A5076955815- Soil and Water Nutrient Dynamics
- Water Quality and Resources Studies
- Hydrology and Watershed Management Studies
- Fish Ecology and Management Studies
- Aquatic Ecosystems and Phytoplankton Dynamics
- Hydrology and Sediment Transport Processes
- Arctic and Antarctic ice dynamics
- Water Quality and Pollution Assessment
- Climate change and permafrost
- Marine and coastal ecosystems
- Groundwater and Isotope Geochemistry
- Cryospheric studies and observations
- Aquatic Invertebrate Ecology and Behavior
- Soil erosion and sediment transport
- Groundwater flow and contamination studies
- Freshwater macroinvertebrate diversity and ecology
- Geology and Paleoclimatology Research
- Oceanographic and Atmospheric Processes
- Peatlands and Wetlands Ecology
- Isotope Analysis in Ecology
- Archaeology and Natural History
- Climate variability and models
- Scientific Computing and Data Management
- Soil Carbon and Nitrogen Dynamics
- Hydraulic Fracturing and Reservoir Analysis
United States Geological Survey
2016-2025
Upper Midwest Water Science Center
2018-2024
Royal Museum for Central Africa
2022
Meise Botanic Garden
2022
Graz University of Technology
2022
EGI
2022
National Research Council Canada
2019
Joint Commission
2019
University of Wisconsin System
2005-2017
ProHealth Oconomowoc Memorial Hospital
2017
Freeze and breakup dates of ice on lakes rivers provide consistent evidence later freezing earlier around the Northern Hemisphere from 1846 to 1995. Over these 150 years, changes in freeze averaged 5.8 days per 100 years later, 6.5 earlier; translate increasing air temperatures about 1.2 degrees C years. Interannual variability both has increased since 1950. A few longer time series reveal reduced cover (a warming trend) beginning as early 16th century, with rates change after 1850.
Robertson, Dale M. and David A. Saad, 2011. Nutrient Inputs to the Laurentian Great Lakes by Source Watershed Estimated Using SPARROW Models. Journal of American Water Resources Association (JAWRA) 47(5):1011-1033. DOI: 10.1111/j.1752-1688.2011.00574.x Abstract: input continues cause problems with eutrophication. To reduce extent severity these problems, target nutrient loads were established Total Maximum Daily Loads are being developed for many tributaries. Without detailed loading...
Abstract Long‐term lake ice phenological records from around the Northern Hemisphere provide unique sensitive indicators of climatic variations, even prior to existence physical meteorological measurement stations. Here, we updated phenology for 60 lakes with time‐series ranging 107–204 years first re‐assessment Hemispheric trends since 2004 by adding 15 additional and 40 our study. We found that, on average, ice‐on was 11.0 days later, ice‐off 6.8 earlier, duration 17.0 shorter per century...
Abstract. Empirical evidence demonstrates that lakes and reservoirs are warming across the globe. Consequently, there is an increased need to project future changes in lake thermal structure resulting biogeochemistry order plan for likely impacts. Previous studies of impacts climate change on have often relied a single model forced with limited scenario-driven projections relatively small number lakes. As result, our understanding effects fragmentary, based scattered using different data...
Herein, we document changes in the Lake Michigan food web between 1970 and 2000 identify factors responsible for these changes. Control of sea lamprey (Petromyzon marinus) alewife (Alosa pseudoharengus) populations Michigan, beginning 1950s 1960s, had profound effects on web. Recoveries lake whitefish (Coregonus clupeaformis) burbot (Lota lota) populations, as well buildup salmonine were attributable, at least part, to control. Based our analyses, predation by salmonines was primarily...
Abstract. The one-dimensional hydrodynamic ice model, DYRESM-WQ-I, was modified to simulate cover and thermal structure of dimictic Lake Mendota, Wisconsin, USA, over a continuous 104-year period (1911–2014). model results were then used examine the drivers changes in water temperature, focusing on responses shifts air wind speed, clarity at multiyear timescales. Observations include change trend warming temperatures from 0.081 °C per decade before 1981 0.334 thereafter, as well shift mean...
Abstract Responses in lake temperatures to climate warming have primarily been characterized using seasonal metrics of surface‐water such as summertime or stratified period average temperatures. However, may not affect water equally across seasons depths. We analyzed a long‐term dataset (1981–2015) biweekly temperature data six temperate lakes Wisconsin, U.S.A. understand (1) variability monthly rates surface‐ and deep‐water warming, (2) how those compared trends, (3) if heterogeneity trends...
Extensive streamflow and water quality data from eight small streams were systematically subsampled to represent various water‐quality sampling strategies. The then used determine the accuracy precision of annual load estimates generated by means a regression approach (typically for big rivers) most effective strategy streams. Estimation loads was imprecise regardless used; strategy, median absolute errors ∼30% based on estimated with an integration method all available data, if is daily...
Records of freezeup and breakup dates for Grand Traverse Bay, Michigan, Lake Mendota, Wisconsin, are among the longest ice records available near Great Lakes, beginning in 1851 1855, respectively. The timing results from an integration meteorological conditions (primarily air temperature) that occur before these events. Changes average ice‐events translated into changes temperature by use empirical process‐driven models. at two locations represents temperatures over slightly different...
Nitrogen (N) and phosphorus (P) loading from the Mississippi/Atchafalaya River Basin (MARB) has been linked to hypoxia in Gulf of Mexico. To describe where what sources those loads originate, SPAtially Referenced Regression On Watershed attributes (SPARROW) models were constructed for MARB using geospatial datasets 2002, including inputs wastewater treatment plants (WWTPs), calibration sites throughout MARB. Previous studies found that highest N P yields north-central part (Corn Belt). Based...
Abstract SPAtially Referenced Regression on Watershed models developed for the Upper Midwest were used to help evaluate nitrogen‐load reductions likely be achieved by a variety of agricultural conservation practices in Mississippi‐Ohio River Basin ( UMORB ) and compare these 45% reduction proposed remediate hypoxia Gulf Mexico GoM ). Our results indicate that nitrogen‐management (improved fertilizer management cover crops) fall short achieving this goal, even if adopted all cropland region....
Despite progress in the implementation of conservation practices, related improvements water quality have been challenging to measure larger river systems. In this paper we quantify these downstream effects by applying empirical U.S. Geological Survey water-quality model SPARROW investigate whether spatial differences intensity were statistically correlated with variations nutrient loads. contrast other forms data analysis, application controls for confounding factors such as hydrologic...
Abstract Nitrogen (N) and phosphorus (P) inputs throughout the Mississippi/Atchafalaya River Basin (MARB) have been linked to Gulf of Mexico hypoxia water‐quality problems MARB. To describe N P loading MARB, SPAtially Referenced Regression On Watershed attributes (SPARROW) models were previously developed based on nutrient management similar 1992 2002. In this study, refined SPARROW with higher resolution basin delineation, updated (2012) source inputs, improved calibration (load) targets,...
Ice breakup dates from 1968 to 1988 were examined for 20 Wisconsin lakes determine whether consistent interannual and long‐term changes exist. Each ice record had a trend toward earlier dates, as demonstrated by negative slope with time, indicating recent warming trend. The average change in was 0.82 d per year the southern Wisconsin, which more extreme than that northern (0.45 yr ‒1 ). Interannual variation related warm phase of El Niño/Southern Oscillation (ENSO) episodes. Niño events...
Abstract: Excessive loads of nutrients transported by tributary rivers have been linked to hypoxia in the Gulf Mexico. Management efforts reduce hypoxic zone Mexico and improve water quality streams could benefit from targeting nutrient reductions toward watersheds with highest yields delivered sensitive downstream waters. One challenge is that most conventional watershed modeling approaches (e.g., mechanistic models) used these management decisions do not consider uncertainties predictions...
Stream-loading information was compiled from federal, state, and local agencies, selected universities as part of an effort to develop regional SPAtially Referenced Regressions On Watershed attributes (SPARROW) models help describe the distribution, sources, transport nutrients in streams throughout much United States. After screening, 2,739 sites, sampled by 73 were identified having suitable data for calculating long-term mean annual nutrient loads required SPARROW model calibration. These...