Brief Summary of Minutes of Annual Meeting

The principle focus of this project is to evaluate the effectiveness of best management practices (BMPs) at the watershed scale. This includes the water quality and environmental benefits of mitigation practices as well as their cost effectiveness. This will be achieved through monitoring at sub-watershed scales, modeling at larger spatial scales, and analysis of uncertainty in both monitoring and modeling efforts. This report summarizes the first year of activity on this project and the following sections highlight accomplishments from project teams.

Objective 1: Monitor water quality from a variety of watersheds with a range of conditions (e.g., differing landuse and associated implemented BMPs, varying geographic/geologic conditions).

University of Rhode Island (A Gold, S Pradhanhang, K Addy) Water quality sensors (YSI EXO2 and the s::can spectro::lyser) were deployed in three streams from October 2015 to early January 2016 and April to September 2016. The three streams were selected as each watershed has a different dominant land use – forested, agricultural, and urban. Grab samples were collected weekly during baseflow and storm event samples were collected using a series of samples via an ISCO automatic water sampler during nine rain events from October 2015-September 2016. We are collecting stream stage data every 10-30 minutes with HOBO water level data loggers. We finalized the stage to field measured discharge relationship with the goal of estimating pollutant fluxes in our streams.

Mississippi State University (J Czarnecki) The objective of this study was to quantify capture and use of water within tailwater recovery systems, including the tailwater recovery ditch (TWR) and the on-farm storage reservoir (OFS) so that the conservation benefit they provide could be evaluated. This effort resulted in a dataset of 31 systems, monitored in 15-min intervals over an entire year. Domain decomposition methods were employed to calculate volumes of water in systems with complicated geometric shapes of OFS based on USDA NRCS build designs and water levels collected with data loggers. Rainfall, evaporation, and infiltration volumes were also calculated. Using these values, future plans are to model the effects of climate change by altering the rainfall values. Systems had a net positive balance of approximately 2,200 ML of captured surface water. Losses from evaporation and infiltration were between 8.68 mm d^-1 and 10.97 mm d^-1 for TWR and 4.96 mm d^-1 to 8.40 mm d^-1 for OFS. The highest losses occurred in the fall for TWR due to the installation cycle, whereas they were highest in the summer for OFS, driven by evaporation. Producers irrigated with an average of 41 ML (TWR) and 84 ML (OFS) of surface water. Irrigation levels were generally below thresholds set by the government for sufficient use. Some producers used their systems at high rates, capturing large volumes of surface water and re-using it for irrigation, while others used their systems very little.

Objective 2: Develop and evaluate models for predicting BMP performance and water quality at the field and watershed­scales when considering climate change.

Purdue University (S. McMillan) We developed and implemented an integrated monitoring and modeling approach to address our goal of understanding and predicting the impact of stormwater best management practices in urban areas at the reach and watershed scales. We applied the Regional Hydro-Ecological Simulation System (RHESSys) model to define the relationship between stormwater mitigation and export of water and nutrients as a function of environmental and hydrometeorological drivers. We first constructed a model of the existing conditions in a larger suburban watershed that includes other land uses as well (e.g., forested, commercial). We also refined the modeling framework to directly represent multiple types of SCMs (e.g., wet ponds, wetlands) within the landscape and simulate their impacts on water, carbon and nitrogen cycling. These refinements included a new representation of SCM storage and drainage within the hillslope hydrology routing network and the inclusion of a SCM algae growth/decay biogeochemical cycling routine. These additions were successfully calibrated with monitoring data from individual BMPs. We are currently applying the revised version of RHESSys to evaluate how different SCM strategies at the watershed scale interact with climate scenarios to alter water and nutrient exports. Model-based scenarios will be designed to understand interactions among topography, the size and spatial arrangement of the SCMs, and climate and land use drivers. Bell, C. , S. McMillan, and C. Tague. 2017. A model of hydrology and water quality in stormwater control measures. Environmental Modeling and Software 95:29-47.

University of Rhode Island (A Gold, S Pradhanhang, K Addy) The SWAT watershed water quality model has been calibrated for streamflow and nitrate loadings in Maidford River (predominantly agricultural). Climate sensitivities to flow and nutrients loadings have been tested. Similarly a SWAT model has been developed for Cork Brook Watershed (predominantly forested) to assess thermally stressful events. We contributed to database development and statistical modeling efforts to predict riparian zone function with respect to nitrogen and phosphorus cycling in agricultural areas of glaciated regions.   We also began to calibrate the Riparian Ecosystem Management Model (REMM) with new default model parameters specific to dominant riparian geomorphic types in these glaciated regions.

Auburn University (P Srivastava) We investigated potential changes in flow, Total Suspended Solid (TSS) and nutrient (nitrogen and phosphorous) loadings under future climate change, land use/cover (LULC) change and combined change scenarios in the Wolf Bay watershed, southern Alabama, USA. Four Global Circulation Models (GCMs) under three Special Report Emission Scenarios (SRES) of greenhouse gas were used to assess the future climate change (2016-2040). Three projected LULC maps (2030) were employed to reflect different extents of urbanization in future. Results indicate that if future loadings are expected to increase/decrease under any individual scenario, then the combined change will intensify that trend. Conversely, if their effects are in opposite directions, an offsetting effect occurs. Science-based management practices are needed to reduce nutrient loadings to the Bay.

Objective 3: Develop methods to quantify modeling and monitoring uncertainty as affected by model representations of watershed processes and model input data.

North Carolina State University (F. Birgand) The increasing availability and use of high-frequency water quality sensors has enabled unprecedented observations of temporal variability in water chemistry in aquatic ecosystems. However, we remain limited by the prohibitive costs of these probes to explore spatial variability in natural systems. To overcome this challenge, we have developed a novel auto-sampler system that sequentially pumps water from up to 12 different sites located within a 12 m radius to a single water quality probe. This system is able to generate high temporal frequency in situ water chemistry data from multiple replicated units during experiments as well as multiple sites and depths within natural aquatic ecosystems. Thus, with one water quality probe, we are able to observe rapid changes in water chemistry concentrations over time and space. Here, we describe the coupled multiplexer-probe system and its performance in two case studies: a mesocosm experiment examining the effects of water current velocity on nitrogen dynamics in constructed wetland sediment cores and a whole-ecosystem manipulation of redox conditions in a reservoir. In both lotic and lentic case studies, we observed minute-scale changes in nutrient concentrations, which provide new insight on the variability of biogeochemical processes. Moreover, in the reservoir, we were able to measure rapid changes in metal concentrations, in addition to those of nutrients, in response to changes in redox. Consequently, we believe that this coupled system holds great promise for measuring biogeochemical fluxes in a diverse suite of aquatic ecosystems and experiments. Birgand, F., Aveni‐Deforge, K., Smith, B., Maxwell, B., Horstman, M., Gerling, A.B. and Carey, C.C., 2016. First report of a novel multiplexer pumping system coupled to a water quality probe to collect high temporal frequency in situ water chemistry measurements at multiple sites. Limnology and Oceanography: Methods, 14(12), pp.767-783.

In our initial proposal, we put forth the following expected outcomes and impacts:

1. Coordination of research and outreach programs involving the use of BMPs for watershed management and mitigating diffuse pollution and the effects of climate change and other emerging environmental issues.
2. New knowledge and exchange of ideas/information/data on the biophysical functioning of BMPs to enable the development of better BMP submodels and watershed and subwatershed models for simulating BMP effectiveness and uncertainties associated with their performance.
3. Publication of joint research articles on BMP performance and monitoring and modeling methods at the watershed and subwatershed scales.
4. Evaluation and standardization of uncertainty analysis techniques for quantifying uncertainties associated with BMP performance and model predictions of BMP effectiveness at the watershed and subwatershed scales.
5. A conference on quantification of best management practice effectiveness for water quality protection at the watershed and subwatershed scales.

Although the project is just completing our year, we have made significant progress on the first objectives. The coordination of research and outreach programs has lead to joint proposal submissions, invited seminars between participating universities, outreach activities with state and local watershed groups, and co-mentoring of students. During our regional project meeting several synthesis papers were proposed and initial outlines have been developed. In addition, we conducted the first quantitative synthesis of denitrifying woodchip bioreactors, a BMP designed to remove nitrate from agricultural watersheds. The meta-analysis assessed nitrate removal across environmental and design conditions from 26 published studies, representing 57 separate bioreactor units. This meta-analysis was published in the Journal of Environmental Quality, and results will be shared with researchers and practitioners. Addy, K., Gold, A.J., Christianson, L.E., David, M.B., Schipper, L.A. and Ratigan, N.A., 2016. Denitrifying bioreactors for nitrate removal: A meta-analysis. Journal of environmental quality, 45(3), pp.873-881.