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Climate Variability and Water Management

Climate change in eastern South ��ֱ���� has been, and is forecast to be, manifested through increases in annual precipitation and annual average temperature. This general statement, however, masks the variability in precipitation and temperature impacts in different months or seasons, and the continuation of inter-seasonal and inter-annual variability that South ��ֱ���� experiences as a continental climate zone in North America. The observation that both floods and droughts are more common in various regions of South ��ֱ���� can be proven true, due in part to the rapid transitions between dry and wet periods from year to year, or even month to month, and also because of the changing nature of precipitation events. The complexity of these extremes brings a challenge to water management, in water supply and quality for urban and rural users, for agriculture, and for other uses like recreation and cultural or ceremonial purposes. While eastern South ��ֱ����, and the Big Sioux River watershed in particular, has had few significant drought periods in recent decades, the recent turn from record wet conditions in 2019 to drought in 2021 has demonstrated the volatility of some water management systems.  This presentation will illustrate some recent water management challenges due to climate variability and highlight updated climate projections for the region.

Impacts of Directional Land Cover Change on Runoff Across Reference Basins in the Conterminous United States

Land cover change plays a critical role in influencing hydrological responses. Change in land cover has impacted runoff across basins with substantial human interference; however, the impacts in basins with minimal human interference have been studied less. In this study, we investigated the impacts of directional land cover changes (forest to/from combined grassland and shrubland) in runoff coefficient (RC; ratio of runoff to precipitation) and runoff volume across 603 low human interference reference basins in the conterminous United States (CONUS). The results indicate a unit percent increase in basin area from grassland and shrubland to forest was associated with a ∼4% decrease in RC across basins with decreasing RC trends. Similarly, a unit percent increase in basin area from forest to a combined grassland and shrubland was associated with a ∼1% increase in RC across increasing RC trend basins. When relating runoff volume with the area of directional land cover changes, each 1 km2 increase in area from grassland and shrubland to forest resulted in a decrease of ∼530,000 m3 runoff volume across basins with decreasing trends. In contrast, each 1 km2 increase in area from forest to grassland and shrubland increased runoff volume by ∼200,000 m3 across increasing trend basins. The findings of this study are useful for planning and managing water availability for sustainable and adaptive water resources management at regional scales.

Measuring Change on the Red River

As populations along the Red River increase, the need to understand the system’s continued evolution and its potential response to a changing climate has become increasingly critical. The subtle complexity of the Red River has made it difficult to interpret the topographic diversity of the basin, but improved remote sensing tools, in particular Lidar, have changed this. Using Lidar we have delineated past river channels in the Red River basin and developed an approximate chronology of channel movement along the Red River mainstem. In addition, Lidar was used to map all evidence of landsliding in the Lake Agassiz plain and identify areas of the greatest activity. Both of these data sets are used to interpret the factors that contribute to differential erosion rates throughout the basin, information that contributes to land management and planning.

Drought Impacts to Outdoor Recreation and Big Sioux River Watershed Habitat and Access Opportunities

The State of South ��ֱ���� is working with USDA to create a new Conservation Reserve Enhancement Program (CREP) project for the Big Sioux River Watershed (BSRW).  This effort is being led by the Department of Game, Fish, & Parks and modeled after the existing James River Watershed CREP. Up to 25,000 acres of marginal cropland and pastureland will be enrolled in the BSRW CREP.  The project’s purpose will be to improve water quality for drinking water and recreation use, restore wildlife habitat leading to increased populations of pheasants, deer, waterfowl, grassland nesting songbirds and pollinators like the monarch butterfly, create additional sources of forage for livestock producers, and improve the quality of life in SD by creating approximately 250 new places open to public hunting and fishing access within the BSRW.  All land enrolled will be open to public hunting and fishing access.    Landowners, farmers, and ranchers will enroll land with the assistance of Farm Service Agency, Natural Resources Conservation Service, Pheasants Forever and SD Game Fish and Parks staff.  CREP contracts will be for 10 to 15 years with a total project cost estimated at $108,826,950.  The State’s portion of that total cost is estimated to be $22,215,600.

Remote Sensing to Support the Intersection of Land Use, Water Use, and Water Availability

Understanding and anticipating change in hydrologic systems is of vital importance to economic, ecological, recreational, and other societal interests. Cross-disciplinary work at the intersection of anthropogenic land use, climate-driven land cover change, water use, and water availability are needed to facilitate hydrologic planning and mitigation efforts. USGS has extensive expertise in monitoring, assessing, and modeling land and water resources, and are developing interdisciplinary modeling frameworks to assess feedbacks among these resources under a changing climate. Remote sensing plays a key role in informing our interdisciplinary Earth system models. We are using long-term landscape monitoring to inform both historical and future projection modeling, with land use modeled at a parcel level to mimic land-owner decisions in aggregate across broad regional to national scales. We are linking land-use models with models of water use, using both an energy balance and a water balance approach that rely on remote sensing inputs. By linking these elements with models of water availability, we are moving towards parcel-level water accounting, where land use is constrained by modeled feedbacks with water use and availability, while aggregate land use and land management changes are used to quantify impacts on available water resources. Prototype work is being conducted in multiple river basins and ecoregions in the US, with a goal of eventual national-scale application.

A “Grass for Water” Blueprint for the Big Sioux River Basin

Grasslands and wetlands of eastern SD’s Big Sioux River Basin provide significant benefits not just as habitat for waterfowl, grassland birds, and other fish and wildlife, but also for water quality, drinking/source water, carbon & water storage, and other watershed “ecosystem services”. The river and its aquifer supplies water and amenities for Sioux Falls and other communities. But the basin also experiences high N loads, bacterial and other impairments, and growing flood and drought vulnerability linked to both climate and land use change. TNC has compiled maps, data, and model outputs designed to explore the contribution of grass cover in different parts of the watershed to production of watershed services and benefits for both local and downstream communities. We have also partnered with SDSU and others on the NRCS CCG Grant “Roadmap to Water Resilience” to explore conservation practices that reduce water risk (too much and too little) at field and watershed scales. This includes modeling the amount of adoption of different practices needed to meet goals at different scales (field/farm, Huc12, and larger watersheds). Developing science-based tools to explore changes in land use, management, and climate can help inform everything from conservation to source water protection and community climate resilience planning. This presentation will introduce our mapping approach and preliminary results, mainly as a tool for dialogue on how to reach our respective goals.

Advanced Remote Sensing Methods for Automated Lake Water Quality Mapping

Using satellite imagery, we have been assessing lake water quality in Minnesota, USA for over 20 years. These assessments at around five year intervals were used for spatial and temporal trends and causative factors. Recent advances in satellite technology (improved spectral, spatial, radiometric and temporal resolution) and atmospheric correction, along with cloud and supercomputing capabilities have enabled the use of satellite data for automated regional scale measurements of water resource characteristics. These new capabilities provide opportunities to improve lake and fisheries management by measuring more variables (chlorophyll, colored dissolved organic matter (CDOM) and total suspended matter, the main determinants of water clarity) more often.

To utilize these capabilities we have developed field-validated methods and implemented them in an automated water quality monitoring system on University of Minnesota supercomputers. This system enables near real-time monitoring capabilities of water quality variables at regional scales, which will enhance our understanding of spatial and temporal variability and responses of surface waters to environmental change. Examples from Minnesota's 10,000+ lakes and from eastern South ��ֱ���� will be presented.

Willow Creek Watershed Project - Every Practice Counts

Environmental phenomenon such as harmful algal blooms, flooding, and topsoil erosion show the need for increased implementation of conservation agriculture practices. Unfortunately, the placement of such practices is often based on factors other than where they will have the greatest impact. One way of determining optimum placement of conservation practices is through watershed modeling. The Willow Creek watershed was chosen to study this in part due to its proximity to the city of Sioux Falls, which has experienced severe flooding in past years. As part of the Willow Creek project, soil moisture data collected from fields with a variety of management practices, along with stream flow and evapotranspiration data, will be used to calibrate a watershed model. Social science and economic portions of this project will also take place. Surveys will be sent out to those in the watershed with questions involving what has influenced their farm management decisions. Input costs, such as fertilizer, seed, and pesticides, along with outputs, like yield, will be used to calculate the profitability of the systems involved in the project in relation to their ability to manage soil moisture. Through this project, we hope to gain a better understanding of how conservation practices can be used to benefit entire communities, both urban and rural.