<p>Recurrent crises of food insecurity and poverty are widespread in sub-Saharan Africa (SSA). There is an urgent need to increase food production so as to reduce bad nutrition and alleviate poverty. The availability and management of water contributes crucially to the variation in yields. Since the majority of farmers in SSA practice rain-fed agriculture under adverse climatic conditions, it is crucial to use water-conserving technologies systematically and make rainwater management an integral part of land use and crop management. While rainwater harvesting technologies (RHT) can increase productivity of rain-fed agriculture significantly at reasonable costs, successful adoption of RHT and accompanying high yields still remain primarily at family level and/or in geographical ‘pockets’. The big question is ‘why have farmers not widely adopted these apparently cheap and beneficial practices?’ An adequate understanding of the factors that lead some farmers to adopt RHT, characteristics of households that use RHT as well as technology transfer approaches offer valuable insights. Based on focus group discussions and a questionnaire survey covering adopters and non-adopters of RHT, and interviews with extension officers conducted in two banana growing districts in Uganda, this paper reveals circumstances, incentives, and support that would facilitate widespread adoption of RHT.</p>

Recurrent crises of food insecurity and poverty are widespread in sub-Saharan Africa (SSA). There is an urgent need to increase food production so as to reduce bad nutrition and alleviate poverty. The availability and management of water contributes crucially to the variation in yields. Since the majority of farmers in SSA practice rain-fed agriculture under adverse climatic conditions, it is crucial to use water-conserving technologies systematically and make rainwater management an integral part of land use and crop management. While rainwater harvesting technologies (RHT) can increase productivity of rain-fed agriculture significantly at reasonable costs, successful adoption of RHT and accompanying high yields still remain primarily at family level and/or in geographical ‘pockets’. The big question is ‘why have farmers not widely adopted these apparently cheap and beneficial practices?’ An adequate understanding of the factors that lead some farmers to adopt RHT, characteristics of households that use RHT as well as technology transfer approaches offer valuable insights. Based on focus group discussions and a questionnaire survey covering adopters and non-adopters of RHT, and interviews with extension officers conducted in two banana growing districts in Uganda, this paper reveals circumstances, incentives, and support that would facilitate widespread adoption of RHT.

At the opposite of numerous countries in the world, despite its natural assets and its enormous surface and underground water potential, Cameroon is still trying to put down effective policies for the supply of safe drinking water for its rural population. Many initiatives to supply these communities through a national water distribution network have remained for the most dead letters or fruitless. A very high number of people still endanger their life daily by relying on archaic water supply techniques – when they are working – and by consuming unsafe water. This study therefore investigates if fog and rainwater harvesting could help in securing safe drinking water to these same rural communities, leaving the remaining demand - if any - to be provided by the existing but too often non-reliable supply system. Two pilot sites have been selected for their different climatic conditions; a village in the mountainous Western Province and another in the low-lying area of the Far-North Province of Cameroon. Average climatic data and basic topographical information from each location were used to determine the size and number of required collectors. The potential monthly water-yield at each site was then assessed using an actual climatic data series (8 years) and the theoretical performance simulated based on an increasing per capita daily consumption (10 – 40 l.d-1). An estimate of implementation cost is provided as part of the discussion on the feasibility of using both fog and rainwater harvesting as low-cost approaches to securing safe drinking water in Cameroon.

As the world population increases, the demand increases for quality drinking water. The harvesting of rainwater has the potential to assist in alleviating pressures on current water supplies and storm water drainage systems. Diversion of a portion of the collected water away from storage is a technique used to improve harvested rainwater water quality prior to storage. Six configurations of a downspout first flush diverter were constructed and tested in the laboratory. The configurations of diverters were evaluated for their affinity to allow diverted water in the diverter chamber to interact with the flow of water to storage. Experiments were conducted at flow rates ranging from 0.76 L/min to 113.56 L/min. This range of flow rates adequately represents a wide range of common storm intensity patterns across the United States to which downspout first flush diverters are subjected. The diverter chamber to downspout transition fittings tested on a 10.16 cm diameter diverter chamber, upward and downward oriented sanitary and straight tee, do not have a significant impact on the mean difference in initial and final total dissolved solids concentrations observed at multiple sample ports. No statistical difference was observed when comparing upward and downward oriented sanitary tees used as diverter chambers to downspout transition fittings on 10.16 and 15.24 cm diverter chambers. Utilizing a straight tee as a transition fitting with a floating ball, acting as a barrier between water collected in the diverter chamber of a downspout first flush diverter and the flow passing through the transition fitting, limited diverted water from interacting with the subsequent flow of harvested rainwater. There is not a significant difference between the use of a downspout first flush diverter with diverter chamber diameters of 10.16 and 15.24 cm utilizing upward and downward oriented sanitary tees as downspout to diverter chamber transition fittings. Tests at flow rates less than or equal to 12.11 L/min exhibited limited changes in total dissolved solids concentrations in the downspout first flush diverters with 15.24 cm diameter diverter chambers. Tests at flow rates less than or equal to 1.51 L/min exhibited limited changes in total dissolved solids concentrations in the downspout first flush diverters with 10.16 cm diameter diverter chambers. The diverter chamber drain flow rate and volume impacts the observed differences in initial and final TDS concentrations at all sample ports on the diverter chamber of a downspout first flush diverter regardless of flow rate. The diverter chamber drain flow rate impacts the flow rate of water entering the diverter chamber through the transition fitting.

Rainwater harvesting is a familiar term for Bangladesh. People in areas that lack drinking water, particularly the coastal areas and the rural areas in the country, practice rain water harvesting. The high annual rainfall in the country makes rainwater harvesting a logical solution for the arsenic contamination of ground water in Bangladesh (Rahman et al. 2003). Also, the increasing population in the urban as well as rural areas is putting increased load on underground aquifers which is evident in the fact that the piezometric level in Dhaka has decreased by more than 65 feet in the last decade. The annual rain fall that the city receives may be an effective answer to the recharge of aquifers. Rain water harvesting during the rainy season can reduce the increasing load on groundwater levels. This study aims to provide some guidelines for economic rainwater harvesting system, especially for urban areas for specific user groups. These guidelines were formulated through literature review, analysis of some case studies on rainwater harvesting, and, to a certain extent, practical experience of the researcher. Data from secondary sources have also been used for the purpose. The guidelines have been formulated using existing data on rainwater harvesting systems. Based on these guidelines, a mathematical model has been developed to figure out cistern sizes for collection of rainwater. The solution is applied to a typical plan of an apartment house in Dhaka (multistoried) using programming and visualization so as to demonstrate the scope and benefit of integration of rain water harvesting technique with the architectural design. The harvested rainwater definitely does not meet the basic domestic requirement, but supplements it during the rainy season which, most importantly, is usable for individual household use. Large-scale rainwater harvesting also, hopefully, results in a decrease of seasonal flooding in the urban areas. The products of this research are a) a computer program for sizing cisterns and b) an animation of the proposed rainwater harvesting system that may be used as a tool to demonstrate the benefits of the technique.

Doctor of Philosophy(PhD) / In many areas of India, increasing groundwater use has led to depleted aquifers. Rainwater harvesting (RWH), the small scale collection and storage of runoff to augment groundwater stores, is seen as a solution to the deepening groundwater crisis in India. However while the social and economic gains of RWH have been highlighted, there has not yet been a thorough attempt to evaluate the impacts of RWH on larger catchment hydrological balances. The thesis here will endeavour to address this research gap through a case study of the 476 km2 ungauged semi-arid Arvari River catchment in the state of Rajasthan. Over 366 RWH structures have been built in this catchment since 1985 by the community and the local non-government organisation (NGO), Tarun Bharat Sangh (TBS). The local effects of RWH structures and general catchment characteristics were determined through field investigations during the monsoon seasons of 2007 and 2008. The analysis described large variability in both climatic patterns and recharge estimates. Potential recharge estimates from seven RWH storages, of three different sizes and in six landscape positions, were calculated using the water balance method, which were compared with recharge estimates from water level rises in twenty-nine dug wells using the water table fluctuation method. The average daily potential recharge from RWH structures is between 12 – 52 mm/day, while recharge reaching the groundwater was between 3 – 7 mm/day. The large difference between recharge estimates could be explained through soil storage, and a large lateral transmissivity in the aquifer. Approximately 7% of rainfall is recharged by RWH in the catchment, which is similar in both the comparatively wet and dry years of the field analysis. This is because the capacity of an individual structure to induce recharge is related to structure size and capacity, catchment runoff characteristics and underlying geology. Due to the large annual fluctuations in groundwater levels, the field study results suggest that RWH has a large impact on the groundwater supply, and that there is a large lateral flow of groundwater in the area. The results inferred from the field analysis were then applied to a conceptual water balance model to study catchment-scale impacts of RWH. An existing model was not used because of the paucity of data, and the need to incorporate an effective representation of RWH function and impact. The model works on a daily time step and is divided into subbasins. Within the subbasin hydrological response units (HRUs) describe the different land use/soil combinations associated with the Arvari River catchment, including irrigated agriculture. Sustainability indices, related to water from groundwater and rainfall for irrigated agriculture demand, were used to compare scenarios of management simulated in the conceptual model. The analysis shows that as RWH area increases, it reaches a limiting capacity from where developing additional RWH area does not increase the benefit to groundwater stores, but substantially reduces streamflow. This limiting capacity was also seen at the local-scale, where cumulative potential recharge from an individual RWH structure reaches a maximum daily recharge rate. These results could have important implications for RWH development, but require further research. The analysis highlighted the important link between irrigation area and RWH area. If the irrigation area is increased at the optimal level of RWH, where the sustainability indices were greatest, the resilience of the system actually decreased. Nevertheless RWH in a system increased the overall sustainability of the water demand for irrigated agriculture, compared to a system without RWH. Also RWH provided a slight buffer in the groundwater store when drought occurred. While RWH addresses the supply-side issues of groundwater operation, the institutions that form rules for groundwater use must also be considered, because of the link between irrigation area and RWH. The Arvari River Parliament, the community-based group in the case study area, was examined according to Ostrom’s factors for collective action. It was found that the major limitation for the effectiveness of this group was the minimal information available about the aquifer characteristics.

Doctor of Philosophy(PhD) / In many areas of India, increasing groundwater use has led to depleted aquifers. Rainwater harvesting (RWH), the small scale collection and storage of runoff to augment groundwater stores, is seen as a solution to the deepening groundwater crisis in India. However while the social and economic gains of RWH have been highlighted, there has not yet been a thorough attempt to evaluate the impacts of RWH on larger catchment hydrological balances. The thesis here will endeavour to address this research gap through a case study of the 476 km2 ungauged semi-arid Arvari River catchment in the state of Rajasthan. Over 366 RWH structures have been built in this catchment since 1985 by the community and the local non-government organisation (NGO), Tarun Bharat Sangh (TBS). The local effects of RWH structures and general catchment characteristics were determined through field investigations during the monsoon seasons of 2007 and 2008. The analysis described large variability in both climatic patterns and recharge estimates. Potential recharge estimates from seven RWH storages, of three different sizes and in six landscape positions, were calculated using the water balance method, which were compared with recharge estimates from water level rises in twenty-nine dug wells using the water table fluctuation method. The average daily potential recharge from RWH structures is between 12 – 52 mm/day, while recharge reaching the groundwater was between 3 – 7 mm/day. The large difference between recharge estimates could be explained through soil storage, and a large lateral transmissivity in the aquifer. Approximately 7% of rainfall is recharged by RWH in the catchment, which is similar in both the comparatively wet and dry years of the field analysis. This is because the capacity of an individual structure to induce recharge is related to structure size and capacity, catchment runoff characteristics and underlying geology. Due to the large annual fluctuations in groundwater levels, the field study results suggest that RWH has a large impact on the groundwater supply, and that there is a large lateral flow of groundwater in the area. The results inferred from the field analysis were then applied to a conceptual water balance model to study catchment-scale impacts of RWH. An existing model was not used because of the paucity of data, and the need to incorporate an effective representation of RWH function and impact. The model works on a daily time step and is divided into subbasins. Within the subbasin hydrological response units (HRUs) describe the different land use/soil combinations associated with the Arvari River catchment, including irrigated agriculture. Sustainability indices, related to water from groundwater and rainfall for irrigated agriculture demand, were used to compare scenarios of management simulated in the conceptual model. The analysis shows that as RWH area increases, it reaches a limiting capacity from where developing additional RWH area does not increase the benefit to groundwater stores, but substantially reduces streamflow. This limiting capacity was also seen at the local-scale, where cumulative potential recharge from an individual RWH structure reaches a maximum daily recharge rate. These results could have important implications for RWH development, but require further research. The analysis highlighted the important link between irrigation area and RWH area. If the irrigation area is increased at the optimal level of RWH, where the sustainability indices were greatest, the resilience of the system actually decreased. Nevertheless RWH in a system increased the overall sustainability of the water demand for irrigated agriculture, compared to a system without RWH. Also RWH provided a slight buffer in the groundwater store when drought occurred. While RWH addresses the supply-side issues of groundwater operation, the institutions that form rules for groundwater use must also be considered, because of the link between irrigation area and RWH. The Arvari River Parliament, the community-based group in the case study area, was examined according to Ostrom’s factors for collective action. It was found that the major limitation for the effectiveness of this group was the minimal information available about the aquifer characteristics.

Para superar o problema de disponibilidade de água e preservar os recursos hídricos, têm sido buscadas fontes alternativas de água para as atividades humanas. Dentre as soluções encontradas está a captação da água de chuva. Esta técnica é possível através da captação da precipitação em áreas impermeáveis e de seu armazenamento em reservatórios para viabilizar seu uso. Como o reservatório é, em geral, a parte mais dispendiosa para a implantação desse tipo de sistema, é necessário avaliar qual método de dimensionamento é o mais adequado. Para tanto, este trabalho analisou os métodos de dimensionamento de reservatórios para sistemas de captação de água de chuva sugeridos pela Associação Brasileira de Normas Técnicas (ABNT), apresentados na norma NBR 15527/07. A partir dos resultados obtidos, foi constatado que o Método Simulação Mensal se destaca por resultar em volumes de reservatórios com garantias de abastecimento elevadas e com capacidades não exageradas. Este método de dimensionamento foi utilizado para desenvolver uma ferramenta eletrônica no Excel®, a fim de auxiliar a tomada de decisão em relação ao pré-dimensionamento de cisternas, localizadas no estado de São Paulo. A ferramenta, denominada SIMCAP, traz como resultados informações técnicas relativas ao volume de reservatório sugerido pelo usuário e a economia resultante da implantação do sistema. Para tanto, a ferramenta necessita que sejam preenchidas as informações sobre a localização, a categoria da edificação e a parcela do consumo a ser abastecido pela captação da água pluvial. A SIMCAP foi testada em estudos de caso com diferentes cenários de consumo de água para uma mesma edificação. Com isso, foi possível concluir que a ferramenta disponibiliza resultados relevantes à tomada de decisão por facilitar a estimativa dos benefícios econômicos e por apresentar a garantia de abastecimento do reservatório analisado. / To overcome the problem of availability of water and to preserve the water resources, there have been sought alternative sources of water for human activities. Among the solutions founded is rainwater harvesting. This technique is based on capturing rainfall in impermeable areas and storing it in reservoirs to enable its use. As the reservoir is usually the most expensive part of the rainwater harvesting system it is necessary to evaluate which method for tank sizing is the most appropriate. Therefore, this paper analyzed the tank sizing methods for rainwater harvesting systems suggested by the Brazilian Association of Technical Standards (Associação Brasileira de Normas Técnicas - ABNT), regulated by NBR 15527/07. From the results obtained, the Simulation Monthly Method stands out since it results in volumes of reservoirs with high supply reliability and non exaggerated capabilities. This method of design was used to develop an electronic tool in Excel®, to assist decision-making in relation to presizing tanks, located in the state of São Paulo. The tool, named SIMCAP, brings as results technical information about the volume of reservoir suggested by the user and the savings results from its implementation. Therefore, this tool requires the information regarding the location of this system, the category of the building and the water consumption to be supplied with rainwater. The SIMCAP was tested in case studies with different scenarios of water consumption for the same building. In conclusion, the tool results are relevant for decision making by facilitating the estimation of the economic benefits and by providing the reliability of supply of the evaluated reservoir.

M.Ing. (Civil Engineering Science) / In recent years, there has been an international trend towards installing rainwater tanks in an attempt to save water. However, there are no clear guidelines for determining the optimal size of such a tank in South Africa. This study investigates the possibility of simplifying the process of sizing a rainwater tank for optimal results. It utilises daily data from four rainfall stations, namely Kimberley, Mossel Bay, Punda Maria and Rustenburg, obtained from the South African Weather Services. The water use is considered to be for indoor purposes only, therefore assuming a constant daily demand to be extracted from the tank. The required size of a rainwater tank is influenced by the MAP, the area of the roof draining into the tank, the water demand (both the average demand and seasonal variations), the desired reliability of supply, and the rainfall patterns. The first step in simplifying the process is to consolidate the above variables. The tank volume is expressed as the number of days it could supply the average daily water demand. Another variable is created which provides the ratio of the total water volume which could theoretically be harvested from the roof in an average year, to the total water demand, from the tank, for a year. This has the effect of consolidating the MAP, the roof area, the water demand and the tank volume into two variables only and eliminates the need to consider numerous demand values. Using simulations over 16 years for each location, the relationships between these variables were determined to ensure 90%, 95% and 98% assurance of supply.

>Magister Scientiae - MSc / The National Water Act of 1998 provides the policy framework for stakeholder participation and the engagement of stakeholders closest to the resource on which they depend to be involved in developing and managing their water resources. Rainwater harvesting presents a viable option for securing water availability in order to increase food production and cash returns from food in the Ehlanzeni District Municipality which is one of the poorest districts in the Mpumalanga Province, South Africa. The study focuses on rural youth (between the ages 18-35 years) in two villages of the Ehlanzeni District, Luphisi and Dwaleni, and seeks to assess the relationship between youth capabilities and food security. The study used both quantitative and qualitative methods but with more emphasis on the quantitative data, with qualitative data providing anecdotal evidence to back up the findings. The qualitative data was collected from focus group discussions and the quantitative data was based on a baseline survey within the context of an Integrated Rain Water Harvesting Project implemented by a local NGO. The data drew on indicators in the questionnaire that were to do with social capital and empowerment. The indicators tapped into attributes/capabilities like trust, social cohesion and inclusion and sociability and examined these within the context of Amartya Sen's Capability Approach, to consider whether and in what ways these attributes relate to food security. The results show that there are youth have high levels of certain attributes/capabilities such as trust, social cohesion and inclusion, collective action and co-operation, self-esteem, and meaning. The findings also show that in other dimensions there are less opportunities and that, in particular, access to networks, access to knowledge and information and sociability are lacking among youth. Low levels of adherence to networks, lack of access to knowledge and information and poor sociability show that there are inadequate opportunities for youth to engage with issues around food and water security. The Chi-square test was used to investigate the relationship between youth capabilities and food security and at p<0.05 results showed that there was no relationship between youth capabilities and food security in Dwaleni. There were only three capabilities which showed any significant statistical relationship between youth capabilities and food security in Luphisi namely; collective action and co-operation, social cohesion and self-esteem. The study recommends that networking opportunities and access to information relating to food and water security should be improved. The thesis claims that there are adequate opportunities to build on existing capabilities such as self-esteem, trust and social cohesion that are not being maximized and that youth are not being adequately engaged in water resources management. / Water Research Commission