The USGS Caribbean-Florida Water Science Center Strategic Science Plan 2017-2027: A blueprint for USGS contributions to water resource science in Florida, Puerto Rico, and the US Virgin Islands
Stamm, J.F., Rodríguez, J.M., Sifuentes, D.F., Sumner, D.M., and Grimsley, K.J. with contributions from Bogeajis, N., Torres-González, S., McBride, W.S., Parks, J., and Decker, J.
Programmatic Areas and Plans
While the concept of water security guides the priorities of the CFWSC, the planned programmatic areas for the Caribbean-Florida Water Science Center are also aligned with those of the Water Mission Area: Water Availability and Use Science, Groundwater and Streamflow Information, Water Quality, and the Water Resources Research Institutes.
Water Availability and Use Science
"Water availability and use" includes traditionally defined uses such as public supply of freshwater, and non-traditional "uses" such as disposal of wastewater. Water availability and use in the Caribbean-Florida region are influenced by the largely coastal to near-coastal environment, tropical to sub-tropical climate, the presence of densely populated urban areas, large agricultural regions, and important natural ecological areas (such as Everglades National Park, Florida, and El Yunque National Forest, Puerto Rico; figs. 3,5). Water resources are particularly susceptible to threats posed by climate change and sea-level rise, and effects have been already observed. Sea-level rise is a prominent concern and coastal communities in south Florida are already developing adaptation plans. For example, the Southeast Florida Regional Climate Change Compact is a joint commitment by Palm Beach, Broward, Miami-Dade, and Monroe counties (fig. 3) to mitigating and adapting to climate change. In south Florida, wastewater disposal in response to growing population is an important issue. The damaging effects on ecosystems of offshore outfalls of treated wastewater, and the limits on reuse applications because of the high natural water table have made sub-surface injection attractive for wastewater disposal in south Florida. In Puerto Rico, the South Coast is an important agricultural area with growing competition for water with public supply in urban areas. This more arid part of Puerto Rico has recently experienced lengthy droughts (Torres-González and Rodríguez, 2016). The response to droughts has included drastic measures, such as shutting off public water supply on an ad hoc basis. In short, natural and anthropogenic factors are imposing greater stresses on the hydrologic system as competition for resources intensifies.
In addition to resource needs, there are specific hazards related to the hydrologic system of concern for the CFWSC, though not related directly to water supply. With increasing sea level, the low elevation coastal areas in Florida are currently experiencing high-tide inundation with increasing frequency. Rising sea level results in decreasing effectiveness of drainage systems during floods, and significant precipitation event is of increasing concern for south Florida coastal communities. In Puerto Rico, aging surface water reservoirs are becoming increasingly at risk of failure with a heavy precipitation event. Declining water table elevation in many parts of Florida are resulting in potential development of hazardous sinkholes.
Water security and sustainability of water supplies will depend on the ability of communities in Florida and Puerto Rico to effectively manage their water resources, which requires an understanding of the hydrologic budget, potential sources and mechanisms of contamination, and factors that affect water demand. The CFWSC is poised to address problems affecting water supply with scientific and technical analyses that will assist resource managers in finding solutions. The CFWSC has science staff that has the expertise to directly address many specific issues now, and can leverage the resources of the greater USGS to develop expertise in some of the emerging areas. The CFWSC has engaged, and foresees continued engagement, in studies designed to quantify components of the hydrologic budget, evaluate properties important in movement of water and constituents in the hydrologic cycle, and use process-based models to evaluate hydrologic conditions and predict changes in the hydrologic system with future changes in such forcings as climate, growing population, and land-use change. Projected contributions of the CFWSC in the upcoming decade include:
- Collection of water-use data and estimates of unmetered uses. Such data have been an important component in hydrologic budgets and models, and for monitoring long-term trends in water use. Agricultural usage has always been difficult to estimate, and recent studies have emphasized the need for better agricultural estimates, both in Florida and Puerto Rico. A cooperative program to compile and publish water-use data for the state of Florida has been ongoing since 1984, and is continuing with the Florida Department of Agriculture and Consumer Services (FDACS).
- The CFWSC is measuring evapotranspiration (ET) at several locations with varying land types and vegetation (open water, forest canopy, meadow). These data have proven valuable to quantify the water budget of Florida. Directions of current and future development of ET products include the use of satellite products (Geostationary Operational Environmental Satellite system [GOES]) to more accurately estimate spatial variability, and using output from weather forecasting models such as the Weather Research and Forecasting Model (WRF) and the North American Regional Reanalysis Model (NARR). These products can be used to more precisely determine the ET for Florida and its counties. Such methodologies could be developed for Puerto Rico, or elsewhere in the country.
- The CFWSC has developed a groundwater-storage estimation tool for the South Coast aquifer in Puerto Rico. This tool provides a volumetric estimate of aquifer resources, and a month-to-month, seasonal to multi-year view of how the resource is being depleted or recharged. This type of tool has potential use in other areas where there is groundwater monitoring and a need for continuous evaluations of water supply, but quantitative and comprehensive models of the hydrologic systems are not available.
- Springs in north Florida have been experiencing declining flows for years/decades and the cause is uncertain (Saint Johns River and Suwannee River Water Management Districts, 2015). Declining spring flows have implications for ecological needs, as well as water use. The CFWSC collects data critical to monitoring springflow, and has the tools and expertise to study causes and effects of declining spring flows. Other potential research on springs include field-tracer studies to estimate the direction and rate of movement within springsheds, and applications of regional Floridan aquifer models to estimate projected trends in spring flows in upcoming decades.
- The storage potential of dammed reservoirs is decreasing, and the CFWSC has been engaged in estimations of capacity change for multiple reservoirs in Puerto Rico, by analyzing bathymetric data. For example, a study by Soler-Lopez (2016) indicated that the storage capacity of Lago Caonillas in northwestern Puerto Rico decreased by 6 percent between 2000 and 2012. Reduction of capacity and age of reservoir dams, and with these the associated hazards for increased flooding or failure are issues for the CFWSC to address.
The CFWSC has developed capabilities in geophysical techniques for characterizing the subsurface, and the interface between subsurface and surface. Characterizing aquifer and confining layer properties provides insight on the potential viability of an aquifer as water resource, as a receptacle for wastewater disposal, and to quantify groundwater-surface water exchanges.
- The CFWSC is actively, and will continue to be, engaged in the collection of borehole geophysical logs for characterizing aquifer properties. These data have been used to help characterize and map the distribution of flow properties of the primary aquifers in Florida (Biscayne aquifer, surficial aquifer system and Floridan aquifer system), and are becoming increasingly important in the hydrogeologic characterization of deeper parts of the Floridan aquifer systems and deeper units, and for understanding confinement of injected treated wastewater. Future hydrogeologic studies of strata for wastewater injection in south Florida could incorporate microbiological stratigraphy and its relation to mitigation of water quality in the subsurface. For example, Lisle (2014) has reported inactivation of Escherichia coli in anaerobic and reduced groundwater; such conditions are observed in the Floridan aquifer system.
- The CFWSC is actively engaged in aquifer characterization projects using seismic reflection and well data to assess structural anomalies (such as from buried sink holes) and stratigraphy of aquifers in south Florida, including Miami-Dade and Broward Counties. Well data include analyses and description of cores, and the CFWSC is the home of the Carbonate Aquifer Characterization Laboratory. Continuing research will inform managers on the characteristics of units that are being considered for waste-water injection in the deep subsurface. In addition, such research could be extended to studies of the Lower Floridan aquifer as a drinking water source. The CFWSC and SWFWMD have a multi-year project to provide geophysical logs and sample water quality for the wells that extend to the Lower Floridan aquifer in central Florida (figs. 4, 13).
- The CFWSC has developed an approach to processing of time-series electromagnetic soundings, to characterize movement of the saltwater interface in the Biscayne aquifer. We have developed a network of sites for collecting these data, which water managers in South Florida rely on to protect the water supply.
- Several non-invasive, surface geophysical techniques, such as Continuous Resistivity Profiling and Time-Domain Electromagnetics, have been used in Florida to indicate areas of saltwater intrusion or freshwater discharge. Some of these techniques show promise for examining hydrologic conditions and processes in estuarine areas that have experienced fish kill events such as in the Indian River Lagoon (fig. 3).
Figure 13. Collection of water quality samples at a well in Florida that extends to the Lower Florida aquifer.
Hydrologic systems can be complex, as can be the problems facing water-resource managers and decision makers. Analytical tools and methods are needed that account for the interdependencies of processes, and the associated uncertainties. The CFWSC has a long-standing history of developing techniques and using advanced quantitative methods for tackling water-availability problems, as well as problems related to hazards. It is no longer enough to simply characterize the hydrologic system or parts of it; to help water managers address issues of resource sustainability, concepts such as uncertainty and "trade-offs" must be examined. The CFWSC will continue to apply its expertise in quantitative applications to help water resource managers better manage complex resource issues under uncertain and changing conditions, with an emphasis on communicating results to allow for timely decisions by water resources managers.
- The hydrologic system in south Florida is largely controlled by a vigorous surface-water/groundwater exchange, and surface water control structures used to route water to satisfy urban, agricultural, and ecological needs. Specific modeling tools have been developed to simulate this unique system, explicitly accounting for surface water and groundwater flow and exchange, and transport of dissolved constituents (see for example Hughes and White ). These types of models have been used to predict effects on water supply for changing climatic conditions, sea-level rise, and adaptive or engineered scenarios. It is expected that these models will continue to be used, extended and refined for applications concerning, for example, restoration and water management in the Everglades, and water supply planning in the urbanized coastal areas.
- Solute transport models, particularly those that account for variable density, have become and will continue to be an important tool for protection of water supply from saltwater intrusion in the shallow aquifers. Examples include Longevin and Zygnerski (2013), Bellino and Spechler (2013), and Hughes and others (2016).
- Recent work in the CFWSC has focused on characterizing and simulating potential transport pathways of injected wastewater effluent in deep parts of the Floridan aquifer system, out of injection zones and toward protected units (Dausman and others, 2010). As the use of deep well injection of treated wastewater increases in coastal areas of Florida, the Center foresees a continued need to provide cutting edge tools and analyses.
- A promising concept in addressing competing water resource needs is the "One-Water Hydrologic flow Model" (OWHM), which is a holistic approach to quantifying water availability in a supply-demand framework. These types of models have been used to account for and manage water use in mixed urban-agricultural settings, which depend on surface water, groundwater, and precipitation to meet water supply needs, and have potentially great value for the south central coast of Puerto Rico, and central Florida. This approach will allow managers to evaluate efficient strategies for meeting water supply needs, and will demonstrate the trade-offs that may need to be made.
- As part of an effort to better understand Everglades hydrology, the CFWSC has developed and managed the Everglades Depth Estimation Network (EDEN) – a tool that calculates daily water levels. This tool has been used extensively to evaluate conditions for various species or sub-ecosystems, and to monitor trends. Future development of EDEN may include calculating surface-water flow rates, estimating shallow groundwater levels when conditions are no longer inundated, and linking to ecosystem models. It is possible that the tools developed for the EDEN program might have applications elsewhere in the Gulf of Mexico coastal region, and might be adapted to Gulf restoration efforts.
- Numerical hydrologic models have been developed to evaluate the potential for coastal inundation, and the conditions at which surface-water control structures may become ineffective. This type of modeling is currently being applied to urban areas in coastal southeastern Florida and there is increasing interest in these types of models in other locations, as communities develop urban plans for the 50-year horizon.
Groundwater and Streamflow Information
The USGS has the principal responsibility within the Federal Government to provide the hydrologic information and understanding needed by others to achieve the best use and management of the Nation's water resources. Part of this mission includes the responsibility of minimizing the loss of life and property from natural disasters such as floods and droughts. The USGS has a nationwide network of groundwater and surface-water monitoring sites. In 2016, the USGS operated approximately 750 surface-water gaging sites, 630 ground-water level monitoring wells, 140 continuous water-quality stations, and 120 precipitation gages in Florida, Puerto Rico, and the US Virgin Islands. These networks are a foundation for water-resource management throughout the CFWSC. The CFWSC will work to maintain its leadership in providing ground- and surface-water resource information for the States and the Nation. The quality of the hydrologic information provided by the USGS will be the standard to which others are compared. The USGS and the CFWSC will strive to be on the forefront of hydrologic research and related technical advances.
An example of the CFWSC's leadership and innovation in groundwater and streamflow information is the unique and numerous springflow gaging stations throughout Florida. Particularly challenging are Florida’s coastal springs where springflow is affected by the varying tidal signature or other backwater influences. Continuous discharge computations at these stations with tidal or backwater influences cannot be accomplished through standard techniques. Standard techniques compute discharge as a function of stage. Other techniques include index velocity (Levesque and Oberg, 2012) and acoustic methods to compute discharge and sediment transport (Turnispseed and Sauer, 2010; Landers and others, 2016). CFWSC staff have developed and improved several innovative computational methods utilizing new hardware and software solutions to estimate springflow in more complex settings. For example, multivariate statistical methods have been used to estimate springflow as a function of stage, instantaneous change in stage, and water levels in nearby wells for coastal springs in western Florida (for example, Knochenmus and Yobbi, 2001). Other methods to be explored include the application of advanced statistical methods, such as convolution analysis (Smith, 1997) to model springflow in tidal regions.
The water-quality related issues in the area served by the CFWSC include: (1) surface- and ground-water contamination associated with human activities such as nutrients transport and dynamics bacterial contamination; (2) atmospheric deposition, including aquatic cycling of mercury; (3) saline water intrusion, and; (4) aquatic-habitat degradation. Contaminants include a variety of microorganisms and chemical compounds, such as nutrients, metals, pesticides, volatile organic compounds, and pharmaceuticals and personal care products (PPCP), and many other synthetic organic compounds. The CFWSC will maintain a high level of expertise in water-quality sampling and data analysis and work with our cooperators to remain a primary source of information on the quality of the waters of Florida, Puerto Rico, and the U.S. Virgin Islands. Projects in the Center range from routine water-quality assessments to advanced research. A brief description of all projects currently (2017) being conducted by the CFWSC can be found at https://fl.water.usgs.gov/. Topics of more immediate interests are discussed below.
Nutrients transport and dynamics and byproducts of algal blooms
Understanding the source and fate of nutrients in the surface water and groundwater water of Florida, Puerto Rico, and the U.S. Virgin Islands are important water-quality issues. The delivery of nitrogen and phosphorus to critical water bodies (such as reservoirs and estuaries) needs to be addressed. Major nutrient sources include nonpoint-source runoff from agricultural and urban areas, atmospheric deposition of nitrogen, and direct and indirect discharges of wastewater. Examples include ways of reducing amounts of nutrients entering Lake Okeechobee (Byrne and Wood, 2012) and its potential effects in streams flowing to rivers and coastal estuaries. These waters are enriched with nutrients resulting in degraded water quality and excessive aquatic-plant growth. On July 2016, Lake Okeechobee and southern Florida's algal blooms caused mass die-offs of aquatic organisms and harm human health (fig. 14). The toxins produced by some species of cyanobacteria (called cyanotoxins) cause acute and chronic illnesses in humans. Harmful algal blooms (HAB) can adversely affect aquatic ecosystem health, both directly through the presence of these toxins and indirectly through the low dissolved oxygen concentrations and changes in aquatic food webs caused by an overabundance of cyanobacteria. Economic damages related to cyanoHABs include the loss of recreational revenue, decreased property values, and increased drinking-water treatment costs (https://www.usgs.gov/news/science-harmful-algae-blooms).
Figure 14. Aerial view of Lake Okeechobee in July 2016 during cyanobacterial bloom (image from https://www.usgs.gov/news/science-harmful-algae-blooms).
Another example are the high nitrate concentration levels in the groundwater from the South Coast aquifer of Puerto Rico, which are related to the intensive agricultural activities in the area (Rodríquez, 2013). An active area of scientific research has emerged for these topics and nationwide strategies to assess water-quality conditions and management options are under consideration because of the significance and complexity of the nutrient-enrichment problems within streams, lakes, and coastal waters. These efforts include developing effective and efficient nutrient monitoring and modeling studies.
An example of the work already underway to investigate nutrient levels in Florida’s waterways is the continuous nitrate monitor network. The CFWSC has made significant investments in equipment over the past 5 years to build what has become the Nation’s largest continuously operated real-time nitrate network. These miniaturized spectrophotometers are deployed in-situ and record nitrate concentrations every 15 minutes which allows us to see temporal variations never before possible. We are hopeful that this network will continue to grow and serve as a basis for future investigative projects.
Bacterial contamination of streams and coastal waters
The sanitary quality of public bathing beaches has been a concern in Florida, Puerto Rico, and the U.S. Virgin Islands. Concentrations of fecal indicators frequently increase after rainfall events causing State public-health and environmental-monitoring agencies to advise the public about the risk of making direct contact with the water (http://www.floridahealth.gov/environmental-health/beach-water-quality/index.html and http://www2.pr.gov/agencias/jca/pages/monitor%C3%ADadeplayas.aspx). Studies by Rodríguez-Martínez and Guzmán-Rios (2017) in Puerto Rico indicate the occurrence of fecal indicator bacteria concentrations in streams above the established standards by regulatory agencies. A major need is to develop in-stream flow requirements in a scientifically defensible manner, to ensure that the multiple and often competing demands for water resources have minimal effects on aquatic ecosystems. Also, the detection of illegal discharges and managing storm water from development is critical to control the water-quality degradation of streams and coastal waters. An area of scientific research focused on these topics could be considered because of the implications of the sanitary conditions of streams, lakes, and coastal waters. These include the implementation of effective and efficient bacteria monitoring and modeling studies.
Anthropogenic Organic Compounds in Groundwater
The occurrence of anthropogenic organic compounds (AOCs) in ground water has been evaluated in the unconfined and semiconfined portions of the Upper Floridan aquifer system as part of the National Water-Quality Assessment (NAWQA) Program (Metz and others, 2007). The AOCs evaluated included volatile organic compounds (VOCs), pesticides, and other AOCs. The occurrence of AOCs was evaluated in groundwater used as source water for large-producing community water system wells. Analyses of population and land use indicated that the number of compounds detected increased as the population surrounding each well increased. The results suggest that additional data are needed to determine how the geochemistry of source waters (water collected at a water-supply well or surface-water intake) compares to finished waters (water that has been processed by a water treatment plant).
The occurrence of VOCs in public-supply was studied by the USGS in Puerto Rico during the 1980s, which detected most of the contamination sites that were eventually classified as Superfund sites. The occurrence of pesticides in groundwater of the South Coast aquifer was recently studied in intensive agricultural areas (Rodríguez, 2013). The detected organic compounds included 8 herbicides, 3 fungicides, and 2 insecticides. The current occurrence and distribution of AOCs in groundwater is an identified need for future research on the principal aquifers of Puerto Rico.
"Emerging contaminants" can be broadly defined as any synthetic or naturally occurring chemical or any microorganism that is not commonly monitored in the environment but has the potential to enter the environment and cause known or suspected adverse ecological and(or) human health effects. These contaminants typically are present in the environment at very low concentrations, and their effect on human health is not well understood. Studies have detected these compounds in low concentrations in streams of Florida (Barnes and other, 2002) and Puerto Rico (Barnes and others, 2008). There is evidence to suggest, however, that some emerging contaminants, by virtue of their ability to interact with the endocrine system, are causing a variety of adverse health effects in humans and wildlife. These contaminants are receiving increased attention in recent years.
Aquatic Cycling of Mercury
For most aquatic ecosystems, atmospheric deposition is the primary source of mercury, although there are numerous instances of geologic and anthropogenic point-source contamination. Atmospheric deposition has received renewed attention, and concerns have broadened to include atmospheric mercury deposition. The USGS South Florida Ecosystem Program works to describe the mercury contamination problem in south Florida and to investigate the underlying processes that cause mercury bioaccumulation The overall objective of this project is to provide resource managers scientific information on the hydrologic, biologic, and geochemical processes controlling mercury cycling in the Everglades. The CFSWS has a continuing program of mercury (and carbon) flux in the Everglades, using fluorescence of dissolved organic matter as a surrogate indicator (fig. 15).
Figure 15. USGS CFWSC employees collecting water samples used to develop surrogate models for carbon and mercury concentrations.
Saline water intrusion
Saline water intrusion might be the most important water-quality issue in upcoming decades for Florida, particularly in coastal regions. Sea-level rise might be on the order of several meters within the next 50–100 years (Hansen and others, 2016). The CFWSC has a saline intrusion monitoring program in south Florida. The Saline Intrusion Monitoring provides:
- access to all of the salinity information collected as part of this project,
- access to data being collected from the modified USGS / Miami-Dade County monitoring network as it evolves,
- resource for integrating the geographic data sets from other researchers and agencies working in the area, and provide an improved means of evaluating salinity changes in the Biscayne Aquifer that will occur even after the project has been completed.
In Puerto Rico, the two principal aquifers—the North Coast Limestone aquifer system (NCLAS) and the South Coast aquifer—have been evaluated and monitored for the increasing concentrations of dissolved solids. Groundwater in the upper aquifer of the NCLAS historically has been the principal source of public-supply and self-supplied industrial water use in north-central Puerto Rico. Development of the aquifer for these two major water-use categories began in about 1930; however, withdrawals did not become an important water-supply source for sustaining local development until the 1960s and peaked in the 1980s. Withdrawals have declined since the reduction in industrial activity in the area. The effects of aquifer overdraft have been documented in the regional thinning of the freshwater lens, with an increase in dissolved-solids concentration in groundwater wells (Gómez-Gómez. 2007). Increasing concentrations of dissolved solids were also documented in some areas of the South Coast aquifer of Puerto Rico. The South Coast aquifer is an important of source of water for public-supply and irrigation in the area. Some towns in the area relies exclusively on groundwater for public-supply. During 2015, a severe drought occurred through most of Puerto Rico (Torres-González and Rodríguez, 2015), which decreased the groundwater levels of the South Coast aquifer causing the implementation of restrictions of water for public-supply. Given the complex interactions of water-use and water resource demands in Puerto Rico, implementation of the One Water Hydrologic Model (OWHM) approach would be a potentially valuable tool to manage the competing needs of water resources in the south coast of Puerto Rico.
Water Resources Research Institute Program
Associated with the Water Resources Research Act of 1984 is the authorization of the Water Resources Research Institute (WRRI) Program. This is a Federal and State/Territory partnership and includes Florida, Puerto Rico and the U.S. Virgin Islands. WRRI Programs are located a universities, in partnership with the USGS. In areas where the USGS CFWSC does not have a physical and continuous staff presence, such as the U.S. Virgin Islands, the WRRI Program provides a local point of contact with agencies and universities. The CFWSC is working with the U.S. Virgin Islands to install Climate Response Monitoring Network wells to monitor water levels, with plans to include additional continuous monitoring and water quality sampling. The goal of this work is to more fully understand the groundwater resources of the U.S. Virgin Islands.