Modeling the Effects of Projected Climate Warming on Stream Temperatures in the Stillaguamish River Basin PDF Download

Author: Emily Esther Gebheim Smoot
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Category : Chinook salmon
Languages : en
Pages : 0

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The Stillaguamish River is a snow-and-rain mixed basin and the fifth largest river in the Puget Sound basin. Elevations in the 1700 km2 Stillaguamish River basin reach roughly 2000 m and historically a snowpack is sustained above 1000 m. Snowmelt in the basin is important for sustaining spring and summer streamflow and buffering stream temperatures. Stream temperature increases are of significant concern because of the threatened Chinook salmon (Oncorhynchus tshawytscha) population. I reexamined projected stream temperatures in the Stillaguamish River by forcing the coupled Distributed Hydrology Soil Vegetation Model and River Basin Model with dynamically downscaled meteorological forcings from the Weather Research and Forecasting model and projected changes in the entire basin, including the Pilchuck subbasin and mainstem through 2099 by applying 12 dynamically downscaled Global Climate Models with high emission scenarios of RCP 8.5. Using an updated version of the River Basin Model, I applied tributary specific calibration parameters and calibrated modeled streamflow and temperature using historical gauges and field measurements. My model calibrations and projections are consistent with other modeling studies in the Stillaguamish and other western Cascade watersheds. Snow covered area in the basin is projected to decrease by 74%, and summer streamflow decreases for the primary locations and at-risk tributaries are projected to be 48% and 53%, respectively for July and August at the end of the century. With the decreases in snowpack and streamflow, stream temperatures reach their peak earlier in the year, in July instead of August which was historically the warmest month. Stream temperatures are projected to increase by 14% on average for the larger primary reaches and 21% for the smaller at-risk tributaries by the 2080s for July and August. The greatest stream temperature increases are in mountainous reaches due to a reduced snowpack. The warmest stream temperatures are projected to occur in late summer along the mainstem of the Stillaguamish River. By the end of the century, six of nine locations examined will exceed the seven-day average daily maximum adult Chinook salmon lethality threshold (22.0 °C). These results indicate that continued work on climate adaptation actions and research will be required to improve Chinook salmon resiliency in the Stillaguamish River as the climate warms.

Author: Katherine Mary Clarke
Publisher:
ISBN:
Category : Salmonidae
Languages : en
Pages : 132

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The Stillaguamish River in northwest Washington State is an important regional water resource for local agriculture, industry, and First Nations tribes and a critical habitat for several threatened and endangered salmonid species, including the Chinook salmon. The river is currently subject to a temperature total maximum daily load, so it is important to understand how projected climate change will affect future stream temperatures and thus salmon populations. Snowpack is the main contributor to spring and summer streamflow and helps to mitigate stream temperatures as air temperatures rise through the summer in the South Fork of the Stillaguamish River. I used gridded historical meteorological data to calibrate the physically-based Distributed Hydrology Soil Vegetation Model and River Basin Model and then applied downscaled, gridded projected climate data to predict how a changing climate will influence hydrology and stream temperature in the South Fork basin through the end of the 21st century.

Author: Susan E. Dickerson
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 0

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The Nooksack River has its headwaters in the North Cascade Mountains and drains an approximately 2300 km2 watershed in northwestern Washington State. The timing and magnitude of streamflow in a high relief, snow-dominated drainage basin such as the Nooksack River basin is strongly influenced by temperature and precipitation. Forecasts of future climate made by general circulation models (GCMs) predict increases in temperature and variable changes to precipitation in western Washington, which will affect streamflow, snowpack, and glaciers in the Nooksack River basin. Anticipating the response of the river to climate change is crucial for water resources planning because municipalities, tribes, and industry depend on the river for water use and for fish habitat. I combined modeled climate forecasts and the Distributed-Hydrology-Soil-Vegetation Model (DHSVM) to simulate future changes to timing and magnitude of streamflow in the higher elevations of the Nooksack River, east of the confluence near Deming, Washington. The DHSVM is a physically based, spatially distributed hydrology model that simulates a water and energy balance at the pixel scale of a digital elevation model. I used recent meteorological and landcover data to calibrate and validate the DHSVM. Coarse-resolution GCM forecasts were downscaled to the Nooksack basin following the methods of previous regional studies (e.g., Palmer, 2007) for use as local-scale meteorological input to the calibrated DHSVM. Simulations of future streamflow and snowpack in the Nooksack River basin predict a range of magnitudes, which reflects the variable predictions of the climate change forecasts and local natural variability. Simulation results forecast increased winter flows, decreased summer flows, decreased snowpack, and a shift in timing of the spring melt peak and maximum snow water equivalent. Modeling results for future peak flow events indicate an increase in both the frequency and magnitudes of floods, but uncertainties are high for modeling the absolute magnitudes of peak flows. These results are consistent with previous regional studies which document that temperature-related effects on precipitation and melting are driving changes to snow-melt dominated basins (e.g., Hamlet et al., 2005; Mote et al., 2005; Mote et al., 2008; Adam et al., 2009).

Author: United States. Congress. Senate. Committee on Commerce, Science, and Transportation. Subcommittee on Oceans, Atmosphere, Fisheries, and Coast Guard
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 60

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Author: Allison Marshall Inouye
Publisher:
ISBN:
Category : Hydrologic models
Languages : en
Pages : 73

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In the Western United States where 50-70% of annual precipitation comes in the form of winter snowfall, water supplies may be particularly sensitive to a warming climate. We worked with a network of stakeholders in the Big Wood Basin, Idaho, to explore how climate change may affect water resources and identify strategies that may help mitigate the impacts. The 8,300 square kilometer region in central Idaho contains a mixture of public and private land ownership, a diversity of landcover ranging from steep forested headwaters to expansive desert shrublands to a concentrated area of urban development that has experienced a quadrupling of population since the 1970s. With nearly 60% of precipitation falling as winter snow, stakeholders expressed concern regarding the vulnerability of the quantity and timing of seasonal snowpack as well as surface water supplies used primarily for agricultural irrigation under projected climate change. Here, we achieve two objectives. The first is the development of a hydrologic model to represent the dynamics of the surface water system in the Big Wood Basin. We use the semi-distributed model Envision-Flow to represent surface water hydrology, reservoir operations, and agricultural irrigation. We calibrated the model using a multi-criteria objective function that considered three metrics related to streamflow and one metric related to snow water equivalent. The model achieved higher an efficiency of 0.74 for the main stem of the Big Wood River and 0.50 for the Camas Creek tributary during the validation period. The second objective is an analysis of the Big Wood Basin hydrology under alternative future climate scenarios. We forced the calibrated model with three downscaled CMIP5 climate model inputs representing a range of possible future conditions over the period 2010-2070. The climate models simulate an increase in basin average annual air temperature ranging from 1.6-5.7oC in the 2060s compared to the 1980-2009 average. The climate models show less of a clear trend regarding precipitation but in general, one model simulates precipitation patterns similar to historic, one is slightly wetter than historic, and one is slightly drier than historic by the mid-21st century. Under these future climate scenarios, the depth of April 1 SWE may decline by as much as 92% in the 2060s compared to the historic average. Mid to high elevations exhibit the largest reductions in SWE. Simulated streamflows show a shift in timing, with peak flows occurring up to three weeks earlier and center of timing from two to seven weeks earlier in the 2050-2069 period compared to the historic period. Reduced peak flows of 14-70% were simulated by mid-century. The simulated total annual streamflow, though, fell within the historic interquartile range for most years in the future period. These and other metrics considered suggest that the surface water hydrology of the Big Wood Basin is likely to be impacted by climate change. If the natural water storage provided by the annual snowpack is reduced and timing of streamflows shifts, water resource use and management may need to change in the future. This work provides a foundation from which to explore alternative management scenarios. The approach used here can be transferred to other watersheds to further assess how water resources may be affected by climate change.

Author: Oriana Shackell Chegwidden
Publisher:
ISBN:
Category :
Languages : en
Pages : 103

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Whether at the scale of a small watershed or a large multinational basin, it has become common practice for water managers to use ensembles of projections to plan for hydrologic change. Better understanding these ensembles can help improve the design of future hydrologic modeling studies. In this dissertation I will describe three uses of hydroclimate ensembles to support water resource planning efforts. In Chapter 2 I present a large ensemble of hydrologic climate change projections for the Columbia River basin within the hydroclimatically diverse Pacific Northwestern United States and Canada (PNW). I show how methodological decisions in the modeling process variously affect the projections of change depending on hydroclimatic regime and metric of interest. In Chapter 3 I delve deeper into the PNW to examine the impactful metric of changes in floods, determining how dominant flood generating processes will evolve under climate change. I also calculate first-order sensitivities of high flows to changes in climate. In Chapter 4, I apply the lessons learned from the first two studies, conducted within the transboundary Columbia River basin, to transboundary rivers around the world. I present a study identifying hot spots of changes in water availability and hydropolitical risk for over 80 rivers (esp. transboundary rivers) around the world as projected by results from the Coupled Model Intercomparison Project Phase 6. Finally, I present how the findings from this dissertation can contribute to improved hydroclimate impacts assessments.

Author: Awoke Dagnew Teshager
Publisher:
ISBN:
Category : Agricultural ecology
Languages : en
Pages : 246

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Applications of the SWAT model typically involve delineation of a watershed into subwatersheds/subbasins that are then further subdivided into hydrologic response units (HRUs) which are homogeneous areas of aggregated soil, landuse, and slope and are the smallest modeling units used within the tool. In a standard SWAT application, multiple potential HRUs (farm fields) in a subbasin are usually aggregated into a single HRU feature. In other words, the standard version of the model combines multiple potential HRUs (farm fields) with the same landuse/landcover (LULC), soil, and slope, but located in different places within a subbasin (spatially non-unique), and considers them as one HRU. In this study, ArcGIS pre-processing procedures were developed to spatially define a one-to-one match between farm fields and HRUs (spatially unique HRUs) within a subbasin prior to SWAT simulations to facilitate input processing, input/output mapping, and further analysis at the individual farm field level. Model input data such as LULC, soil, crop rotation and other management data were processed through these HRUs. The SWAT model was then calibrated/validated for the Raccoon River watershed in Iowa for 2002 to 2010 and the Big Creek River watershed in Illinois for 2000 to 2003. SWAT was able to replicate annual, monthly and daily streamflow, as well as sediment, nitrate and mineral phosphorous within recommended accuracy in most cases. The one-to-one match between farm fields and HRUs created and used in this study is a first step in performing LULC change, climate change impact, and other analyses in a more spatially explicit manner. The calibrated and validated SWAT model was then used to assess agricultural scenario and climate change impacts on watershed water quantity, quality, and crop yields. Modeling impacts of agricultural scenarios and climate change on surface water quantity and quality provides useful information for planning effective water, environmental, and land use policies. Despite the significant impacts of agriculture on water quantity and quality, limited literature exists modeling the combined impacts of agricultural scenarios and climate change on crop yields and watershed hydrology. Here, SWAT, was used to model the combined impacts of five agricultural scenarios and three climate scenarios downscaled using eight climate models. These scenarios were implemented in a well calibrated SWAT model for the Raccoon River watershed (RRW), IA. We run the scenarios for the historical baseline, early-century, mid-century, and late-century periods. Results indicate that historical and more corn intensive agricultural scenarios with higher CO2 emissions consistently result in more water in the streams and greater water quality problems, especially late in the 21st century. Planting more switchgrass, on the other hand, results in less water in the streams and water quality improvements relative to the baseline. For all given agricultural landscapes simulated, all flow, sediment and nutrient outputs increase from early-to-late century periods for the RCP4.5 and RCP8.5 climate scenarios. We also find that corn and switchgrass yields are negatively impacted under RCP4.5 and RCP8.5 scenarios in the mid and late 21st century. Finally, various agricultural best management practice (BMP) scenarios were evaluated for their efficiency in alleviating watershed water quality problems. The vast majority of the literature on efficiency assessment of BMPs in alleviating water quality problems base their scenarios analysis on identifying subbasin level simulation results. In the this study, we used spatially explicit HRUs, defined using ArcGIS-based pre-processing methodology, to identify Nitrate (NO3) and Total Suspended Solids (TSS) hotspots at the HRU/field level, and evaluate the efficiency of selected BMPs in a large watershed, RRW, using the SWAT model. Accordingly, analysis of fourteen management scenarios were performed based on systematic combinations of five agricultural BMPs (fertilizer/manure management, changing cropland to perennial grass, vegetative filter strips, cover crops and shallower tile drainage systems) aimed to reduce NO3 and TSS yields from targeted hotspot areas in the watershed at field level. Moreover, implications of climate change on management practices, and impacts of management practices on water availability and crop yield and total production were assessed. Results indicated that either implementation of multiple BMPs or conversion of an extensive area into perennial grass may be required to sufficiently reduce nitrate loads to meet the drinking water standard. Moreover, climate change may undermine the effectiveness of management practices, especially late in the 21 st century. The targeted approach used in this study resulted in slight decreases in watershed average crop yields, hence the reduction in total crop production is mainly due to conversion of croplands to perennial grass.

Author: Manoj Jha
Publisher:
ISBN:
Category :
Languages : en
Pages : 396

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This dissertation describes the modeling efforts on the Upper Mississippi River Basin (UMRB) using the Soil and Water Assessment Tool (SWAT) model. The main goal of this study is to apply the SWAT model to the UMRB to evaluate the model as a tool for agricultural policy analysis and climate change impact analysis. A sensitivity analysis using influence coefficient method was conducted for eight selected hydrologic input parameters to identify the most to the least sensitive parameters. Calibration and validation of SWAT were performed for the Maquoketa River Watershed for streamflow on annual and monthly basis. The model was then validated for the entire UMRB streamflow and evaluated for a climate change impact analysis. The results indicate that the UMRB hydrology is very sensitve to potential future climate changes. The impact of future climate change was then explored for the streamflow by using two 10-year scenario periods (1990 and 2040s) generated by introducing a regional climate model (RegCM2) to dynamically downscale global model (HadCM2) results. The combined GCM-RCM-SWAT model system produced an increase in future scenario climate precipitation of 21% with a resulting 50% increase in total water yield in the UMRB. Furthermore, evaluation of model-introduced uncertainties due to use of SWAT, GCM, and RCM models yielded the highest percentage bias (18%) for the GCM downscaling error. Building upon the above SWAT validation, a SWAT modeling framework was constructed for the entire UMRB, which incorporates more detailed input data and is designed to assess the effects of land use, climate, and soil conditions on streamflow and water quality. An application of SWAT is presented for the Iowa and Des Moines River watersheds within the modeling framework constructed for the UMRB. A scenario run where conservation tillage adoption increased to 100% found a small sediment reduction of 5.8% for Iowa River Watershed and 5.7% for Des Moines River Watershed. On per-acre basis, sediment reduction for Iowa and Des Moines River Watersheds was found to be 1.86 and 1.18 metric tons respectively. Furthermore an attempt to validate the model for the entire UMRB yielded strong annual results.

Author: Joe Allen Intermill
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 306

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 28

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We develop and test a physically based semi-Lagrangian water body temperature model to apply climatological data and thermal pollution from river-based power plants to historical river flow data in order to better understand climate change impacts on surface water temperature and thermal power plant withdrawal allowances. The model is built for rapid assessment and use in Integrated Assessment Models. We first test the standalone model on a 190km river reach, the Delaware River, where we have detailed flow and temperature data. An R2 of 0.88 is obtained on hourly data for this initial test. Next, we integrate the standalone temperature model into a series of models -- rainfall-runoff model, water demand model, water resource management model, and power plant uptake and release model -- for the contiguous USA (CONUS), with about 19,000 segments total. With this system in place, we then validate the standalone water temperature model within the system for 16 river stations throughout the CONUS, where we have measured daily temperature data. The model performs reasonably well with a median R2 of 0.88. A variety of climate and emissions scenarios are then applied to the model to test regions of higher vulnerability to river temperature environmental violations, making use of output from two GCMs and six emissions scenarios focusing on projections out to 2050. We find that the two GCMs project significantly different impacts to water temperature, driven largely by the resulting changes in streamflow from the two models. We also find significantly different impacts on the withdrawal allowed by thermal power plants due to environmental regulations. Potential impacts on generation are between +3% and -4% by 2050 for the unconstrained emissions case and +3.5% to -2% for the stringent GHG mitigation policy (where 1% is equivalent to 32 TWh, or about 3 billion USD/year using 2005 electricity prices). We also find that once-through cooling plants are most vulnerable to climate change impacts, with summer impacts ranging from -0.8% to -6% for the unconstrained emissions case and +2.1% to -3.7% for the stringent GHG emissions case.