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.

In many developing countries, the stress of rapidly growing populations, mismanagement of resources and changing climate has created a burden on already compromised water resources. In Africa, where a significant proportion of the population is without access to improved water source, the urgency for clean available water sources to sustain healthy and productive human and natural populations has become a priority. As a water scarce country, Kenya has seen an increased investment in rainwater harvesting (RWH) projects to harness the vastly untapped rainwater resource, particularly in rural areas. Most of RWH literature is centered on the potential and implementation of rainwater harvesting systems, however not much focus has been placed on examining the demand satisfaction of these systems. This study investigates the reliability of rooftop rainwater harvesting (RRWH) as a key priority source of water supply for domestic use in three towns in Western Kenya: Kisumu, Nakuru and Lodwar. This was done using two approaches (1) the fraction of time water was available and (2) the fraction of time that a minimum demand was met, with acceptable reliability of 0.95 or higher. Actual rainfall data and RRWH parameters were used to produce supply/demand simulations of the system under Constant-Demand and Responsive-Demand scenarios over ten years. It was observed that all towns achieved acceptable reliability values for RRWH in terms of water availability however Lodwar only achieved demand satisfaction below 0.95. This study concluded that though RRWH cannot satisfy the minimum demand requirement through all days of the year, it is more than able to provide an alternative water supply for the domestic household in periods of long dry spells or when primary water source are inadequate.

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.

Research was performed at Crag Cave, Castleisland, southwest Ireland, and P8 Cave, Castleton, Derbyshire, in order to determine the main factors responsible for modifying rainwater geochemistry during flow through soil and karstic aquifer zones. Monitoring was performed on a daily basis in summer and winter at Crag Cave, and on a monthly basis over one year at P8 Cave. At both sites, biannual peaks in karst system Ca2+concentrations occurred due to: (i) promotion of microbial C02 production by increased summer temperatures, and (ii) retardation of gaseous exchange by ponding of elevated winter rainfall input leading to an unseasonable build up in soil zone C02. Therefore, speleothems at both sites may form biannual bands in hydrological years subject to elevated winter rainfall input. In addition to variations in carbonate weathering due to fluctuations in C02 levels, cation yields in Crag Cave matrix soil water were controlled by dolomite dissolution (Mg2+), plant uptake (K+), and evapotranspiration balanced by enhanced winter marine aerosol input (Na+). Strontium isotope analysis indicates that S~+ was derived from a 50:50 silicate/carbonate mixture, whilst the relatively light 313C signal was related to direct evolution of C02 into the aqueous phase in waterlogged pores. Within the Crag Cave aquifer variations in karst water geochemistry were controlled by dilution, flow switching, prior precipitation of calcite and dolomite dissolution along the flow path. Strontium isotope analysis indicates that dissolution in the aquifer dominated, with S~+ being sourced from a 25:75 silicate/carbonate mixture. Light karst water 313C values were constrained by the supply of light soil gas to the aquifer. Elevation in the Mg/Ca and Sr/Ca ratios in the Crag Cave speleothem record compared to present day analogues indicates that the former Holocene climate was drier, whilst heavier 87Sr/86Srratios and 813C values suggest variation in soil hydrology over time.

2 pp. / RainScapes are the ultimate in water efficient landscaping. RainScapes are beautiful landscapes that once established rely entirely on rain and stormwater (gray water too if available)while preserving tap water for indoor and drinking water needs.

56 pp. / Second Edition, October 2004 / In the arid Southwest, rainfall is scarce and evapotranspiration rates are high. Only natives and some desert-adapted plants can live on 10 or 11 inches of annual rainfall. Other plants require some supplemental irrigation and harvesting rainwater can reduce the use of drinking water for landscape irrigation. This publication discusses the water requirements for some plants and the way to collect rainwater. Its topics include: - Water Harvesting System Components - Simple Water Harvesting System Design and Construction - Complex Water Harvesting Systems

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Student Number : 7336898 - MSc (Eng) research report - School of Civil and Environmental Engineering - Faculty of Engineering and the Built Environment / Theme and Context Despite being the source of two of Africa’s greatest rivers, the Nile and the Congo, Rwanda is a water scarce country and 50% of the citizens of the capital, Kigali, do not have access to safe drinking water. Rwanda’s tragic history of violent social upheaval combined with regional macro-economic factors and the effects of globalization have made this tiny country one of the poorest on the African continent. Aim and Objectives of this Study The aim of this report is to establish the value that Rainwater Harvesting holds as a supplementary water source for the city of. To evaluate this potential intervention, the suitability of the climate for the harvesting of rainwater is reviewed as well as the availability of the required resources and the effect that the prevailing social environment may have on an implementation program. The current developments in the practice of Rainwater Harvesting are researched and ways in which Rainwater Harvesting could be utilized are explored as well as the possible impediments that might be encountered. Scope and Methodology Adopted The scope of the report includes: 1. Providing an overview of the country both geographically as well as socially. 2. Establishing the need for alternative water sources by: a. Reviewing the present water supplies for the city particularly with regard to their vulnerability to the rapid environmental degradation being experienced within the country, b. Reviewing the prevailing water/health nexus. 3. Investigating metrological records, specifically rainfall patterns, and the quality of the statistics. 4. Review international trends and research in rainwater harvesting specifically in poor countries. 5. Considering obstacles to implementing a wide-ranging scheme to harvest rainwater. The methodology adopted includes: 1. Reviewing published research on the subject of Rainwater Harvesting techniques and implementation. 2. Attending symposia on the subject. 3. Meeting with water practitioners both in the public sector as well as in NGOs to establish the current status of water availability, quality and consumption. 4. Conducting on-site research into water sourcing problems in and around Kigali. 5. Designing, sizing and costing hypothetical installations suitable for local conditions. Summary of Main Findings, Conclusions and Recommendations Although the climate and topography are very favorable to the use of Rainwater Harvesting, this report finds that the promotion of Rainwater harvesting is just one of a number of possible interventions which should be pursued in order to improve the availability of water to the citizens of Kigali The cost and sophistication of Rainwater Harvesting schemes vary considerably but at the lower end of the scale the technology would be affordable to most Kigali residents and the community has the potential human resource to be trained to execute the work. Obstacles to this approach include ignorance about the safety of storing water, the comparative low cost of municipal water the perception that water collection is the responsibility of a family’s women and children. This report also found that a household using a Rainwater Harvesting scheme is likely to require some supplementary water on occasions. Furthermore, as the potential to catch sufficient water is a function of the ratio of a dwelling’s roof area to the number of inhabitants, its efficacy is limited in densely inhabited poor communities. Strong leadership and coordination would be necessary for a successful wideranging Rainwater Harvesting implementation project. In addition a coordinated educational programme will have to be conducted to dispel myths about stored water and to create the required skills base. The statutes and bylaws regarding water would also have to be reviewed to avoid legal impediments. This report concludes that rainwater harvesting cannot be relied upon to fulfill all the communities’ water needs but it can go a long way to improving the general access to safe water and in so doing reduce the time and labour presently demanded, mainly of women and children, in the carrying of heavy loads of water.

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements of the degree of Doctor of Philosophy. Johannesburg, February 2017 / Rainwater harvesting is used as a way of improving crop yields in rain fed agriculture by capturing excess rainfall and storing it in-situ or in reservoirs for use during dry spells. Contour ridges are one of the many rainwater harvesting technologies that are used although little is known about their effectiveness. Contour ridges harvest runoff generated in the cropped field upstream of the ridges. The traditional contour ridge type in Zimbabwe was introduced by the government in the 1950s to control soil erosion through safely draining away runoff from cropped fields and is commonly referred to as graded contour (GC) ridges. In the 1990s the country experienced severe and more frequent droughts leading stakeholders to experiment on contour ridges that retain the runoff instead of draining it away which are known as dead level contour (DLC) ridges. There was therefore the need to find out if there are benefits derived from this change and assess conditions under which benefits would be experienced. Previous studies have shown that rainwater harvested by contour ridges can improve water availability in downstream fields. However these studies did not investigate the conditions under which such benefits are realised. In addition no attempt to model water harvesting by contour ridges have been made in Zimbabwe while the contour ridges are widely being used for soil and water conservation. This research investigated the effect of contour ridges by comparing soil moisture between plots with DLC and GC ridges using plots with no contours as a control. Experimental work was carried out in Zhulube, in Matebeleland South Province of Zimbabwe. Matebeleland South Province falls within the semi-arid area in which rainfall is characterised by mid-season dry spells leading to frequent crop failure. In addition, the area often receives high rainfall intensities leading to soil erosion and sedimentation of rivers. DLC and GC ridges were constructed in farmers’ fields where maize crops were planted. Soil moisture measurements were done using a micro gopher soil moisture profiler while runoff plots were used to measure runoff generation. A fuzzy model was developed using data from this experiment and a previous study in Masvingo Province of Zimbabwe to simulate runoff generation at field scale while a process based water balance model was also developed to simulate soil moisture changes within the root zone of the cropped area. The results from this study indicate that DLC are effective in clay and loamy soils where runoff generation is significant and not in sandy soils due to insignificant generation of runoff under the rainfall regimes of semi-arid areas. Fuzzy logic was found to be a useful method of incorporating uncertainty in modelling runoff at field scale. A mass water balance model developed on process based principles was able to model soil moisture in the root zone reasonably well (NSE =0.55 to 0.66 and PBIAS=-1.3% to 6.1%) and could help to predict the water dynamics in contour ridged areas as would be required in determining the suitable dimensions and spacing of contour ridges. Further research is required to improve the fuzzy component of the model for estimation of runoff when more data becomes available. In addition experiments to validate methods of estimating macro pore fluxes and lateral transfer of water from the contour ridge channel to the downslope field are also recommended. The model structure can be improved by adopting the representative elementary watershed approaches to include momentum and energy balances in addition to mass balance that was used in this study. / MT2017

Background: With the MDG 7 target deadline approaching to halve the global population lacking access to improved water and sanitation by 2015, many nations find the need to explore alternative water sources. Rainwater may be a viable alternative water source. However, there have been concerns raised in recent decades as to the quality of rainwater harvested for potable use. Methods: Data from the Demographic and Health Surveys database which included 50,579 household surveys between 2002 and 2007 from the Dominican Republic were examined. STATA 8 was used for data analysis. Descriptive statistics were computed, and logistic regression analysis was used to compare toilet type, water source, and type of place of residence with prevalence of diarrheal disease in children under five. Results: This study found that rainwater presents less risk for diarrheal disease when compared to all other water sources (excluding bottled water). In 2002, people who consumed all other sources of water (excluding bottled) were 1.28 times more likely to have diarrhea in children under 5 (95% CI 1.05-1.57) compared to those who consumed rainwater. They were 1.33 times more likely to have diarrhea in children under 5 (95% CI 1.08-1.65) in 2007 and 1.31 times more likely in both years combined (95% CI 1.13-1.51). Discussion: This study concluded that consuming rainwater presents a decreased risk for diarrheal disease compared to all other sources (excluding bottled water). More studies are needed to add more evidence to the existing literature regarding health risks associated with rainwater consumption.