's body of water law is unique, neither courts nor legislature can rely on solutions used in other states.

Using satellite-based estimates of evapotranspiration and groundwater changes to determine anthropogenic water fluxes in land surface models

Abstract. Irrigation is a widely used water management practice that is often poorly parameterized in land surface and climate models. Previous studies have addressed this issue via use of irrigation area, applied water inventory data, or soil moisture content. These approaches have a variety of drawbacks including data latency, accurately prescribing irrigation intensity, and a lack of conservation of water volume for models using a prescribed soil moisture approach. In this study, we parameterize irrigation fluxes using satellite observations of evapotranspiration (ET) compared to ET from a suite of land surface models without irrigation. We then incorporate the irrigation flux into the Community Land Model (CLM) and use a systematic trial-and-error procedure to determine the ground- and surface-water withdrawals that are necessary to balance the new irrigation flux. The resulting CLM simulation with irrigation produces ET that matches the magnitude and seasonality of observed satellite ET well, with a mean difference of 6.3 mm month−1 and a correlation of 0.95. Differences between the new CLM ET values and satellite-observed ET values are always less than 30 mm month−1 and the differences show no pattern with respect to seasonality. The results reinforce the importance of accurately parameterizing anthropogenic hydrologic fluxes into land surface and climate models to assess environmental change under current and future climates and land management regimes.

Climate-water quality relationships in Texas reservoirs

Water temperature, dissolved oxygen, and concentrations of salts in surface water bodies can be affected by the natural environment and local human activities such as surface and ground water withdrawals, land use and energy extraction, and variability and long-term trends in atmospheric conditions including temperature and precipitation. Here, we quantify the relationship between 121 indicators of mean and extreme temperature and precipitation and 24 water quality parameters in 57 Texas reservoirs using observational data records covering the period 1960 to 2010. Over time scales ranging from 1 week to 2 years, we find that water temperature, dissolved oxygen, pH, specific conductance, chloride, sulfate, and phosphorus all show consistent correlations with atmospheric predictors, including high and low temperature extremes, dry days, heavy precipitation events, and mean temperature and precipitation. Based on these relationships combined with regional climate projections, we expect climate change to increase water temperatures, decrease dissolved oxygen levels, decrease pH, increase specific conductance, and increase levels of sulfate and chloride in Texas reservoirs. Over decadal time scales, this may affect aquatic ecosystems in the reservoirs, including altering the risk of conditions conducive to algae occurrence, as well as affecting the quality of water available for human consumption and recreation. Copyright © 2015 John Wiley & Sons, Ltd.

Evaluating Municipal Water Management Options with the Incorporation of Water Quality and Energy Consumption

Rapidly growing population and associated socio-economic development are placing increasing stress on water resources and posing challenges for water management. This study develops a system dynamics model for municipal water management in Hillsborough County by incorporating water quality and energy consumption associated with water supply in decision-making. The result shows that the percentage of surface water withdrawal will decrease by 11.7~23.3 % with considering water quality, and this results in the simulated surface water level increases by 1.32~1.39 %. With considering both water quality and energy consumption, the surface water level increases by 1.10~1.30 %. There is a slight decrease in groundwater storage (0.02~0.08 %) compared with the reference behavior. The result also finds that water conservation education is the most effective option among the seven management options reducing the freshwater withdrawals. It reduces the freshwater withdrawals by 14.9 %, followed by rebates on indoor water appliances. Rebates on outdoor water appliances and irrigation restriction are effective to decrease the outdoor water demand. The model is sensitive to precipitation and a more accurate representation of precipitation should be employed.

Land use and surface water withdrawal effects on fish and macroinvertebrate assemblages in the Susquehanna River basin, USA

Water withdrawals in the Susquehanna River basin, USA, are increasing due to burgeoning shale gas extraction activities. In order to determine if flow alteration resulting from shale gas industry surface water withdrawals impacts fish and macroinvertebrate assemblages in lotic habitats, data were collected upstream and downstream of 12 withdrawal and three reference sites in headwater, cold water, and large warm water streams. Watershed size ranged from 4 to 517 km2 and average daily withdrawals ranged from 0.05 to 1.4 million liters. Analysis of withdrawal data indicated that approved withdrawals far exceeded actual withdrawals across all stream types. The largest withdrawals relative to stream size were from headwater streams, where on average 6.8% of average daily flow was withdrawn daily. Fish and macroinvertebrate assemblage similarity at study sites depended largely on stream sampled, rather than position upstream or downstream of withdrawals. Regression techniques were employed to determine if catchment-level variables or withdrawal metrics best described variation in fish and macroinvertebrate metrics shown to be sensitive to flow alteration. The catchment-level variables were responsible for the majority of observed variation in fish metrics. Macroinvertebrate models performed poorly, indicating that the stream sampled or variables not included in the analyses were responsible for the majority of variation. Overall, evidence suggests impacts of shale gas withdrawals within the Susquehanna basin are limited at the present state of flow alteration. Potential reasons include protective measures such as pass-by flow restrictions, which require withdrawals to cease when flows drop below a predetermined low flow threshold, maximum instantaneous and daily withdrawal limits, and recent initiation of withdrawals (1–3 years of operation).

A new watershed assessment framework for Nova Scotia: A high-level, integrated approach for regions without a dense network of monitoring stations

Summary High-level, integrated watershed assessments are a basic requirement for freshwater planning, as they create regional summaries of multiple environmental stressors for the prioritization of watershed conservation, restoration, monitoring, and mitigation. There is a heightened need for a high-level, integrated watershed assessment in Nova Scotia as it faces pressing watershed issues relating to acidification, soil erosion, acid rock drainage, eutrophication, and water withdrawals related to potential shale gas development. But because of the relative sparseness of the on-the-ground effects-based data, for example on water quality or fish assemblages, previously created approaches for integrated watershed assessment cannot be used. In a government/university collaboration, we developed a new approach that relies solely on easier-to-collect and more available exposure-based variables to perform the first high-level watershed assessment in Nova Scotia. In this assessment, a total of 295 watershed units were studied. We used Geographic Information Systems (GIS) to map and analyze 13 stressor variables that represent risks to aquatic environment (e.g., road/stream crossing density, acid rock drainage risk, surface water withdrawals, human land use, and dam density). We developed a model to link stressors with impacts to aquatic systems to serve as a basis for a watershed threat ranking system. Resource management activities performed by government and other stakeholders were also included in this analysis. Our assessment identifies the most threatened watersheds, enables informed comparisons among watersheds, and indicates where to focus resource management and monitoring efforts. Stakeholder communication tools produced by the NSWAP include a watershed atlas to communicate the assessment results to a broader audience, including policy makers and public stakeholders. This new framework for high-level watershed assessments provides a resource for other regions that also have limited availability of effects-based data, an important consideration as expanding human activities impact water resources in less densely monitored regions.

Exploring the long-term balance between net precipitation and net groundwater exchange in Florida seepage lakes

The long-term balance between net precipitation and net groundwater exchange that maintains thousands of seepage lakes in Florida’s karst terrain is explored at a representative lake basin and then regionally for the State’s peninsular lake district. The 15-year water budget of Lake Starr includes El Niño Southern Oscillation (ENSO)-related extremes in rainfall, and provides the longest record of Bowen ratio energy-budget (BREB) lake evaporation and lake-groundwater exchanges in the southeastern United States. Negative net precipitation averaging −25 cm/yr at Lake Starr overturns the previously-held conclusion that lakes in this region receive surplus net precipitation. Net groundwater exchange with the lake was positive on average but too small to balance the net precipitation deficit. Groundwater pumping effects and surface-water withdrawals from the lake widened the imbalance. Satellite-based regional estimates of potential evapotranspiration at five large lakes in peninsular Florida compared well with basin-scale evaporation measurements from seven open-water sites that used BREB methods. The regional average lake evaporation estimated for Lake Starr during 1996–2011 was within 5% of its measured average, and regional net precipitation agreed within 10%. Regional net precipitation to lakes was negative throughout central peninsular Florida and the net precipitation deficit increased by about 20 cm from north to south. Results indicate that seepage lakes farther south on the peninsula receive greater net groundwater inflow than northern lakes and imply that northern lakes are in comparatively leakier hydrogeologic settings. Findings reveal the peninsular lake district to be more vulnerable than was previously realized to drier climate, surface-water withdrawals from lakes, and groundwater pumping effects.

Soil Phosphorus Dynamics and Saltwater Intrusion in a Florida Estuary

Soils in riparian wetlands are thought to stifle eutrophication in coastal water bodies by entraining and transforming nutrients. Altered hydrology and sea level rise underscore the need to evaluate the role of salinity in nutrient cycling within these settings. We studied three intertidal wetlands along the St. Johns River estuary, Florida in order to relate soil phosphorus composition with the distribution of saltwater. Sites represented a tidal freshwater forest, a brackish marsh, and a saltmarsh. Total phosphorus and organic composition decreased along the axis of the estuary as ambient salinity increased. At upstream wetlands, porewater revealed an inverse correlation between PO4 3− and the presence of saltwater (Cl− and SO4 2−) suggesting soil efflux. During experiments, aerobic soils did not liberate PO4 3− when exposed to seawater. During anaerobic experiments, SO4 2− amended soils from a saltmarsh mobilized substantial amounts of PO4 3− but the same effect was not observed in low-salinity wetland soils. Results indicate that P availability is shaped by saltwater access in the estuary and that SO4 2− reduction may regenerate PO4 3− in the saltmarsh. We suggest this is relevant to the St. John’s river in light of ongoing eutrophication and planned surfacewater withdrawals, which may draw saline water farther upstream.

Global modeling of withdrawal, allocation and consumptive use of surface water and groundwater resources

Abstract. To sustain growing food demand and increasing standard of living, global water withdrawal and consumptive water use have been increasing rapidly. To analyze the human perturbation on water resources consistently over large scales, a number of macro-scale hydrological models (MHMs) have been developed in recent decades. However, few models consider the interaction between terrestrial water fluxes, and human activities and associated water use, and even fewer models distinguish water use from surface water and groundwater resources. Here, we couple a global water demand model with a global hydrological model and dynamically simulate daily water withdrawal and consumptive water use over the period 1979–2010, using two re-analysis products: ERA-Interim and MERRA. We explicitly take into account the mutual feedback between supply and demand, and implement a newly developed water allocation scheme to distinguish surface water and groundwater use. Moreover, we include a new irrigation scheme, which works dynamically with a daily surface and soil water balance, and incorporate the newly available extensive Global Reservoir and Dams data set (GRanD). Simulated surface water and groundwater withdrawals generally show good agreement with reported national and subnational statistics. The results show a consistent increase in both surface water and groundwater use worldwide, with a more rapid increase in groundwater use since the 1990s. Human impacts on terrestrial water storage (TWS) signals are evident, altering the seasonal and interannual variability. This alteration is particularly large over heavily regulated basins such as the Colorado and the Columbia, and over the major irrigated basins such as the Mississippi, the Indus, and the Ganges. Including human water use and associated reservoir operations generally improves the correlation of simulated TWS anomalies with those of the GRACE observations.

Surface Water Withdrawals for Marcellus Shale Gas Development: Performance of Alternative Regulatory Approaches in the Upper Ohio River Basin

Almost all of the water used for developing Marcellus Shale gas is withdrawn from surface water sources. State environmental and interstate water authorities take different approaches to managing these withdrawals. In the Upper Ohio River Basin, which covers the western third of Pennsylvania, the Pennsylvania Department of Environmental Protection requires that all water sources used for development have an approved water management plan. For surface water sources the plans stipulate the amount and timing of withdrawals from each source as a function of annual streamflow statistics. Neighboring regulatory authorities and some environmental groups now favor the use of monthly streamflow statistics to establish the conditions for water withdrawals. Our analysis indicates that, given the state of flow measurement data in the Upper Ohio River Basin, the annual streamflow statistics are more likely to prevent water withdrawals during the driest times of the year when aquatic ecosystems are most stressed, and to result in fewer and smaller occurrences of computed low-flow ecodeficits.

On the Use of System Performance Metrics for Assessing the Value of Incremental Water-Use Permits

AbstractA novel approach on quantifying the value of an incremental surface water–use permit in an integrated water resources system consisting of groundwater, surface water, off-stream reservoir, and desalinated seawater sources is presented. First, a stochastic framework that accounts for demand uncertainties and variations in climatic parameters was used to generate regional demand and supply realizations. Second, a linked optimization-simulation model was used to navigate through complex system constraints and sustainable operational constraints. The resulting decision variables were then used to calculate system performance metrics, demonstrating the benefit of an increase in surface-water withdrawals at high flows. The Monte Carlo–based model took advantage of distributed computing capabilities on a private cloud computing system to significantly reduce the total run time. The model codes were developed in two different software environments, executed on different platforms, in which information was...