Browsing by Subject "Flood"

Now showing 1 - 9 of 9

Application of dynamic optimization methods for foam floods in stratified reservoirs
(2018-08-17) Tang, Brandon Chok-Yie; Nguyen, Quoc P.
Efficient recovery of oil from heavily stratified carbonate reservoirs can be very technically challenging, even when applying waterflood, gasflood, or WAG (water-alternating gas) processes. To date, relatively few field or pilot applications of foam flooding have been conducted due to an incomplete understanding of how foam will behave in the field. The reservoir of interest studied in this work is oil-wet and consists of a stratified upper high-permeability zone overlaying a lower low-permeability zone. This study seeks to assess the performance of the foam flooding process in oil recovery and develop an optimum field injection strategy based upon various objective functions. In the process, the impact of initial waterflooding and varying foam strength on the optimum project termination time, as well as the sensitivity of foam parameters on the optimum field injection strategy is investigated. Two main optimization techniques are tested: static optimization, where the injection parameters are set once at the beginning of the simulation, and dynamic optimization, where injection parameters are optimized in five-year intervals over the life of the well. The dynamic optimization was performed in two ways: a local dynamic optimization and an early-time weighted optimization. In general, the dynamic optimization outperformed the static optimization with respect to all objective functions. Over the course of the study, a variety of objective functions were utilized. The objective functions began with maximizing cumulative oil recovery and evolved to maximizing oil recovery while minimizing gas utilization ratio, and finally maximizing net present value (NPV). From the results, it was ultimately shown that the global dynamic optimization of NPV was the most useful way of obtaining a field injection strategy. The optimal process design parameters indicated that high volumes of surfactant as well as gas in the lower zone needed to be injected early in the life of the project to best maximize NPV. From the optimal termination time study, it was found that the optimal termination time for the project was around ten years. Varying extents of initial waterflooding and alteration of foam strength did not have an impact on the suggested termination time. From the foam strength sensitivity, it was found that among the factors (water saturation, oil saturation, surfactant concentration) considered, the maximum dry-out water saturation had the most profound impact on the NPV. Ultimately, this work develops the framework necessary to create a field injection strategy for foam flooding in the stratified oil-wet reservoir used in this study, but can be extended to other types of reservoirs.
Error assessment for Height Above the Nearest Drainage inundation mapping
(2018-05-04) Godbout, Lukas Daniel; Passalacqua, Paola
Floods are natural events that can have disastrous impacts in terms of loss of life and damage to property. Flood modelling and mapping allow cities, emergency response and individuals to better prepare for and react to these potential disasters. While detailed flood models and maps are available at some locations in the U.S., many locations are left without. Automatic flood modelling and mapping using remote sensed data allows the possibility of providing flood maps on a large scale without the need for field studies on each and every river. As of 2016 the National Water Model is using rainfall forecasts from the National Weather Service to predict discharge estimates for approximately 2.7 million reaches across the entire continental U.S. To use these discharge values for inundation mapping, relationships between discharge and stage height known as rating curves are used. While rating curves are typically derived for river cross sections using detailed field studies, the proposed methodology for the National Water Model is to derive rating curves purely from remote sensed data. Manning’s equation is applied to derive a relationship between discharge and stage height using topographic data to estimate reach geometry, known as “synthetic” rating curves. The focus of this thesis is to assess the accuracy of these synthetic rating curves and to propose possible improvements. The synthetic rating curves are assessed for 527 reaches across four rivers in Texas, and the effect of terrain characteristics such as slope and reach length on accuracy are explored. An approach to recalculate the slope for Manning’s equation is proposed and evaluated using our method to quantify synthetic rating curve performance.
Give that building C.P.R.! : bringing life back into flooded mid-century modern residences
(2023-05) Quigley, Cara Elizabeth; Holleran, Michael
Repeated adverse weather events have changed the way we must approach historic preservation practices for the future. The Mid-Century Modern housing stock of Houston, TX is among the nation’s largest and has been continuously threatened by severe flooding in recent years. Between 2015-2017, approximately 30 percent of the Mid-Century Modern homes in the Meyerland neighborhood of Houston flooded multiple times, resulting in a rapid increase of teardowns and significant loss of original fabric. Out-of-date floodplain maps, inadequate government assistance, and the inevitability of future disasters leave homeowners faced with challenges regarding the treatment of their historic-age properties (50 years or older). Flood resilience and adaptation strategies such as elevating a slab-on-grade home above the base flood elevation or extensive material adaptation of historic interiors must be carefully approached to avoid a negative impact on the distinct character of the modern building typology. The research in this thesis examines resilience-based preservation approaches that are supported by three case study properties in Houston. Each of the highlighted historic-age residences has incorporated various measures of flood resilience that are consciously focused on keeping with the Mid-Century Modern aesthetic. In an effort to retain the integrity of materials, design, and workmanship of flood-vulnerable Mid-Century Modern residences, finding common ground between preservation and flood resiliency is the epitome of this discussion to properly adapt and protect the at-risk edifices in preparation for sustaining the existence of the postwar building stock in future flood events
Height above nearest drainage : assessment and recommendations for improved rating curve generation
Ruess, Paul Joseph; Maidment, David R.
Real-time flood forecasting for the Conterminous United States is currently underway. Powered by improvements to the Height Above Nearest Drainage methodology, coupled with the recent publication of streamflow predictions through the National Water Model, few uncertainties remain before implementation can be realized. Of these uncertainties, rating curve generalizations for all NHDPlusV2 stream reaches in the nation has persistently proven problematic, particularly regarding approximations of Manning’s roughness and stream reach slope values. This research attempts to address these concerns through detailed analyses of various rating curves along Onion Creek in Austin, Texas. From this research, alternatives are proposed to the currently used roughness and slope values, and the overall performance of these alternatives is assessed to provide recommendations for future rating curve approximations.
Historic preservation and disaster resilience : flooding in Santiago de Querétaro, Mexico
(2015-05) Lule-Hurtado, Gibrán N.; Holleran, Michael; Ibarra-Sevilla, Benjamín
Santiago de Querétaro is a UNESCO World Heritage City in central Mexico experiencing exacerbating rates of flooding in its historic center due to increased uphill urbanization overwhelming the aging drainage infrastructure. Historic districts are important economic drivers and shrines of heritage that should be considered when planning for disaster resiliency. This Report explores flood mitigation considerations for historic structures and districts, identifying those best suited for Querétaro and can be implemented at the parcel, district, or public administrative levels.
Intra-meander groundwater-surface water interactions in a losing experimental stream
(2010-08) Nowinski, John David; Cardenas, Meinhard Bayani, 1977-; Sharp, John M.; Bennett, Philip C.
Groundwater-surface water interactions between streams and shallow alluvial aquifers can significantly affect their thermal and chemical regimes and thus are critical for effective management of water resources and riparian ecosystems. Of particular significance is the hyporheic zone, an area delineated by subsurface flow paths that begin and end in surface water bodies. Although detailed work has examined hyporheic flow in the vertical dimension, some studies have suggested that the drop in a stream’s elevation as it flows downstream can laterally extend the hyporheic zone. This study examines intra-meander hyporheic flow using extensive field measurements in a full-scale experimental stream-aquifer system. Synoptic head measurements from 2008 and 2009 and a lithium tracer test were conducted to determine the extent and nature of hyporheic flow within the meander. Permeability was measured and sediment cores were analyzed from 2008 to 2009 to assess aquifer properties. Finally, transient head and temperature measurements were collected during flooding events to assess the sensitivity of intra-meander hyporheic flow and temperature to stream discharge. Results verify that hyporheic flow through meanders occurs, but show that it is sensitive to whether a stream is gaining or losing water to the subsurface overall. In addition, permeability and core grain size results indicate moderate heterogeneity in permeability can occur in aquifers composed of relatively uniform sediment. Results also demonstrate that permeability in alluvial aquifers can evolve through time. Such evolution may be driven by groundwater flow, which transports fine particles from areas where porosity and permeability are relatively high and deposits them where they are relatively low, thus creating a positive feedback loop. Finally, measurements during flooding indicate that steady-state hyporheic flow and the thermal regime within the aquifer are largely insensitive to stream discharge. Together, these results expand upon previous field studies of intra-meander hyporheic flow and verify previous modeling work, although they demonstrate a level of complexity within these systems that should be considered in future work.
Patient evacuation optimization for health care facilities during hurricanes
(2021-05-20) Kim, Kyoung Yoon; Kutanoglu, Erhan; Hasenbein, John J.; Hanasusanto, Grani; Iyoob, Ilyas; Yang, Zong-Liang
The total cost for weather-related disasters in the U.S. increases over time, and hurricanes usually create the most damage. Patient evacuation missions continue to be one of the most prevalent challenges, present in almost every major hurricane event. This research develops a comprehensive modeling and methodological framework for a large-scale patient evacuation problem when an area is faced with a forecasted disaster such as a hurricane. In this work, a hurricane scenario generation scheme using hydrological models for forecasting inland and coastal flooding and a scenario-based stochastic integer program are integrated to make decisions on patient movements, staging area locations and positioning of emergency medical vehicles. The objective is to minimize the total expected cost of evacuation and the setup cost of staging areas. The hurricane scenario generation scheme incorporates uncertainties in the hurricane intensity, direction, forward speed, and tide level. To obtain hurricane scenarios, a hurricane landfall distribution is developed, and stratified sampling is applied to generate potential flooding scenarios. This research also explores different stochastic integer programming formulations of patient evacuation operation, and chooses the most efficient approach for representing the unique characteristics of patient evacuation operation. Finally, to demonstrate the modeling approach, real-world data from the Southeast Texas region is used in numerical experiments. These experiments address exact and approximate methods for finding solutions of the patient evacuation problem for a large network. These results also highlight the importance of operation time limits, the number of available resources, when making evacuation decisions.
Stratovolcanoes
(2009-03) Barker, Daniel S.
The ties that bind : a study of neighborhood place attachment and its potential influence on the choice to relocate or rebuild after a natural disaster
(2019-08-12) Atlas, Laura Weekley; Sletto, Bjørn
This professional report addresses 1) how a three-dimensional, person-process-place framework (Scannell & Gifford, 2010) captures the complex interrelationship between individuals and collective groups who form place attachment, the ways in which they attach themselves to a place, and the place that is the object of their attachment; 2) how place attachment influences individual decisions to rebuild or relocate after a natural disaster; and 3) what the implications are for planners faced with these individual and collective decisions to remain or relocate. Using a case study from Meyerland, a close-in suburban neighborhood in southwest Houston which has recently endured a 27-month period of three massive flooding events culminating in Hurricane Harvey, the report addresses these questions through qualitative analysis of interviews and surveys of current and former residents of Meyerland, history of the neighborhood, and a thorough literature review of place attachment.