Increasing dependence on groundwater in the Wakal River basin, India, jeopardizes water supply sustainability. A numerical groundwater model was developed to better understand the aquifer system and to evaluate its potential in terms of quantity and replenishment. Potential artificial recharge areas were delineated using landscape and hydrogeologic parameters, Geographic Information System (GIS), and remote sensing. Groundwater models are powerful tools for recharge estimation when transmissivity is known. Proper recharge must be applied to reproduce field-measured heads. The model showed that groundwater levels could decline significantly if there are two drought years in every four years that result in reduced recharge, and groundwater withdrawal is increased by 15%. The effect of such drought is currently uncertain however, because runoff from the basin is unknown. Remote sensing and GIS revealed areas with slopes less than 5%, forest cover, and Normalized Difference Vegetative Index greater than 0.5 that are suitable recharge sites.

Eastern box turtles are declining throughout their range as a result of habitat loss and fragmentation, associated road mortality, collection for the pet trade, and other localized threats such as incidental collection, disease, mowing, and fire. We evaluated the geomorphic habitat suitability for Eastern box turtles in Massachusetts using a Mahalanobis distance modeling approach. To evaluate habitat use, home range size, and box turtle population status in the Connecticut River Valley, Massachusetts, we conducted a four year mark-recapture and radio-telemetry effort. We surveyed over 30 sites, captured 191 animals and radio-tracked 91 animals at eight sites for 1-4 years for a total of 217 turtle-years. Estimated population sizes at these sites ranged from a summer high of 3.8 to a winter low of 0.3 turtles/ha. Home range size ranged from 140–2145 m straight line and 0.5–136 ha. These densities are much lower and home range sizes much larger than reported throughout the rest of the species range. Conservation efforts based on data from previous studies elsewhere in the species range would have underestimated habitat requirements and space needs, highlighting the need for local and regional information when planning for rare species conservation. We evaluated over-wintering habitat at multiple levels of habitat selection and spatial scales using logistic regression and classification trees in conjunction with remotely sensed geomorphic and land-use variables. We also conducted a micro-habitat assessment of over-wintering sites using variables measured in the field. Microtopography proved important, with 59% of transmitting turtles over-wintering in depressions (typically behind tip-up mounds of fallen trees). Other variables distinguishable between turtle and random locations were high basal areas of hardwood trees and abundant downed wood and mountain laurel. These results can be used to inform management practices and focus future survey efforts. We evaluated the influence of landscape composition and structure on the movements of box turtles using mixed effects linear regression models. Eastern box turtles have smaller home ranges in more urbanized landscapes and move further in more forested, less fragmented areas. The relationship varies significantly by site, underscoring the importance of evaluating effects across multiple sites, and suggesting that single-site studies may not be generalizable throughout regions. Population density estimates from five of the sites suggest a unimodal rather than linear relationship with urbanization. The highest-density site had a moderate level of fragmentation, suggesting that low levels of urbanization may be compatible with Eastern box turtle conservation, but that high levels of fragmentation may be detrimental to box turtle populations. Early successional habitat comprised more than 50% of June locations, suggesting these habitat features are important and may be limited on the landscape. We evaluated whether habitat management to create such areas could be effective by using utility distribution volume and a randomization approach to assess habitat use before and after forest was cleared at two sites. Use of the treatment areas increased significantly after clearing. Our results suggest that Eastern box turtles are willing to incorporate newly cleared areas into their home range within one year, and that it may be possible to improve habitat and minimize movement distance through active management. We also characterized seasonal movement and activity patterns, nesting habitat and reproductive parameters, and adult mortality rates. We suspect that mortality rates are much higher statewide and that habitat loss is likely the largest cause of mortality. Using our observed clutch size, nest success rate, and adult mortality rate and a deterministic population model, we estimated that hatchling and juvenile survival rates must exceed 77.6% annually in order to maintain a stable population in the absence of stochastic events. This survival rate is unrealistically high, particularly since the model does not account for variability and we suspect that our adult survival rate was artificially inflated, suggesting that populations may be declining in the Connecticut River Valley, even at protected sites. (Abstract shortened by UMI.)

No description available.

Living shoreline stabilization has become a popular practice in shoreline restoration and bank protection; however, there are still many uncertainties regarding effective site design using living materials. For example, natural wave-breaks may be formed of created reefs, but the optimum water depth for hydrodynamic influence may differ from the preferred depth to ensure organism recruitment. The objective of this research is to understand how water depth relative to the crest of submerged artificial oyster reef structures influences nearshore hydrodynamic processes and sediment transport or retention in nearshore areas. A field study, sited in a microtidal estuary on the Atlantic coast of Florida, applied a controlled, two-way block experimental design testing varied configurations of oyster reef structures constructed by bagged oyster shell: continuous vs. gapped structures located close (3 m) and far (12 m) from the edge of existing black mangrove vegetation. Bed elevations, sediment texture and organic matter content, and hydrodynamic data were measured in each treatment and control plot and compared before and after structure implementation over three years. Distance from shore influenced reef submergence such that far from shore structures were sited in deeper water and subtidal while closer to shore structures were in shallower water and were intertidal. The difference in water level over reefs influenced wave attenuation rates from the channel to shoreline, both at the individual plot level and across the treatments. More variable and lower attenuation rates were observed over structures far from shore in deeper water (range of mean attenuation, η = -6 – 36%). Shallower nearshore structures were associated with greater mean attenuation rates (η = 30 – 70 %), which also outpaced attenuation observed before structure placement (η = 0 – 10%). Repeat Real Time Kinematic (RTK) surveys before and after reef creation indicated that sizable sediment deposits formed in the areas between the created reefs and the shoreline, totaling a net gain of 418.5 m3 of sediment, an approximate mean deposition depth of 7.9 cm, within three years of reef creation. Accretion at gapped and continuous reef plots were similar whereas accretion behind far from shore reefs was about 20 % greater than behind near to shore reefs. Texture of nearshore sediments coarsened across all plots after structure placement, changing from majority fine sand (150-250 μm) to medium sand (250-500 μm). For example, fine sand composed of 69 % of nearshore sediments prior to structure placement, but only 11 % after three years. Additionally, mean organic matter content of shoreline sediments increased three folds, from 10.6 g/kg to 32.0 g/kg, while no change was documented seaward of reef structures. Study results can be applied to improve designs of created oyster reef as self-sustaining natural infrastructure. The results suggest that design water levels and thus placement of created reefs relative to shoreline vegetation can be flexible, as the far from shore reefs enhanced sediment retention and deposition nearshore despite the lower wave attenuation. Greater flexibility in living shoreline designs allowed under common permits would allow artificial reefs to be sited to better optimize conditions for oyster recruitment, which will ensure the longevity and ecological function of the infrastructure.

Microcystins (MCs) are toxins produced by cyanobacteria commonly found in harmful algal blooms (HAB) occurring in many surface waters. Due to their toxicity to humans and other organisms, the World Health Organization (WHO) set a guideline of 1 µg/L for microcystin-leucine-arginine (MC-LR) in drinking water. However, current analytical techniques for the detection of MC-LR such as liquid chromatography-mass spectrometry (LC-MS) and enzyme-linked immunosorbent assay (ELISA) are costly, bulky, time-consuming, and mostly conducted in a laboratory, requiring highly trained personnel. Therefore, an analytical method that can be used in the field for rapid determination is essential. In this study, an Anti-MC-LR/MC-LR/Cysteamine coated screen-printed carbon electrode (SPCE) biosensor was newly developed to detect MC-LR, bioelectrochemically, in water. The functionalization of the electrode surface was examined using scanning electron microscopy-energy dispersive X-Ray spectroscopy (SEM-EDX) and X-Ray photoelectron spectroscopy (XPS). The sensor performance was evaluated by electrochemical impedance spectroscopy (EIS), obtaining a linear working range of MC-LR concentrations between 0.1 and 100 µg/L with a limit of detection (LOD) of 0.69 ng/L. Natural water samples experiencing HABs were then collected and analyzed using the developed biosensor and validated using ELISA, demonstrating the excellent performance of the biosensor with a relative standard deviation (RSD) of 0.65%. The interference and selectivity tests showed a minimal error and RSD values against other common MCs and possible coexisting ions found in water, suggesting high selectivity and low sensitivity of the biosensor. The biosensor showed acceptable functionality with a shelf life of up to 12 weeks. Overall, the Anti-MC-LR/MC-LR/Cysteamine/SPCE biosensors can be an innovative solution with characteristics that allow for in situ, low-cost, and easy-to-use capabilities which are essential for developing an overarching and integrated "smart" environmental management system.

Coastal archaeological sites are threatened by a host of environmental change processes, including sea level rise, land subsidence, and shoreline erosion. The rates at which these processes have been occurring are increasing, exacerbated by climate change, and are expected to increase even more rapidly in the future. This will cause further loss of archaeological sites and with them, the loss of our knowledge of how coastal inhabitants lived and interacted with their landscape. My research assesses the vulnerability of prehistoric and Contact period Native American sites situated around Indian Field Creek in Virginia. This area saw multiple prehistoric occupations, culminating in the protohistoric village of Kiskiak, which was part of the Powhatan chiefdom at the time of European contact. Recent archaeological excavations and the careful study of shell middens found in this area have added to our knowledge of how the Kiskiak people dwelled within this landscape and interacted with their environment. However, field observations have revealed that these midden deposits are actively being eroded. My research takes into consideration a variety of environmental and cultural variables to determine which sites in this area are most at risk from the natural environment and which would be the greatest loss to our understanding of the past if they were washed away from the archaeological record. The results of this research presented here provide guidance for environmental and cultural managers to best preserve the archaeological record and our knowledge of the native people of this region.

No description available.

No description available.

Understanding the groundwater flow in karst aquifers and the effect of best management practices (BMPs) on nitrate decrease in spring discharge is critical for effective management and protection of karst water resources. However, the control on the conduit network's impacts on spring discharge and nitrate concentration is not fully understood, and the cumulative effects of BMP on reducing nitrate in karst groundwater systems have not been evaluated at the basin scale. In this dissertation, a coupled Conduit Flow Process (CFPv2) and Conduit Mass Three-Dimensional (CMT3D) model was applied to evaluate the biosorption-activated media (BAM)-based BMP on nitrate removal in Silver Springs in Florida. It is found that the effect of BMP by implementing BAM blanket filters in twenty-six stormwater retention basins is limited; whereas, for implementing BAM blanket filters in 50% of the urban area, the nitrate-N concentration in spring discharge would be decreased by 10.7% in a normal hydrologic year. The controls on the contribution of conduit flow to spring discharge are evaluated. For aquifer with turbulent flow in a single conduit, the effects of three dimensionless numbers (Reynolds number, relative surface roughness, and hydraulic conductivity ratio) and recharge on conduit flow contribution are quantified. Moreover, the effects of conduit geometry and density on conduit flow contribution are evaluated for conduit networks. Finally, the prediction of long-term average discharge in ungauged basins is assessed for improving recharge estimation.

The use of ultraviolet (UV) light and chlorine dioxide (ClO2) as an advanced oxidation process (AOP) has been investigated at the bench-scale to understand the effects of their use on disinfection by-product (DBP) formation potential (FP) in chlorinated groundwater (GW) and surface water (SW) supplies. Two GWs and two SWs of varying qualities were subject to a series of AOP treatment sequences at the bench scale: sodium hypochlorite, to serve as a baseline; ClO2-Cl2, UV-Cl2, and UV-ClO2-Cl2. In these treatment sequences, Cl2 is used as a primary and secondary disinfectant. Several water quality parameters were measured throughout the experiments, including chlorite (ClO2-) and chlorate (ClO3-) when ClO2 was used for process testing. Total trihalomethane (TTHM) FP curves were developed for each experiment along with the 7-day haloacetic acid (HAA) FP. The treatment sequence UV-ClO2 followed by Cl2 addition for GW supplies was shown to remove between 8 and 35 percent of the TTHM FP as compared to little to no change in formation potential with UV treatment alone followed by Cl2 addition. The SW supplies resulted in reductions between 16 and 27 percent for the treatment sequence UV-ClO2 followed by Cl2, approximately double the reduction from ClO2 alone followed by Cl2. GW treatment using the UV-ClO2 AOP followed by Cl2 was found to increase HAA formation, in one case by almost 50 percent compared to the baseline HAA concentrations. The research indicated the reduction of DBP FP AOP effectiveness to reduce DBP formation was highly dependent on the specific source water type and quality.