Hydrologic and water-quality equilibria are greatly affected by changing land use. This study presents a methodology that integrates the use of remote sensing, geographical information systems (GIS) and water-quality modeling. Archived aerial photography proved to be a valuable source of historical land use data. GIS technology was used to compile and analyze spatial data. A comprehensive watershed model was used to link the effects of land use change to water quality. The Cub Run watershed study area, located in northern Virginia experienced significant land use change between 1979 and 1988. Two aspects of development, impervious surface area and construction activity, that impact discharge and water quality were quantified. Developed land increased 11 percent between 1979 and 1988. Seven percent of the 11 percent increase occurred between 1984 and 1988 with medium-density residential housing and commercial areas accounting for most of the change. As a result of development, the impervious component of the watershed increased 6 percent. Agricultural areas were affected the most by development, decreasing by 13 percent over the 1979 - 1988 time period. Watershed discharge did not increase as expected with increasing impermeable watershed surface area, indicating that either stormwater control efforts are working and/or the 6 percent increase in impermeable surface area has not affected discharge. Soil exposed by construction activity increased 5 percent from approximately 1 percent of total surface area in 1979 to 6 percent total surface area in 1988. Significant increases in suspended sediment loads were recorded between 1982 and 1988 when compared to the 1979- 1982 time period. Construction activity is the probable cause of this increase. A watershed-scale comprehensive water-quality model was successfully calibrated and verified to watershed discharge and, to a lesser degree, suspended solids output. Simulation of suspended solids became less reliable with increased construction activity within the watershed. / Master of Science

Two approaches for the examination of microbially-caused degradation of water quality within water distribution systems were considered: the results of a questionnaire were analyzed and a sampling technique utilizing a concentrator was evaluated. A questionnaire, completed by water treatment plant operators in Virginia, was analyzed to ascertain what complaints regarding water quality were being received and what the causes of the complaints were. The most frequently reported complaints were those of taste and odor. Although they were not the sole factor, it appears nuisance bacteria were causative agents in degradation problems related to turbidity and red water. The Pellicon cassette system concentrator was evaluated for use during sampling in water distribution systems. The evaluation included determining the range of percent recovery in the retentate to be expected and the factors affecting this recovery. Thirty to sixty percent recovery of bacteria (Pseudomonas cepacia or Escherichia coli) in the retentate can be expected. The percent reduction in volume was the system parameter which most affected the percent recovery. / Master of Science

No description available.

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M. Sc.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 65-68).

M.Sc. (Aquatic Health) / The increased supply of water to areas targeted for development and the concomitant increase in land use and waste disposal activities has lead to the deterioration in the quality of water in South Africa‟s freshwater systems (DWA, 2011a). In order to manage this, the South African Department of Water Affairs (DWA) has developed numerous water quality policies and management approaches. One such approach is the determination and use of Resource Water Quality Objectives (RWQOs) (DWAF, 2006a). Resource Water Quality Objectives are a set of instream water quality objectives that aim to ensure that water that is fit for use is supplied to downstream users through the management and control of upstream impacts (DWAF, 2006b). In this study, site specific RWQOs were determined for the Modder and Riet Rivers as a means of providing a basis for reporting on instream water quality. As with many of the freshwater catchments in South Africa, the Modder-Riet catchment, located in the Free State and Northern Cape Provinces, is a water limited catchment (Slabbert, 2007). Historically most of the Modder and Riet Rivers would typically have had low water yields, with dry periods and pools forming in large endorheic areas (Grobler and Davies, 1981). As the need to supply water for crop production and domestic use grew, various transfer schemes and reservoirs were developed between the Caledon, Orange and Modder-Riet River systems (DWAF, 2006a). In order to distribute this water, various canal systems and operating rules for the storage dams were developed to transport water to the predominantly agricultural and domestic water users in the various parts of the catchment. Much of the water that is used in the Modder-Riet catchment therefore originates from reservoirs and from outside the catchment, completely transforming it from its natural state. This change in land-use and hydrology of the Modder-Riet catchment resulted in a concomitant change in the water quality. Salinisation, microbial contamination and eutrophication have, in particular, been recorded as the most significant problems affecting the fitness for use of the water in the Modder-Riet catchment. In order to manage these water quality problems and the effects on downstream users, a Catchment Management Strategy (CMS) for the Modder-Riet catchment was developed in 2006 which identified the users in the catchment and put forth a set of catchment-wide RWQOs (DWAF, 2006a). Further studies in the area have also subsequently highlighted that, given the current growth in water use, the associated negative water balance and the potential for serious deleterious effects of increased return flows on the water users, the need for improved efficiency of water use and the management of water quality in this catchment (as well as in those catchments which support the Modder and Riet Rivers) will become ever increasingly important (DWA, 2006a; DWA, 2012a; DWA, 2013a). The aim of this study was to: 1) determine whether catchment characteristics, water quality and user requirements across the catchment differed enough to warrant the separation of the catchment into different Management Units (MUs) for which site specific instead of generic RWQOs should be set, 2) to set low confidence level 3 RWQOs for various sites which represent each MU and 3) to determine the implications for the future management of the water quality in the Modder-Riet catchment. Fourteen Level 3 RWQOs for the main constituents of concern, namely phosphate (PO4), ammonia (NH3), ammonium (NH4+), nitrate and nitrite (NO3 + NO2-N), Escherichia coliform (E. coli), Electrical Conductivity (EC), chloride (Cl), sodium (Na), the Sodium Adsorption Ratio (SAR), aluminium (Al) and fluoride (F), were determined at strategic sites within six water quality MUs. These MUs were roughly the same as those determined in the Modder-Riet CMS, with a few exceptions:  the Upper and Middle Riet MUs from the CMS were not found to be different enough in terms of land use and water quality to warrant their separation and in this study were lumped together to form the Upper Riet MU, and  the Lower Riet MU from the CMS did not take account of the operation of the Kalkfontein and Orange-Riet transfer schemes which, in this study, resulted in the delineation of the Middle Riet River MU from Kalkfontein Dam to the outlet of Kalkfontein Canal and the Lower Riet MU from below the Kalkfontein Canal end point on the Riet River and the transfer site on the Modder River (at Scholzburg Weir) to just above the zone of influence from the Vaal River on the lower Riet River below Soutpansdrift. As with the delineation of the MUs, the location of the RWQO sites were determined in consultation with the Modder-Riet Catchment Management Forum (CMF) and were based on 1) their ability to exercise control over the quality of water entering a MU (resulting from upstream water uses) and 2) the need to provide water that is fit for use for the downstream users in areas of similar land uses. Within each MU, additional sites were added that would ensure fitness for use at specific strategic points. Since the RWQOs that were set at these sites were based predominantly on the current state of the water quality in the Modder and Riet Rivers they varied widely, with the strictest RWQOs being set for the transfers from the Caledon River via Novo Transfer Scheme, at Mazelspoort Weir on the Modder River and within the Kalkfontein Canal at the outlet of Kalkfontein Dam on the Riet River. Whether the status quo should be maintained, improved or allowed to deteriorate was determined by considering the water quality management vision and goals for the catchment, the water quality needs of the downstream users and the potential impact on the upstream uses. Although the RWQOs in almost all cases were more stringent than those set for Modder and Riet Rivers in the. CMS, of greater significance was the variation between the RWQOs set at each of the sites. By using the current state of water quality as a reflection of fluvial processes (such as assimilation, deposition and dilution), the RWQOs in this study took account of the differences in the effects of the various land uses and allowed for the determination of objectives which were tailored to specific areas of the catchment. They therefore more accurately represented the user requirements and the need for interventions. The RWQOs set by the CMS on the other hand were applied at catchment scale (i.e. there was one set of RWQOs for the entire catchment) and as such may have been too lenient in some areas and too strict in others. Thus although broad scale objectives set by the CMS may be useful for water quality assessments in the Modder-Riet catchment, the need to account for differences in local factors which influence water quality across the catchment (such as the presence of multiple transfer systems and large dams, and variations in land and water use) would warrant the determination of level 3 RWQOs. Based on an assessment of the compliance to the RWQOs over the past three to five years, PO4, NH3, EC, E.coli and Al were identified as the major water quality variables which have the potential to impact on the downstream users and for which Source Management Objectives (SMOs) and water quality allocation, management and implementation plans for the urban and agricultural sectors will be required. This is especially evident in the middle Modder and lower Riet catchments as well as below the numerous small urban areas which occur throughout the catchment. Key factors which have been highlighted for consideration in the future management of water quality in these catchments include inter alia: the consideration of appropriate water quality models, the development and implementation of agricultural Best Management Practices (BMPs) and the improved management of Sewerage Treatment Works (STWs). In addition, Persistent Organic Pollutants (POPs) and metals such as Al, chromium and manganese have been identified as potential variables which may affect users and for which further investigations are required. In conclusion, the hypothesis that that “the characteristics of the Modder-Riet catchment were different enough to warrant the determination of level 3 RWQOs, where in the more impacted portions of the catchment, water quality stress would be evident and would require a number of source directed interventions” could be accepted. It was however also found that interventions to improve instream water quality should not only be based on Source Directed Controls (SDCs) in their strictest sense, but should also incorporate aspects of good governance and effective regulation. This includes improved co-ordination of water quality monitoring and data management and reporting, effective and sustained capacity building and community learning and the establishment of functional, multi-scale feedback mechanisms. The application of the principles of Strategic Adaptive Management (SAM) was also identified a key element in the future management of water quality in this catchment.

Pollution from nonpoint sources is a leading cause of receiving water quality impairment. The largest source of nonpoint pollution is storm water runoff, which includes pollutants such as sediment, nutrients, metals, microorganisms, and organic compounds. Sediment is of particular importance because many pollutants are readily 5 adsorbed onto particles. In the Lake Tahoe basin, sediment is also significant because of its direct contribution to clarity attenuation. The most prudent control measure for mitigating sediment flux in the Lake Tahoe basin is infiltration, which captures runoff volume, allowing it to percolate into the soil and enter groundwater. All residential parcels in the Lake Tahoe basin are required to have an on-site infiltration system. These systems require rigorous maintenance to maintain full function. Negligence can lead to premature clogging from debris and accumulated sediment, and the cost of rehabilitating or replacing the system can be significant to homeowners. It is mandatory for a sediment trapping device to be installed to pretreat runoff discharged into the infiltration system; however, there is limited infomation regarding sediment trapping devices designed for residential use. The objective of this research was to evaluate the performance of an on-site stormwater treatment device in removing sediment from simulated stormwater runoff. The sediment trapping device consists of removable, porous 200-micron nylon inserts for filtration and is designed to mitigate premature clogging infiltrative runoff control measures. Laboratory analysis of a full scale device model was performed. Removal efficiency, effluent concentration, and bulk solids removal were assessed for perfomance evaluation. The device demonstrated a median removal efficiency from grab samples of 74%, median total suspended solids effluent concentration of 72 mg/L, and removed 89% of the total solids introduced into the system. Economic and sustainability implications of the device were also assessed.

published_or_final_version / Urban Planning / Master / Master of Science in Urban Planning

published_or_final_version / Urban Planning / Master / Master of Science in Urban Planning

published_or_final_version / abstract / China Development Studies / Master / Master of Arts