京都大学 / 新制・課程博士 / 博士(地球環境学) / 甲第25467号 / 地環博第253号 / 新制||地環||51(附属図書館) / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)准教授 田中 周平, 教授 越後 信哉, 教授 梶井 克純 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

Khartoum State in Sudan is subject to the erratic and intense rainfall during the short rainy season and dryness and heat throughout the rest of the year. High intensity rainstorms with a short duration have become more frequent in the area during the last two decades resulting in cities inundation and flash floods in the rural parts. On the other hand, the dry season means hot weather in the urban parts and water shortage in the rural part. Rural areas are dependent on the runoff water brought about by the seasonal streams as a source of water. For this study, Khartoum City Center and Seleit area were taken to investigate the application of water harvesting in the urban and rural areas, respectively. Accordingly, the hydrological characteristics and the specification of the potential water harvesting sites and systems were examined. For Khartoum City Center, characteristics of the drainage system were examined using ArcGIS platform. It is found that the drainage system covers 42% of the area with total capacity of 24000 m3. Daily rainfall data for urban meteorological station were used to calculate the probability and the return period of the rainfall, as well as the potential runoff. Rainfall probability of occurrence was calculated applying Gumbel distribution method for extreme events that were arranged according to the Peak-over-Threshold method. The potential runoff that could be generated from a certain rainfall was calculated using the Natural Resources Conservation Services method provided by the United States Department of Agriculture (US-NRCS). Accordingly, the curve number was calculated depending on the land use/land cover and the hydrological soil group. Consequently, the weighted curve number is found to be 94%, indicating dominant imperviousness. 13.1 mm rainfall depth produces runoff volume equal to the drainage system capacity with return period of one year; whereas more than four folds the drainage system capacity is produced by 30 mm rainfall depth that is considered the threshold for raising flood hazard. Six potential sites for roof rainwater harvesting were selected. Accordingly, it is found that, the application of roof water harvesting in 18% and 72% of the commercial and business district buildings can accommodate the runoff resulting from the 13.1 and 30 mm rainfall depth, respectively. Hence, impounding rainstorm water would help managing the urban runoff water, and consequently, the stored water could be used for making more green areas that will enhance the urban environment. Three watersheds of ephemeral streams (wadi), namely Wadi El Kangar, Wadi El Seleit, and Wadi El Kabbashi make up Seleit area. Distinct maps were prepared in ArcMap for the calculation of the potential runoff and the specification of the appropriate water harvesting sites and systems. The Wadis watersheds areas are found to be 540, 344 and 42 km2 for Wadi El Kangar, Wadi El Seleit and Wadi El Kabbashi, respectively. Daily rainfall data of rural meteorological station were classified into three groups representing the soil dry (AMCI), moderate (AMCII), and wet (AMCIII) moisture conditions; the respective CNI, CNII, and CNIII values were calculated accordingly. The weighted CN values indicate high runoff potential within the three soil moisture conditions. Accordingly, the rainfall thresholds for runoff generation for AMCI, AMCII and AMCIII conditions are found to be respectively 18.3 mm, 9.1 mm and 4.4 mm for Wadi El Kabbashi and 22 mm, 11 mm and 5 mm for both Wadi El Seleit and Wadi El Kangar. El Kangar dam subwatershed was used for calibrating the potential runoff calculated by the NRCS method. Since the Wadis are ungauged, Google Earth and GIS platforms were used to calculate geometrically the volume of the dam reservoir water for three years. This volume was compared to the annual runoff calculated by the NRCS method. Consideration to different factors was made to locate the potential water harvesting sites. Accordingly, water harvesting systems for fodder and crop plantation; sand storage surface or subsurface dams; or groundwater recharge, were specified. The socio-economic study revealed that the financial capacity, if any, of the villagers is very limited. Thus, the financial source for the construction of the suggested potential water harvesting or the rehabilitation of the existing ones is questionable. Hence, other potential financial sources are needed to help executing water harvesting projects in the region, e.g. Khartoum State Government. Applying water harvesting in Seleit area is found to be promising. Improving the livelihood of the villagers by applying runoff water harvesting could assure better water accessibility, better income generation from farms production, and allocation of time for other activities, e.g. education. This would be reflected in reduced migration to nearby cities and stabilized market supply of agricultural and animal products. Therefore, the development of the rural part is of great benefit to the development of Khartoum State, as long as the interdependency and mutual benefit between the rural and urban areas, represented by the local food and labor market, remain exist.

Khartoum State in Sudan is subject to the erratic and intense rainfall during the short rainy season and dryness and heat throughout the rest of the year. High intensity rainstorms with a short duration have become more frequent in the area during the last two decades resulting in cities inundation and flash floods in the rural parts. On the other hand, the dry season means hot weather in the urban parts and water shortage in the rural part. Rural areas are dependent on the runoff water brought about by the seasonal streams as a source of water. For this study, Khartoum City Center and Seleit area were taken to investigate the application of water harvesting in the urban and rural areas, respectively. Accordingly, the hydrological characteristics and the specification of the potential water harvesting sites and systems were examined. For Khartoum City Center, characteristics of the drainage system were examined using ArcGIS platform. It is found that the drainage system covers 42% of the area with total capacity of 24000 m3. Daily rainfall data for urban meteorological station were used to calculate the probability and the return period of the rainfall, as well as the potential runoff. Rainfall probability of occurrence was calculated applying Gumbel distribution method for extreme events that were arranged according to the Peak-over-Threshold method. The potential runoff that could be generated from a certain rainfall was calculated using the Natural Resources Conservation Services method provided by the United States Department of Agriculture (US-NRCS). Accordingly, the curve number was calculated depending on the land use/land cover and the hydrological soil group. Consequently, the weighted curve number is found to be 94%, indicating dominant imperviousness. 13.1 mm rainfall depth produces runoff volume equal to the drainage system capacity with return period of one year; whereas more than four folds the drainage system capacity is produced by 30 mm rainfall depth that is considered the threshold for raising flood hazard. Six potential sites for roof rainwater harvesting were selected. Accordingly, it is found that, the application of roof water harvesting in 18% and 72% of the commercial and business district buildings can accommodate the runoff resulting from the 13.1 and 30 mm rainfall depth, respectively. Hence, impounding rainstorm water would help managing the urban runoff water, and consequently, the stored water could be used for making more green areas that will enhance the urban environment. Three watersheds of ephemeral streams (wadi), namely Wadi El Kangar, Wadi El Seleit, and Wadi El Kabbashi make up Seleit area. Distinct maps were prepared in ArcMap for the calculation of the potential runoff and the specification of the appropriate water harvesting sites and systems. The Wadis watersheds areas are found to be 540, 344 and 42 km2 for Wadi El Kangar, Wadi El Seleit and Wadi El Kabbashi, respectively. Daily rainfall data of rural meteorological station were classified into three groups representing the soil dry (AMCI), moderate (AMCII), and wet (AMCIII) moisture conditions; the respective CNI, CNII, and CNIII values were calculated accordingly. The weighted CN values indicate high runoff potential within the three soil moisture conditions. Accordingly, the rainfall thresholds for runoff generation for AMCI, AMCII and AMCIII conditions are found to be respectively 18.3 mm, 9.1 mm and 4.4 mm for Wadi El Kabbashi and 22 mm, 11 mm and 5 mm for both Wadi El Seleit and Wadi El Kangar. El Kangar dam subwatershed was used for calibrating the potential runoff calculated by the NRCS method. Since the Wadis are ungauged, Google Earth and GIS platforms were used to calculate geometrically the volume of the dam reservoir water for three years. This volume was compared to the annual runoff calculated by the NRCS method. Consideration to different factors was made to locate the potential water harvesting sites. Accordingly, water harvesting systems for fodder and crop plantation; sand storage surface or subsurface dams; or groundwater recharge, were specified. The socio-economic study revealed that the financial capacity, if any, of the villagers is very limited. Thus, the financial source for the construction of the suggested potential water harvesting or the rehabilitation of the existing ones is questionable. Hence, other potential financial sources are needed to help executing water harvesting projects in the region, e.g. Khartoum State Government. Applying water harvesting in Seleit area is found to be promising. Improving the livelihood of the villagers by applying runoff water harvesting could assure better water accessibility, better income generation from farms production, and allocation of time for other activities, e.g. education. This would be reflected in reduced migration to nearby cities and stabilized market supply of agricultural and animal products. Therefore, the development of the rural part is of great benefit to the development of Khartoum State, as long as the interdependency and mutual benefit between the rural and urban areas, represented by the local food and labor market, remain exist.

Stormwater runoff from urban and urbanizing areas poses a serious threat to water quality, and unless managed properly will impede efforts to restore the Chesapeake Bay.Water quantity, as well as quality, must be considered, and Low Impact Development(LID) is an innovative stormwater management approach that addresses both. LID seeks to mimic a site's predevelopment hydrologic regime by retaining and treating stormwater at the lot level using small, cost-effective landscape features.The purpose for this study was to identify and rank impediments to the implementation of LID in the Virginia portion of the Chesapeake Bay watershed. This was accomplished by going to LID workshops and distributing a survey to stakeholders in attendance. The survey asked respondents to rank the following impediments to the implementation of LID: site-specific & non-structural, property owner acceptance, pollutant removal benefit, development rules, lack of education, maintenance considerations, flooding problems, and cost. Lack of education was ranked as the most important impediment, with development rules following close behind. Pollutant removal benefit was ranked the least important impediment. A second purpose was to assess whether there is a relationship between a county's growth rate and adoption of Better Site Design principles (BSD) and LID. A Code and Ordinance Worksheet was used to evaluate the development rules of 13 counties (6 high growth, 3 medium growth and 4 low growth) within Virginia's portion of the Chesapeake Bay Watershed. The scores from the worksheets were used to determine if the amount of growth pressure experienced by a county influenced the degree to which they incorporated BSD and LID in their local development codes. Statistical testing revealed that the relationship between growth pressure and score on the Code and Ordinance Worksheet was moderate, at best.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 250-274).

This study assessed the effect of an application of mycorrhizal fungi to stormwater filter media on urban bioswale soil and stormwater in an infiltration-based bioswale aged 20 years with established vegetation. The study tested the use of commercially available general purpose biotic soil blend PermaMatrix® BSP Foundation as a treatment to enhance Earthlite™ stormwater filter media amelioration of zinc, copper, and phosphorus in an ecologically engineered structure designed to collect and infiltrate urban stormwater runoff before it entered the nearby Willamette River. These results show that the application of PermaMatrix® BSP Foundation biotic soil amendment to Earthlite™ stormwater filter media contributed to the reduction of extractable zinc in bioswale soil (-24% and -26%), as compared to the control, which received a treatment of Earthlite™ stormwater filter media only, and experienced an increase in extractable zinc levels (23% and 39%). The results presented also show evidence that after establishment mycorrhizal treatment demonstrated lowered levels of phosphorus in bioswale soil (-41%) and stormwater (-100%), in contrast to the control, which had increased phosphorus levels. The treatment contributed to reductions between 67% and 100% in every metric detected in stormwater after an establishment period of 17 weeks, while the bioswale with no mycorrhizal treatment had increases between 50% and 117%. Treatment also appeared to enhance the reduction of ammonium and nitrates, while contributing to a greater increase in soil pH.

There are many possible ways to mitigate stormwater pollution, but this study focused on the DrainPacTM catchment basin insert and the feasibility of integrating N-halamine biocidal brominated beads into the filter system. This study was divided into three sections. The first section involved testing a DrainPacTM filter for treatable flow rates, head loss, and removal of solids, oil, and bacteria. The DrainPacTM filter is designed to be installed in a stormwater catch basin. The filter is composed of a 12 x 41 inch metal frame with textile filter media attached to it in a basket shape. The upper portion of one panel of the filter basket is made from a plastic mesh to allow overflow if the filter is overloaded. The second section of this study involved testing N-halamine brominated biocidal beads in laboratory-scale columns, and the third section involved integrating the beads into the DrainPacTM filter and testing it full scale. For the DrainPacTM filter tests, the unit was installed into a custom-built test flume which was designed to mimic the conditions that would be encountered in a real stormwater application. The flume was supplied with a gravity-fed stream of water from a retention pond located on the Cal Poly, San Luis Obispo campus. The initial tests were conducted to determine the amount of head loss produced by the filter. First, the clean filter was subjected to flow rates between 20 and 200 GPM. The filter showed very minimal head loss (0.5 to 9.1 cm for 20 to 200 GPM) when not loaded with solids. Next, the filter was subjected to 200 GPM flow with a solids concentration of between 80 and 100 mg/L until it failed (overflowed). This occurred after 625 g of solids had been added to the filter. After the filter had been loaded with solids to the point of overflow at 200 GPM, it was tested to determine what flow rate could be filtered with the solids present. The fully loaded filter was able to pass a flow rate of up to 80 GPM before overflowing. The DrainPacTM filter removed solids at a range of efficiencies from 83 to 91% at flow rates between 20 and 200 GPM. The higher removal efficiencies were achieved at the lower flow rates. The filter removed oil at efficiencies ranging between 40 and 80%. The oil removal efficiency did not appear to depend on the flow rate. The DrainPacTM filter did not remove bacteria under the test conditions. Following the DrainPacTM experiments, 0.3 mm and 0.8 mm diameter N-halamine brominated biocidal beads were tested in the lab using a laboratory glass column. At flow rates between 0.28 and 1.4 mL/sec, a 1 cm bed height of the 0.3 mm beads was found to produce head losses between 19 and 51.7 cm. The 0.8 mm beads produced head losses ranging from 11.9 to 47.7 cm when tested over the same range of flow rates. These flow rates represent nominal velocities between 0.36 and 1.8 cm/sec which would be expected in the DrainPacTM filter. The beads were then tested to determine how effectively they inactivate bacteria in a stream of water. Contact time after flowing through the column was found to be the key factor in how efficiently the beads worked. When the effluent samples were instantly quenched with sodium thiosulfate, the bacteria removal results matched those observed for the control (beads without bromine). When the samples were quenched directly after collection by adding the sodium thiosulfate to the sample as soon as the desired sample volume had been collected (95 to 285 seconds depending on flow rate), between 95 and over 99 percent of the bacteria were inactivated. After 10 minutes, all of the bacteria were inactivated. The final test involved integrating the N-halamine brominated beads into the DrainPacTM filter for a full scale test. Two sleeves containing 1400 grams of beads were laid into a DrainPacTM filter which was custom built to concentrate the flow through the beads. This system was tested using pond water with an average of 298 CFU/100 mL coliform bacteria at a flow rate of 36 GPM. The results of this test were very similar to the results of the lab scale testing. Contact time again proved to be necessary for bacteria inactivation. The filter with integrated N-halamine beads removed between 72 and 100% of bacteria with contact time between 30 seconds and 10 minutes.

No description available.

An analysis of drainage channel stability in urbanizing watersheds was completed in this study for areas in Pima County, Arizona. Existing channel geometry and longitudinal slope were compared to original design channel geometry and longitudinal slope. Original design channels existed in undeveloped watersheds. Information on current amounts and types of development were gathered for each channel location as well as current channel geometry and longitudinal slope. The analysis of these data showed a significant relationship between basin urbanization and reduced channel stability.

Pecan Creek flows southeast through the City of Denton, Texas. Characterized as an urban watershed, the basin covers approximately 63.5 km2. Pecan Creek is an intermittent stream that receives nonpoint runoff from urban landuses, and the City of Denton's wastewater treatment plant, Pecan Creek Water Reclamation Plant, discharges effluent to the stream. Downstream from the City of Denton and the wastewater treatment plant, Pecan Creek flows about 6,000 m through agricultural, pasture, and forested landscapes into Copas Cove of Lake Lewisville, creating backwater conditions. Pecan Creek water quality and chemistry were monitored from August 1997 to October 2001. Water quality was influenced by seasonal, spatial, climatic, and diurnal dynamics. Wastewater effluent discharged from the Pecan Creek Water Reclamation Plant had the greatest influence on water quality of the stream and backwaters. Water quality monitoring of Pecan Creek demonstrated that dissolved oxygen standards for the protection of aquatic life were being achieved. Water quality modeling of Pecan Creek was completed to assess future increases in effluent flow from the Pecan Creek Water Reclamation Plant. Water quality modeling indicated that dissolved oxygen standards would not be achieved at the future effluent flow of 21 MGD and at NPDES permitted loadings. Model results with application of a safety factor indicated that the maximum allowable concentrations for a 21 MGD discharge would be 2.3 mg/L of ammonia and 7.0 mg/L of biochemical oxygen demand at summer conditions. Drought conditions that occurred from 1998 to 2001 reduced water levels in Lake Lewisville and impacted dissolved oxygen water quality in Pecan Creek. Water quality observations made during the period of drought allowed for the development of a model to estimate the zone of the dissolved oxygen sag in Pecan Creek based on reservoir elevation. Finally, monitoring results were analyzed with nonparametric statistical procedures to detect water quality changes in the backwater area of Pecan Creek, as influenced by storm events.