Browsing by Subject "Watershed"

Now showing 1 - 14 of 14
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    Application of the Soil and Water Assessment Tool (SWAT) to the Willow River Watershed, St. Croix County, Wisconsin.
    (2010-12) Murphy, Marylee Smith
    Identifying critical source areas of sediment and phosphorus nonpoint pollutant loads under alternative land use scenarios is aided by the use of hydrologic models. We applied the Soil and Water Assessment Tool (SWAT) to the Willow River watershed in St. Croix County, Wisconsin, to examine the effects of possible future scenarios and best management practices. The model was calibrated and validated to water year (WY) 1999 and WY2006 datasets, respectively, with land use configured for each year. The model performed well in calibration, but could not simulate conditions outside of the calibration conditions in the validation dataset. Sediment and phosphorus trapping was influenced by trapping between the landscape source and the watershed outlet in closed-drainage lakes, flow-through wetlands, and on-stream reservoirs. The relative contributions of pollutants were related to the landscape position of the source area and the number and trapping efficiency of the intermediate traps in the flow path. We simulated best management practices including lowered soil-test phosphorus, increased conservation tillage, lowered cattle dietary phosphorus, and changed agricultural crop rotations. Simulations demonstrated that conversion to mulch tillage and no-till from conventional tillage could reduce sediment yield on the converted lands by 3% to 27% and phosphorus yield by 5% to 21%. For the current mix of agricultural land management in the Willow Watershed, converting all cropland to mulch tillage would reduce watershed export of phosphorus by 1% and sediment export by 1%. Converting all of the agricultural land to no-till produced a modeled decrease in watershed export of sediment of 2% and a decrease in phosphorus of 7%. Simulations also demonstrated a 22% reduction watershed phosphorus export by reducing average agricultural soil-test phosphorus to 20 ppm. Converting all farm land from a mixture of cash grain rotations to a dairy rotation that included two years of corn and three years of alfalfa caused a modeled reduction in watershed phosphorus export of 15% and a modeled reduction in sediment export of iii 5%. Continued conversion of agricultural land to rural residential land uses produced lower modeled loads of watershed sediment export up to 13% and phosphorus export up to 27% depending on the area developed and the average lot size. Changes in point source phosphorus because of better wastewater treatment caused a decrease in modeled phosphorus delivery of 13% between the calibration and validation time periods. Alternative climate scenarios were also simulated, showing that evapotranspiration was the driver of the altered hydrologic cycle, and thus the driver of reduced sediment and phosphorus export.
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    Effects of Forest Cover Change on Streamflow in Low Relief Glaciated Catchments
    (2020-08) McEachran, Zachary
    Forest cover disturbance, climate change, and their interaction can alter how catchments store and process water, which has ramifications for all aspects of the hydrologic cycle, including flood risk, channel geomorphology, and water quality. Catchments in the boreal-temperate transition zone may be especially vulnerable to these factors. While streams in this glaciated region have low-topographic relief and may originate from expansive wetlands, much of the past research on forest disturbance-streamflow relationships comes from regions where landscape characteristics and subsequent hydrological function is substantially different, e.g. mountainous regions with bedrock close to the soil surface. Further, most work investigating the forest-streamflow relationship occurs at small spatial scales (< 10 km2). I seek to fill a knowledge gap by 1) creating a new conceptual model for how forest cover change affects sediment yield in managed temperate forested catchments that accounts for how sediment yield responds to altered catchment hydrology, 2) developing a new approach to peak-flow analysis using paired catchment experiments at the Marcell Experimental Forest (MEF) in north-central Minnesota, and 3) investigating how forest cover change and climate affect peak flows and water yield in large (> 10 km2) catchments in Minnesota. My results indicate that in low-relief glaciated regions, glacial geology controls sediment yield response to forest harvesting; forest harvesting may affect large peak flows by altering the occurrence probabilities of large peaks at the small catchment scale; and streamflow in larger catchments is largely controlled by climate variation, with land cover a minor yet discernable driver of peak flows and water yield. These results are framed within a new forest harvesting/water quality framework that holistically accounts for all sources of increased sediment yield after forest harvesting in diverse landscapes. Please note that multiple of these chapters are under peer review in scientific journals as of August 2020, and those versions will supersede this dissertation for purposes of citations.
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    Essays on the economics of bioenergy and emissions trading.
    (2012-06) Moon, Jin-Young
    The three essays in this dissertation focus on the economics of bioenergy and emissions trading. Chapter Two analyzes the economic impacts of cellulosic feedstock production in a major watershed of south-central Minnesota. A regional economic model of agricultural production in the watershed is constructed. By integrating environmental parameters from a biophysical simulation analysis of the watershed, the model focuses on economic and environmental issues associated with increasing use of two cellulosic feedstocks, corn stover and switchgrass, at the watershed level. Results indicate that corn stover can be produced at a relatively low marginal cost compared to switchgrass. Sediment and nutrient losses from corn stover production make switchgrass more promising on environmental grounds but the high marginal cost of production causes switchgrass to cover only small part of crop land if farmers have unrestricted choice about how to supply cellulosic feedstocks. Chapter Three extends the model of chapter Two to examine the tradeoffs between cellulosic feedstock production and water quality by analyzing policy options targeted to address those tradeoffs. Policy alternatives considered include restrictions on total nitrate-N load in the watershed and production subsidies for switchgrass – an energy crop with potential environmental benefits. Restricting nitrate-N loads increases the cost of cellulosic feedstock supply and in some circumstances makes switchgrass production an economical alternative. Switchgrass production subsidies, if sufficiently high can increase feedstock supply while reducing or eliminating the negative effects of feedstock production on water quality. Chapter Four examines how uncertainty in emissions affects firms’ decision of permit purchase and abatement. This paper extends previous models of emissions trading by considering uncertainty as well as the order of firms’ decisions about abatement and permit trading. When there is uncertainty about emissions, total expected emissions are the same regardless of the order of moves. The results show that whether firms abate more under uncertainty is dependent on the expected penalty cost and marginal abatement cost. If the expected marginal penalty cost is greater than the marginal abatement cost, the firm will choose to reduce emissions and abate more under uncertainty. When expected penalty is greater than marginal cost of abatement, increase in uncertainty makes expected emissions decrease given unit penalty fee.
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    Estimating renewable water flux using landscape features.
    (2011-07) Peterson, Heidi Marie
    The complexity of vadose zone, groundwater and surface water interactions presents hydrological research challenges specifically in the area of quantifying groundwater recharge. To acknowledge unity of the surface and groundwater systems requires an interdisciplinary approach that organizes knowledge about an analysis domain based on hydrologic units rather than on aquifers, enabling an integrative, system viewpoint of the terrestrial hydrologic system. By establishing the relationship between landscape components and water balance characteristics, hydrologic response units are established. This dissertation hypothesizes that regionalization can identify hierarchical hydrogeological units (HHUs) composed of unique combinations of surface water, groundwater and vadose zone landscape characteristics with statistically different recharge rates (p<0.05), and that these units can be used to estimate the renewable water flux of the groundwater system. Three interdependent studies were pursued to address the hypothesis: (i)a statewide regionalization of mean annual streamflow that defined independent hydrologic regimes within Minnesota; (ii) a regionalization focusing on East Central Minnesota which established unique HHUs based on unique combinations of landscape characteristics with statistically significant differences in mean minimum recharge; (iii) a water management application which used the regionalization methodology to quantify the renewable groundwater flux and assess a water resources sustainability indicator within the Twin Cities Metropolitan Area. Results from the three studies indicate that landscape characteristics control the rate of renewable water flux within the groundwater system. The results identified at one analysis scale could be used to extrapolate data at refined scales where long-term hydrologic monitoring data is lacking but informed water management decisions are crucial for the sustainable future of freshwater resources. Within the state of Minnesota, five hydrologic regimes were identified, each with varying inter- and intra-annual flow characteristics. Kendall-tau results suggest that mean annual streamflow within the regimes is either increasing or remaining stable. Focusing on a smaller, regional analysis territory within East-Central Minnesota, regionalization using the Watershed Characteristics Approach (WCA) identified HHUs composed of unique combinations of hydrogeologic characteristics, bedrock material, Quaternary thickness, topography and available water capacity. These HHUs and their corresponding minimum monthly recharge rates represent the renewable groundwater flux. HHUs previously identified within the Twin Cities Metropolitan Area (TCMA) were used together with water use estimates to calculate the sustainability indicator for each community within the TCMA. Although the WCA has few assumptions, limitations of the methodology include that the hierarchical refinement is based on the availability of streamflow data, and the accuracy of the estimated recharge rates associated with each HHU is pre-determined by the resolution of spatial landscape attribute data. Future research should further evaluate the defined HHUs to confirm that they are consistent for all five of the hydrologic regimes identified within Minnesota.
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    Factors influencing roadside erosion and in-stream geomorphic stability at road-stream crossings for selected watersheds, North Shore, Minnesota, USA.
    (2012-07) Dutton, Patricia Danielle
    Currently, 10 major watersheds in Minnesota's North Shore exceed state water quality standards for turbidity (10 NTU) a surrogate for total suspended solids. In this region, recent anthropogenic disturbances can be attributed to roadway construction and maintenance. The presence of roadways can pose a serious threat to ecosystem functions, altering local and landscape hydrology, fragmenting riparian areas, and delivering chemical pollutants and suspended sediments to nearby waterways via surface runoff and seepage. This study examined the current extent of hydrologic connectivity between roads and streams, by investigating roadside erosion for select sub-watersheds within the North Shore watershed of Minnesota, USA. Surveys were conducted at 54 road-stream crossings along 12.2 km of roadways in the summer of 2010. A Road-stream connectivity analysis found roads increase the drainage density of North Shore watersheds by approx. 1.45-9.47%. Measureable erosion was observed at 64.8% of survey sites (gully, or rill) totaling 93.26 m3, with an average loss per site of 1.73 m3, or 7.64 m3/km. Traffic intensity, road construction, parent material, stream order, soil k factor, hillslope gradient best predicted erosion for this dataset using logistic regression at local and watershed wide scales. The effect road-stream crossings as a localized stress on stream stability was also examined at seven sites, using Rosgen level I classification and Pfankuch stability metrics. This qualitative analysis of stream stability upstream and downstream of road-stream crossing structures indicated study road-stream crossings are causing localized instability. Assessments indicated stream segments are negatively impacted both upstream and downstream of crossing structures.
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    iPaddle - Incorporating the Use of iPads ® into an Outdoor Education Curriculum
    (2016-06) Fillmore, Sheila G
    The intersection of hand-held mobile digital technology and environmental education (EE) is a relatively new and unexplored concept. Thus, there is little information on how to effectively incorporate the use of iPads ® (tablet computers) in an EE setting. The purpose of this project was to write curriculum designed to take advantage of iPad technology to enhance middle school students’ ecological and local cultural historical knowledge and their nature awareness as they studied various aspects of a local watershed. The curriculum covered a wide variety of topics such as using your senses, nature journaling, aquatic macroinvertebrates, and local cultural history. This project resulted in recommendations for including iPad applications (apps) that may strengthen portions of local watershed lessons. Techniques for more effectively incorporating this technology are suggested for teachers, in both formal and non-formal educational settings. By implementing the curriculum using iPad technology, educators will learn skills and methods to help students become more engaged in learning outdoors.
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    Modeling Flow and Nitrate Losses for Small Watersheds in Southeastern Minnesota
    (2021-07) Greve, Mark
    Watershed planners and decision makers need tools to determine which best management practices (BMPs) are most effective at reducing nitrate pollution in the Root River Basin of southeastern Minnesota. The Root River Field to Stream Partnership is monitoring three subwatersheds of the Root River (Headwaters, Crystal Creek, and Bridge Creek) for flow and nutrient flux. Additionally, an individual agricultural field in each subwatershed is also being monitored. The Soil and Water Assessment Tool (SWAT) used data from these monitored sites to attempt to create calibrated hydrology and nitrate flux models. Inputs for modeling were obtained using publicly available sources for land cover, soils, elevation, and weather data. Model calibration for hydrology and nitrate flux was done via the trial and error method. Accurate hydrology models were produced for both the Headwaters and Crystal Creek subwatersheds, but a good nitrate model was produced only for the Headwaters due to several complications from underlying karst features in the Crystal and Bridge Creek subwatersheds that were difficult to account for using the SWAT model. Accurate SWAT models could not be developed for Bridge Creek and the field sites. The Headwaters model was then run using ten combinations of BMP scenarios to determine their effectiveness at reducing nitrate losses. Reducing nitrogen fertilizer application rates to economical rates and splitting applications of nitrogen resulted in a fourteen and sixteen percent decrease in nitrate losses, respectively. Applying nitrogen only in the spring and placing filter strips on steeply sloping agricultural land reduced nitrate flux by six percent each.
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    Modeling Stream Thermal Dynamics: The Influence of Beaver Dams in a Minnesota Watershed
    (2020-08) Behar, Hannah
    Beaver dams are known to alter the thermal regime of ponds, streams, and adjacent subsurface waters. Downstream of a dam, stream temperature is influenced by increased exchange with the hyporheic zone, which may cool and buffer the stream’s diel temperature cycles. Concurrently, reduced shading in the beaver forage zone is likely to increase heat flux at the stream-atmosphere boundary. The dynamics of these processes can be analyzed to understand how stream temperature is affected on diel time scales, as well as longitudinally at distances downstream from the dam. At two beaver dam-impacted stream sites in the Knife River Watershed in Minnesota, USA, I monitored in-stream and shallow subsurface flow and temperature during low-flow summer conditions. I used a dye tracer test, vertical heat transport modelling, and soil characterization to estimate flux through the streambed at multiple locations. Temperature, stream flow, and atmospheric data were also collected throughout the summer from the two sites. A one-dimensional model of longitudinal stream temperature, calibrated to in-stream temperature measurements, was developed to determine which physical parameters and heat flux components have the greatest influence on stream temperature. The model was then used to demonstrate how these changes persist downstream, as well as to simulate stream temperature under potential future site conditions. These findings increase scientific understanding of stream temperature regime in the context of beaver dam-altered watersheds.
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    Quantifying the Impacts of Climate Change on Soil Erosion and Runoff in Minnesota Agricultural Watersheds using the WEPP Model
    (2022-08) Kohrell, Garner
    In the past several decades, soil water erosion and runoff in agricultural regions across the Midwestern United States have contributed to significant A-horizon soil losses, declining soil productivity, and the widespread impairment of water resources. Rising temperatures and changes in precipitation trends have the potential to significantly impact future soil water erosion and runoff in the Midwest, yet relatively few studies have attempted to quantify these impacts. To help expand this area of research, the Water Erosion Prediction Project (WEPP) Model was used to quantify growing season soil water erosion and runoff for a baseline period (1965-2019) and two future periods (2020-2059 & 2060-2099) in agricultural hillslopes across three Minnesota HUC12 watersheds. Future daily weather inputs were generated for WEPP using downscaled daily climate projections from two CMIP5 climate models (HadGEM2-CC and GFDL-ESM2G) and three emissions scenarios (RCP 4.5, RCP 6.0, and RCP 8.5). The climate scenarios were combined with varying adoption rates of perennial crops, conservation tillage systems, and cover crops in order to determine the effectiveness of these mitigation strategies in reducing future soil loss and runoff. When the baseline management scenario was used, most future climate scenarios showed decreases in runoff (34-58%), soil loss (3.3-40%), and the number of hillslopes with unsustainable soil loss (1-8%). However, there were also moderate to significant increases in runoff (17-38%), soil loss (4.2-40%), and the number of hillslopes with unsustainable soil loss (+3%) in several of the moderate emissions scenarios (RCP 4.5 and RCP 6.0). Watersheds with steep slopes and widespread conventional row crop systems had a significantly greater number of hillslopes with unsustainable soil losses, even if runoff and soil loss were projected to decrease in the future. Additionally, growing season runoff and edge-of-field sediment delivery values required to meet TSS total maximum daily loads (TMDLs) were only met in the highest emissions scenarios (RCP 8.5) where future soil loss and runoff significantly decreased. In order to mitigate agricultural runoff and unsustainable soil losses in Minnesota under current and future climates, we recommend implementing a combination of perennial alfalfa cropping systems and reduced tillage systems across hillslopes in watersheds with widespread steep slopes and conventional row cropping systems. However, requirements for TSS TMDLs were still only met in the highest emissions scenarios when these systems were implemented into the majority of hillslopes. As a result, additional off-site mitigation measures will likely be required in at-risk watersheds to meet TSS TMDLs and soil conservation goals under most future climates.
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    Response of chironomidae assemblages to land use in an urban stream
    (2014-03) Miller, Jessica Wyn
    No abstract
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    Water yield in the southern Appalachian Mountains.
    (2011-05) Kove, Katherine Marie
    With over 55% forest cover, the southern Appalachians (SA) are a main water resource for the surrounding areas. These water resources are at risk due to changing climate and precipitation regimes as well as changes in forest cover. Understanding the implications of these risks will help to develop management strategies for an increasingly valuable resource. Evapotranspiration (ET), the combination of plant transpiration and surface evaporation, can vary across space and time, and is a significant component of the hydrological cycle in densely forested regions. Quantifying ET is critical to understanding the available water resource, especially in the SA. In the SA, ET averages 50% of annual precipitation in forested watersheds and can climb to 85%. However, ET is among the most difficult and complex component of the water cycle to measure and model. This dissertation addresses these complexities by investigating the ability of sap flow models to estimate ET and examining the impact of potential temperature and compositional shifts on water yield. We also examined sap flow input variables to determine the best methods for the SA including the spatial estimation of climatological variables, phenological dates, and leaf area index (LAI) estimates all of which would particularly enhance the development of our hydrological models.
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    Watershed Research Symposium February 21, 2013 Final Report
    (2013) Sleeper, Faye
    The University of Minnesota Water Resources Center (WRC) led and hosted a Watershed Research Symposium on February 21, 2013 to suggest a water resources research agenda in Minnesota for the next five years, 2013 through 2018. The WRC and Department of Bioproducts and Biosystems Engineering hosted a similar event, the Impaired Waters Research Symposium, in February 2008, which resulted in a five-year research agenda. The purpose of both symposia was to bring together researchers, state decision makers, practitioners and citizen representatives to understand the current state of research in managing Minnesota’s water resources and to identify gaps in information and knowledge that could be bridged through additional research. The final report from the first symposium can be found at: http://z.umn.edu/researchsymp1.
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    Watershed-based Stressors for the Great Lakes Basin
    (2024-01-11) Host, George; Kovalenko, Katya; Brown, Terry; Johnson, Lucinda; Ciborowski, Jan; ljohnson@d.umn.edu; Johnson, Lucinda; Natural Resources Research Institute (NRRI)
    The Watershed-based Stressors for the Great Lakes Basin dataset includes component and aggregated measures of environmental stress to coastal ecosystems from watersheds of the Great Lakes Basin. Stressors include the amount of agricultural and developed land use, as well as road and population density. These summaries are based on a set of 5971 watersheds that cover the US and Canadian Great Lakes basin, derived using methods from Hollenhorst et al. (2007). Indices presented in this dataset include SumRel (Host et al. 2011) and the more recent combined Agriculture and Development - AgDev index (Host et al. 2019). These were developed as part of the Great Lakes Environmental Indicators II (GLEI-II) project, funded through the Great Lakes Restoration Initiative and used to quantify the response of biota (birds, fish, macroinvertebrates, diatoms and wetland vegetation) to varying degrees of watershed stress (Kovalenko et al. 2014). As of 2015, a more recent version of watersheds has been created by the Great Lakes Aquatic Habitat Framework and stressors recalculated based on those watersheds.
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    Winter rye cover cropping to improve water quality in corn-based cropping systems
    (2013-03) Herges, Adam Paul
    Winter rye (Secale cereale L.) cover cropping as a best management practice aimed at improving surface water quality by providing more ground cover, retaining nutrients, and preventing movement of surface water that carries nitrogen, phosphorus, and sediment to rivers, lakes, and streams. These four studies evaluated winter rye effects on surface water quality using different seeding methods in a variety of cropping systems. The first study (chapter 1) evaluated surface water quality under a one hour simulated rainfall event using different seeding methods of establishing winter rye following soybean (Glycine max L.) in fall and spring. Aerial, airflow, and broadcast seeding methods provided optimal winter rye ground cover to reduce surface runoff, NO3-N, NH4-N, phosphorus, and sediment compared to fallow. The second study (chapter 2) evaluated surface water quality under a one hour simulated rainfall event using different management practices of winter rye following corn (Zea mays L.) stover removal for silage in spring of 2010 and 2011. Standing and harvested rye treatments reduced surface runoff, NO3-N, NH4-N, phosphorus, and sediment compared to fallow, with standing rye being superior to harvested rye. Harvesting the rye for forage or bedding still provided exceptional environmental benefits for improving water quality compared to fallow. The last two studies (chapters 3 and 4) monitored and evaluated surface runoff in a paired watershed design. The longitudinal limitations of these studies provided insufficient results to conclude if winter rye was effective at reducing surface runoff and improving water quality at the field edge. Overall, simulated rainfall studies showed that winter rye was effective at reducing surface runoff and improving water quality, but the results of field scale studies were less clear.