A COMPARISON OF DELTA CHANGE AND DOWNSCALED GCM SCENARIOS FOR THREE MOUNTAINOUS BASINS IN THE UNITED STATES1

ABSTRACT: Simulated daily precipitation, temperature, and runoff time series were compared in three mountainous basins in the United States: (1) the Animas River basin in Colorado, (2) the East Fork of the Carson River basin in Nevada and California, and (3) the Cle Elum River basin in Washington State. Two methods of climate scenario generation were compared: delta change and statistical downscaling. The delta change method uses differences between simulated current and future climate conditions from the Hadley Centre for Climate Prediction and Research (HadCM2) General Circulation Model (GCM) added to observed time series of climate variables. A statistical downscaling (SDS) model was developed for each basin using station data and output from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEPINCAR) reanalysis regridded to the scale of HadCM2. The SDS model was then used to simulate local climate variables using HadCM2 output for current and future conditions. Surface climate variables from each scenario were used in a precipitation‐runoff model. Results from this study show that, in the basins tested, a precipitation‐runoff model can simulate realistic runoff series for current conditions using statistically down‐scaled NCEP output. But, use of downscaled HadCM2 output for current or future climate assessments are questionable because the GCM does not produce accurate estimates of the surface variables needed for runoff in these regions. Given the uncertainties in the GCMs ability to simulate current conditions based on either the delta change or downscaling approaches, future climate assessments based on either of these approaches must be treated with caution.     

Climate Change Impacts on Water Resources in the Upper Blue Nile River Basin,Ethiopia1

Kim, Ungtae and Jagath J. Kaluarachchi, 2009. Climate Change Impacts on Water Resources in the Upper Blue Nile River Basin, Ethiopia. Journal of the American Water Resources Association (JAWRA) 45(6):1361‐1378. Abstract: Climate change affects water resources availability of international river basins that are vulnerable to runoff variability of upstream countries especially with increasing water demands. The upper Blue Nile River Basin is a good example because its downstream countries, Sudan and Egypt, depend solely on Nile waters for their economic development. In this study, the impacts of climate change on both hydrology and water resources operations were analyzed using the outcomes of six different general circulation models (GCMs) for the 2050s. The outcomes of these six GCMs were weighted to provide average future changes. Hydrologic sensitivity, flow statistics, a drought index, and water resources assessment indices (reliability, resiliency, and vulnerability) were used as quantitative indicators. The changes in outflows from the two proposed dams (Karadobi and Border) to downstream countries were also assessed. Given the uncertainty of different GCMs, the simulation results of the weighted scenario suggested mild increases in hydrologic variables (precipitation, temperature, potential evapotranspiration, and runoff) across the study area. The weighted scenario also showed that low‐flow statistics and the reliability of streamflows are increased and severe drought events are decreased mainly due to increased precipitation. Joint dam operation performed better than single dam operation in terms of both hydropower generation and mean annual storage without affecting the runoff volume to downstream countries, but enhancing flow characteristics and the robustness of streamflows. This study provides useful information to decision makers for the planning and management of future water resources of the study area and downstream countries.     

Climate Change Impacts on Local Flood Risks in the U.S. Northeast: A Case Study on the Connecticut and Merrimack River Basins

This study investigates the potential impacts of climate change on future flows in the main stem of the Connecticut and Merrimack rivers within Massachusetts. The study applies two common climate projections based on (Representative Concentration Pathways), RCP 4.5 and RCP 8.5 and downscaled gridded climate projections from 14 global climate models (GCMs) to estimate the 100‐year, 24‐h extreme precipitation events for two future time‐periods: near‐term (2021–2060) and far‐term (2060–2099). 100‐year 24‐h precipitation events at near‐ and far‐term are compared to GCM‐driven historical extreme precipitation events during a base period (1960–1999) and results for RCP 8.5 scenario show average increases between 25%–50% during the near‐term compared to the base period and increases of over 50% during the far‐term. Streamflow conditions are generated with a distributed hydrological model where downscaled climate projections are used as inputs. For the near‐term, the medians of the GCMs using the RCP 4.5 and RCP 8.5 suggest 2.9%–8.1% increases in the 100‐year, 24‐h flow event in the Connecticut and an increase of 9.9%–13.7% in the Merrimack River. For the far‐term, the medians of the GCMs using the RCP 4.5 and RCP 8.5 suggest a 9.0%–14.1% increase in the Connecticut and 15.8%–20.6% for the Merrimack River. Ultimately, the results presented here can be used as a guidance for the long‐term management of infrastructures on the Connecticut and Merrimack River floodplains.     

CLIMATE CHHANGE SENSITIVITY ASSESSMENT ON UPPER MISSISSIPPI RIVER BASIN STREAMFLOWS USING SWAT1

ABSTRACT: The Soil and Water Assessment Tool (SWAT) model was used to assess the effects of potential future climate change on the hydrology of the Upper Mississippi River Basin (UMRB). Calibration and validation of SWAT were performed using monthly stream flows for 1968–1987 and 1988–1997, respectively. The R² and Nash‐Sutcliffe simulation efficiency values computed for the monthly comparisons were 0.74 and 0.69 for the calibration period and 0.82 and 0.81 for the validation period. The effects of nine 30‐year (1968 to 1997) sensitivity runs and six climate change scenarios were then analyzed, relative to a scenario baseline. A doubling of atmospheric CO₂ to 660 ppmv (while holding other climate variables constant) resulted in a 36 percent increase in average annual streamflow while average annual flow changes of ?49, ?26, 28, and 58 percent were predicted for precipitation change scenarios of ?20, ?10, 10, and 20 percent, respectively. Mean annual streamflow changes of 51,10, 2, ?6, 38, and 27 percent were predicted by SWAT in response to climate change projections generated from the CISRO‐RegCM2, CCC, CCSR, CISRO‐Mk2, GFDL, and HadCMS general circulation model scenarios. High seasonal variability was also predicted within individual climate change scenarios and large variability was indicated between scenarios within specific months. Overall, the climate change scenarios reveal a large degree of uncertainty in current climate change forecasts for the region. The results also indicate that the simulated UMRB hydrology is very sensitive to current forecasted future climate changes.     

The Sensitivity of Northern Groundwater Recharge to Climate Change: A Case Study in Northwest Alaska1

Clilverd, Hannah M., Daniel M. White, Amy C. Tidwell, and Michael A. Rawlins, 2011. The Sensitivity of Northern Groundwater Recharge to Climate Change: A Case Study in Northwest Alaska. Journal of the American Water Resources Association (JAWRA) 47(6):1228–1240. DOI: 10.1111/j.1752‐1688.2011.00569.x Abstract: The potential impacts of climate change on northern groundwater supplies were examined at a fractured‐marble mountain aquifer near Nome, Alaska. Well water surface elevations (WSE) were monitored from 2004‐2009 and analyzed with local meteorological data. Future aquifer response was simulated with the Pan‐Arctic Water Balance Model (PWBM) using forcings (air temperature and precipitation) derived from fifth‐generation European Centre Hamburg Model (ECHAM5) global circulation model climate scenarios for extreme and modest increases in greenhouse gases. We observed changes in WSE due to the onset of spring snowmelt, low intensity and high intensity rainfall events, and aquifer head recession during the winter freeze period. Observed WSE and snow depth compared well with PWBM‐simulated groundwater recharge and snow storage. Using ECHAM5‐simulated increases in mean annual temperature of 4‐8°C by 2099, the PWBM predicted that by 2099 later freeze‐up and earlier snowmelt will decrease seasonal snow cover by one to two months. Annual evapotranspiration and precipitation are predicted to increase 27‐40% (55‐81 mm) and 33‐42% (81‐102 mm), respectively, with the proportion of snowfall in annual precipitation decreasing on average 9‐25% (p < 0.05). The amount of snowmelt is not predicted to change significantly by 2099; however, a decreasing trend is evident from 2060 in the extreme ECHAM5 greenhouse gas scenario. Increases in effective precipitation were predicted to be great enough to sustain sufficient groundwater recharge.     

IMPACTS OF CLIMATE CHANGE ON WATER YIELD IN THE UPPER WIND RIVER BASIN1

ABSTRACT: The potential impacts of climate change on water yield are examined in the Upper Wind River Basin. This is a high‐elevation, mountain basin with a snowfall/snowmelt dominated stream‐flow hydrograph. A variety of physiographic conditions are represented in the rangeland, coniferous forests, and high‐elevation alpine regions. The Soil Water Assessment Tool (SWAT) is used to model the baseline input time series data and climate change scenarios. Five hydroclimatic variables (temperature, precipitation, CO₂, radiation, and humidity) are examined using sensitivity tests of individual and coupled variables with a constant change and coupled variables with a monthly change. Results indicate that the most influential variable on annual water yield is precipitation; and, the most influential variable on the timing of streamflow is temperature. Carbon dioxide, radiation, and humidity each noticeably impact water yield, but less significantly. The coupled variable analyses represent a more realistic climate change regime and reflect the combined response of the basin to each variable; for example, increased temperature offsets the effects of increased precipitation and magnifies the effects of decreased precipitation. This paper shows that the hydrologic response to climate change depends largely on the hydroclimatic variables examined and that each variable has a unique effect (e.g., magnitude, timing) on water yield.     

Impacts of Dams on Flow Regimes in Three Headwater Subbasins of the Columbia River Basin,United States1

Moore, Johnnie N., Alicia S. Arrigoni, and Andrew C. Wilcox, 2012. Impacts of Dams on Flow Regimes in Three Headwater Subbasins of the Columbia River Basin, United States. Journal of the American Water Resources Association (JAWRA) 48(5): 925‐938. DOI: 10.1111/j.1752‐1688.2012.00660.x Abstract: We compared long‐term changes in flow regimes resulting from climate change with those resulting from dams in three matched pairs of natural and modified headwater subbasins of the Columbia River. Based on the analysis of 12 flow‐regime metrics, we found that damming had minimal effect on most quantity of flow metrics, but major effect on timing of flow metrics, especially those representing “spring runoff.” In all modified subbasins, “spring runoff” metrics occurred much earlier than natural flow (up to ～44 days earlier for April‐July flows). Storage capacity modulated the magnitude of timing of flow‐metric changes, with the largest storage capacity leading to the most change. However, even in subbasins with low storage capacity, we found significant change in most timing of flow metrics. We also found that damming, especially in subbasins with higher storage capacity, overwhelmed climate variability in all basins for most flow metrics. This shows that reservoir operations need to be modified to more closely match the natural timing of flow regimes to promote positive ecologic response in modified rivers, even in basins where quantity of flow metrics have not changed substantially as a result of damming.     

Oregon Hydrologic Landscapes: A Classification Framework1

Wigington, Parker J., Jr., Scott G. Leibowitz, Randy L. Comeleo, and Joseph L. Ebersole, 2012. Oregon Hydrologic Landscapes: A Classification Framework. Journal of the American Water Resources Association (JAWRA) 1‐20. DOI: 10.1111/jawr.12009 Abstract: There is a growing need for hydrologic classification systems that can provide a basis for broad‐scale assessments of the hydrologic functions of landscapes and watersheds and their responses to stressors such as climate change. We developed a hydrologic landscape (HL) classification approach that describes factors of climate‐watershed systems that control the hydrologic characteristics of watersheds. Our assessment units are incremental watersheds (i.e., headwater watersheds or areas draining directly into stream reaches). Major components of the classification include indices of annual climate, climate seasonality, aquifer permeability, terrain, and soil permeability. To evaluate the usefulness of our approach, we identified 30 rivers with long‐term streamflow‐gauging records and without major diversions and impoundments. We used statistical clustering to group the streams based on the shapes of their annual hydrographs. Comparison of the streamflow clusters and HL distributions within river basin clusters shows that the Oregon HL approach has the ability to provide insights about the expected hydrologic behavior of HLs and larger river basins. The Oregon HL approach has potential to be a useful framework for comparing hydrologic attributes of streams and rivers in the Pacific Northwest.     

REGULATED RIVER MODELING FOR CLIMATE CHANGE IMPACT ASSESSMENT: THE MISSOURI RIVER1

ABSTRACT: The Great Plains of the United States, drained primanly by the Missouri River, are very sensitive to shifts in climate. The six main stem dams on the Missouri River control more than one‐half of the nearly 1.5 million square kilometer basin and can store three times the annual inflow from upstream. The dams are operated by the U.S. Army Corps of Engineers using a Master Manual that describes system priorities and benefits. The complex operational rules were incorporated into the Soil and Water Assessment Tool computer model (SWAT). SWAT is a distributed parameter rainfall‐runoff model capable of simulating the transpiration suppression effects of CO₂ enrichment. The new reservoir algorithms were calibrated using a 25‐year long historic record of basin climate and discharge records. Results demonstrate that it is possible to incorporate the operation of a highly regulated river system into a complex rainfall‐runoff model. The algorithms were then tested using extreme climate scenarios indicative of a prolonged drought, a short drought, and a ten percent increase in basin‐wide precipitation. It is apparent that the rules for operating the reservoirs will likely require modification if, for example, upper‐basin precipitation were to increase only ten percent under changed climate conditions.     

A System Dynamics Model for Conjunctive Management of Water Resources in the Snake River Basin

The Pacific Northwest is expected to witness changes in temperature and precipitation due to climate change. In this study, we enhance the Snake River Planning Model (SRPM) by modeling the feedback loop between incidental recharge and surface water supply resulting from surface water and groundwater extraction for irrigation and provide a case study involving climate change impacts and management scenarios. The new System Dynamics‐Snake River Planning Model (SD‐SRPM) is calibrated to flow at Box Canyon Springs located along a major outlet of the East Snake Plain Aquifer. A calibration of the model to flow at Box Canyon Springs, based on historic diversions (1950‐1995) resulted in an r² value of 0.74 and a validation (1996‐2005) r² value of 0.60. After adding irrigation entities to the model an r² value of 0.91, 0.88, and 0.87 were maintained for modeled vs. observed (1991‐2005) end‐of‐month reservoir content in Jackson Lake, Palisades, and American Falls, the three largest irrigation reservoirs in the system. The scenarios that compared the impacts of climate change were based on ensemble mean precipitation change scenarios and estimated changes to crop evapotranspiration (ET). Increased ET, despite increased precipitation, generally increased surface water shortages and discharge of springs. This study highlights the need to develop and implement models that integrate the human‐natural system to understand the impacts of climate change.     

Assessing the Impact of Areal Precipitation Input on Streamflow Simulations Using the SWAT Model1

Masih Ilyas, Shreedhar Maskey, Stefan Uhlenbrook, and Vladimir Smakhtin, 2011. Assessing the Impact of Areal Precipitation Input on Streamflow Simulations Using the SWAT Model. Journal of the American Water Resources Association (JAWRA) 47(1):179‐195. DOI: 10.1111/j.1752‐1688.2010.00502.x Abstract: Reduction of input uncertainty is a challenge in hydrological modeling. The widely used model Soil Water Assessment Tool (SWAT) uses the data of a precipitation gauge nearest to the centroid of each subcatchment as an input for that subcatchment. This may not represent overall catchment precipitation conditions well. This paper suggests an alternative – using areal precipitation obtained through interpolation. The effectiveness of this alternative is evaluated by comparing its simulations with those based on the standard SWAT precipitation input procedure. The model is applied to mountainous semiarid catchments in the Karkheh River basin, Iran. The model performance is evaluated at daily, monthly, and annual scales by using a number of performance indicators at 15 streamflow gauging stations each draining an area in the range of 590‐42,620 km². The comparison suggests that the use of areal precipitation improves model performance particularly in small subcatchments in the range of 600‐1,600 km². The modified areal precipitation input results in increased reliability of simulated streamflows in the areas of low rain gauge density. Both precipitation input methods result in reasonably good simulations for larger catchments (over 5,000 km²). The use of areal precipitation input improves the accuracy of simulated streamflows with spatial resolution and density of rain gauges having significant impact on results.     

Trends in Western U.S. Snowpack and Related Upper Colorado River Basin Streamflow1

Miller, W. Paul and Thomas C. Piechota, 2011. Trends in Western U.S. Snowpack and Related Upper Colorado River Basin Streamflow. Journal of the American Water Resources Association (JAWRA) 47(6):1197–1210. DOI: 10.1111/j.1752‐1688.2011.00565.x Abstract: Water resource managers in the Western United States (U.S.) are currently faced with the challenge of adapting to unprecedented drought and uncertain impacts of climate change. Recent research has indicated increasing regional temperature and changes to precipitation and streamflow characteristics throughout the Western U.S. As such, there is increased uncertainty in hydroclimatological forecasts, which impact reservoir operations and water availability throughout the Western U.S., particularly in the Colorado River Basin. Previous research by the authors hypothesized a change in the character of precipitation (i.e., the frequency and amount of rainfall and snowfall events) throughout the Colorado River Basin. In the current study, 398 snowpack telemetry stations were investigated for trends in cumulative precipitation, snow water equivalent, and precipitation events. Observations of snow water equivalent characteristics were compared to observations in streamflow characteristics. Results indicate that the timing of the last day of the snow season corresponds well to the volume of runoff observed over the traditional peak flow season (April through July); conversely, the timing of the first day of the snow season does not correspond well to the volume of runoff observed over the peak flow season. This is significant to water resource managers and river forecasters, as snowpack characteristics may be indicative of a productive or unproductive runoff season.     

Climate Change and Floodplain Delineation in Two Southern Quebec River Basins1

Laforce, Serge, Marie‐Claude Simard, Robert Leconte, and François Brissette, 2011. Climate Change and Floodplain Delineation in Two Southern Quebec River Basins. Journal of the American Water Resources Association (JAWRA) 47(4):785‐799. DOI: 10.1111/j.1752‐1688.2011.00560.x Abstract: A methodology is presented for mapping the flooded extent of rivers under projected climate change. The methodology follows a top‐down modeling approach, where future climate projections generated by global climate models (GCMs) are downscaled to the watershed scale and used as input to hydrological and hydrodynamic models for predicting future river flows and associated open water levels. A range of possible future climate responses are taken into account, allowing quantification of flood‐mapping uncertainties resulting from GCM structure and greenhouse gas emission scenarios (GHGES). Probabilistic projections of future flood zones are developed by assuming that all GCMs and GHGES be equally weighted. The proposed methodology was applied to two river basins located in southern Quebec, Canada, for the time horizons 2020 and 2080. Twenty‐ and hundred‐year floods were computed and corresponding flood maps have been produced. Results indicate that there is a general trend toward an increased spring peak discharge for the Châteauguay River Basin and a decrease for the du Nord River Basin at the 2020 horizon. A less obvious trend was observed for the 2080 horizon, some GCM‐GHGES producing an increase in spring peak flows, whereas others would result in a less severe spring flood. These uncertainties in flood flows have cascaded into uncertainties in the corresponding flooded extent and represented as probabilistic flood maps.     

APPLICATIONS OF A GIS FOR MODELING THE SENSITIVITY OF WATER RESOURCES TO ALTERATIONS IN CLIMATE IN THE GUNNISON RIVER BASIN,COLORADO1

ABSTRACT: The Gunnison River drains a mountainous basin in western Colorado, and is a large contributor of water to the Colorado River. As part of a study to assess water resource sensitivity to alterations in climate in the Gunnison River basin, climatic and hydrologic processes are being modeled. A geographic information system (GIS) is being used in this study as a link between data and modelers - serving as a common data base for project personnel with differing specialties, providing a means to investigate the effects of scale on model results, and providing a framework for the transfer of parameter values among models. Specific applications presented include: (1) developing elevation grids for a precipitation model from digital elevation model (DEM) point-elevation values, and visualizing the effects of grid resolution on model results; (2) using a GIS to facilitate the definition and parameterization of a distributed-parameters, watershed model in multiple basins; and (3) nesting atmospheric and hydrologic models to produce possible scenarios of climate change.     

IMPACTS OF CLIMATE CHANGE ON MISSOURI RWER BASIN WATER YIELD1

ABSTRACT: Water from the Missouri River Basin is used for multiple purposes. The climatic change of doubling the atmospheric carbon dioxide may produce dramatic water yield changes across the basin. Estimated changes in basin water yield from doubled CO₂ climate were simulated using a Regional Climate Model (RegCM) and a physically based rainfall‐runoff model. RegCM output from a five‐year, equilibrium climate simulation at twice present CO₂ levels was compared to a similar present‐day climate run to extract monthly changes in meteorologic variables needed by the hydrologic model. These changes, simulated on a 50‐km grid, were matched at a commensurate scale to the 310 subbasin in the rainfall‐runoff model climate change impact analysis. The Soil and Water Assessment Tool (SWAT) rainfall‐runoff model was used in this study. The climate changes were applied to the 1965 to 1989 historic period. Overall water yield at the mouth of the Basin decreased by 10 to 20 percent during spring and summer months, but increased during fall and winter. Yields generally decreased in the southern portions of the basin but increased in the northern reaches. Northern subbasin yields increased up to 80 percent: equivalent to 1.3 cm of runoff on an annual basis.     

Temporal and Spatial Variability of Water Supply Stress in the Haihe River Basin,Northern China1

Ji, Yuhe, Liding Chen, and Ranhao Sun, 2012. Temporal and Spatial Variability of Water Supply Stress in the Haihe River Basin, Northern China. Journal of the American Water Resources Association (JAWRA) 48(5): 999‐1007. DOI: 10.1111/j.1752‐1688.2012.00671.x Abstract: Water resources are becoming increasingly stressed under the influence of climate change and population growth in the Haihe River Basin, Northern China. Assessing the temporal and spatial variability of water supply stress is urgently needed to mitigate water crisis caused by water resource reallocation. Water supply and use data were compiled for the time period of 1998‐2003 in this synthesis study. The Water Supply Stress Index (WSSI) as defined as Water Demand/Water Supply was used to quantitate whether water supply could meet the demand of human activities across the study region. We found a large spatial gradient of water supply stress in the study region, being much higher in the eastern subbasins (ranging from 2.56 to 4.31) than the west subbasins (ranging from 0.56 to 1.92). The eastern plain region not only suffered more serious water supply stress but also had a much higher interannual variability than the western hilly region. The uneven spatial distribution of water supply stress might result from the distribution of land use, population, and climate. Future climate change and rapid economic development are likely to aggravate the existing water crisis in the study region.     

Incorporating Climate Change Into Water Resources Planning in England and Wales1

Arnell, Nigel W., 2011. Incorporating Climate Change Into Water Resources Planning in England and Wales. Journal of the American Water Resources Association (JAWRA) 47(3):541‐549. DOI: 10.1111/j.1752‐1688.2011.00548.x Abstract: Public water supplies in England and Wales are provided by around 25 private‐sector companies, regulated by an economic regulator (Ofwat) and environmental regulator (Environment Agency). As part of the regulatory process, companies are required periodically to review their investment needs to maintain safe and secure supplies, and this involves an assessment of the future balance between water supply and demand. The water industry and regulators have developed an agreed set of procedures for this assessment. Climate change has been incorporated into these procedures since the late 1990s, although has been included increasingly seriously over time and it has been an effective legal requirement to consider climate change since the 2003 Water Act. In the most recent assessment in 2009, companies were required explicitly to plan for a defined amount of climate change, taking into account climate change uncertainty. A “medium” climate change scenario was defined, together with “wet” and “dry” extremes, based on scenarios developed from a number of climate models. The water industry and its regulators are now gearing up to exploit the new UKCP09 probabilistic climate change projections – but these pose significant practical and conceptual challenges. This paper outlines how the procedures for incorporating climate change information into water resources planning have evolved, and explores the issues currently facing the industry in adapting to climate change.     

Water Resources Modeling of the Ganges‐Brahmaputra‐Meghna River Basins Using Satellite Remote Sensing Data1

Nishat, Bushra and S.M. Mahbubur Rahman, 2009. Water Resources Modeling of the Ganges‐Brahmaputra‐Meghna River Basins Using Satellite Remote Sensing Data. Journal of the American Water Resources Association (JAWRA) 45(6):1313‐1327. Abstract: Large‐scale water resources modeling can provide useful insights on future water availability scenarios for downstream nations in anticipation of proposed upstream water resources projects in large international river basins (IRBs). However, model set up can be challenging due to the large amounts of data requirement on both static states (soils, vegetation, topography, drainage network, etc.) and dynamic variables (rainfall, streamflow, soil moisture, evapotranspiration, etc.) over the basin from multiple nations and data collection agencies. Under such circumstances, satellite remote sensing provides a more pragmatic and convenient alternative because of the vantage of space and easy availability from a single data platform. In this paper, we demonstrate a modeling effort to set up a water resources management model, MIKE BASIN, over the Ganges, Brahmaputra, and Meghna (GBM) river basins. The model is set up with the objective of providing Bangladesh, the lowermost riparian nation in the GBM basins, a framework for assessing proposed water diversion scenarios in the upstream transboundary regions of India and deriving quantitative impacts on water availability. Using an array of satellite remote sensing data on topography, vegetation, and rainfall from the transboundary regions, we demonstrate that it is possible to calibrate MIKE BASIN to a satisfactory level and predict streamflow in the Ganges and Brahmaputra rivers at the entry points of Bangladesh at relevant scales of water resources management. Simulated runoff for the Ganges and Brahmaputra rivers follow the trends in the rated discharge for the calibration period. However, monthly flow volume differs from the actual rated flow by (?) 8% to (+) 20% in the Ganges basin, by (?) 15 to (+) 12% in the Brahmaputra basin, and by (?) 15 to (+) 19% in the Meghna basin. Our large‐scale modeling initiative is generic enough for other downstream nations in IRBs to adopt for their own modeling needs.     

Multicriteria Evaluation of Water Resources Sustainability in the Context of Watershed Management1

Kang, Min‐Goo and Gwang‐Man Lee, 2011. Multicriteria Evaluation of Water Resources Sustainability in the Context of Watershed Management. Journal of the American Water Resources Association (JAWRA) 47(4):813‐827. DOI: 10.1111/j.1752‐1688.2011.00559.x Abstract: To evaluate water resources sustainability at the watershed scale within a river basin’s context, the Water Resources Sustainability Evaluation Model is developed. The model employs 4 criteria (economic efficiency, social equity, environmental conservation, and maintenance capacity) and has 16 indicators, integrating them using their relative weights. The model is applied to evaluate the water resources sustainability of watersheds in the Geum River basin, South Korea. A geographic information system is employed to efficiently build a database for the indicators, and the values of the indicators are normalized using the probability distribution functions fitted to the datasets of the indicators. The evaluation results show that, overall, the water resources sustainability of the watersheds in the upper basin is better than other areas due to the good environmental conditions and the dam management policies of South Korea. The analysis of the correlations among the model’s components and the comparison between the results of the model and the Water Poverty Index show that the model can provide reasonable evaluation results for the water resources sustainability of watersheds. Consequently, it is concluded that the model can be an effective tool for evaluating the states of water resource management from the perspective of sustainable development and provide a basis on which to create policies for improving any inadequacies in watersheds.     

Modeling Hydrological and Environmental Consequences of Climate Change and Urbanization in the Boise River Watershed,Idaho

The potential impacts driven by climate variability and urbanization in the Boise River Watershed (BRW), located in southwestern Idaho, are evaluated. The outcomes from Global Circulation Models (GCMs) and land use and land cover (LULC) analysis have been incorporated into a hydrological and environmental modeling framework to characterize how climate variability and urbanization can affect the local hydrology and environment at the BRW. The combined impacts of future climate and LULC change are also evaluated relative to the historical baseline conditions. For modeling exercises, Hydrological Simulation Program‐Fortran (HSPF) is used in parallel computing and statistical techniques, including spatial downscaling and bias correlation, are employed to evaluate climate consequences derived from GCMs as well. The implications of climate variability and land use change driven by urbanization are then observed to evaluate how these overall global challenges can affect water quantity and quality conditions at the BRW. The results show the combined impacts of both climate change and urbanization can lead to more seasonal variability of streamflow (from ?27.5% to 12.5%) and water quality, including sediment (from ?36.5% to 49.3%), nitrogen (from ?24% to 124.2%), and phosphorus (from ?13.3% to 21.2%) during summer and early fall over the next several decades.