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For countries with an abundance of rain, there is definite potential to implement a rainwater harvesting system for different applications. This paper describes feasibility studies of an open-pond rainwater harvesting system for ablution purposes, analysing the quality of harvested rainwater and formulating a rainwater harvesting model with suitable performance measures. The formulated model can be used to analyse the feasibility of the system in any locality by inputting local meteorological data. Quality analysis has shown that the harvested rainwater can be used safely for ablution purposes, albeit with a slightly acidic pH below 6.5. At a depth of 1.0 m and using the current pond configuration of a local mosque, the reliability of the system is 62.5% (228 days per year), and the amount of water saved is 345 m3, which is 60.7% of the water demand. It has been shown that a pond surface area of 60–70 m2 provides optimum reliability and water saving, and more water savings can be expected with a more economical usage of water during ablution. These results indicate the feasibility of implementing a rainwater harvesting system for ablution purposes in religious institutions to help curb the water shortage crisis.

The use of rainwater is a reliable alternative for reducing clean water consumption and water bills. This study assessed the willingness of Haitians to invest in rainwater infrastructure (RWI). A questionnaire with closed and open-ended questions was used for this purpose. For closed-ended questions, ‘0’ and ‘1’ were used for negative and positive answers, respectively. Other numbers were used to encode the open-ended questions. The two-tailed Z-test was used to compare two proportions, where a result was statistically significant when the p-value was less than 0.05. Of 362 rainwater users, 81.2% used it for washing, bathing, cooking, flushing, and drinking. Approximately 73.4% of households with 1–3 people, compared with 84.0% of families with 4–6 people, used rainwater. Of all the respondents, 82.3% would invest in RWI if the government agreed to finance up to 50.0% of the project. More than 73.0% of respondents in each locality would invest in rainwater in RWI under the conditions previously mentioned. It is concluded that the implementation of RWI and decentralization of water systems would be welcomed by the rainwater users in Haiti, but the unwillingness of the Haitian government could be the main barrier to such a transition. HIGHLIGHTS This is the first study that assesses both users and professionals in the water supply on investment in rainwater infrastructures (RWIs).; More than 82.3% of the rainwater users would invest in RWI.; More than 81% of dwellers in Haiti used rainwater for washing, bathing, cooking, flushing, and drinking.; The lack of Haitian governmental politics is the main barrier to decentralization of the water system in Haiti.

Water risk has been continuously rising due to climate change and ownership disputes of water resources. Dam construction to secure water resources may lead to environmental problems and upstream immersion. On the other hand, rainwater harvesting systems can effectively supply water at a low cost, although economic efficiency of these systems is still debatable. This study evaluates financial support programs to promote installation of rainwater harvesting systems, increasing economic feasibility. Based on a cost–benefit analysis, capacity optimization methods are further suggested. A sensitivity analysis is performed to determine the relative importance among uncertain parameters such as inflation and discount rates. In doing so, priority factors to consider in the design of rainwater harvesting systems are ultimately identified. A net present value, although it is sensitive to the inflation rate, is shown to be more appropriate to estimate the economic efficiency of rainwater harvesting system, compared to the typical cost–benefit ratio. Because the high future value overestimates the economic feasibility of rainwater harvesting systems, proper inflation rates should be applied. All in all, a funding program to promote rainwater harvesting systems significantly increases the benefits. Thus, national financial support policies are recommended to ensure economic feasibility of rainwater harvesting systems.

Freshwater resources are uncertain in Palestine and their uncertainty is expected to intensify due to climate change and the political situation. Yet, in this region, a stable freshwater supply is vital for domestic and agricultural uses. Rainwater harvesting could help to increase freshwater availability. This study investigates the economic feasibility of two rainwater harvesting applications in the West Bank, with eyebrow terracing in olive groves in rural areas and domestic rooftop harvesting in urban areas. Cost-effectiveness is estimated using a spatially explicit cost–benefit analysis. Three land zones varying in suitability for the implementation of eyebrow terracing in olive groves are analyzed. The potential increase in olive yield is estimated with a crop–water balance model. The potential amount of rainfall that can be harvested with domestic rooftop harvesting is calculated based on the average rooftop area for each of the 11 governorates individually. Costs and benefits are considered at the household level to calculate the economic feasibility of these two applications. Although eyebrow terracing enlarges soil moisture availability for olive trees and thereby increases olive yield by about 10–14%, construction costs are too high to make implementation cost-effective. Similarly, rooftop harvesting can harvest about 30% on average of the annual domestic water demand and is worthwhile in the northern and southern governorates. Yet, in this case, construction costs are generally too high to be cost-effective. This obstructs more widespread adoption of rainwater harvesting in the West Bank, which is urgently needed given the large impacts of climate change. Providing subsidies for rainwater harvesting could help to make adoption more attractive for households.

International audience; In semi-arid regions as in India, where agriculture relies on groundwater abstraction, increase of water resources availability through managed aquifer recharge (MAR) or rainwater harvesting (RWH) is often perceived as a major solution. Studies on these structures efficiency exists but despite the interest, limited information is available on the temporal variation of their replenishment. In a monsoon driven climate, the inter-annual variations are crucial to assess the potential of water storage and multi-year management especially for these structures. Here, we aim at developing a methodology to reconstruct water storage of RWH tanks to further improve our understanding on long term efficiency and multi-years drought management. To tackle this issue, long-term monitoring of a RWH tank located in Telangana in southern India is achieved by a combination of field monitoring over 2 years (tanks surface and water levels) and a daily water balance compared to LANDSAT measurements of the tank area. The procedure allows reconstructing the tank filling dynamic over a 14-years period at a daily time step and show the extreme variability of the tank filling level. During this period, the yearly maximum tank volume ranges from 8 650 to ~ 200 000 m 3. On the 14-years period, the tank reach its maximum capacity only once and, for 1/3 of the time, yearly maximum replenishment is below 15 % of its capacity. The surface water availability remains limited in time since the tank dries-up annually, except for 2 years. However, water percolation to the aquifer is slightly enhanced for some years. During this monitoring period, very few extreme raining events (6) contribute for more than 50 % of the collected volume. This observation highlights (1) the dependency of the structure to extreme storm events, (2) the limited capacity for a multiyear's management and (3) the farmers vulnerability to successive droughts.

Rainwater harvesting (RWH) is an alternative technique to potentially overcome the increasing need for water. However, identifying suitable sites for RWH remains a complex task. The present study o...

In response to water scarcity in Ajloun governorate, Jordan, the effectiveness of implementing rooftop rainwater harvesting (RRWH) was investigated. In addition, a structured questionnaire was prepared and distributed to randomly selected residents to assess the status of the current RRWH practices in the governorate and the people's perceptions of this practice. It was found that between 0.39 million cubic meters (MCM) in a dry year (2017) and 0.96 MCM in a wet year (2018) can be harvested, which is equivalent to 7.6% and 16.8% of the domestic water supply for these years, respectively. The analysis of a total of 360 questionnaires revealed that only 14.2% of the households in Ajloun governorate own an RRWH system. However, the majority, 80.6%, of those who do not own an RRWH system showed interest in installing one. An overwhelming majority of the sample, 96.7%, believes that the government should provide incentives to subsidize the construction of RRWH systems, which is attributed to the high initial cost of these systems. The technical and social feasibilities of RRWH, in addition to the high cost of the alternatives, justifies providing incentives, such as cost sharing for the consumers in Ajloun to implement RRWH systems.

The spatial and temporal variability of quantity and quality of water are important aspects of water resources management. Water demand has been increasing across the globe, but the fresh water supply is limited. Rainwater harvesting (RWH) systems are increasingly being embraced as an alternative freshwater source. This study reviews the dynamics of global research on RWH that utilises geographic information systems (GIS). It is found that the interest and use of RWH utilising GIS have increased over the recent years. However, the full potential of GIS in large scale RWH is yet to be untapped. We make recommendations for future research on RWH based on GIS. This includes new software and model development that links RWH with GIS to plan and design large scale RWH and automated building footprint extraction for estimating RWH potential. GIS can play a bigger role in achieving Sustainable Development Goals (SDGs) by incorporating GIS with RWH since GIS can handle large spatial data efficiently, which can help in locating areas that are suitable for rainwater harvesting.

Rainwater harvesting and treatment systems (RHTS) are used in many places around the world as a part of sustainable water management. They decrease the risk of overloading the sewage network and environmental pollution. The efficiency and reasonableness of using such solutions in specific erosive conditions are not sufficiently understood. The aim of the study was to evaluate the operation of RHTS, receiving effluents from the wholesale market and fuel station (twenty years of observations). The studied system is located in an area endangered by water erosion. In the study period, due to the accumulation of erosive phenomena, it was necessary to optimise the system (including the installation of new devices and increasing the capacity of reservoirs). The analyses referred to the stability and work safety of the most important equipment and water treatment efficiency. The quality of water in the reservoirs was measured before and after the modernisation of the system. Selected physical, oxygen, biogenic and salinity indicators were determined in the water. During the study, RHTS had a positive effect on the quality of rainwater runoff – the values of many contaminants were reduced (RHTS 1: suspended solids, nitrogen, iron, potassium; RHTS 2: conductivity, suspended solids, nitrogen). Design and operational errors were noticed that in the long run may contribute to deteriorating the operational efficiency and even lead to a building collapse (intense erosive phenomena). This study clearly demonstrates that building a rainwater management system is a highly site-specific issue.

Seepage well is an emerging Low Impact Development (LID) technology that can effectively control the storm runoff. However, its rainwater infiltration rate and storage capacity still require further enhancement. By setting a horizontal infiltration structure at the bottom of conventional rainwater seepage well (CSW), an enhanced seepage well (ESW) was proposed in this study, and its infiltration performances compared with the permeable pavement (PP) and the CSW were systemically investigated using static infiltration experiment and HYDRUS-2D simulation. The results showed that the infiltration efficiency of ESW was significantly higher than that of PP and CSW, and the process of water infiltrated through soil mainly controlled the macroscopic infiltration rate. The Nash-Sutcliff Efficient (NSE) index was used to evaluate the accuracy and reliability of the HYDRUS-2D model, and the results of NSE values greater than 0.75 (varied between 0.75 and 0.91) confirmed the applicability of HYDRUS-2D to describe correctly the hydraulic behavior of the ESW system. Simulation infiltration tests showed that the ESW performed a higher average infiltration rate and fewer total runoff volume than the CSW, indicating the effectively enhancement of the infiltration and water retention capacity of ESW, especially under heavy rainfall intensities. Additionally, the ESW system exhibited an excellent runoff-control and rainwater retention capacity in an actual rainfall scenario.

Many rainwater harvesting systems have been installed and operated to supply drinking water to rural regions. However, they often lacked the management method to supply safe and reliable drinking water. The current practice of operating rainwater harvesting systems did not have systematic monitoring as the basis of reliable operation so that the operators did not have confidence in their operation. To overcome these limitations, a rainwater for drinking (RFD) system has been suggested which was to produce drinking water by adding the proper treatment processes and setting up the proper operational mode. This study aimed to evaluate stable regular monitoring results from a pilot RFD system at a local hospital in Vietnam. Water quality and quantity were monitored by the trained local operator on a quarterly and weekly basis. The raw dataset was then shared with the study team by uploading into an open data access platform, from where the technical support was provided to prevent the provision of unsafe water to users. Ultimately, employing systematic monitoring would help to enhance the resilience of the RFD system, contributing to resolving the drinking water issue in rural areas of developing countries, aiming at the achievement of Sustainable Development Goal 6. HIGHLIGHTS Rainwater can be a viable drinking water supply option in developing countries.; A pilot rainwater for drinking (RFD) system has been in operation successfully at a rural hospital in Vietnam.; A weekly and quarterly monitoring system by the local operators was developed for safe and reliable operation.; Open data sharing was also developed and used for distance technical support.; This systematic monitoring system can enhance the resilience of future RFD systems.

Urban development and climate change have led to severe waterlogging in cities. To study the degree of mitigation of urban waterlogging using the design of sponge city roads, this study employed No. 9 Road in the Sino-German Eco-park. By establishing the scaled physical model, the pavement structure of the sponge city road was optimized. Furthermore, water migration (seepage, impoundment, and drainage) rule was obtained under different rainfall intensities using the optimal pavement scheme. The following conclusions were drawn from the studies. Good permeability of the sidewalk surface structure is conducive for rainwater collection. The sponge urban road rainwater collection and utilization system could absorb up to 88% of rainwater under the rainfall intensity of 173 mm (extra heavy rain), and could absorb up to 100% of rainwater under heavy rain conditions. The seepage volume increased exponentially with the rise in rainfall intensity, and the amount of water storage increased linearly with the rainfall intensity. These results can provide guidance for safety early warning of urban waterlogging on No. 9 Road in the Sino-German Eco-park and deeper insights in the design of sponge city roads.

Many basins in the Cerrado biome already face increases in water disputes caused by agricultural expansion without long-term planning and monitoring of natural resources. The amount and timing of water availability are crucial for the socioeconomic development of agricultural activities and climate change resilience enhancement in the Cerrado. This study relied on a dataset developed for the Cerrado to characterize its climate and current water availability status. Different climate indices and hydrological signatures were adopted to describe the energy and water budget, climate seasonality, flow magnitude, flow dynamics, and average duration of low-flow events. Risk analysis was carried out to classify the monthly risk severity and identify periods and regions under a higher pressure regarding water availability in the Cerrado. Overall, the water availability is higher in the western and southern regions and lower in the eastern and northern regions, which experience a transition to a humid and semiarid climate, respectively. The water resources in the Cerrado occur under the highest pressure in September and October. We also identified regions with the potential to increase sustainable water use. These regions exhibit a low ratio between the flow equal to or exceeded 95% of the time and the mean flow (Q95/Q), which indicates that sustainable water use may be improved with techniques related to flow regularization and rainwater/runoff harvesting.

Rainfall infiltration, rainwater retention, runoff and evapotranspiration (ET) are important components of the water balance in green roofs. These components are expected to be influenced by variations in the structural configurations (i.e., substrate layers) of green roofs. This study explores the influence of layered soil and green roof configurations on the rainwater retention capacity (RRC) of the roofs as compared to conventional improvements (i.e., soil conditioning and enhanced substrate depth). Ten different extensive green roof modules were designed by varying the substrate materials, substrate depths, storage/drainage layers and vegetation layers. For all modules, the RRCs ranged from 34 to 59%. The RRCs of layered soil were 1–4% higher than that for single-layer soil. The RRC increased by 13% in the presence of a water storage module. It can be concluded that highest RRC corresponds to a combination of high-permeability soil in the upper layer along with a relatively large water holding capacity in the deep layer. Water storage layer and layered soil could significantly delay the water stress in vegetation. The importance of wick irrigation, vegetation types, back-to-back rain events and the ET rate on the RRC were also discussed. HIGHLIGHTS The capacity of rainwater management and substrate moisture replenishment of green roof with water storage layer was pointed out.; Layered soil could significantly improve the substrate rainwater retention capacity compared with those obtained in single-layer substrates.; The increase rate of rainwater retention declined with an increase in depth beyond a certain point.

Rainwater harvesting (RWH) is a novel way for developing countries to construct and maintain long-term water supply systems. As a result, this review paper draws on actual findings and lessons learned from various places in Ethiopia to assess the country's achievements and opportunities when it comes to RWH, as well as to guide future alternatives toward its sustainability. RWH acts as to help throughout the rainy season's dry spells, as a potential asset for the dry season, aiding human and livestock consumption as well as crop production through irrigation. So, for successful well-organized rain water collection, watershed treatment, seepage and evaporation control, soil and water conservation, conservation tillage, and integration of low-cost water lifting techniques and family drip systems should all be undertaken. Given that the country has not been significantly modernized, it has outdated experience in the operation and exploitation of RWH systems. Aside from financial inadequacies, historical and political instability, lack of understanding among farmers, and resistance to new technologies, the country has opportunities and has made some progress on RWH systems. In general, RWH could enable smallholder farmers to diversify their crops, thereby enhancing household food security, dietary status, and economic return. In addition, the much-needed green revolution and climate change adaptations should combine RWH ideas with agronomic principles in the country. More work is needed to strengthen indigenous practices and share best practices to a larger scale.

Alternative water sources offer opportunities to contribute to the water supply to meet non-potable urban demand, closing water supply–demand gaps. Detailed assessments of these schemes are often d...

This paper presents a study to assess the roof-harvested rainwater (RHRW) in the Ikorodu area of Lagos state, Nigeria, and recommends guidance to minimise the health risk for its households. The types, design and use of rainwater harvesting systems have been evaluated in the study area to inspect the human risk of exposure to Escherichia coli (E. coli). To achieve these objectives, a detailed survey involving 125 households has been conducted which showed that 25% of them drink RHRW. Quantitative microbial risk assessment (QMRA) analysis has been used to quantify the risk of exposure to harmful E. coli from RHRW utilised as potable water, based on the ingestion of 2 L of rainwater per day per capita. Results have revealed that the maximum E. coli exposure risk from the consumption of RHRW, without application of any household water treatment technique (HWTTs) and with application of alum only, were 100 and 96 respectively, for the estimated number of infection risk per 10,000 exposed households per year. This estimation has been done based on 7% of E. coli as viable and harmful. Conclusively, it is necessary that a form of disinfectant be applied to the RHRW before use. HIGHLIGHTS It consists of a case study of roof-harvested rainwater at Ikorodu area of Lagos, Nigeria.; The QMRA analysis has been used to quantify the risk of infection associated with the exposure to potential pathogens from roof-harvested rainwater.; This paper presents a pilot rainwater quality study at the investigated area, which involves a detailed household surveying technique to acquire the needed research information.

Rainfall-induced slope failures commonly occur in residual soil slopes. Slope failures are triggered by the reduction in soil strength. This is attributed to the decrease in soil suction due to rainwater infiltration. Slope covers like capillary barrier system and vegetative cover are effective methods that can be used to prevent rainfall-induced slope failures. The capillary barrier system is able to limit the rainwater infiltration, and vegetation can contribute to the increase in soil strength. Vetiver grass is widely planted in tropical and subtropical areas of the world for soil and water conservation. This study investigates the characteristics of unsaturated soil slope covered with capillary barrier system and Vetiver grass in comparison with the original slope through numerical analyses and field measurements. The analyses were carried out under the advanced, normal, and delayed rainfall patterns. The results of the analyses indicated that the capillary barrier system played a more significant role than the Vetiver grass in maintaining slope stability, although both the capillary barrier system and Vetiver grass contributed to the slope stability. In addition, both numerical analyses and field measurements showed that under the delayed and normal rainfall patterns, when antecedent rainwater infiltration could increase the soil moisture, the capillary barrier system performed much better compared to Vetiver grass in maintaining soil matric suctions and slope stability. Housing & Development Board Published version This study was supported by the Housing and Development Board and Nanyang Technological University, Singapore.

Challenges faced by water resource systems are multi-faceted. The problem can be even more pronounced in a dry continent like Australia where the water resources can often be afflicted by high salinity and turbidity. Therefore, modern water resource systems require to appropriately manage both water quality and quantity. This study aims to illustrate the trade-offs between water quantity and quality in a reservoir, based on decisions to harvest different inflow sources. Taylors Lake of the Grampians reservoir system in Western Victoria, Australia was chosen as the case study for this research as it is sufficiently complex and includes many of the contemporary water resources challenges seen around the world. Different operational scenarios were analysed which included increasingly stringent water quality criteria before the water was harvested or otherwise allowed to by-pass the storage. The study suggests that selective harvesting of water can be an option to improve the overall and long-term water quality within a reservoir, but stringent water quality measures can lead to an associated loss of overall water quantity. This research study provides useful insight to water planners and stakeholders in similar catchment settings around the world, to identify water harvesting regimes with competing water quality constraints.

The use of a sunken lawn is an emerging Low Impact Development (LID) technique to effectively control storm runoffs. However, the random infiltration of rainwater that occurs due to the construction of a sunken lawn in an area of collapsible loess seriously threatens the safety of buildings around it. Setting up a vertical soil sand layer (VSSL) structure next to a sunken lawn as an anti-permeate method has been proposed in this study. To analyze the lateral anti-seepage effects of a VSSL, a sunken lawn model around a building was established based on soil physical parameters, and water seepage in the sunken lawn was investigated using a infiltration experiment and HYDRUS-2D software. The results show that the anti-seepage effects of a VSSL can significantly reduce the average wetting front migration length and water content at the observation points behind the sand layer. The Nash-Sutcliff Efficiency (NSE) index was used to evaluate the accuracy and reliability of the HYDRUS-2D model. The values of the NSE index obtained were greater than 0.82 (varied between 0.82 and 0.98) which confirmed the applicability of the HYDRUS-2D software in accurately describing the hydraulic behavior of the lateral anti-seepage effects of the VSSL in a sunken lawn. Simulation infiltration tests showed that, on the side of the VSSL, the wetting front migration length was reduced by 55.5% on average, and the water content of the observation points behind the sand layer was reduced by 40.5%, increasing the stability of the loess around the building infrastructure. The results are of value in practical applications, such as for devising engineering or non-engineering measures to avoid loess collapsibility around sunken lawns.

With many countries facing water scarcity and the demand for water ever-increasing, more people are turning to rainwater harvesting (RWH) as a feasible way of supplementing supply. However, the success of RWH systems depends on several factors, including rainfall, catchment characteristics and socio-economic factors. Hence it is essential to carry out location-specific studies to evaluate the potential of RWH in a particular area. This study sought to assess the influence of seasonal rainfall and climate change, and socio-economic constraints on RWH in the City of Johannesburg. A GIS-based MCDA was run to estimate RWH suitable sites as influenced by various socio-economic factors. The RWH suitability map shows that at least 50% of the city is suitable for RWH. These, together with climate data was embedded into a rainfall-runoff model developed in HEC-HMS to simulate runoff volumes up to the year 2050. The Deficit and Constant loss method was employed to calculate infiltration losses. After calibration, the model results were within acceptable limits (R2 = 0.68 and 0.79). The rainfall-runoff simulation results show that high runoff volumes are received during the wet season, which is more than double the non-potable water demand. These results indicate that, with ample storage, RWH systems are feasible despite the rainfall seasonality. Therefore, it is recommended to invest in diverse and multipurpose storage to improve RWH reliability.

This study uses a multi-criteria decision analysis approach based on geographic information system (GIS) to identify suitable sites for rainwater harvesting (RWH) structures (such as farm dam, check dam and contour bund) to meet irrigation demand in Greater Western Sydney region, New South Wales, Australia. Data on satellite image, soil, climate, and digital elevation model (DEM) were stored in GIS layers and merged to create a ranking system, which were then used to identify suitable RWH (rainwater harvesting) areas. The resulting thematic layers (such as rainfall, land use/land cover, soil type, slope, runoff depth, drainage density, stream order and distance from road) were combined into one overlay to produce map of RWH suitability. The results showed that 9% of the study region is ‘very highly suitable’ and 25% is ‘highly suitable’. On the other hand, 36% of the area, distributed in the north-west, west and south-west of the study region, is ‘moderately suitable’. While 21% of the region, distributed in east and south-east part of the region, has ‘low suitability’ and 9% is found as ‘unsuitable area’. The findings of this research will contribute towards wider adoption of RWH in Greater Western Sydney region to meet irrigation demand. The developed methodology can be adapted to any other region/country.

Water Sensitive Urban Design (WSUD) presents a process towards the objective of a water-sensitive city. An integrated approach requires community acceptance to implement WSUD at household level. An...

Hybrid water systems (HWSs) are emerging as an alternative decentralised and cost-effective approach for urban water management. Although continuous monitoring is recognised as an essential step to inform the planning and design of water services, a knowledge gap has been identified in the integration of water use monitoring, HWSs and community participation. This research compares water practices of households with and without HWSs, integrating both quantitative and qualitative data. Water use data were collected at selected households via smart meters at 30 minute intervals. R computing software was used for data analytics and dashboard visualisation. Qualitative data on water practices was collected through one-to-one interviews, on-line surveys and community workshops. On a per capita basis, sites with HWSs have a 20% lower total water demand and 41% lower mains water demand than sites without HWSs. Depending on the level of sophistication of the installed HWS, the reduction of mains water use across the participants ranged from 20% to as high as 80%. Almost all sites with HWSs were able to meet the state government targets (40–60 kL/person/y) on annual per capita mains water usage. The seasonality of rainwater supply versus the weather-independent supply of greywater was observed in the data. The qualitative data collected during community engagement highlighted the importance of establishing a personal connection between the individual and the water resource and of involving the resident in the different stages of harvesting, using and disposing of water. This is expected to contribute to a higher perceived value of the water resources by improving awareness, making knowledge more accessible, improving the transparency between the community needs and the water utility decisions. To this end, the role of digital technologies in the water sector plays a role in assisting with the paradigm shift from centralised water networks to an integrated and community-empowered, centralised-hybrid water system.

When Charles Darwin moved to Down House, England (UK), in 1842, he inherited a deep well, penetrating 325 ft (~100 m) into the Chalk. The groundwater from this well was used exclusively for the household, whereas his garden was watered from buried rainwater tanks. It was perceived that drinking the “chalky” groundwater provided him with health benefits, whereas its high lime content was considered detrimental to his plants. The seasonal variations in water level are presented from Darwin’s notes and allow the reduced level of the potentiometric surface to be calculated. Groundwater quality is also assessed. Historical records including the English Heritage Down House archives, Darwin’s correspondence and the recollections of his children, for the first time allow for a description of the design and operation of the well. The well has been abandoned and capped but the detail provided will allow the wellhead to be reconstructed at its original location.

This research is aimed at assessing the possibility of using a rainwater harvesting (RWH) system to supplement domestic water supply in the Mvog-Betsi neighbourhood of Yaoundé. The research made use of a 63-year long data series on the amount of rainfall available in the study area, an analysis of rainwater quality and an estimate of the population's monthly water demand in relation to the monthly harvestable rainwater supply. Rainwater supply for the months of September, October and November is 53.05 m3 which is considerably greater than the households' water demand of 25.56 m3 during the long dry season. This led to the design of a 27 m3 ferrocement tank as minimum storage requirement. Furthermore, a rainwater quality analysis showed that all tested parameters conform to water quality standards except for microbiological quality. The rainwater needs to be disinfected before consumption as potable water. Finally, cost estimates for installing RWH systems for low ($419), medium ($549) and high standard ($668) habitations were calculated. RWH can effectively serve as a water supply supplement in the Mvog-Betsi neighbourhood.

There is increasing awareness of household self-supply and the role it can play in securing water for domestic needs in low- and middle-income countries (LMICs), but its scale across the Asia-Pacific has not previously been quantified. This study analysed 77 datasets from 26 countries to estimate the prevalence of self-supplied drinking water, and its associated trends in LMICs in South Asia, Southeast Asia and the Pacific. When factoring in temporal trends, results suggest that >760 million people—or 31% of the population—relied on self-supply for their drinking water in these regions in 2018, with the number of users increasing by >9 million each year. Reliance on self-supply for drinking water is greater in rural areas than in urban areas (37% of rural population vs 20% of urban population), though results vary considerably between countries. Groundwater sources constitute the most common form of self-supply in South Asia and Southeast Asia, while rainwater collection is dominant in the Pacific. The results confirm the significance of self-supply in the Asia-Pacific and suggest that households are a major but often overlooked source of financing within the water sector. The findings raise important questions about how policy and practice should respond to this widespread phenomenon.

Underground space is becoming increasingly vulnerable to inundation owing to the enhanced likelihood and consequences of urban flooding. However, previous studies on flooding of underground space have paid little attention to how rainwater flows inside an underground space, what the optimal escape route might be, how much time would be required to escape, and how dangerous one specific area might be in comparison with another. This study investigated a method for assessing the spatiotemporal risk of flooding of an underground space considering both the flood intensity and the escape route. Two-dimensional hydrodynamic flow analysis was implemented to evaluate the flood intensity. Then, the shortest escape route was determined by applying the Dijkstra algorithm to the nodes and elements used in the 2D flow analysis. In addition, the risk of flooding in the underground space for a case without a water shield was compared with that determined for a case with an installed water shield.

The chemical characteristics of rainwater in the south-eastern region of Bangladesh were investigated in this study in addition to identifying the potential sources of different precipitation constituents, which have often been unexplored or not well covered in the literature. Rainwater pH, major ions and trace metals were measured in samples collected from five different locations with different land-use patterns of the Chattogram Metropolitan area (CMA) during two rainy seasons. The results of this study showed variability in rainwater quality across the sites signifying site-specific influences. The mean concentration of all measured physicochemical parameters, ions and trace metals in rainwater samples was also found to be significantly lower compared with the drinking water quality standard of Bangladesh and WHO guidelines. The correlation matrix and principal component analysis (PCA) indicated that and originated from anthropogenic sources, while the average concentration of trace metals found in rainwater was exhibited in the following order: Zn>Cu>Fe>Cr>Mn>Pb>Cd. The findings of this study could be used as a reference to further investigate the influences of industrial, urban and agricultural emissions that regulate the chemical characteristics of the atmosphere in particular areas of study. Highlights Chemical composition of rainwater is investigated.; Influence of land-use pattern on rainwater quality is reported.; The concentrations of trace metals are found in order of Zn > Cu > Fe > Cr > Mn > Pb > Cd.; Anthropogenic sources and environmental conditions are found that the controlling sources affecting the chemical composition of rainwater.

Green infrastructure (GI) distribution from 1995 to 2018 was interpreted based on Normalized Differential Vegetation Index threshold method. According to the leaf area index and soil bulk density, ...

Intensifying urban stormwater runoff and pollution caused by urbanization and climate change threatens property and lives in cities around the world. Low-impact development (LID) is an effective approach to improve urban flood resistance, but there is a lack of quantitative evaluation criteria to determine the best scenario in the newly built and built-up urban areas. In this study, based on the Fuzzy Comprehensive Evaluation method (FCE), a multi-index evaluation system is established to quantify the LID performance for the environment, technology, economy, and society. For overcoming subjective arbitrariness, the Criteria Importance Though Intercriteria Correlation (CRITIC) and Analytical Hierarchy Process (AHP) methods are used to evaluate the weight of each evaluation index. The proposed method is demonstrated for the Xi’an City, China. Results show that the integrated configuration of green roof, infiltration pavement and grass swale has the best comprehensive efficiency under the proposed method. More specifically, the allocation of different LID combinations in the newly built area can effectively manage the flooding in this area. However, the comprehensive efficiency of increasing the diameter of the storm sewer is optimal in the built-up area. The increased pipe diameter can discharge more rainwater through the urban storm sewer and mitigate overflow. A multi-index evaluation framework beyond the traditional subjective evaluation standard is established, which can quantitatively evaluate the effectiveness of LID facilities. The proposed quantification evaluation method can provide an efficient recommendation for sponge city construction and evaluation.

Agricultural water management (AWM) interventions play an important role in ensuring sustainable food production and mitigating climate risks. This study was carried out in a watershed located in a low rainfall (400–600 mm) region of western India. The Soil and Water Assessment Tool model was calibrated using surface runoff, soil loss, and reservoir storage levels, between the year 2000 and 2006. The investigation indicated that the various AWM interventions increased groundwater recharge from 30mm/year to 80 mm/year and reduced surface runoff from 250 mm/year to 100 mm/year. The intervention structures were refilled two to three times during the monsoon season depending on rainfall intensity and duration. The interventions have the advantage of building a resilient system by enhancing groundwater availability even in dry years, stimulating crop intensification and protecting the landscape from severe erosion. The results indicate that soil erosion has been reduced by more than 75% compared to the nonintervention situation. Moreover, the AWM interventions led to the cultivation of 100–150 ha of fallow land with high-value crops (horticulture, vegetables, and fodder). Household income increased by several folds compared to the nonintervention situation. The study showed about 50% reduction in downstream water availability, which could be a major concern. However, there are a number of ecosystem trade-offs such as improved base flow to the stream and reduction in soil loss that should be considered. The study is of great importance to stakeholders to decide on the optimal design for AWM interventions to achieve sustainable development goals.

The potential for a rainwater harvesting (RWH) system to supplement the water supply in Chittagong city, Bangladesh, was assessed. Two years were selected for the analysis (2006 and 2020); the projected rainfall for 2020 was evaluated using the Statistical Downscaling Model. Data on projected runoff, land use changes, population growth and catchment areas were also accumulated. The whole city was divided into 22 sub-basins and 176 354 building rooftops were studied for RWH opportunities. Using the weighted linear combination method in a geographic information system environment, potential rooftops and zones were identified for 2006 and 2020. The results showed that the areas with a high RWH potentiality index could supplement water demand by up to 13.03% and 29.68% in 2006 and 2020, respectively. With proper data, this novel approach for a decision support system can be applied to investigate RWH potential in any urban area.

Where water resources are limited, rainwater harvesting (RWH) can provide on-site access to improved water sources. Community institutions are uniquely positioned to benefit from RWH; advocates have encouraged the installation of community-based RWH systems as a way to ameliorate water supply insufficiencies in low-income settings. However, poor quality RWH system installations and insufficient attention to management support have resulted in sustainability challenges, necessitating a commitment to higher standards for community-based RWH. Spurred on by an iterative learning cycle and commitment to innovation, the Ugandan Water Project has achieved RWH system design, installation, and management practices that are well adapted to Ugandan institutions. By investing in a professional crew, high-quality materials, and post-installation support, the Ugandan Water Project has achieved 96 per cent functionality two years after installation. The professionalized approach that the Ugandan Water Project employs can be used as a model to guide future RWH system installations in Uganda and elsewhere.

Made available in DSpace on 2021-06-25T11:55:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-30 This study investigated the impact of sedimentation on rainwater storage system using a case study at the Ikorodu area of Lagos state, a rural area in Nigeria. In this investigation, the proportions of Escherichia coli (E. coli) that were settleable (due to sedimentation) and those that were at the free phase have been studied. Water samples were collected from different depths in the inspected rainwater storage tank at two different periods (i.e. rainy and dry periods) for 20 days. The samples collected from these periods have been analysed for physical and microbial measures before passing it through the serial filters with pore sizes of 500 mu m, 100 mu m, 10 mu m and 1.5 mu m to measure the retained particle mass. From the results, it was observed that: (1) the water quality at the free-phase zone was better than that at the tank's bottom; (2) the settleable bacteria rapidly sinked to bottom; (3) the correlation of turbidity, E. coli and total suspended solids (TSS) for all the rain events showed a relatively high Pearson's coefficient of 0.9 to one another; and (4) over 70% of settling TSS occurred within first 36 hours. Finally, it has been found that the physical sedimentation process can significantly reduce the microbial measures. Univ Bradford, Fac Engn & Informat, Bradford DB7 1DP, W Yorkshire, England Natl Inst Technol NIT, Warangal 506004, Telangana, India UNESP Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, Sao Paulo, Brazil UNESP Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, Sao Paulo, Brazil

A small-scale water harvesting structure known as a sand dam has gained popularity across East Africa due to the efforts of non-governmental organizations. A sand dam is a subsurface water reservoir that stores water between sand grains. Stored thus, the water is filtered and protected from evaporation. This study uses remotely sensed data to investigate the impact of these structures on water storage and vegetative growth. The relationship between sand dams and water storage was modeled using a binary sand dam factor, climate data from the Famine Early Warning Systems Network Land Data Assimilation System (FLDAS), and water storage data measured by the Gravity Recovery and Climate Experiment (GRACE) twin satellites. The analysis revealed that GRACE largely fails to detect a statistically significant impact of sand dams on regional water storage. However, analysis of the Normalized Difference Vegetation Index (NDVI) indicated that sand dams have a significant impact on regional vegetation. Vegetative growth is correlated with groundwater levels, indicating that sand dams have a positive impact on water storage albeit on a smaller scale than GRACE can regularly detect. Significantly, this study shows that NDVI data can be used effectively to study small-scale, regional changes in vegetation and water storage. HIGHLIGHTS The impact of small-scale water harvesting structures on regional water resources is explored through spatial generalized linear models of remote sensing products.; Sand dams increase regional vegetation, which suggests groundwater levels are also positively impacted.; Sand dams may have a smaller impact on groundwater levels than believed.; NDVI and, to a lesser extent, GRACE record the impact of sand dams.

The migration critical velocity of small-sized sediment particles was investigated through experiments under different particle sizes, pipe wall roughness, and sediment thickness. Such experiments were carried out to simulate the erosion process of small-sized sediment particles in a rainwater pipeline during rainfall. The mathematical models were established via quadratic fitting to calculate the critical velocity of migration. Results showed that small particles had powerful cohesive force, and aggregates had strong erosion resistance. So, for the small-sized particles (in the range of 0.33–0.83 mm), the smaller the particle size, the larger the critical velocity. When the pipe wall roughness was large, the ‘starting’ particle resistance was high. A large flow dynamic was needed to overcome such resistance. Thus, the critical velocity was great. The critical velocity was also large when the sediment thickness was large. The difference rate between the critical velocity calculated by mathematical models and the measured value was within the range of −3.60% to 5.33% and had good consistency. Under the research conditions, the critical velocity ranges of the four commonly used pipes; namely, plexiglass, steel/PVC, galvanized/clay, and cast iron pipes, were calculated. HIGHLIGHTS The aggregates of small particles in rainwater pipes have strong erosion resistance.; The critical velocity is great when particle size is small (d50 = 0.33–0.83 mm).; Critical velocity significantly decreases when the pipe wall roughness reduces.; Difference rate between calculated and measured values is from −3.60% to 5.33%.; The critical velocity ranges of the four commonly used pipes have been calculated.

Potentially toxic elements (PTEs) in manganese ore areas are prevalent in rainwater runoff and pose a major threat to human health. In this study, field investigation and geostatistical analysis methods of positive matrix factorization (PMF) and geographic information systems (GIS) were used to systematically study the pollution in rainwater runoff from a manganese mining area in Xiangtan, China, to evaluate source contributions for the health risk assessment of PTEs. The average concentrations (mg/L) of six PTEs were: 0.3357 (Mn), 0.0450 (Ni), 0.0106 (Cu), 0.0148 (Zn), 0.0068 (Cd) and 0.0390 (Pb). The coefficients of variation (CV) for Mn and Zn were >180% and >130%, with the other analytes having values below 70%. The GIS and PMF analysis produced more refined spatial source apportionments, including mining, smelting, transportation, agricultural production and natural sources. The results of the health risk assessment showed that the non-carcinogenic risk was negligible, and the carcinogenic risk was potentially dangerous but acceptable for both adults and children. In addition, the children's total carcinogenic risk value was greater than that of adults, highlighting their vulnerability. This study demonstrates the potential of PMF to provide a framework to spatially prioritize treatment objectives within the mining region to improve environmental conditions. HIGHLIGHTS Mn is the most serious contaminating element in rainwater runoff.; PMF was used to analyze five sources of PTEs in rainwater runoff.; These present no health risks in the region.

In many areas of the world, rainwater has been collected and consumed by people. Our research aims to assess the use of rainwater and the impact of operation and maintenance activities of the rainwater system on drinking water quality in rural areas where there is no access to a public drinking water system. Through the questionnaire, direct visits, interviews and sampling of water at surveyed households (HHs), it was found that 100 and 98% of surveyed HHs used rainwater for drinking and cooking, respectively. Nearly, 80% of them were aware of the necessity of frequent reservoir cleaning as well as first-flush removal. Cleaning the water reservoir had a significant impact on water quality, in particular the total dissolved solids (p-value < 0.05). The use of strainers and more frequency of cleaning the catchment roofs and gutters would make the lower turbidity in water. However, the use of strainers would reduce the dissolution of oxygen in the reservoirs. A recommendation on the frequency of maintaining the rainwater harvesting systems was proposed after assessment of the operation and maintenance behaviors at surveyed HHs. HIGHLIGHTS This is the first study on assessment of the operation and maintenance of rainwater harvesting (RWH) systems at the household scale in the rural area.; Most of them (>90%) were aware of frequent reservoir cleaning as well as eliminating the first rains.; The majority (95%) of households did not add disinfectant in the reservoirs but boiled water or filtered with membrane units before drinking.; Harvested rainwater showed significantly higher pH, dissolved oxygen (DO) and coliforms but much less dissolved solids than groundwater.

In a water-scarce country such as Pakistan, rainfall is the third-largest source of freshwater. In most of the urban cities of the country, rainwater is mixed with sewerage and is rendered useless for managed aquifer recharge purposes. Therefore, this study investigates the rainfall potential for managed aquifer recharge in Lahore (Pakistan). The present research was designed and conducted by the Irrigation Research Institute (IRI). Three different sites were selected for rainwater sample collection across the study area (Lahore), ranging from urban to rural areas. The rainwater samples were collected and divided into three categories (direct capture, rooftop runoff, street runoff). For longer rainfall events, the effect of time on the quality of the collected rainwater samples was also studied. Spatiotemporal trends of turbidity, pH, electrical conductivity, total dissolved solids, carbonates, bicarbonates, chloride, calcium, magnesium, and hardness in the collected rainwater samples were investigated. In terms of TDS, results indicated that directly captured rainwater is most suitable for managed aquifer recharge (TDS < 50 ppm), followed by rooftop runoff (TDS < 100 ppm). In addition, the quality of rainwater samples collected at the rural site was comparatively better. Moreover, the quality of rainwater samples improved after the initial ten minutes. All in all, this study concludes that direct capture of rainwater is the most suitable option for managed aquifer recharge.

Study region Dudu station, Rajasthan, India Study focus Rainwater harvesting can be used as a method to recharge aquifers. This can happen with a variety of scales and technologies. One such example is shallow infiltration ponds (Chaukas) which recharge groundwater and increase soil moisture facilitating pastureland development. A HYDRUS-1D model was used to estimate potential groundwater recharge. The model was calibrated using field data from 2019 and validated using data from 2020. The time series of Normalized Difference Vegetation Index (NDVI) was derived at annual scale to assess changes in the vegetation cover. New hydrological insights for the region The modeling revealed that an additional 5% of the rainfall depth was being recharged into the groundwater. In addition, the additional soil moisture was allowing natural grass cover to develop, which could be used by the local community as pastureland. These twin benefits that the local communities are realizing could be scaled up beyond Dudu, to India, and worldwide, as many regions have barren land that is slightly sloping, together with permeable soils, which are the only conditions for the construction of Chaukas. These Chauka systems have helped in sustainable water resources management in these water-stressed regions and the additional livelihood support through developed pastures for animal husbandry.

This paper presents a review of water research, development, and management in Bangladesh, with examples drawn from the past and present. A bibliometric analysis is adopted here to analyze the water-related publication data of Bangladesh. Water-quality-related research is the dominating research field in Bangladesh as compared to water-quantity (floods and droughts)-related ones. The most productive author was found to be Ahmed KM for water-related publication in Bangladesh. The arsenic contamination in Bangladesh has received the highest attention (13 out of the top 15 highly cited papers are related to arsenic contamination). Climate-change-related topics have been showing an increasing trend in research publications over the last 5 years. Bangladesh Delta Plan 2100, prepared recently, is a visionary master plan that is expected to shape water management in Bangladesh in the coming decades to adapt to climate change. A set of recommendations is made here to achieve sustainable water management in Bangladesh.

Rainwater Harvesting System (RWHS) can play a multipurpose role, contributing to the management of rainwater runoff, in addition to the water supply. This article assessed the potential reduction i...

In the current study, the effect of operating conditions including membrane characteristics and applied pressure on natural organic matter and sulphate removal of nanofiltration (NF) membranes for drinking water production was investigated. Water stress has been increasing all over the world due to population growth, climate change, and pollution; rainwater management stands out as one of the key solutions to this problem. Nanofiltration to treat rainwater stored in a cistern was studied. The objectives were sufficient treatment performance to overcome the taste problem and lower energy consumption. In this regard, three commercial nanofiltration membranes (NP010, NP030, and NF90) were used for the experiments carried out at 6–12 bar operating pressure regarding the response surface methodology. The correlation among the results of experiments and the model parameters were also calculated for all steps. According to the results, the effect of membrane characteristics was more abundant than the effect of the operating pressure. Finally, over 99% of natural organic matter and sulphate were eliminated in the optimum conditions. The results showed that it is possible to obtain treated rainwater with desired qualities, in a non-continuous NF plant operated at the pressure of 6 bar to reuse the rainwater and achieve water sustainability.

Until recently, households in the most chronic kidney disease-affected rural areas of Sri Lanka used untreated groundwater for drinking and cooking, but, by 2018, that share was only 35%. About 50%...

Atmospheric substances can enter surface water through dry and wet deposition, which contributes to surface water pollution and is one indispensable cause of water eutrophication. Rainwater is a high-quality alternative drinking water source in water shortage areas. Rainwater disinfection is necessary to ensure its microbiological safety, but disinfection usually produces disinfection by-products (DBPs) and brings chemical risk to water. Dissolved organic matter (DOM) derived from the atmosphere may contribute to the formation of DBPs during water disinfection. In this study, the effects of wet and dry deposition on surface water quality and rainwater DBP formation as well as the control technologies of rainwater DBPs were comprehensively reviewed. Dry and wet deposition contributed compounds (sulphates, ammonium, alkali and ions), trace elements (Fe, Mn, Al, Cu, Zn, La, U, Th, Cd, As and Hg) and microplastics to surface water. The contribution of dry deposition to water pollution was enhanced in gale weather in areas with severe air pollution. The formation potential of CX3R-type DBPs (THMs, HAAs, HALs, HANs, HNMs and HAMs) was increased, because dry and wet deposition contributed DBP precursors. Low molecular weight DOM was more likely to generate DBPs, so it is suggested to develop effective technology targeting low molecular weight DOM removal from rainwater. Among conventional drinking water treatment processes, the combination of GAC and chloramination is very promising for controlling the comprehensive toxicity risk of DBPs in rainwater. Future studies should focus on the correlation between DBP formation in rainwater and atmospheric pollution, especially in severely polluted areas, and the key factors affecting rainwater quality and DBP formation.

Abstract The quality of surface waters in the territory of Poland, despite the implemented remedial measures, is mostly classified as bad. This article presents the results of research on the composition of water macroelements in 24 artificial reservoirs located in Opole province (southern Poland), searching for the reasons behind their pollution. Concentrations of the anions F−, Cl−, Br−, NO2−, NO3−, PO43− and SO42− and cations Na+, NH4+, K+, Mg2+ and Ca2+ were taken into account. An analysis of seasonal changes was carried out and, on the example of a dam reservoir (Turawa Big Reservoir), a multi-point analysis of the distribution of ion concentrations in water at the reservoir surface was also carried out. It was shown that retention and flow-through reservoirs, where the main source of pollution is the water feeding the reservoirs, are the most vulnerable to pollution. The second group consists of closed reservoirs located in industrial and agricultural areas, which are exposed to pollution from rainwater run-off and field leachate. In the case of reservoirs created in marl mining areas, a significant effect was also indicated from the chemical composition of the substrate on the formation of ionic equilibria in waters filling the excavations. The research shows that there are no hard and fast rules regarding the seasonal variability of ion concentrations during the growing season, indicating that eutrophic reservoirs show greater variability of ion concentration. Graphical Abstract

Rainwater harvesting is adopted to face water scarcity in arid regions. Many studies were developed in Jordan to estimate the potential of water harvesting for several uses. However, the precise estimation of water saving and cost benefits for the potential of rainwater harvesting from the roofs of residential urban areas is insufficient. Therefore, the objective of this study was to investigate the feasibility of rainwater harvesting from residential rooftops in all the eighty-nine Jordanian districts. The forecast number of buildings was calculated from 2016 to 2025 using building growth rate, where the number of houses and villas was adopted only. The long-term rainfall average from 1937 to 2017 was used. Two scenarios were used to assess the potential of rainwater harvesting; numerical (as scenario 1) and tabulated by plumbing code (as scenario 2) for the years from 2019 to 2025. Also, the growth rate of one cubic meter of water cost was calculated to find the money saving potential for the water companies in Jordan. The results indicated that the water harvesting potential was different between two scenarios in the districts which have annual rainfall more than 100 mm was efficient in scenario 1 compared to scenario 2 with the projected financial return which was increased from $5.4 million at 2019 to reach $33.4 million at 2025, while in the districts which have annual rainfall less than 100 mm was more efficient in scenario 2 compared to scenario 1 with the projected financial return which was increased from $2.4 million at 2019 to reach $14.6 million at 2025.