Planning researchers believe that property losses from natural hazards, such as floods can be reduced if governments address this issue and adopt appropriate policies in their plans. However, little empirical research has examined the relationship between plan quality and actual property loss from floods. My research addresses this critical gap in the planning and hazard research literature by evaluating the effectiveness of current plans and policies in mitigating property damage from floods. Specifically, this study: 1) assesses the extent to which local comprehensive plans integrate flood mitigation policies in Florida; and 2) it examines the impact of the quality of flood mitigation policies on actual insured flood damages. Study results show that fifty-three local plans in the sample received a mean score for total flood mitigation policy quality of 38.55, which represents 35.69% of the total possible points. These findings indicate that there is still considerable room for improvement by local governments on flooding issues. The scores of local plans varied widely, with coastal communities receiving significantly higher scores than non-coastal communities. While most communities adopted land use management tools, such as permitted land use and wetland permits as primary flood mitigation tools, incentive based tools/taxing tools and acquisition tools were rarely adopted. This study also finds that plan quality associated with flood mitigation policy had little discernible effect on reducing insured flood damage while controlling for biophysical, built environment and socio-economic variables. This result counters the assumption inherent in previous plan quality research that better plans mitigate the adverse effects associated with floods and other natural hazards. There are some possible explanations for this result in terms of plan implementation, land use management paradox and characteristics of insurance policies. The statistical analysis also suggests that insured flood loss is considerably affected by wetland alteration and a community's location on the coast. Another finding indicates that very strong leadership and dam construction are factors in mitigating flood loss.

The Woodlands, Texas, is a 27,000-acre new town created with Ian McHarg's ecohydrological planning approach. The Woodlands is the best example of ecologically based new town planning in the United States during the 1970s. The Woodlands survived storms in excess of one-hundred-year levels in 1979 and 1994 with little property damage, while Houston, 31 miles away, was severely flooded in both events. For the past three decades, very few studies have been conducted to assess the effectiveness of McHarg's planning approach. The objective of this study is three fold: (1) To document McHarg's ecohydrological planning concepts, implementation and unveil the barriers to continue his approach; (2) To compare flood mitigation effectiveness of different drainage systems used in The Woodlands development; and (3) To simulate "what if" land-use scenarios using different planning approaches. Original development information is collected from published monographs, journal articles, newspapers and designers' collections. Geographic Information System (GIS) parcel data are obtained from Montgomery County Appraisal District. Streamflow data are acquired from the USGS website. Weather data are downloaded from the NOAA website. Land use and land cover data are collected from various national datasets. Two GIS hydrologic models--the Soil and Water Assessment Tool (SWAT) and the Kinematic Runoff and Erosion model (KINEROS)--are used for watershed simulation. The statistic analysis tool SPSS is used for correlation analysis. Results show that McHarg's planning approach was followed in the early phases of development (1974-1996) but was largely abandoned in the later phases when its ownership was changed in 1997. McHarg's approach ceased to be implemented because of the low public acceptance of ecohydrological planning strategies and the conflicts between short-term investment return and long-term environmental stewardship. In addition, comparative study shows that the early phases of development responded to rainfall similarly to its pre-development forest conditions. However, the later phases generated runoff volumes three times greater than the early phases. Therefore, McHarg's ecohydrological planning approach demonstrates flood mitigation effectiveness that is superior to the conventional approach. Finally, using soil permeability to coordinate development density and land use presents a viable solution for mitigating environmental impacts from a stormwater perspective.

In this study, alternative solution of Kayraktepe Dam is investigated. Kayraktepe Dam was planned more than 30 years ago, but due to various reasons the construction could not be realized. In this study, an alternative feasible formulation was developed. Former Kayraktepe Dam was planned for multiple objectives: flood control, energy generation and water supply for irrigation. The newly developed formulation was designed to meet these objects as well.

The main objective of this research is to devise a risk-based methodology for developing emergency operation schedules (EOS). EOS are decision tools that provide guidance to reservoir operators in charge of making real-time release decisions during major flood events. A computer program named REOS was created to perform the computations to develop risk-based EOS. The computational algorithm in REOS is divided in three major components: (1) synthetic streamflow generation, (2) mass balance computations, and (3) frequency analysis. The methodology computes the required releases to limit storage to the capacity available based on the probabilistic properties of future flows, conditional to current streamflow conditions. The final product is a series of alternative risk-based EOS in which releases, specified as a function of reservoir storage level, current and past inflows, and time of year, are associated with a certain risk of failing to attain the emergency operations objectives. The assumption is that once emergency operations are triggered by a flood event, the risk associated with a particular EOS reflects the probability of exceeding a pre-established critical storage level given that the same EOS is followed throughout the event. This provides reservoir operators with a mechanism for evaluating the tradeoffs and potential consequences of release decisions. The methodology was applied and tested using the Addicks and Barker Reservoir system in Houston, TX as a case study. Upstream flooding is also a major concern for these reservoirs. Modifications to the current emergency policies that would allow emergency releases based on the probability of upstream flooding are evaluated. Riskbased EOS were tested through a series of flood control simulations. The simulations were performed using the HEC-ResSim reservoir simulation model. Rainfall data recorded from Tropical Storm Allison was transposed over the Addicks and Barker watersheds to compute hypothetical hydrographs using HEC-HMS. Repeated runs of the HEC-ResSim model were made using different flooding and residual storage scenarios to compare regulation of the floods under alternative operating policies. An alternative application of the risk-based EOS in which their associated risk was used to help quantify the actual probability of upstream flooding in Addicks and Barker was also presented.

Includes bibliographical references. / Cover title. "February 2003." 4/8/03: Also available via Internet.

Awakening Days at Dead River traces the history of a remote public park in north Hillsborough County that was once a privately-owned riverside enclave with modest cabins, and home to a popular fish camp on the Hillsborough River. The timeframe focuses on the mid-twentieth century to present, with a contextual background of earlier history in the immediate area. The story recounts the adventures and challenges of a select group of homeowners and visitors who experienced life on the Hillsborough and Dead Rivers during that timeframe. It also shows how the area evolved into a public property when regional flood control trumped private landownership, in some cases through eminent domain. Finally, the story shows how this event altered Dead River's course from Florida developed, to Florida reclaimed, the clues of the former often hidden by the growth of the woods. Research entails: interviews with former Dead River homeowners and their families (some shared photographs), and people who frequented the fish camp; a journal with text and photographs by Dead River homeowner Arthur Yates; interviews with two year-round live-in rangers who have overseen Dead River since it became a park; studying records of the Southwest Florida Water Management District (SWFWMD or Swiftmud), the state-run agency that acquired the property to manage regional flooding , including detailed appraisals, maps and correspondence; interviews with Swiftmud officials associated with Dead River; and keeping a first-hand journal of observances walking the woods at Dead River and paddling its waters. As offered above, Dead River Park has many intriguing themes worth studying. That several of its former residents and weekenders are still living, are still Floridians, and have distinct memories of their "Old Florida" fun, makes it a timely study, as well. Finally, since Dead River Park is a public entity, it is worth knowing its history; park-goers might embrace its legacy as theirs.

The demand for energy and new oil reservoirs around the world has increased rapidly while oil recovery from depleted reservoirs has become more difficult. Oil production from fractured carbonate reservoirs by water flooding is often inefficient due to the commonly oil-wet nature of matrix rocks. Chemical enhanced oil recovery (EOR) processes such as surfactant-induced wettability alteration and interfacial tension reduction are required to decrease the residual oil saturation in matrix blocks, leading to incremental oil recovery. However, improvement in recovery will depend on the degree of wettability alteration and interfacial tension (IFT) reduction, which in turn are functions of matrix permeability, fracture intensity, temperature, pressure, and fluid properties. The oil recovery from fractured carbonate reservoirs is frequently considered to be dominated by the spontaneous imbibition mechanism which is a combination of viscous, capillary, and gravity forces. The primary purpose of this study is to model wettability alteration in the lab scale for both coreflood and imbibition cell tests using the chemical flooding reservoir simulator. The experimental recovery data for fractured carbonate rocks with different petrophysical properties were history-matched with UTCHEM, The University of Texas in-house compositional chemical flooding simulator, using a highly heterogeneous permeability distribution. Extensive simulation work demonstrates the validity and ranges of applicability of upscaled procedures, and also indicates the importance of viscous and capillary forces in larger fields. The results of this work will be useful for designing field-scale chemical EOR processes. / text

Reservoir pressure and solution gas can significantly alter the microemulsion phase behavior and the design of a surfactant-polymer flood. This dissertation shows how to predict changes in microemulsion phase behavior from dead oil at atmospheric pressure to live crude at reservoir pressure. Our method requires obtaining only a few glass pipette measurements of microemulsion phase behavior at atmospheric pressure. The key finding is that at reservoir pressure the optimum solubilization ratio and the logarithm of optimal salinity behave linearly with equivalent alkane carbon number (EACN). These trends are predicted from the experimental data at atmospheric pressure based on density calculations of pure components using the Peng-Robinson equation-of-state (PREOS). We show that predictions of the optimum conditions for live oil are in good agreement with the few experimental measurements that are available in the literature. We also present new measurements at atmospheric pressure to verify the established trends. The experiments show that while pressure induces a phase transition from upper microemulsion (Winsor Type II+) to lower microemulsion (Winsor Type II-), solution gas does the opposite. An increase in pressure decreases the optimum solubilization ratio and shifts the optimum salinity to a larger value. Adding methane to dead oil at constant pressure does the reverse. Thus, these effects are coupled and both must be taken into account. We show using a numerical simulator that these changes in the optimum conditions can impact oil recovery if not accounted for in the SP design. / text

The primary objectives of this research were to understand the potential for gravity-stable surfactant floods for enhanced oil recovery without the need for mobility control agents and to optimize the performance of such floods. Surfactants are added to injected water to mobilize the residual oil and increase the oil production. Surfactants reduce the interfacial tension (IFT) between oil and water. This reduction in IFT reduces the capillary pressure and thus the residual oil saturation, which then results in an increase in the water relative permeability. The mobility of the surfactant solution is then greater than the mobility of the oil bank it is displacing. This unfavorable mobility ratio can lead to hydrodynamic instabilities (fingering). The presence of these instabilities results in low reservoir sweep efficiency. Fingering can be prevented by increasing the viscosity of the surfactant solution or by using gravity to stabilize the displacement below a critical velocity. The former can be accomplished by using mobility control agents such as polymer or foam. The latter is called gravity-stable surfactant flooding, which is the subject of this study. Gravity-stable surfactant flooding is an attractive alternative to surfactant polymer flooding under certain favorable reservoir conditions. However, a gravity-stable flood requires a low velocity less than the critical velocity. Classical stability theory predicts the critical velocity needed to stabilize a miscible flood by gravity forces. This theory was tested for surfactant floods with ultralow interfacial tension and found to over-estimate the critical velocity compared to both laboratory displacement experiments and fine-grid simulations. Predictions using classical stability theory for miscible floods were not accurate because this theory did not take into account the specific physics of surfactant flooding. Stability criteria for gravity-stable surfactant flooding were developed and validated by comparison with both experiments and fine-grid numerical simulations. The effects of vertical permeability, oil viscosity and heterogeneity were investigated. Reasonable values of critical velocity require a high vertical permeability without any continuous barriers to vertical flow in the reservoir. This capability to predict when and under what reservoir conditions a gravity-stable surfactant flood can be performed at a reasonable velocity is highly significant. Numerical simulations were also used to show how gravity-stable surfactant flooding can be optimized to increase critical velocity, which shortens the project life and improves the economics of the process. The critical velocity for a stable surfactant flood is a function of the microemulsion viscosity and it turns out there is an optimum value that can be used to significantly increase the velocity and maintain stability. For example, the salinity gradient can be optimized to gradually decrease the microemulsion viscosity. Another alternative is to inject a polymer drive following the surfactant solution, but using polymer complicates the process and adds to its cost without significant benefit in most gravity-stable surfactant floods. A systematic approach was introduced to make decisions on using polymer in applications based on stability criteria and cost. Also, the effect of an aquifer on gravity-stable surfactant floods was investigated as part of a field-scale study and strategies were developed to minimize its effect on the process. This study has provided new insights into the design of an optimized gravity-stable surfactant flood. The results of the numerical simulations show the potential for high oil recovery from gravity-stable surfactant floods using horizontal wells. Application of gravity-stable surfactant floods reduces the cost and complexity of the process. The widespread use of horizontal wells has greatly increased the attractiveness and potential for conducting surfactant floods in a gravity-stable mode. This research has provided the necessary criteria and tools needed to determine when gravity-stable surfactant flooding is an attractive alternative to conventional surfactant-polymer flooding. / text

Many water resources throughout the world are demonstrating changes in historic water levels. Potential reasons for these changes include climate shifts, anthropogenic alterations or basin urbanization. The focus of this research was threefold: 1) to determine the extent of spatio-temporal changes in regional precipitation patterns 2) to determine the statistical changes that occur in lakes with urbanizing watersheds and 3) to develop accurate prediction of trends and lake level return frequencies. To investigate rainfall patterns regionally, appropriate distributions, either gamma or generalized extreme value (GEV), were fitted to variables at a number of rainfall gages utilizing maximum likelihood estimation. The spatial distribution of rainfall variables was found to be quite homogenous within the region in terms of an average annual expectation. Furthermore, the temporal distribution of rainfall variables was found to be stationary with only one gage evidencing a significant trend. In order to study statistical changes of lake water surface levels in urbanizing watersheds, serial changes in time series parameters, autocorrelation and variance were evaluated and a regression model to estimate weekly lake level fluctuations was developed. The following general conclusions about lakes in urbanizing watersheds were reached: 1) The statistical structure of lake level time series is systematically altered and is related to the extent of urbanization 2) in the absence of other forcing mechanisms, autocorrelation and baseflow appear to decrease and 3) the presence of wetlands adjacent to lakes can offset the reduction in baseflow. In regards to the third objective, the direction and magnitude of trends in flood and drought stages were estimated and both long-term and short-term flood and drought stage return frequencies were predicted utilizing the generalized extreme value (GEV) distribution with time and starting stage covariates. All of the lakes researched evidenced either no trend or very small trends unlikely to significantly alter prediction of future flood or drought return levels. However, for all of the lakes, significant improvement in the prediction of extremes was obtained with the inclusion of starting lake stage as a covariate.