SFS Annual Meeting

6/05/2024  |   10:45 - 11:00   |  Freedom Ballroom H/G

Understanding Social Vulnerability to Climate Change-Modified Water Hazards in the Vietnamese Mekong Delta Coastal Zone Concern for climate change impacts to the Vietnamese Mekong Delta is rapidly increasing due to the compound risks of a changing climate, environmental change and sensitivity and social-economic transformation. The Delta, located in the downstream section of the Mekong River is considered globally as one of the three most vulnerable deltas to climate change. Variations in precipitation, temperature changes, sea-level rise, progressive saline instructions, riverbank erosion, flooding and extreme weather events all aggravate the risk to the existing socio-ecological system. Using Ben Tre Province as an in-depth case study, this paper develops a social vulnerability index (SVI) to understand the water hazards-modified by climate change in terms of their association between vulnerability, existing infrastructures and socio-economic patterns. A mix-method of qualitative and quantitative approaches was framed to procure and analyse data. This consisted of group discussions, individual surveys and key informant panel interview. Spatially mapped results of cluster analysis showed a strong spatial trend of SVI increasing from upstream to the downstream areas The multivariate regression model found linear correlations between the SVI and the proximity to the dike system and waterways. Additionally, the Moran’s I autocorrelation indicated the statistically significant difference between the SVI spatially of various household clusters. These findings contribute y to the understanding of the array of biophysical and socio-ecological impacts, their variability and their interlinkages.

Trung Phan (Primary Presenter/Author), Can Tho University, phantrung2612@gmail.com;

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6/05/2024  |   11:00 - 11:15   |  Freedom Ballroom H/G

Long-term reconstruction of the hydrological mass balance and subsequent changes in water quality of a highly regulated lake The ecological functioning of freshwater lakes is intrinsically connected to their hydrology, which dictates water and nutrient circulation. Globally, many lakes undergo hydrological alterations due to morphological changes and human interventions like land reclamations, dam constructions, water level regulations and alterations in land use patterns. This study delved into the impacts of such alterations on the water quality of the large freshwater lake Markermeer (The Netherlands) through a comprehensive long-term analysis. By integrating fragmented monitoring data with meteorological information, we devised a novel methodology to reconstruct changes in the water mass balance and nutrient fluxes of the lake over the past four decades. Our approach enabled us to discern daily water discharges into and out of the lake, as well as the subsequent changes in the phosphorous load entering lake Markermeer. Our study revealed distinct variations in water sources (and water quality) during dry and wet periods and a substantial reduction in phosphorous load over the 40-year period. Additionally, this reconstructed water mass balance provided crucial insights into the influence of surrounding land use on water quality, highlighting the intricate hydrological linkages between the lake, its catchment area and water management measures. Understanding these dynamics is pivotal for comprehending the ecology of highly engineered, human-altered aquatic ecosystems like lake Markermeer, thereby facilitating informed management efforts to improve the water quality and ecological functioning.

Laura Tack (Primary Presenter/Author), University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, laura.tack@rws.nl;

Harm Van der Geest (Co-Presenter/Co-Author), University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, H.G.vandergeest@uva.nl;

Arie Vonk (Co-Presenter/Co-Author), University of Amsterdam, Institute of Biodiversity and Ecosystem Dynamics, J.A.Vonk@uva.nl;

Emiel van Loon (Co-Presenter/Co-Author), University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, e.e.vanloon@uva.nl;

Maarten Ouboter (Co-Presenter/Co-Author), Waternet, Maarten.Ouboter@waternet.nl;

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6/05/2024  |   11:15 - 11:30   |  Freedom Ballroom H/G

Determining Streamflow Conditions at Select Tributaries to the Barnegat Bay Watershed as the First Step Towards the Development of Ecological Flow Targets Maintaining streamflow to support human water needs and ecosystem services requires a fundamental understanding of the relations between streamflow processes and ecosystem response. To meet this need for the Barnegat Bay watershed (BBW), NJ, an ecological flow framework will be implemented. We report on the first steps by comparing streamflow from historical and current periods of record (POR: spanning 1933-2020) for four streams in the BBW to evaluate if there are any statistically significant differences in streamflow metrics between POR. Analysis of monthly, seasonal, and annual low-flow patterns are useful in developing a better understanding of flow conditions. Preliminary findings indicate notable changes in flow occurred between POR for the four study streams. For example, the mean of the daily streamflow decreased between the historical and current POR. Larger and more significant changes occurred during specific months or were related to the variability or seasonality of flow. Negative changes to low-flow metrics were identified at the two most developed sites. Decreases in the 75-percentile exceedance flows were evident at three study streams; however, there was little to no evidence of changes to low-flow metrics at the least developed site. Human-driven changes in streamflow need to be synthesized into a scientifically defensible and socially acceptable set of standards for the management of streamflow. This study represents the critical initial steps in building the hydrologic foundation needed to inform management and promote the development of future ecological flow targets that balance water availability for human and ecosystem needs.

Jonathan Kennen (Primary Presenter/Author), U.S. Geological Survey, New Jersey Water Science Center, 3450 Princeton Pike, Suite 110, Lawrenceville, NJ 08648, jgkennen@usgs.gov;

Christine Wieben (Co-Presenter/Co-Author), U.S. Geological Survey, New Jersey Water Science Center, 3450 Princeton Pike, Suite 110, Lawrenceville, NJ 08648, cwieben@usgs.gov;

Thomas Suro (Co-Presenter/Co-Author), U.S. Geological Survey, New Jersey Water Science Center, 3450 Princeton Pike, Suite 110, Lawrenceville, NJ 08648, tsuro@usgs.gov;

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6/05/2024  |   11:30 - 11:45   |  Freedom Ballroom H/G

GO WITH THE FLOW: INCREASING SPRING DISCHARGE IN KEY TRIBUTARIES MAY COMPROMISE WATER QUALITY IN A KEY DRINKING WATER RESOURCE Climate change is altering precipitation patterns worldwide, yielding changes in streamflow and availability of water resources. Specifically, storm frequency and intensity has increased, driving higher peak flows, while prolonged droughts cause lower baseflow conditions. In turn, these events can alter the timing and magnitude of nutrient and sediment transport to downstream systems. Thus, it is critical to understand long-term changes in streamflow delivery to critical water resources to protect drinking water supplies. Here, we document changes in streamflow delivery to Beaver Lake, the main drinking water source in the rapidly urbanizing Northwest Arkansas region. We used publicly available United States Geological Survey data to analyze flow records in four key tributaries to Beaver Lake for the 2000-2022 water years. We found tributaries generally responded similarly to storm events, though the magnitude among tributaries varied. Results indicate mean spring discharge has increased in all watersheds over the study period, suggesting that nutrient loads are likely increasing during spring as well; future analyses will explore this directly. Notably, spring nutrient loads predict the risk of summer harmful algal blooms (HABs). Thus, as spring discharge increases, the risk of HABs in Beaver Lake may also be increasing, compromising a key drinking water source for a rapidly growing region of the USA.

Alana Strauss (Primary Presenter/Author), University of Arkansas, alanas@uark.edu;

Shannon Speir (Co-Presenter/Co-Author), University of Arkansas, slspeir@uark.edu;

Ireyra Tamayo (Co-Presenter/Co-Author), University of Arkansas, tamayoireyra01@gmail.com;

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6/05/2024  |   11:45 - 12:00   |  Freedom Ballroom H/G

Drivers of nutrient dynamics during floodpulses in the Lower Ogeechee River The Flood Pulse Concept characterizes the lateral interaction of rivers and their adjacent floodplains as a driver for both nutrient and food web dynamics. Many studies have added to this first theory describing the complexity of riverine floodplain interactions and how different drivers such as seasonality, location, and flood pulse mechanics. The Ogeechee River is an undammed, sixth order, blackwater river in Southeast Georgia that has been part of several studies in both the main channel and its adjacent floodplain. We sampled water in four sites along the Lower Ogeechee River during eleven flood pulses during the beginning (ascending limb), and end (descending limb) of each event. We analyzed for NOx, TN, NH3, POP-4, and DOC. We also measured suspended solids, conductivity, and pH. These flood pulses were categorized by seasonality (early, late, and tropical) according to the pulse season, and by magnitude according to the gage discharge of the uppermost site. Nutrient concentrations were mainly affected by pulse magnitude, location, and seasonality. Surprisingly, floodplain and river concentrations as well as pH and conductivity measurements were comparable. With the expected changes in precipitation patterns as well as unpredictable temperatures, floodplain functions to retain and internally process pollutant nutrients are expected to also change. Understanding nutrient dynamics in extreme conditions such as flood pulses during both predictable and unpredictable times could help develop projections on floodplain function for management planning.

Gabriela Cardona Rivera (Primary Presenter/Author), University of Georgia, gc68521@uga.edu;

Darold Batzer (Co-Presenter/Co-Author), Department of Entomology, University of Georgia, dbatzer@uga.edu;

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