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(1 - 10 of 10)
- Title
- PREDICTING HERBIVORE INDUCED PHYTOCHEMICAL SHIFTS IN HELIANTHUS USING SPECTRAL REFLECTANCE.
- Creator
-
Jowais, Jessica, Bohlen, Patrick, University of Central Florida
- Abstract / Description
-
Induced defense responses in plants vary greatly among species, with many species exhibiting strong upregulation of secondary metabolites under attack by herbivores or pathogens. Secondary metabolite responses are most commonly analyzed using nuclear magnetic resonance or mass spectroscopy, though such approaches are costly and time-intensive. This study explores the use of hyperspectral reflectance as a more time- and cost-efficient method of detecting herbivore-induced secondary metabolite...
Show moreInduced defense responses in plants vary greatly among species, with many species exhibiting strong upregulation of secondary metabolites under attack by herbivores or pathogens. Secondary metabolite responses are most commonly analyzed using nuclear magnetic resonance or mass spectroscopy, though such approaches are costly and time-intensive. This study explores the use of hyperspectral reflectance as a more time- and cost-efficient method of detecting herbivore-induced secondary metabolite responses in plants. A diverse cross-section of wild sunflowers (genus Helianthus) were grown under controlled conditions and challenged with insect herbivory. Hyperspectral reflectance data was collected and analyzed using a principal component analysis in conjuncture with a support vector classification model to detect herbivore-induced versus control plants. The best model had a 93% accuracy rate at predicting whether a sample came from an induced or control plants when using data from all species tested. However, the changes in hyperspectral reflectance under herbivore induction varied greatly across species.
Show less - Date Issued
- 2018
- Identifier
- CFH2000422, ucf:45907
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH2000422
- Title
- Mucking About: Hydrologic Regime and Soil Carbon Storage in Restored Subtropical Wetlands.
- Creator
-
Huber, Alicia, Bohlen, Patrick, Hinkle, Ross, Chambers, Lisa, University of Central Florida
- Abstract / Description
-
Wetlands are extremely important ecosystems that have declined drastically worldwide, continue to be lost, and are threatened globally. They perform a number of important ecosystem services such as flood control, provide habitat for many species, and have aesthetic and recreational value. Wetlands are also important to the global carbon (C) cycle. Wetland soils are especially effective C sinks because they have high primary productivity and low decomposition rates due to flooded, anoxic...
Show moreWetlands are extremely important ecosystems that have declined drastically worldwide, continue to be lost, and are threatened globally. They perform a number of important ecosystem services such as flood control, provide habitat for many species, and have aesthetic and recreational value. Wetlands are also important to the global carbon (C) cycle. Wetland soils are especially effective C sinks because they have high primary productivity and low decomposition rates due to flooded, anoxic conditions. Increased recognition of wetlands' value has led to more ecological and hydrological restoration of degraded wetlands to mitigate the effects of wetland destruction. Hydrological restoration, which attempts to recreate natural hydroperiod and water levels in wetlands, is expected to increase soil C storage. Many studies have estimated the C stock in different wetland ecosystems across biomes, but few have examined hydrological drivers of soil C variation across wetland types. This study investigated the relationship between hydrologic variables (hydroperiod and average water depth) and soil C storage in three types of hydrologically restored wetlands (marsh, bay swamp, and cypress swamp) at the Disney Wilderness Preserve (DWP) in central Florida, USA. I collected 150 50-cm soil cores along existing monitoring transects in sampled wetlands where water elevation data had been collected since 1995 to examine the relationship between hydrologic variable and soil C storage. I analyzed a combination of generalized linear mixed models (glmm), evaluated using AICc. Mean water depth was a better predictor than hydroperiod of soil C concentration and stock. Mean water depth had a significant positive relationship with soil C concentration in bay swamps and marshes and soil C stock in marshes. However, this effect was small and often outweighed by other factors such as differences in vegetative community, soil depth, or local site conditions. Water depth had no significant relationship with soil C concentration in cypress swamps or upland communities or on soil C stock in bay swamps, cypress swamps, or uplands. Wetland community type had a strong influence on soil C variation, with bay swamp soils having the highest mean soil C concentration followed by cypress swamp, marsh, and upland soils, respectively. Soil C concentration generally decreased with soil depth. Bay swamps also had the highest soil C stock, followed by cypress swamp, marsh, and upland soils, respectively. Together, the sampled wetland communities cover approximately 22% of the sampled communities at DWP, yet store an estimated 47% of the total soil C to a 90 cm depth. The results of this study affirm the importance of inundation for soil C storage in wetlands, but also highlight that there are a number of other complex variables affecting soil C in different types of wetlands such as differences in litter quality and decomposition rates.
Show less - Date Issued
- 2017
- Identifier
- CFE0007122, ucf:51930
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007122
- Title
- Variation in Prospecting Behavior and Drivers of Post-Fire Habitat Preference Among Juvenile Florida Scrub-Jays.
- Creator
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Sherer, David, Bohlen, Patrick, Bowman, Reed, Jenkins, David, University of Central Florida
- Abstract / Description
-
Florida Scrub-Jays (Aphelocoma coerulescens, FLSJ; federally Threatened) are cooperatively breeding birds endemic to Florida and dependent on fire-maintained xeric oak scrub. FLSJs are year-round residents, highly territorial, and rarely disperse far from their natal territory. Lifetime reproductive success is highest among individuals breeding in early-successional habitat, usually less than 9 to 10 years post-fire. However, because scrub burns infrequently such early-successional, high...
Show moreFlorida Scrub-Jays (Aphelocoma coerulescens, FLSJ; federally Threatened) are cooperatively breeding birds endemic to Florida and dependent on fire-maintained xeric oak scrub. FLSJs are year-round residents, highly territorial, and rarely disperse far from their natal territory. Lifetime reproductive success is highest among individuals breeding in early-successional habitat, usually less than 9 to 10 years post-fire. However, because scrub burns infrequently such early-successional, high-quality habitat is extremely limited and competition for it as breeding space is likely intense. Because some birds live long enough to experience habitat succession, FLSJs also occupy later-successional overgrown scrub, even though both survival and fecundity decline. Although immigration rates into later-successional habitat decline, some birds settle there, perhaps to avoid competition. Prior to dispersal into new breeding territories, most non-breeders engage in pre-dispersal forays, which occur before and immediately after the breeding season. Because FLSJ territories occur across a gradient of post-fire succession, and young birds make frequent forays beyond their natal territories, and are highly visible while doing so, they are ideal models to test how individual and environmental factors drive habitat preference when exploring a post-fire mosaic. I investigated how individual behavioral phenotype, natal territory condition, and body condition relative to conspecifics influence extra-territorial foray behavior across a habitat mosaic that includes various time-since-fire (TSF) intervals. My study system was a population of individually marked FLSJs on 1,214-ha of managed scrub at Archbold Biological Station (Highlands County, Florida). I measured off-territory movements of 114 yearling birds in three annual cohorts and quantified habitat preference using fine-scale fire history records. These data, paired with behavioral assays and morphometric records for each individual FLSJ, allowed me to create and compare models of exploratory behavior underlying searching patterns during pre-breeding forays. My results indicate significant variation in habitat preference by individual FLSJs during forays, driven by an individual's behavioral phenotype and the TSF of its natal territory.
Show less - Date Issued
- 2019
- Identifier
- CFE0007864, ucf:52790
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007864
- Title
- Transforming the Aquatic Urban Landscape: Nutrient Status and Management of Stormwater Basins.
- Creator
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Skovira, Lindsay, Bohlen, Patrick, Fauth, John, Wang, Dingbao, University of Central Florida
- Abstract / Description
-
Urbanization is a largely irreversible anthropogenic change that degrades environmental quality, including aquatic ecosystems. Stormwater ponds are a popular best management practice (BMP) to mitigate the effects of urban land use on downstream water bodies and contribute significantly to the total area of aquatic ecosystems in some urban watersheds. My research investigated the distribution of stormwater ponds and examined how different urban land uses influenced biophysicochemical...
Show moreUrbanization is a largely irreversible anthropogenic change that degrades environmental quality, including aquatic ecosystems. Stormwater ponds are a popular best management practice (BMP) to mitigate the effects of urban land use on downstream water bodies and contribute significantly to the total area of aquatic ecosystems in some urban watersheds. My research investigated the distribution of stormwater ponds and examined how different urban land uses influenced biophysicochemical conditions and management of those ponds in a rapidly developing suburban watershed in the Econlockhatchee River basin in Florida, USA. I evaluated limnological and ecological parameters in randomly-selected ponds distributed among three urban land-use classes: high-density residential, institutional, and roadways. Ecological measures included characterizing percentage cover and composition of littoral zone plant community and the extent of any algal mats. Limnological measures included physical parameters (pH, conductivity, dissolved oxygen, and clarity), and nutrient concentrations (nitrate, ammonium, total nitrogen, dissolved reactive phosphorus, total phosphorus, and chlorophyll a). I used a subjective management intensity index to compare pond management among land-use classes. Stormwater ponds represented 40.2% of the total area of non-forested freshwater systems in the watershed, and were dominated by residential land uses (43.7%), followed by roadways (14.7%), industrial (2.7%) and institutional (2.3%). Principal Component Analysis (PCA) revealed that ponds with higher total nitrogen (TN) and chlorophyll a (chla) concentrations had lower water clarity, and that both. TN and TP were positively correlated with chla. PCA scores for school ponds, which had the highest water clarity, differed significantly from those of expressway and residential ponds, along the first PCA axis. Repeated-measures analysis of variance showed that TN concentrations differed significantly between expressway and school ponds, with expressway ponds having TN concentrations 51.7% higher than schools. Both TP and TN varied differently through time in the different lands uses. Management intensity for removal of aquatic vegetation and algae was lower in school ponds than in expressway and residential ponds, and school ponds contained the highest abundance and diversity of vegetation. Different urban land uses had varying impacts on water quality, and more intense chemical use to control vegetation and algae was related to greater nutrient and chla concentrations and lower water clarity.
Show less - Date Issued
- 2016
- Identifier
- CFE0006845, ucf:51781
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006845
- Title
- Evaluating Floating Treatment Wetlands to Improve Nitrogen Removal in a Wet Detention Pond.
- Creator
-
Marimon, Zachary, Chang, Ni-bin, Fauth, John, Bohlen, Patrick, University of Central Florida
- Abstract / Description
-
Wet detention ponds are used for stormwater treatment across the United States and reduce most pollutants by at least 60%, but only remove 30% of total nitrogen. Floating Treatment Wetlands (FTWs) are an emerging technology that uses aquatic plants suspended in the pelagic zone to remove nitrogen through vegetative assimilation and microbial denitrification. A before-after field experiment evaluated nitrogen removal in a an existing pond in Orlando, FL, retrofitted with BioHaven(&)#174; FTWs...
Show moreWet detention ponds are used for stormwater treatment across the United States and reduce most pollutants by at least 60%, but only remove 30% of total nitrogen. Floating Treatment Wetlands (FTWs) are an emerging technology that uses aquatic plants suspended in the pelagic zone to remove nitrogen through vegetative assimilation and microbial denitrification. A before-after field experiment evaluated nitrogen removal in a an existing pond in Orlando, FL, retrofitted with BioHaven(&)#174; FTWs planted with the aquatic macrophytes Juncus effusus (Soft Rush) and Pontederia cordata (Pickerelweed). Surface water samples were used to compare the nitrogen-removal performance of the pond under both storm and non-storm conditions during a pre-analysis phase (control) to post-analysis after FTW deployment. The evaluation revealed similar TN removals in non-storm conditions during pre-analysis and post-analysis periods (-1% and -3%, respectively). During storm conditions, there was a negative TN removal of -26% in the pre-analysis compared to the positive 29% removal post-analysis. In addition, nitrogen concentrations for organic-nitrogen, ammonia/ammonium, and nitrites/nitrates were used as input for calibrating and validating a system dynamics model to predict multiple, interacting nitrogen species' transformation and translocation across the abiotic and biotic components of water, sediment, plants, and atmosphere. The validated model created in STELLA v.9.4.1 was used to simulate alternative designs to achieve maximum nitrogen removal based on the treatment efficiency in the evaluation. Simulations predicted 60% FTW coverage at the experimental planting density (22 per square meter) could achieve maximum nitrogen removal. Alternatively, similar nitrogen removal could be achieved at only 15% FTW coverage by increasing plant density. The model can be used as a low-cost tool for designing FTW technology applications and monitoring nitrogen transport.
Show less - Date Issued
- 2016
- Identifier
- CFE0006140, ucf:51168
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006140
- Title
- Assessing the Effectiveness of Living Shoreline Restoration and Quantifying Wave Attenuation in Mosquito Lagoon, Florida.
- Creator
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Manis, Jennifer, Walters, Linda, Bohlen, Patrick, Jachec, Steven, University of Central Florida
- Abstract / Description
-
Coastal counties make up only 17% of the land area in the continental United States, yet 53% of the nation's population resides in these locations. With sea level rise, erosion, and human disturbances all effecting coastal areas, researchers are working to find strategies to protect and stabilize current and future shorelines. In order to maintain shoreline stability while maintaining intertidal habitat, multipurpose living shorelines have been developed to mimic natural shoreline assemblages...
Show moreCoastal counties make up only 17% of the land area in the continental United States, yet 53% of the nation's population resides in these locations. With sea level rise, erosion, and human disturbances all effecting coastal areas, researchers are working to find strategies to protect and stabilize current and future shorelines. In order to maintain shoreline stability while maintaining intertidal habitat, multipurpose living shorelines have been developed to mimic natural shoreline assemblages while preventing erosion. This project determined the effectiveness of a living shoreline stabilization containing Crassostrea virginica (eastern oyster) and Spartina alterniflora (smooth cordgrass) in the field and through controlled wave tank experiments. First, fringing oyster reefs constructed of stabilized oyster shell and smooth cordgrass plugs were placed along three eroding shoreline areas (shell middens) within Canaveral National Seashore (CANA), New Smyrna Beach, FL. For each shell midden site, four treatments (bare shoreline control, oyster shell only, S. alterniflora only, and oyster shell + S. alterniflora) were tested in replicate 3.5 x 3.5 meter areas in the lower and middle intertidal zones. Each treatment was replicated five times at each site; erosion stakes within each replicate allowed measurement of changes in sedimentation. After one year in the field, the living shoreline treatments that contained oyster shells (oyster shell only and oyster shell + S. alterniflora) vertically accreted on average 4.9 cm of sediment at two of the sites, and an average of 2.9 cm of sediment at the third, while the controls lost an average of 0.5 cm of sediment. S. alterniflora did not significantly contribute to the accretion at any site due to seagrass wrack covering and killing plants within one month of deployment. Next, the reduction in wave energy caused by these living shoreline stabilization techniques relative to bare sediment (control) was quantified. The energy reduction immediately after deployment, and the change in energy reduction when S. alterniflora had been allowed to grow for one year, and the stabilized shell was able to recruit oysters for one year was tested. Laboratory experiments were conducted in a nine-meter long wave tank using capacitance wave gauges to ultimately measure changes in wave height before and after treatments. Wave energy was calculated for each newly deployed and one-year old shoreline stabilization treatment. Boat wake characteristics from CANA shorelines were measured in the field and used as inputs to drive the physical modeling. Likewise, in the wave tank, the topography adjacent to the shell midden sites was measured and replicated. Oyster shell plus S. alterniflora attenuated significantly more wave energy than either the shells or plants alone. Also, one-year old treatments attenuated significantly more energy than the newly deployed treatments. The combination of one-year old S. alterniflora plus live oysters reduced 67% of the wave energy. With the information gathered from both the field and wave experiments, CANA chose to utilize living shorelines to stabilize three shell middens within the park. Oyster shell, marsh grass and two types of mangroves (Rhizophora mangle, Avicennia germinans) were deployed on the intertidal zones of the eroding middens. Significant accretion occurred at all middens. Two sites (Castle Windy and Garver Island) vertically accreted an average 2.3 cm of sediment after nine months, and six months respectively, and the other site (Hong Kong) received on average 1.6 cm of sediment after six months. All control areas (no stabilization) experienced sediment loss, with erosion up to 5.01 cm at Hong Kong. Plant survival was low ((<) 20%) at Castle Windy and Garver Island, while Hong Kong had moderate survival (48-65%). Of the surviving marsh grass and mangroves on the three sites, almost all ((>) 85%) had documented growth in the form of increased height or the production on new shoots. Landowners facing shoreline erosion issues, including park managers at CANA, can use this information in the future to create effective shoreline stabilization protocols. Even though the techniques will vary from location to location, the overall goal of wave attenuation while maintaining shoreline habitat remains. As the research associated with the effectiveness of living shorelines increases, we hope to see more landowners and land managers utilize this form of soft stabilization to armor shorelines.
Show less - Date Issued
- 2013
- Identifier
- CFE0004713, ucf:49809
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004713
- Title
- Chemophysical Characteristics and Application of Biosorption Activated Media (BAM) for Copper and Nutrient Removal in Stormwater Management.
- Creator
-
Jones, Jamie, Chang, Ni-bin, Bohlen, Patrick, Wanielista, Martin, University of Central Florida
- Abstract / Description
-
For high groundwater table areas, stormwater wet detention ponds are utilized as the preferred stormwater management throughout the state of Florida. Previous research has found that accumulations of nutrients, algae, heavy metals, pesticides, chlorophyll a, fecal coliform bacteria and low concentrations of dissolved oxygen (DO) are common characteristics of stormwater wet detention ponds. Although these pollutant levels are not regulated within the ponds, states are required to compute the...
Show moreFor high groundwater table areas, stormwater wet detention ponds are utilized as the preferred stormwater management throughout the state of Florida. Previous research has found that accumulations of nutrients, algae, heavy metals, pesticides, chlorophyll a, fecal coliform bacteria and low concentrations of dissolved oxygen (DO) are common characteristics of stormwater wet detention ponds. Although these pollutant levels are not regulated within the ponds, states are required to compute the pollutant load reductions through total maximum daily load (TMDL) programs to meet the water quality requirements addressed by the Clean Water Act (CWA). In this study, field sampling data of stormwater ponds throughout Florida are presented to identify concentration levels of the main contaminants of concern in the discharge of wet detention ponds. Sampling was done to identify possible sources, in addition to possible removal mechanisms via the use of specific sorption media. Nutrients were found as a main problematic pollutant, of which orthophosphate, total phosphorus, ammonia, nitrate, and total nitrogen were targeted whereas heavy metals exhibited minor concerns. Accumulation of high nutrient concentrations may be mitigated by the adoption of best management practices (BMPs) utilizing biosorption activated media (BAM) to remove phosphorus and nitrogen species through physical, chemical, and biological processes. This study aims to increase overall scientific understanding of phosphorus removal dynamics in sorption media systems via Langmuir and Freundlich isotherms and column studies. The removal of phosphorus (P) was proven effective primarily through chemophysical processes. The maximum orthophosphate adsorption capacities were determined under varying conditions of the media within the columns, which were found up to 0.000534 mg-P adsorbed per gram BAM with influent concentrations of 1 mg?L-1 orthophosphate in distilled water and 1 hour hydraulic residence time (HRT). When using spiked pond water under the same conditions, the adsorption capacity was increased about 30 times to 0.01507 mg-P?g-1 BAM presumably due to the properties and concentrations of ions affecting the diffusion rate regulating the surface orthophosphate reactions. These equilibrium media uptake values (q) were used to calculate the life expectancies of the media under varying HRT and influent concentrations of treatment. Chemophysical and biological removal capabilities of the media for total nitrogen, ammonia, and nitrate were effective in columns using 1100 g of BAM. In flow-through column conditions, ammonia had a consistent ~95% removal while effluent nitrate concentrations were highly variable due to the simultaneous nitrification-denitrification processes once an aerobic-anaerobic environment was established. Batch column experiments simulating no-flow conditions within a media bed reactor resulted in orthophosphate removals comparable with the continuous flow conditions, increased total phosphorus effluents indicative of chemical precipitation of orthophosphate, decreased ammonia removal, and increased nitrate removal. Due to a biofilm's sensitivity to even low copper concentrations and accumulation in ponds, a copper sorption media mix of (")green(") materials was generated. Freundlich and Langmuir isotherm tests concluded a successful mix resulting in copper removal efficiencies up to 96%.
Show less - Date Issued
- 2013
- Identifier
- CFE0005009, ucf:49995
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005009
- Title
- Biogeochemical effects of sea level rise-induced transitions within coastal wetlands.
- Creator
-
Steinmuller, Havalend, Chambers, Lisa, Hinkle, Ross, Bohlen, Patrick, Beazley, Melanie, University of Central Florida
- Abstract / Description
-
As sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation...
Show moreAs sea level rise (SLR) affects coastal wetlands, ecosystem responses can include vertical accretion, landward transgression, or submergence. Sea level rise-induced transitions can alter key biogeochemical transformations within wetland soils, impacting the ability of these systems to provide ecosystem services, specifically carbon (C) storage and water quality regulation. Through a series of complementary laboratory and field-based studies, biogeochemical responses to salinity, vegetation shifts, and submergence were investigated. Changes in nutrient dynamics associated with saltwater intrusion were evaluated by artificially adding saline water to different freshwater wetland soil types, indicating that potential exports of critical nutrients (forms of nitrogen, phosphorus, and C) out of freshwater wetland soils is mediated by soil type. A controlled laboratory experiment was conducted to determine the potential degradability of C stored within submerging coastal wetland soils under both aerobic and anaerobic conditions. Under aerobic conditions, 66% more carbon dioxide was produced than under anaerobic conditions and 4x greater carbon dioxide was produced at 90-100cm depths than at the surface. At the same site, the degradability of carbon stores was examined through organic matter fractionation, stable isotopic examination, and determining the abundance of key microbial genes. Both total soil C and stores of bioavailable nutrients increased with depth, while organic matter quality decreased. Finally, the biogeochemical impacts of two separate vegetation transitions occurring co-incidentally with sea level rise were investigated: mangrove encroachment into salt marsh, and more salt- and inundation-tolerant herbaceous encroachment into herbaceous marsh. Conclusions from these studies demonstrate that vegetation transitions alter both soil nutrient storage and fast-cycling nutrient pools, indicating that biogeochemical transitions occur in advance of changes in vegetative species dominance. Results from these chapters holistically address how biogeochemical functioning, specifically nutrient cycling, regulation of water quality, and C sequestration, within coastal wetlands responds to stressors associated with SLR.
Show less - Date Issued
- 2019
- Identifier
- CFE0007536, ucf:52584
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007536
- Title
- Base Flow Recession Analysis for Streamflow and Spring Flow.
- Creator
-
Ghosh, Debapi, Wang, Dingbao, Chopra, Manoj, Singh, Arvind, Medeiros, Stephen, Bohlen, Patrick, University of Central Florida
- Abstract / Description
-
Base flow recession curve during a dry period is a distinct hydrologic signature of a watershed. The base flow recession analysis for both streamflow and spring flow has been extensively studied in the literature. Studies have shown that the recession behaviors during the early stage and the late stage are different in many watersheds. However, research on the transition from early stage to late stage is limited and the hydrologic control on the transition is not completely understood. In...
Show moreBase flow recession curve during a dry period is a distinct hydrologic signature of a watershed. The base flow recession analysis for both streamflow and spring flow has been extensively studied in the literature. Studies have shown that the recession behaviors during the early stage and the late stage are different in many watersheds. However, research on the transition from early stage to late stage is limited and the hydrologic control on the transition is not completely understood. In this dissertation, a novel cumulative regression analysis method is developed to identify the transition flow objectively for individual recession events in the well-studied Panola Mountain Research Watershed in Georgia, USA. The streamflow at the watershed outlet is identified when the streamflow at the perennial stream head approaches zero, i.e., flowing streams contract to perennial streams. The identified transition flows are then compared with observed flows when the flowing stream contracts to the perennial stream head. As evidenced by a correlation coefficient of 0.90, these two characteristics of streamflow are found to be highly correlated, suggesting a fundamental linkage between the transition of base flow recession from early to late stages and the drying up of ephemeral streams. At the early stage, the contraction of ephemeral streams mostly controls the recession behavior. At the late stage, perennial streams dominate the flowing streams and groundwater hydraulics governs the recession behavior. The ephemeral stream densities vary from arid regions to humid regions. Therefore, the characteristics of transition flow across the climate gradients are also tested in 40 watersheds. It is found that climate, which is represented by climate aridity index, is the dominant controlling factor on transition flows from early to late recession stages. Transition flows and long-term average base flows are highly correlated with a correlation coefficient of 0.82. Long-term average base flow and the transition flow of recession are base flow characteristics at two temporal scales, i.e., the long-term scale and the event scale during a recession period. This is a signature of the co-evolution of climate, vegetation, soil, and topography at the watershed scale. The characteristics of early and late recession are applied for quantifying human impacts on streamflow in agricultural watersheds with extensive groundwater pumping for irrigation. A recession model is developed to incorporate the impacts of human activities (such as groundwater pumping) and climate variability (such as evapotranspiration) on base flow recession. Groundwater pumping is estimated based on the change of observed base flow recession in watersheds in the High Plains Aquifer. The estimated groundwater pumping rate is found consistent compared with the observed data of groundwater uses for irrigation. Besides streamflow recession analysis, this dissertation also presents a novel spring recession model for Silver Springs in Florida by incorporating groundwater head, spring pool altitude, and net recharge into the existing Torricelli model. The results show that the effective springshed area has continuously declined since 1988. The net recharge has declined since the 1970s with a significant drop in 2002. Subsequent to 2002, the net recharge increased modestly but not to the levels prior to the 1990s. The decreases in effective springshed area and net recharge caused by changes in hydroclimatic conditions including rainfall and temperature, along with groundwater withdrawals, contribute to the declined spring flow.
Show less - Date Issued
- 2015
- Identifier
- CFE0005951, ucf:50814
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005951
- Title
- Drinking Water Infrastructure Assessment with Teleconnection Signals, Satellite Data Fusion and Mining.
- Creator
-
Imen, Sanaz, Chang, Ni-bin, Wang, Dingbao, Wanielista, Martin, Bohlen, Patrick, University of Central Florida
- Abstract / Description
-
Adjustment of the drinking water treatment process as a simultaneous response to climate variations and water quality impact has been a grand challenge in water resource management in recent years. This desired and preferred capability depends on timely and quantitative knowledge to monitor the quality and availability of water. This issue is of great importance for the largest reservoir in the United States, Lake Mead, which is located in the proximity of a big metropolitan region - Las...
Show moreAdjustment of the drinking water treatment process as a simultaneous response to climate variations and water quality impact has been a grand challenge in water resource management in recent years. This desired and preferred capability depends on timely and quantitative knowledge to monitor the quality and availability of water. This issue is of great importance for the largest reservoir in the United States, Lake Mead, which is located in the proximity of a big metropolitan region - Las Vegas, Nevada. The water quality in Lake Mead is impaired by forest fires, soil erosion, and land use changes in nearby watersheds and wastewater effluents from the Las Vegas Wash. In addition, more than a decade of drought has caused a sharp drop by about 100 feet in the elevation of Lake Mead. These hydrological processes in the drought event led to the increased concentration of total organic carbon (TOC) and total suspended solids (TSS) in the lake. TOC in surface water is known as a precursor of disinfection byproducts in drinking water, and high TSS concentration in source water is a threat leading to possible clogging in the water treatment process. Since Lake Mead is a principal source of drinking water for over 25 million people, high concentrations of TOC and TSS may have a potential health impact. Therefore, it is crucial to develop an early warning system which is able to support rapid forecasting of water quality and availability. In this study, the creation of the nowcasting water quality model with satellite remote sensing technologies lays down the foundation for monitoring TSS and TOC, on a near real-time basis. Yet the novelty of this study lies in the development of a forecasting model to predict TOC and TSS values with the aid of remote sensing technologies on a daily basis. The forecasting process is aided by an iterative scheme via updating the daily satellite imagery in concert with retrieving the long-term memory from the past states with the aid of nonlinear autoregressive neural network with external input on a rolling basis onward. To account for the potential impact of long-term hydrological droughts, teleconnection signals were included on a seasonal basis in the Upper Colorado River basin which provides 97% of the inflow into Lake Mead. Identification of teleconnection patterns at a local scale is challenging, largely due to the coexistence of non-stationary and non-linear signals embedded within the ocean-atmosphere system. Empirical mode decomposition as well as wavelet analysis are utilized to extract the intrinsic trend and the dominant oscillation of the sea surface temperature (SST) and precipitation time series. After finding possible associations between the dominant oscillation of seasonal precipitation and global SST through lagged correlation analysis, the statistically significant index regions in the oceans are extracted. With these characterized associations, individual contribution of these SST forcing regions that are linked to the related precipitation responses are further quantified through the use of the extreme learning machine. Results indicate that the non-leading SST regions also contribute saliently to the terrestrial precipitation variability compared to some of the known leading SST regions and confirm the capability of predicting the hydrological drought events one season ahead of time. With such an integrated advancement, an early warning system can be constructed to bridge the current gap in source water monitoring for water supply.
Show less - Date Issued
- 2015
- Identifier
- CFE0005632, ucf:50215
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005632
