Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Environmental Sciences." Includes bibliographical references (p. 132-139).

Thesis (M.L.A.) -- University of Texas at Arlington, 2008.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: John M. Sharp. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--University of Oregon, 2003. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 177-185). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 197-203). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Ohio State University, 1967. / Includes bibliographical references. Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 107-116).

Stormwater management is always a problem in Hong Kong since its development from a fishing village. Contributed by abundant precipitation, hilly topography, and dense urban development, flooding has been causing enormous economic losses to Hong Kong and is a main focus of local stormwater management. With the construction of many conventional hardcore engineering stormwater management structures in recent decades, such as underground detention tanks and stormwater tunnels, the flooding problem in Hong Kong has been well alleviated. It is now the time to move forward and incorporate more sustainable stormwater management principles and techniques, namely the strategy of low-impact development (LID), into the local practices in Hong Kong. Stormwater should be viewed not only as a problem, but also as a valuable resource. This research aims at a feasibility study on the possible applications and hydrologic benefits of bioretention and permeable pavements under the local conditions of Hong Kong. The buildability of infiltration devices in Hong Kong is examined by constructing pilot-scale physical models of both bioretention and permeable pavements in this study. Hydrologic monitoring of these physical models under Hong Kong rainfall events is carried out for at least one wet season. The monitoring data are analyzed to evaluate the hydrologic performance of bioretention and permeable pavements, as indicated by peak flow reduction and volume retention of stormwater runoff. The long-term hydrologic performance is also evaluated by the numerical model SWMM (Stormwater Management Model). After model calibration and validation using field data on the physical model, SWMM isused to simulate bioretention performance for the past ten year precipitation records of Hong Kong under systematic variations of two relevant parameters, namely the exfiltration rate and the area ratio of bioretention to catchment. Results show that both bioretention and permeable pavements are feasible to be applied in Hong Kong. The hydrologic performance of bioretention is influenced by the precipitation patterns, the size of bioretention, the stormwater storage, and the properties of soil. As in common practice, the available storage of bioretention is much smaller than design rainfalls in Hong Kong. Therefore, peak flow reduction shall not be the target of incorporating bioretention in local storm drain designs. The influence on long-term water balance in the urban area may be considered as the main benefits from bioretention, using the annual retention ratio as a performance indicator. The hydrologic performance of permeable pavements is influenced by the storage depth provided by the gravel layer and the properties of in-situ soil. Considerably good peak flow reduction and volume retention are obtained in the experimental permeable pavements subjected to the local extreme precipitation events. In actually applications, the storage of permeable pavement may be designed to capture the total depth of design storms in Hong Kong, after which peak flow reduction may be obtained. It is anticipated that this research can provide reference information on both the design and hydrologic benefit estimation of bioretention and permeable pavements practices for applications in Hong Kong. / published_or_final_version / Civil Engineering / Master / Master of Philosophy

The release of ionic solute from melting seasonal snow produces an influx of ion laden water into hydrologic systems at the start of spring snowmelt. The spatial and temporal variability of meltwater and solute release from melting snow was investigated at different spatial scales to assess the magnitude and variability of this process. Four laboratory experiments were performed where an 0.4 m³ volume of snow was placed in a plexiglass box and melted from above. NaCl and dye tracer experiments revealed contemporaneous areas of concentrated dye and dilute meltwater in flow fingers, indicating that meltwater in preferential flow paths is diluted by low concentration water from the top of the snowpack. Meltwater discharge and meltwater electrical conductivity were measured in snow lysimeters, and snow accumulation and electrical conductivity of samples from snowpits were measured over four snowmelt seasons at an alpine field site. Peak snow-water equivalent ranged from 0.57 to 2.92 m, and lysimeter discharges ranged from 20 to 205% of the mean flow; however mean lysimeter flow was representative of snow ablation observed in snow pits. The electrical conductivity in snowpit samples and lysimeter meltwater averaged 2-3 μS cm⁻¹. Peak meltwater electrical conductivity ranged from 6 to 14 times that of the bulk premelt snowpack. The highest conductivities were observed during the first few days following the onset of flow, and the lysimeters that began flowing earliest tended to have the highest conductivities at the onset of flow. A mathematical model for solute transport in snow was developed that includes the effects of mass transfer between mobile and immobile liquid phases, advection, hydrodynamic dispersion, and melt—freeze episodes. The ability of the model to accurately simulate solute movement and release depends on the validity of the assumption of one—dimensional flow and on the accuracy of modeling the snowpack energy balance. This model is preferable to the empirical models of solute elution currently in use for investigations of watershed hydrogeochemical response because it has the ability to respond directly to changes in snow accumulation or meteorlogical conditions.

Environmental change is currently regarded as one of the greatest threats to water resources. Limited knowledge of hydrological processes prevents from adequate characterization of systems behaviour to future changes. Geochemical and isotope tracers are considered reliable tools to study physical processes, but tracer studies are often constrained by the temporal and spatial variability in the tracer response and coarse data sets. Novel automatic sampling devices and inexpensive laser spectroscopy made higher-resolution stable isotope tracer data feasible. This thesis presents approaches to integrate geochemical tracer data, high-resolution stable isotope tracer data and process dynamics observed in the field into lumped conceptual rainfall-runoff models to study catchment hydrological processes at different scales. The use of such process-based data successfully aided model conceptualization and calibration in the quest for simple water and solute transport models with improved representation of process dynamics. In particular, high-resolution isotope data could identify temporally and spatially variable flow pathways to assess diffuse pollution transport, which otherwise might have been lost. This work showed that pollutants in some catchments are likely to rapidly discharge into the stream and due to geological properties reside over longer periods in deeper groundwater systems. In other words, changes to these systems today are likely to show an immediate effect fading persistently over decadal time periods. Such knowledge is important if catchment remediation and recovery has to be assessed from a management point of view such as for example targeting measures and cost-effective land management to improve water quality status.