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Contaminated stormwater discharge is a major concern in the United States due to a steady increase of harmful pollutants entering fresh water sources. The many congressional mandates that require local governments to reduce the impact of storm water discharge on the natural ecology have greatly increased the need for economically and environmentally viable solutions to pollution reduction. One such solution is that of constructed wetlands. Previous research conducted at the Sustainable Bio-products Department at Mississippi State University demonstrated the feasibility of kenaf fiber and wood shavings to remove toxins and crude oil from the bio-oil process water. This study proposes to amend contaminated storm water runoff from a biomass to bio-oil conversion facility through a simulated constructed wetland. The constructed wetlands were contaminated with varying dilution levels of bio-oil process water in a series of six phases. It was hypothesized that the contaminated rainwater can be remediated by constructed wetlands and safely released back into the native waterways. This study concluded that there was a significant decrease in biological oxygen demand (BOD) and micro-toxicity over a ten day cycle within the constructed wetlands for the lower levels of contaminated stormwater. A comparative screen of the bacterial community within the wetlands during the contamination process showed a similar trend in species richness and composition for the first three Phases of contamination. There was a shift in richness and diversity for the final three Phases of contamination after ten days within the constructed wetlands. The constructed wetlands were successful at lowering BOD and toxicity levels and achieving permissible pH levels when the concentration of contaminated stormwater was less than or equal to 400x dilution. Much of the BOD reduction was due to volatilization of the contaminated wastewater. When the concentration of contaminated water exceeded 300x dilution, the constructed wetland were only successful at achieving permissible pH discharge levels. Better results may be achievable with longer residence time in the wetlands.

Coastal wetlands of Georgian Bay have been virtually ignored by ecologists until recently, when these ecosystems were found to have exceptionally high biodiversity compared to other Gr,~at Lakes wetlands. To address this deficiency, we conducted a baseline survey (2002 to 2007) to determine the biotic and abiotic characteristics of 92 wetlands in 18 quatemary watersheds, using a suite of published ecological indices developed specifically for coastal wetlands (Water Quality Index (WQI); adjusted Wetland Macrophyte Index (WMiadj), and the Wetland Fish IndexBasinPAex (WFIBasinPAex)). Although a majority of the watersheds are located in remote eastern and northern parts of the Bay and therefore receive minimal human disturbance, one watershed, Sturgeon River, located in southern Georgian Bay receives relatively high urban, recreational and agricultural disturbance. Mean scores of WQI and WMiadj varied significantly across the watersheds, ranging from 0.48 to 2.15, and from 2.29 to 3.77, respectively. Mean WFIBasinPAex scores, however, were less variable and only ranged from 3.53 to 3.86. Of the 88 macrophyte species identified, the most common were hardstem bulrush. (Schoenoplectus acutus), water celery (Vallisneria americana), richardson's pondweed (Potamogeton richardsonii), slender waternymph (Najasjlexilis) and Canadian waterweed (Elodea canadensis). Six non-native macrophytes, Purple loosestrife (Lythrum wlicaria), narrow-leaf cattail (Typha angustifolia), hybrid cattail (Typha x glauca), Eurasian milfoil (Myriophyllum spicatum), curly pondweed (Potamogeton crispw) and frogbit (Hydrocharus morsus-ranae) were also recorded, the most common ofwhieh was Eurasian milfoil. Sago pondweed (Stuckenia pectinata), a native species that can be invasive, and is tolerant of poor water-quality, was present in about half of the watersheds. Ofthe 51 fish species, pumpkinseed (Lepomis gibbosus) bluntnose minnow (Pfmephales notatus), brown bullhead (Ameiurus nebulosus), rock bass (Ambloplites rupestris), and yellow perch (Percajlavescens) were the most widespread and abundant. Three non-native species, common carp (Cyprinus carpio), alewife (Alosa pesudoharengus), and round goby (Neogobius melanostomus) were present but not dominant. WMI scores were highly correlated with WQI scores, and as expected, wetlands in the most disturbed southern watershed were associated with the lowest WQI and WM[ scores, and had the greatest number of exotic species. However, WMI scores of wetlands in a few exposed sites located at the tip of the Bruce Peninsula were similarly low, even though these sites are not yet impacted by human activities. There was no significant relationship between WFIBasinPAand WQI scores, although the WFIBasin PA did not seem to be affected by exposure. We recommend that the WQI and WMiadj be used in long-term monitoring programs of Georgian Bay to track negative impacts of human disturbance on these valuable ecosystems. / Thesis / Master of Science (MS)

No / Demand for water in the Usangu Basin is driven by a number of competing uses. These include domestic supplies, irrigated agriculture, livestock, fishing, maintenance of the Usangu wetland, a National Park and major hydroelectric system downstream. As a result of a number of driving forces including the growing population, the water resources of the basin are becoming increasingly stressed, and downstream flows have now reduced to zero during the dry season. The paper is based on recent work to study to situation and work with local stakeholders to develop a sustainable management plan for the basin. Irrigated rice is by far the biggest user of water in the basin. The paper traces the successful development of irrigation there since the 1950s, based both on state-managed mechanised farms and on smallholder production. However, the expansion of irrigation has been a major factor in the change in water availability downstream, particularly as the cropping calendar expands into the dry season, when river flows are at their lowest. A number of initiatives are under way to try to reduce the impact of irrigation on the basin's water resources. These include projects to increase irrigation efficiency in smallholder systems, and improvements to water management institutions and processes. The aim is to restore dry season flows for downstream users by the year 2010.

A 0.2-hectare wetland was constructed in the floodplain of Opequon Creek in Northern Virginia as a best management practice (BMP) for stormwater management. The research goals were to 1) determine if wetland hydrology existed and quantify the role of groundwater exchange in the constructed wetland (CW) water budget, 2) estimate wetland hydraulic characteristics during overbank flows, and 3) quantify the event-scale nutrient assimilative capacity of the constructed wetland. CW water table elevations and hydraulic gradients were measured through an array of nested piezometers. During controlled flooding events, stream water was pumped from the creek and amended with nutrients and a conservative tracer in two seasons to determine hydraulic characteristics and nutrient reduction. Samples were collected at the inlet, outlet structure, and at three locations along three transects along the wetland flowpath. Water table elevation monitoring demonstrated that wetland hydrology existed on the site. The mean residence time of the wetland was found to be 100 min for flow-rates of 4.25-5.1 m3/min. Residence time distributions of the high and low marsh features identified a considerable degree of flow dispersion. Manning's n varied between macrotopographic features and was significantly higher in the spring event as compared to the fall event, likely due to the presence of rigid-stem vegetation. Average wetland n was 0.62. Total suspended solid concentrations decreased with increasing residence time during both experiments. Mass reduction of pollutants were 73% total suspended solids (TSS), 54% ammonia-nitrogen (NH3-N), 16% nitrate-N (NO3-N), 16% total nitrogen (TN), 23% orthophosphate-phosphorus (PO4-P), and 37% total P (TP) in the fall, and 69% TSS, 58% NH3-N, 7% NO3-N, 22% TN, 8% PO4-P, and 25% TP in the spring. Linear regression of mass flux over the event hydrograph was used to determine pollutant removal rates between the wetland inlet and outlet. Pollutant removal rates were determined through linear regression of mass flux and were higher in the spring event than in the fall. Dissolved nitrogen species were more rapidly removed than dissolved phosphorus. TSS, TP, and TN removal were greater and faster than dissolved nutrient species, suggesting that physical settling was the dominant removal mechanism for stormwater pollutants. / Ph. D.

The restoration of natural wetlands is a wonderful, noble and pragmatic idea, but such efforts often meet resistance from certain segments of society. One reason for this is that the public perceives the environment in different ways than do the experts, such as landscape architects and land managers. This dissertation analyzes people's preferences for wetlands in comparison to those of landscape architects. It specifically studies the conflict about the wetland restoration program in the Malaysia's Kelana Jaya Municipal Park. This dissertation is based on data obtained from a preference survey using photo questionnaires that polled both the public's and landscape architects' group preferences for wetlands. The data was analyzed using the Content Identifying Method (CIM) to determine group preferences for wetlands and factors that influence these preferences. Park managers from several local authorities also were interviewed to determine their expectations of public preferences and attitudes toward wetland restoration and public participation. The public and landscape architects have significantly differed in stated preferences for wetlands. The public strongly prefers park-like landscapes that demonstrate human influences and provide the potential for human involvement; in contrast, landscape architects prefer natural wetlands that are visually pleasing, with well-defined spaces, visual coherence, and visual complexity. In addition, park managers did not accurately predict the public's view of wetlands. Their prediction was similar to landscape architects' preferences. Attitudes toward wetland activities and safety, knowledge about wetland benefits, the motivation to use urban natural open spaces, and familiarity with nature significantly affected the public's preferences. Further, the motivation to use urban natural open spaces was the best predictor of public's preferences. The primary implications of this dissertation are that environmental education should be a core activity in changing people's perceptions of natural wetlands and that opinions of local people should be incorporated in many aspect of wetlands restoration, planning, design, and policymaking, especially in Malaysia. / Ph. D.

Models to estimate hydraulic resistance due to vegetation in emergent wetlands are crucial to wetland design and management. Hydraulic models that consider vegetation rely on an accurate determination of a resistance parameter such as a friction factor or a bulk drag coefficient. At low Reynolds numbers typical of flows in wetlands, hydraulic resistance is orders of magnitude higher than fully turbulent flows and resistance parameters are functions of the flow regime as well as the vegetation density and structure. The exact relationship between hydraulic resistance, flow regime and vegetation properties at low-Reynolds number flows is unclear. The project goal was to improve modeling of emergent wetlands by linking vegetation and flow properties to hydraulic resistance. A 12.2-m x 1.2 m vegetated flume was constructed to evaluate seven models of vegetated hydraulic resistance through woolgrass (Scirpus cyperinus (L.) Kunth), a common native emergent wetland plant. Measurements of vegetation geometry and structure were collected after each set of flume runs. Study results showed at low stem-Reynolds numbers (<100), the drag coefficient is inversely proportional to the Reynolds number and can vary greatly with flow conditions. Empirical models that were developed from data collected in natural wetlands predicted flow velocity most accurately. Using data from this flume study, regression models were developed to predict hydraulic resistance. Results indicated stem Reynolds number, stem diameter, and vegetation area per unit volume were the best predictors of friction factor. Vegetation flexibility and water depth were also important parameters but to a lesser extent. The spatial distribution of hydraulic resistance was estimated in a small floodplain wetland near Stephens City, VA using the regression models developed from the flume data. MODFLOW was used to simulate a 4-hour flood event through the wetland. The vegetated open water surface was modeled as a highly conductive aquifer layer. On average, MODFLOW slightly underpredicted the water surface elevation. However, the model error was within the range of survey error. MODFLOW was not highly sensitive to small changes in the estimated surface hydraulic conductivity caused by small changes in vegetation properties, but large decreases in surface hydraulic conductivity dramatically raised the elevation of the water surface. / Ph. D.

Correctly predicting water levels is key to the success of created wetlands. The Pierce method is a commonly used technique for modeling and designing mitigation wetlands that assumes minimal groundwater interaction with the wetland. This technique for mitigation wetland design relies primarily on surface water inputs, assuming a relatively impermeable substrate (perched system), and level pool routing. The Pierce method was applied utilizing two different evapotranspiration estimation methods: Thornthwaite (IPM) and FAO-56 Penman-Monteith (IPM-FAO). A second process-based model, utilizing MODFLOW-2005, was constructed to better predict water levels in mitigation wetlands. Modeled processes included groundwater movement and vegetative resistance to flow, which can be a significant factor in wetland water levels. The two versions of the Pierce method were compared to the process-based wetland representation developed in MODFLOW-2005 using data from an existing mitigation wetland. Output from these models were compared to observed data from an existing mitigation wetland near Manassas, VA, USA. Results indicate the use of Thornthwaite's method to estimate wetland evapotranspiration (ET) does not capture the timing or magnitude of wetland ET losses, leading to over-prediction of wetland water levels during the growing season. The Modflow-based approach resulted in more accurate hydroperiod predictions on a yearly basis than the Pierce Method. However, the Integrated Pierce method model, utilizing the FAO-56 Penman-Monteith method of estimating potential evapotranspiration instead of Thornthwaite's method most accurately predicted water levels during the growing season (March-October). / Master of Science

A wetland was constructed near Norton, VA by Westmoreland Coal Company to treat acid mine drainage (AMD) from an inactive coal refuse pile. The AMD had an average inflow pH of 7.0, and average inflow concentrations measuring 4 mg/L total Fe, 3 mg/L total Mn and 450 mg/L dissolved sulfate. An 18 month field study of water quality improvement and sulfate-reducing bacterial (SRB) populations revealed that the wetland was effectively treating the AMD. Iron and Mn both met compliance standards set by the EPA requiring an instream Fe concentration of 3 mg/L and an instream Mn concentration of 2 mg/L. SRB averaged 8.7 x 10⁴ through the 18 month study period as determined by the Most Probable Number (MPN) method. The concentration of sulfate was decreased by an average of 360 mg/L as the AMD passed through the wetland. In a separate laboratory study, the effect of carbon addition, pH and Fe concentration on microbial sulfate reduction and the subsequent precipitation of Fe and Mn was determined in mesocosms built to simulate a wetland. Mesocosms were constructed with plexiglass sheets and measured 6" x 6" x 24". Each mesocosm was filled with a 4-inch layer of limestone gravel beneath 17 inches of weathered pine bark mulch. A perforated PVC pipe was installed within the limestone layer to act as an underground drain. With mulch as the only source of available carbon, a 15% decrease in total sulfate concentration occurred in AMD containing initial concentrations of 1500, 750 and 375 mg/L sulfate. The population of SRB averaged 10⁵/ g dry mulch. The addition of 300 mg/L carbon as lactate resulted in an a 3 log₁₀ increase in SRB population. Following the addition of carbon as lactate, the concentration of sulfate decreased 95%. Total Fe decreased 90% from inflow concentrations prior to the addition of lactate, and decreased 96% following the addition of lactate to the AMD. The effect of varying the influent pH of AMD was studied using wetland mesocosms, and a pH of 3.5 adversely affected microbial sulfate reduction and water quality improvement. Populations of SRB decreased by 3 log₁₀ from an initial population of 10⁸ SRB/g dry mulch. Iron and Mn concentrations decreased 70 and 37% respectively. Hydrogen ion concentration increased to 7.0 and above when inflow pH was 4.5 and 6.0, but increased to an average of 6.4 when inflow pH was 3.5. The effect of different concentrations of Fe within AMD was investigated using wetland mesocosms, and total inflow Fe concentrations of 155 and 301 mg/L resulted in a greater percent decrease in sulfate concentrations than at a lessor Fe concentration averaging 85 mg/L. Total Mn decreased 12% at an inflow Fe concentration of 85 mg/L, and decreased 43% at an inflow Fe concentration of 301 mg/L. The results generated from both the analysis of the Pine Branch wetland and the laboratory mesocosm experiments demonstrate that subsurface flow constructed wetlands are a viable form for treatment of AMD. 2197820b-4775-4425-b667-55393f34b513,"This thesis deals with the deliberate insertion of nonlinear elements in second-order linear control systems for the purpose of improving their transient response. The main body consists of a method of obtaining a desired step response by placing a nonlinear computer in the forward loop. This computer fixes the system trajectory in the phase plane by determining the required output velocity for the error present at any time. An inner control loop adjusts the output velocity to agree with the computed signal in an extremely short time, thus giving a very close agreement between actual and desired responses. Several examples are presented to show the application of this method, and experimental verification is obtained with an analog computer. Areas of future study and practical limitations are discussed in the final sections of the thesis. / Master of Science