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Watershed Monitoring & Land Use 2023 ANNUAL CONFERENCE David Hensley & Dr. Brittany Lancellotti Meet The Team David Hensley, research lead Dr. Brittany Lancellotti, postdoctoral fellow 2023 ANNUAL CONFERENCE David Hensley & Dr. Brittany Lancellotti – Watershed Monitoring and Land Use Sabrina Sorace*, graduate research assistant SaVaughna John- Baptiste*, undergraduate research assistant Race Stryker, graduate research assistant N’Bari Alexander*, undergraduate research assistant N’Quoia Christian, undergraduate research assistant Zach Eldridge, graduate exchange student (UF) 2023 ANNUAL CONFERENCE Persistent Questions ● To understand the flow from Ridge to Reef, many questions were unanswered at the start of the project: ○ Why do the guts flow when they do? Can we predict when they will flow? ○ Does the water flow all the way from Ridge to Reef? Or does it stop somewhere? ● The community and our policy-makers need answers to these questions to take actions that will make a difference! How connected are these two images really?? How often does this happen? And when? 2023 ANNUAL CONFERENCE Salt River Bay watershed ● Recently designated a Priority Watershed by the U.S. Coral Reef Task Force ● Contains a mixture of land uses (commercial, residential, cropland, pasture, forest, marina, and national parkland/historic sites) ● And a mixture of topography (rocky hillslopes and broad sedimentary plains) ● And multiple habitats from Ridge to Reef: ○ Mangroves ○ Seagrass beds ○ Coral reefs ● But our “persistent questions” remain! 2023 ANNUAL CONFERENCE A predictive model of runoff Steep, rocky upstream catchment runs off more easily than downstream Soil moisture makes a difference, especially at the downstream location This is the first step towards accurate flood forecasting, as well as statistics about how often the gut empties into the bay Example rain event: the night of July 29th, 2022 (0.8 inches) Example rain event: the night of July 29th, 2022 (0.8 inches) 2023 ANNUAL CONFERENCE Availability of existing information on USVI surface water and groundwater ● Compiled and reviewed existing information on surface and groundwater for the USVI ● History of water availability (pre-colonial to present) ● Chronology of research efforts and data generation ● Summarized data gaps and research needs, and provided recommendations for overcoming data scarcity Lancellotti & Hensley (in review). 2023 ANNUAL CONFERENCE Data on USVI surface water and groundwater are scarce and scattered ● Streamflow was last monitored in 2006 (part of USGS program that no longer exists) ● Very few water quality data available, especially for guts. Most consistent monitoring of gut water quality was in the 1960s and 1980s ● Data are scattered among different sources (old reports, USGS databases, inaccessible online), making them difficult to access Lancellotti & Hensley (in review). 2023 ANNUAL CONFERENCE The lack of long-term monitoring poses significant challenges ● Data on surface and groundwater are essential for effective water management ● Without complete, long-term monitoring of our freshwater resources, we can’t fully assess how water quantity and quality have changed overtime ● This is of special concern, since the USVI is a naturally water-scarce environment and faces water security issues ● Climate change may amplify these water security concerns ● Remote sensing, modeling studies, or other techniques that require less field-collected data could help overcome issues posed by data scarcity Lancellotti & Hensley (in review). 2023 ANNUAL CONFERENCE Gut water quality monitoring: nitrogen and phosphorus ● N and P are essential nutrients for plant and algae growth ● Excess N and P in marine and freshwater systems can cause ecosystem disruptions and imbalances ● N and P can be mobilized to the ocean via guts or surface runoff, or can contaminate groundwater stores ● Sources of N and P in the watershed include wastewater, agricultural activities, landscaping, stormwater runoff, atmospheric deposition 2023 ANNUAL CONFERENCE 17% 29% 25% 59% 32% Percent developed Land use explains some variability in nitrate concentrations ● Turpentine watershed the second highest median nitrate concentration 2023 ANNUAL CONFERENCE 17% 29% 25% 59% 32% Percent developed Land use explains some variability in nitrate concentrations ● Other factors, like physical watershed characteristics, impact hydrological processes that control nutrient delivery to the watersheds ● Site - specific pollution sources 2023 ANNUAL CONFERENCE 68% 79% 39% 34% 33% Percent forested ● Phosphate displays a different trend, with undetectable levels at Dorothea and Fish Bay watersheds ● Phosphorus uptake by plants is accelerated in forests, which could explain lower concentrations in Dorothea and Fish Bay Phosphate concentrations are lower in catchments that are more forested 2023 ANNUAL CONFERENCE N and P displayed differing temporal patterns ● Nitrogen concentrations decreased as the wet season progressed (flushing behavior), suggesting nitrogen supply was eventually depleted ● Once the soil became sufficiently saturated, groundwater supplied the guts with streamflow, which contained less nitrogen ● Phosphorus displayed a different behavior/ different transport mechanism (concentration increased in the middle of the wet season) Salt River, 2022 2023 ANNUAL CONFERENCE N and P on a shorter timescale: similar behavior to 2022 ● Nitrogen became depleted during a storm event ● Phosphorus source could be further away in the watershed ● Identifying how nutrient concentrations change throughout the wet season or the duration of a storm can help us pinpoint when the largest nutrient loads occur Salt River, 2022 Salt River, 2023 2023 ANNUAL CONFERENCE What’s next? ● Developing a statistical model to help us understand how hydrologic conditions influence N and P concentrations ● Collaboration with USGS using stable isotopes to identify where nitrogen is coming from in Salt River watershed Collaborations 2023 ANNUAL CONFERENCE David Hensley & Dr. Brittany Lancellotti – Watershed Monitoring and Land Use Thank you! David Hensley & Dr. Brittany Lancellotti EMAIL: david.hensley@uvi.edu PHONE: 713-444-2659 2023 ANNUAL CONFERENCE