<p>Aquaplaning accidents are relatively rare, but could have fatal effects. The task of this master’s thesis is to use data from the Laser Road Surface Tester to detect road sections with risk of aquaplaning. </p><p>A three-dimensional model based on data from road surface measurements is created using MATLAB (version 6.1). From this general geometrical model of the road, a pond model is produced from which the theoretical risk ponds are detected. A risk pond indication table is fur-ther created. </p><p>The pond model seems to work well assuming that the data from the road model is correct. Determining limits for depth and length of risk ponds can be made directly by the user. MATLAB code is reasonably easy to understand and this leaves great opportunities for changing different parameters in a simple way. </p><p>Supplementary research is needed to further improve the risk pond detection model. Collecting data at smaller intervals and with more measurement points would be desirable for achieving better correlation with reality. In a future perspective, it would be wise to port the code to another programming language and this could make the computations faster.</p>

No description available.

Floods are one of the most important natural disasters regarding damages caused by them. Major reasons of huge damages of floods are unplanned urbanization, narrowing of river beds and incorrect operation of water control structures. Geographic Information Systems (GIS) can provide important tools to be used in flood modeling studies. In this study, Lake Mogan, Lake Eymir and Incesu Detention Pond subbasins are studied for flooding events within GIS framework. These subbasins are important catchment areas of city of Ankara with total drainage area of 1070 km2. Soil Conservation Service (SCS) method is used to obtain flood hydrographs for 12 hour duration and 50, 100 and 500 year return periods. Flood routing procedure is applied to obtain discharges at the outlet of the Mogan and Eymir Lakes and Incesu Detention Pond. Operation performance of water control structures are tried to be estimated by using hydrographs which are obtained for different scenarios. Results show that elements of Lake Mogan Water Control Structure do not have capability to discharge 500 year storm safely to the downstream of the lake. However, 100 year storm can be routed without creating problem if necessary small precautions are taken. On the other hand, water control elements of Lake Eymir and Incesu Detention Pond can transmit obtained flood volumes to the downstream parts by assuming that closed conduit at the exit of Incesu Detention Pond can safely convey resultant flood discharges.

Storm water is defined as runoff from precipitation such as rain or snow. It is collected in sewage disposal systems and since it mainly originates from urban areas it can contain high levels of heavy metals, nutrients and oil etc. Polluted storm water is currently treated by different methods such as wet ponds, constructed wetlands and filter strips. This study investigates these methods, which in earlier studies have shown to give varying results regarding their treatment efficiency. This thesis has been written on commission of SWECO VIAK and was aimed at studying those parameters that may affect the treatment efficiency of nutrients and heavy metals in storm water treatment facilities (STF:s). Through literature studies the dominating treatment processes in ponds and wetlands were examined. The flow pattern was then simulated in four different storm water ponds, of varying shape and size, by using a physically based computer model. The residence time distribution for each pond could then be calculated as well as the hydraulic efficiency, which is a measure on how well the inflowing water is spread throughout a pond. Finally a multiple regression analysis was performed. This analysis examined how the reduction of lead, copper, zinc and cadmium depends on the following factors: the specific pond area, the variance of the residence time distribution, the hydraulic efficiency and the concentration of incoming metals and suspended solids. The specific pond area is a factor which is defined as the pond area divided by the reduced run off area. The results from the multiple regression analysis indicate that an increasing content of inflowing suspended solids leads to a better treatment efficiency regarding lead and copper. The specific area showed to have some effect on the treatment efficiency, but this effect was less than that of the content of inflowing suspended solids. The reduction of cadmium depended mainly on the specific area and the incoming concentration of cadmium. An increasing reduction of zinc could to some extent be explained by an increasing specific area. The results from this analysis and earlier studies are emphasizing the fact that adsorption to particles and sediment is one of the main processes for a good separation of heavy metals from storm water. Longer measurements series from additional treatment facilities are needed to build a statistical model which, in the future, can be used to predict the treatment efficiency of storm water ponds. / Dagvatten är regn- och smältvatten som samlas upp i avloppssystem. Då detta vatten huvudsakligen härstammar från urban bebyggelse så kan det innehålla höga halter tungmetaller, närsalter och olja med mera. Idag behandlas förorenat dagvatten bland annat genom nyttjande av dammar, våtmarker och översilningsytor. Dessa behandlingsalternativ har dock visat sig ge varierande resultat med avseende på dess reningseffektivitet. Detta arbete har utförts på uppdrag av konsultföretaget SWECO VIAK och syftade till att studera vilka parametrar som påverkar reningseffekten av närsalter och tungmetaller i dagvattendammar. Genom litteraturstudier undersöktes de dominerande reningsprocesserna i dammar och våtmarker. Därefter modellerades strömningen i 4 dammar med varierande form och storlek. Vid detta arbete erhölls en fördelning av uppehållstiden hos vattnet för respektive damm samt ett värde på den hydrauliska effektiviteten, vilken är ett mått på hur väl det inströmmande vattnet sprids ut i dammen. Slutligen utfördes en multipel regressionsanalys. Vid denna analys undersöktes hur reningen av bly, koppar, zink och kadmium beror av den specifika dammarean, variansen hos vattnets uppehållstidsfördelning, den hydrauliska effektiviteten samt inkommande metall- och TSS-koncentration (suspenderat material). Den specifika dammarean är en faktor vilken defineras som kvoten mellan dammens area och dess reducerade avrinningsområde. Resultaten från den multipla regressionen tyder på att en ökad inkommande halt av suspenderat material till dammen har störst betydelse för en förbättrad avskiljning av bly och koppar. Även den specifika arean och metallkoncentrationen i inflödet visade sig ha en viss, men något mindre, betydelse. Reduktionen av kadmium berodde däremot till störst del av den specifika arean och inkommande kadmiumkoncentration. En ökad reduktion av zink förklarades till viss del av en ökad specifik area. Resultatet att halten av suspenderat material i hög grad avgör reningen samt tidigare studier understryker det faktum att adsorption till partiklar och sediment verkar vara en av de viktigaste processerna för en god avskiljning av tungmetaller. Längre mätserier från fler dagvattendammar krävs dock för att i framtiden ta fram en statistisk modell vilken skulle kunna användas till att prediktera reningseffekten.

Aquaplaning accidents are relatively rare, but could have fatal effects. The task of this master’s thesis is to use data from the Laser Road Surface Tester to detect road sections with risk of aquaplaning. A three-dimensional model based on data from road surface measurements is created using MATLAB (version 6.1). From this general geometrical model of the road, a pond model is produced from which the theoretical risk ponds are detected. A risk pond indication table is fur-ther created. The pond model seems to work well assuming that the data from the road model is correct. Determining limits for depth and length of risk ponds can be made directly by the user. MATLAB code is reasonably easy to understand and this leaves great opportunities for changing different parameters in a simple way. Supplementary research is needed to further improve the risk pond detection model. Collecting data at smaller intervals and with more measurement points would be desirable for achieving better correlation with reality. In a future perspective, it would be wise to port the code to another programming language and this could make the computations faster.

Rubber tree is one of the main plants which play an important role in the economy of Southeastern region, Vietnam. Approximately 90% of Vietnamese natural rubber latex is exported as raw products. The preliminary process of natural rubber latex discharges a large amount of wastewater to the environment. In Vietnam, there are many available technologies set up and operated for treatment wastewater of rubber latex processing. However, the effluent quality is still poor and the concentration of pollutants is higher than the required national technical regulation on the effluent of the natural rubber processing industry (QCVN 01:2008/BTNMT). Thus, this paper summarizes various technologies and methods currently applied for the treatment of latex processing wastewater in Vietnam. Additionally, the new effective methods being researched and applied in Thailand and Malaysia are also mentioned (countries with the highest production of natural rubber in the world). This paper also provides a screening of treatment technologies for reducing environmental pollution and contributing to high-quality effluent for meeting the required standard. / Cao su là một trong những cây trồng chính và đóng vai trò quan trọng trong nền kinh tế của miền Đông Nam Bộ, Việt Nam. Sản phẩm từ cây cao su thiên nhiên tại Việt Nam chủ yếu là xuất khẩu (khoảng 90%), tuy nhiên chỉ mới là dạng cao su thiên nhiên sơ chế. Quá trình sơ chế mủ cao su thiên nhiên thải bỏ một lượng lớn nước thải vào môi trường. Ở Việt Nam, hiện tại có rất nhiều công nghệ xử lý nước thải sơ chế mủ cao su đã được thiết lập và vận hành. Tuy nhiên, nồng độ ô nhiễm trong nước thải sau quá trình xử lý còn cao so với tiêu chuẩn yêu cầu (QCVN 01:2008/BTNMT). Vì vậy, bài báo này tóm tắt những công nghệ và phương pháp khác nhau được sử dụng để xử lý nước thải sơ chế mủ cao su tại Việt Nam gần đây. Thêm vào đó, những phương pháp mới và hiệu quả đang được nghiên cứu và áp dụng tại Malaysia và Thái Lan, những quốc gia có sản lượng sản xuất mủ cao su cao nhất trên thế giới cũng được giới thiệu. Bài báo này cũng cung cấp sự đa dạng của những phương pháp xử lý nhằm giảm thiểu ô nhiễm môi trường và góp phần đảm bảo chất lượng nước đầu ra đạt tiêu chuẩn cho phép.

No description available.

Links between the pond and surrounding land for horticulture is a distinctive feature of farming households in Bangladesh. It was hypothesised that the role of fishponds in integrated aquaculture systems has potential towards improving livelihoods and poverty alleviation. Rural and peri-urban settlements in Mymensingh District, Bangladesh were selected for assessing the importance and role of pond-dike systems on the livelihoods of households of different socio-economic level. The study was carried out in view of the sustainable livelihood approaches of the Department for International Development, U.K. Participation of all levels of stakeholders was ensured in the first and last phase of the study. The combination of quantitative and qualitative analysis at community and household level was a major strength and challenge of the study, and was used to explore the potential of integrated farming and factors that undermine such potential to contribute to a sustainable livelihood. The research commenced with a comprehensive situation appraisal and baseline survey to explore the context and characterize farming systems, followed by a longitudinal household survey to understand the effect of seasons on livelihoods. Households with access to ponds were identified as active or passive integrators based on a simple set of criteria and their resources and livelihoods assessed in comparison with non-pond households. During the last phase of the study a farmer participatory research (FPR) trial, based on a priority issue identified during the 1st phase of the study, was launched to investigate the potential of the integrated systems. The situation appraisal conducted within four communities revealed the effects of gender, well-being and location on farmers' regular activities and food consumption patterns. Fish culture was equally important as an enterprise among richer and poorer men, whereas vegetable cultivation was more important to men than women but wealth and location also affected its importance. Lack of knowledge was a particular problem for farmers growing fish and vegetables in the rural areas. Fish disease, high price of input, lack of money were also identified as constraints by fish producers. The expected use and current use of ponds, problems and benefits associated with fish culture were also found to be affected by groups emphasising vegetable, orchard and fish culture within their systems. The role of the pond for family use, which was a major objective for pond construction, was found to be significantly different between rural and peri-urban areas. Fish culture is now the dominant use of ponds for households irrespective of their focus on vegetable, orchard or fish production and they are utilised less for general domestic use. Ponds are relatively more important as a source of irrigation water in rural than in peri-urban communities. Significant differences were observed between locations and well-being categories for the percentage of fish retained for consumption and that sell. Rice bran was the most commonly used pond input (80% of all pond households) but active integrated farmers applied rice bran more frequently than passive groups (91 compared to 63 times/season). ‘Ease of production’ was a major incentive for farmers to integrate fish and vegetable production and this opinion was related to household type i.e. active integrators were more aware and confident about the practice. The literacy levels of household heads, access to information and capital and contact with formal and informal institutions of active producers and the better-off households was significantly higher than other groups and poorer households respectively. It is revealed from the longitudinal households’ analysis that the consumption pattern in terms of food types and amount are linked with income, expenses and food availability in different well-being categories between seasons across locations. The empirical analysis showed that as active households’ income increased, expenditure on food purchases, agricultural labour, pond inputs and poultry per household also increased. However, on-farm contributions as a source of fish and vegetables were important during the lower income and least productive months. Performance of integrated farming systems varied by location. Resource base, accessibility to market and information played key roles in the development of integrated farming system in the study area. Active integrated households in peri-urban areas, in response to higher demand in the nearby market, produced significantly more fish and vegetables than those in the rural areas. The result showed clearly the need for due consideration of these factors while promoting IAA systems in Bangladesh. Farmer participatory research showed that production of fish could be increased by a substantial level through increasing pond nutrient inputs rather than stocking an additional species (tilapia), although this may be related to the ‘improved’ nutrition used by farmers still being well below the level required for optimal tilapia performance. Rural households benefited more than peri-urban through direct consumption of both fish and vegetables; in contrast peri-urban households benefited more through cash sales of both fish and vegetables than rural households. Higher production did not lead to increased consumption, rather households benefited financially through selling fish. Similar production levels of vegetables between groups followed different levels of fish culture practices suggesting that increased investment in fish production is complementary rather than competitive with associated vegetable production. It could be concluded that considerable potential exists for further integration and development of pond-dike systems, which could contribute towards improved livelihoods of both better off and worse off people.

Most global and regional "greenhouse gas" budgets have neglected beaver ponds, but they have been found to be relatively high emitters of methane (CH$ sb4$) (Roulet et. al., 1992). Static chambers, bubble traps, benthic chambers. piezometers, and water column and sediment profiles were used to determine the dynamics of CH$ sb4$ production, oxidation, storage, and emissions from a northern boreal beaver pond, as part of the Boreal Forest Ecosystem-Atmosphere Study (BOREAS) from May 1 to September 15, 1994. Samples were analysed by gas chromatography, and isotopic analyses were performed by mass spectrometry. / The mean flux of CH$ sb4$ from the beaver pond (155 and 320 mg CH$ sb4$ m$ sp{-2}$ d$ sp{-1}$ for vegetated and open water sites, respectively) was greater than the flux from most other northern boreal wetlands (Bubier et. al., 1995). CH$ sb4$ availability was primarily controlled by sediment temperature, and CH$ sb4$ transport was controlled by windspeed (diffusion) and atmospheric pressure (bubbles). Bubbles comprised 20 to 52% of the net annual flux comprising the remainder. A large difference in bubble flux was observed between open water (15.7 g CH$ sb4$ m$ sp{-2}$ yr$ sp{-1}$) and vegetated sites (2.9 g CH$ sb4$ m$ sp{-2}$ yr$ sp{-1}$), and isotopic analyses indicate that this difference is due, in part, to a difference in CH$ sb4$ production pathways between sites. Greater oxidation also reduced the CH$ sb4$ flux from shallow, vegetated sites. / A preliminary CH$ sb4$ budget for the BOREAS northern study area indicates that beaver ponds contribute significantly (6% to 30%) to the regional CH$ sb4$ flux. The areal extent of beaver ponds needs to be determined for inclusion in regional and global CH$ sb4$ budgets.

Thesis (M.A. (Research Psychology))--North-West University, Potchefstroom Campus, 2010.