Research Findings

ULTRA-MIA collaborators Colin Saunders, Gaiser, Ogden and the Florida Coastal Everglades LTER Modeling/Synthesis team have developed a two-tiered conceptual model to understand interactions between water use policies and water resource protection (Figures 7 and 8). The first tier shows the feedbacks between water use and protection as they are linked via the valued services provided. The second tier identifies conflicting and interacting uses of water within the developed urban environment and the third examines particular tradeoffs among potential use choices. The second tier will be a focal introductory point of the ULTRA-MIA Freshwater Sustainability Workshop, the goal of which will be to develop the third tier model to enable directed data gathering, analysis and model parameterization. Cross-site activities are contributing to a greater understanding of the position of Miami-Dade along water demand and climate change vulnerability gradients, and new collaborations with east coast LTER and ULTRA sites will enable developments from conceptual approaches to coordinated science. ( insert two diagrams from the word file : Figure 7: Tier 1 model shows feedbacks between water use and protection as they are linked via ecosystem services (Saunders et al.) and Figure 8: The Tier 2 model identifies conflicting and interacting uses of water within the developed urban environment (Saunders et al.).

Extent of Seawater Intrusion : The Everglades serves as a critical source of water storage and recharge for South Florida’s urban areas. Understanding the extent of seawater intrusion to the Everglades provides insight into the dynamics of urban freshwater water resources and vulnerability (particularly to urban well fields). Project collaborator René Price’s work provides long term data on seawater intrusion in the Everglades and links research findings from the FCE LTER program to new ULTRA MIA research. Groundwater salinity shows an increasing trend over time in both the Shark and Taylor Slough regions of the southern Everglades (Figs. 9a,b) between 2003 and 2009 although the increases do not occur at a fixed rate. Also at both sites, the groundwater salinity and water levels vary seasonally. At Taylor Slough, low water levels correspond with times of high salinity (Fig. 9b). At the Shark Slough site (SH2) groundwater salinity values are dynamic and co-vary with groundwater levels, with higher salinity values observed with higher groundwater levels (Fig. 9a). This may signify that both groundwater salinity and levels are more effected by seawater intrusion, which in turn is governed by upstream freshwater heads as well as from downstream sea level fluctuations The reverse seems to be observed at the Taylor Slough site (G-3337) with higher groundwater salinity values observed at times of lowest water levels (Fig. 9b). The results of the long-term groundwater salinity records in the region suggest that the position of the FWSWI in the southern Everglades is dynamic, and has migrated inland between 2003 and 2009. Given this variability, it is necessary to continue monitoring groundwater salinity in the existing wells as well as expanding the well network.