Near‐infrared spectroscopy of a hydroecological indicator: new tool for determining sustainable yield for Floridan aquifer system

Abstract

Abstract:Pond-cypress (Taxodium ascendens Brong.) is a dominant canopy species in depressional wetlands of the south-eastern Coastal Plain. Unsustainable withdrawals from the karst Floridan aquifer system have caused premature decline and death of pond-cypress trees, presumably owing to altered hydroperiods (which alter the flow of water and nutrients in trees). There has been no scientifically based means to determine sustainable yield from this regional aquifer system or to detect early stages of physical/ecological damage associated with groundwater mining and aquifer storage and recovery (ASR, which also can alter natural hydroperiods). In this study, the relationship between visual symptoms (indicators) of stress or premature decline, and spectral reflectance was evaluated using dried, milled branch tips collected from natural stands of mature pond-cypress. Depressional systems evaluated represented four of the six aquifer system subregions where subsurface perturbations from groundwater mining: (i) were presumed not to be occurring (reference wetlands); (ii) may be occurring but are not documented; and (iii) have been confirmed. Sampled trees were assigned to one of three stress classes (1, no/minimal; 2, moderate; 3, severe) based on the visual indicators. Partial least squares-linear discriminant analysis of second derivative spectral transformations in the visible/shortwave near-infrared (NIR) region (400-1100 nm) and the NIR region (1100-2500 nm) was used to evaluate the samples in assigned classes.Class 1 samples were discriminated from combined class 2 and 3 samples in the NIR region with 100% and 97% accuracy for consecutive winter sample periods (before bud-break). The percentage of correctly classified samples in this spectral region was lower (85%) for summer samples (full leaf-out). Second-derivative models for the NIR region developed from the winter data sets predicted assigned classes for alternate winter's samples with an accuracy of 97% and 100%. High correlation between spectral reflectance of dried, milled branch tips collected from mature pond-cypress in winter and visual indicators of premature decline suggests in situ pond-cypress are hydroecological indicators of anthropogenic subsurface hydroperiod perturbations. This approach provides objective means for early detection of unsustainable aquifer yield and adverse impacts from ASR activities in the south-eastern Coastal Plain. Used in conjunction with hydrological monitoring and modelling, the hydroecological indicators should provide the means with which sustainable yield in the south-eastern Coastal Plain can be achieved and maintained.

Mitigation Banks and Other Conservation Lands at Risk from Preferential Groundwater Flow and Hydroperiod Alterations by Existing and Proposed Northeast Florida Mines

“…In an attempt to evaluate areas that could be more susceptible to experiencing adverse environmental impacts from mining and other groundwater alterations, such as those described by Bacchus (2006) and Bacchus et al (2003), ground reconnaissance was conducted for this study prior to the georectification of features mapped as lineaments in the study area and the mapping of modern sinkholes in the study area from the state's sinkhole database. Some of the procedural steps recommended by Ogden (1984) for sinkhole analysis also were used as guidance in selecting areas for ground reconnaissance for adverse environmental impacts in the vicinity of the mine sites.…”

“…Some of the procedural steps recommended by Ogden (1984) for sinkhole analysis also were used as guidance in selecting areas for ground reconnaissance for adverse environmental impacts in the vicinity of the mine sites. Figure 9 shows the numbered Global Positioning System (GPS) locations of some of those areas of ground reconnaissance that were identified using U.S. Geological Survey (USGS) topographic maps and established hydroecological indicators of groundwater alterations, such as those described by Bacchus et al (2003), and knowledge from other sites in Florida where adverse environmental impacts occurred from mining and other groundwater alterations. In all cases, adverse environmental impacts were identified at the ground reconnaissance locations where greater susceptibility was predicted.…”

“…Cumulative impacts of groundwater pumping have resulted in significant impacts to existing legal users (shallow wells) and property damage from sinkholes are well documented and resulted in several studies conducted in the vicinity of phosphate mining in west-central Florida, documenting approximately 760 dry wells and 140 sinkholes created within 10 miles (16 km) of the drawdown in that area (Peterson & Rumbaugh, III, 2012). Bacchus (2001), Bacchus et al (2003) and Bacchus, Archibald, Britton, and Haines (2005) provided examples of the types of cumulative adverse environmental effects from hydroperiod alterations, like those that would occur from the proposed mines in our northeast Florida study area. Lines et al (2012) included the definition of hydroperiod, more detailed discussions and photographs of environmental damage from cumulative impacts of hydroperiod alterations that also are relevant to the northeast Florida study area, with emphasis on adverse impacts to wildlife habitat such as wetlands throughout the FAS, including habitat critical for the survival and recovery of threatened and endangered species.…”

“…Those impacts also were addressed by Bacchus (1998;2006) and include destructive fires and premature decline and death of trees from hydroperiod alterations. Impacts such as bark beetle infestations and fungal infections have been shown to occur in the absence of, or to precede destructive wildfires that further injure or destroy stem, crown, or root tissues in areas where the natural defenses of trees have been compromised by hydroperiod alterations (Bacchus, 2007;Bacchus et al, 2003;Bacchus, Archibald, Britton, & Haines, 2005). Authors who have considered bark beetle infestations (Dixon, Corneil, Wilkinson, & Foltz, 1984;McHugh, Kolb, & Wilson, 2003;Menges & Deyrup, 200l) and fungal infections (Otrosina, Bannwart, & Roncadori, 1999;Otrosina, Hess, Zamoch, Perry, & Jones, 1997) as responses to fire, or second-order fire effects resulting in post-fire tree decline and mortality have not evaluated hydroperiod alterations as the triggering mechanism for destructive fire in their research.…”

Mapped Fractures and Sinkholes in the Coastal Plain of Florida and Georgia to Infer Environmental Impacts from Aquifer Storage and Recovery (ASR) and Supply Wells in the Regional Karst Floridan Aquifer System

“…Research has shown that natural depressional wetlands that are characteristic of the FAS (e.g., pond-cypress wetlands and wet prairies) have historic surfacewater connections to navigable waters and occur in relict sinkholes that are aligned along fractures and connected to the underlying regional karst aquifer system, as summarized by Bacchus (1998;2006;2007) and Bacchus et al (2003). Therefore, The ruling simply clarified that CWA jurisdiction did not include that man-made mine pit, simply because the mine pit included wetlands and migratory birds were utilizing that area.…”