RWH Systems Research Articles

Should we value rain harvesting more in Türkiye for mitigating precipitation extremes

Mitigating precipitation extremes is a major issue due to destructive global warming and climate change. Heavy rainfall and drought have posed a threat to human life and ecology. That said, new strategies and new action plans are needed at local and global levels through needed cooperation from different stakeholders to handle the possible risks associated with precipitation extremes. Turkey has become one of the most vulnerable countries involved in climate change due to its geographical location, rapid urbanization, and deforestation. Many forests have been destroyed to make room for agriculture, animal grazing as well as for manufacturing and construction. The impact has caused complications in landscapes. Precipitation extremes, such as heavy rainfalls and drought, are posing significant threats for many cities in Turkey. In recent years Turkey has faced a large number of extreme events regarding precipitation. In this line, the present study aims to explore the potential benefits of rainwater harvesting (RHH) in mitigating precipitation extremes by overviewing regulatory actions of rainwater harvesting and best practices worldwide. In addition an interview-based survey was conducted with domain experts in the water management field to better understand the current challenges of stormwater management in Turkey and discuss the role of rainwater harvesting against precipitation extremes. The results of the study have shown that Turkey has several problems with infrastructure to mitigate precipitation extremes, such as shortcomings in capacity and old water management systems, unseparated water collection and sewage systems, and lack of green infrastructure. In addition to urbanization, expansion in industry and tourism may cause water unavailability. The study has also indicated that many authorities around the globe try to boost RWH use by stipulating or encouraging RWH through incentives to save a large amount of water by implementing different projects. This research has argued that RWH promises several benefits thanks to its cost-effectiveness and contribution to water storage. Therefore, this study has recommended that policymakers should take immediate action against precipitation extremes by introducing new regulations, such as mandating rainwater harvesting for old buildings, industrial and touristic places. Preparing new guidelines and applying rooftop RWH systems that comply with Building Code requirements should also be considered for the widespread use of rainwater in rural and urban areas.

Impact of Urbanization on Runoff and Its Potential Solution Through the Viability Study of RWH Systems for Households

Impact of Urbanization on Runoff and Its Potential Solution Through the Viability Study of RWH Systems for Households

Adoption of rainwater harvesting as a sustainable approach to improving the climate resilience of small landholders in Kenya

AbstractThe African Water Vision 2025 emphasized the disadvantages of the rural population in the context of water supply infrastructure, water management, and access. The vision extolled the virtues of providing improved decentralized governance and localized actions to deliver on this agenda. Furthermore, policies and investment should support climate resilience, by strengthening the security and availability of adequate water quality and quantity in rural communities, for example, by mainstreaming the adoption of rainwater harvesting systems. This is reflected in the government policy alignment towards enabling a devolution of responsibilities to regional and local political structures, while addressing concerns linked with water availability, climate change, and its impact on a country's water resources in Kenya. Despite efforts through different strategic plans and policies, there is a perceived gap between the general understanding of the importance of the RWH system at the national level and actions at the operational level in the counties. An absence of formal policy frameworks and coordination of investments has resulted in insufficient adoption and implementation of RWH systems in Kenya to date. This is despite the fact that in some counties, RWH systems are considered a key solution for increasing climate resilience and suggestions for improvement have been formulated by the affected communities. This analysis shows that RWH systems strengthen the resilience of rural populations but are dependent on a well‐formulated governmental structure, which could be improved by refining national policies and investment in RWH systems.

Economic attractiveness of domestic rainwater harvesting in Brazilian cities

Brazil is the fifth largest country by area in the world, with a variety of climates in its territory. This work assesses the economic attractiveness of domestic rainwater harvesting direct feed systems, for the replacement of non-drinking water, in 148 locations of the Brazilian territory considering hourly rainfall data for the 14-year period between 2008 and 2021. The water tariff and consumption data for each location were also considered along with estimated hourly and monthly consumption patterns. With annual operating expenses at 1% of the capital expenditure and an annual discount rate of 8%, the net present value for the 14-year period is positive in only 15 locations, which are among those with the highest water tariffs in the country. The results of these base case simulations discourage the installation of domestic RWH systems in most of the Brazilian locations considered. However, the results also show that, depending on house occupancy, filtration equipment cost, water tariff, and catchment area, outcomes more favorable to the installation of RWH systems are obtained, especially in cities of Brazil’s southern and southeastern regions.

A GIS-based agroecological model for sustainable agricultural production in arid and semi-arid areas: The case of Kerman Province, Iran

Promoting the adoption of crop species with medicinal and commercial value can provide new opportunities for local communities to export their products. Meanwhile, using sustainable water resources and minimizing the over-exploitation of groundwater are urgently needed due to the critical status of aquifers in many parts of the world. Most existing studies are focused on a single aspect of this issue. However, few studies have incorporated the results of several suitability models in agroecological processes. Rossa Damascena Mill is recognized as a crop species and raw material with added value and considerable profitability. In addition, it is resistant to drought and adapts to different climatic conditions. This paper presents a framework for the optimal detection of suitable land for agroecological activities. We tested the framework in Kerman Province (Iran) to identify: 1) suitable lands for Rossa Damascena Mill cultivation, 2) suitable lands for agricultural rainwater harvesting (ARWH) systems, and 3) suitable lands for developing both Rosa farms and RWH simultaneously. Results revealed that approximately 24,808.5 km2 of land (14% of the province's land) is suitable for dry farming. Also, RWH systems can be implemented in 19,024.4 km2 of land (11% of the province). Overlapping land suitability for rainfed agriculture and RWH systems highlights that only 4% of the study area can be cultivated. Finally, two strategies are suggested: developing Rosa Damascena cultivation in a) ranked areas for rainfed agriculture and b) farms/gardens that can be supplied by RWH systems nearby. Sensitivity analysis and overall accuracy assessment validated the results and robustness of the modeling. This proposed model can be helpful for making effective decisions regarding the region's sustainable development to strengthen the local economy and address water stress issues, especially in arid and semi-arid areas. The results have implications for different SDGs, including SDG 12 on sustainable consumption and production and SDG 15 on life on land. They can also be used to enhance resilience against stressors induced by climate change.

Assessment of Household Rainwater Harvesting Systems in the Southwestern Coastal Region of Bangladesh: Existing Practices and Household Perception

This study aims to assess the post-installation rainwater management issues associated with household RWH systems in the southwestern coastal regions of Bangladesh. A face-to-face questionnaire survey (including free listing) was administered to over 300 households in the Khulna and Satkhira districts to understand the water consumption behavior of users, operation and maintenance of the RWH system components, governance and capacity-building needs, and overall perception. It was found that the current capacity of most household storage tanks is insufficient to meet the year-round water demands (cited by 151 users; Smith’s Salience Index (SSI) = 0.671), and around 53% of the users relied on another water source besides the RWH system. The users frequently cleaned various components of the RWH system, although they did not pay much attention to cleaning the roof catchment. Most users did not have sufficient knowledge of water treatment methods (cited by 10 users; SSI = 0.033) or water quality testing protocol (cited by 29 users; SSI = 0.084). Proximity to the house (cited 222 times by the users, SSI = 0.589) is considered the primary benefit of the RWH system. The absence of adequate functional components (cited by 56 users; SSI = 0.170) and having to share water with other households (cited by 23 users; SSI = 0.068) were highlighted as the two main problems associated with the use of the RWH system. The users also highlighted the lack of training on operation and maintenance (O&M) and the absence of monitoring support. This study provides clues to strengthening existing RWH system intervention programs in the water-challenged regions of Bangladesh.

Reliability and economic assessment of rainwater harvesting systems for dairy production

The need for rainwater harvesting is continuously growing as a supplement to other water sources and the operation and maintenance costs remain low after the initial investment. The daily water balance method was used to determine the optimal rainwater harvesting tank size. Princeton Global Forcing (PGF) data gridded at (0.25° × 0.25°) is used after comparison with observed data. Correlations between PGF and observed stations varied by under or overestimating the precipitation. PGF series could ably reproduce observed rainfall, hence were used. The optimum water tank size varies based on the collection area, climatic conditions, and water pricing. According to the results, reliability is higher for larger rainwater tank sizes and higher for larger collections areas. Areas that receive more rainfall have higher reliabilities and require smaller tank sizes. Meeting 100% reliabilities requires collection areas greater than 500 m2 for demand of 750 L/day. Reliability was investigated for different tank volumes and an insignificant increase in reliability was observed for tank sizes greater than 50 m3. A roof collection area of at least 250 m2 and a tank size of 120 m3 and above is recommended to achieve more than 50% reliability. Installation of RWH systems is viable with a payback period of fewer than 4 years. The payback period is shorter for areas that receive high rainfall. The results in this study serve as a tool for comparison with other studies on evaluating the performance of rainwater harvesting systems and the possibility of using RWH systems beyond domestic and irrigation purposes.

Development of a Generalization Solution for Optimum Design of Rwh Systems—A Case Study in Guangzhou

Development of a Generalization Solution for Optimum Design of Rwh Systems—A Case Study in Guangzhou

Achievements, challenges and opportunities of rainwater harvesting in the Ethiopia context: a review

Abstract 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.

Performance evaluation of technical aspects of ex-situ rainwater harvesting systems at Wag-Lasta, Northern, Ethiopia

The most severe constraints for agriculture are water shortages in semi-arid areas of Northern Ethiopia. Rainfall is extremely variable; therefore, it is necessary to harvest rainwater to safeguard improved crop production. The objective of the study is to characterize, identifying problems and evaluating the performance of existing RWH systems in the Wag-Lasta areas. Tweleve RWH ponds were selected from six kebeles in the study area. Primary and secondary data were collected and evaluated using descriptive statistics to assess the technical performance of water harvesting ponds by field observation, direct measurements, and interviews with zone, woreda, kebele experts, and owners. The technical performance assessment showed that the collected runoff and system efficiency were negligible for the total rainwater catchment area. The problems in a portion of the non-functional ponds had found to be poor site selection, lack of maintenance, and standardization of techniques, and some of them were efficient with low performance.

An investigation on the adaptability of residential rainwater harvesting system in Tamil Nadu – techno-economic considerations and the way forward

Abstract Rainwater harvesting (RWH) is one of the most important means of water conservation today. Although there is tremendous emphasis on the implementation of this versatile technology at various levels, many of us are unaware of its significance and its consequences. This study examines the perception and awareness of people in the state of Tamil Nadu, India, of the RWH system through a questionnaire survey. The survey was conducted to infer basic information on rainwater harvesting features, water quality and conservation, economics of implementation and financial support. The results show that there is an increasing need to promote the usage of harvested rainwater for domestic purposes rather than direct groundwater recharge. The potential risks in the reliable supply of available water sources demand large-scale implementation of RWH especially in apartments. Fewer people are aware of the technical details of operation and maintenance of the RWH system (22.2%) while more people are aware of the general layout of the system (50.5%). Longer experience in using RWH systems (for more than two years) builds confidence in using them for consumptive uses compared with the response from recent adopters. This also demonstrates the scope for a radical change in the perception of water quality by continuous awareness and financial incentives.

Maintenance practices and water quality from rainwater harvesting in south-west Uganda

Abstract Rainwater harvesting (RWH) provides household water supply to rural and peri-urban populations that do not have access to centralised water services. The climate in south-west Uganda is particularly well suited to RWH due to bi-annual rainy seasons, which allows for the collection of rainwater to occur over two periods throughout the year. Water quality from RWH, however, depends on how well risk of contamination (ROC), from catchment to consumption, is managed. Using a mixed-methods approach, we assessed the maintenance practices and water quality of 20 RWH installations in Uganda in the dry and rainy seasons. Both domestic and institutional RWH systems were assessed. Sanitary surveys, site inspections, key informant interviews and physiochemical and bacteriological tests were conducted to identify the factors that have an impact on water quality. Water quality test results were compared to guidelines recommended by the World Health Organisation (WHO). We looked at measures that can reduce the ROC across the RWH system. We found that water quality at 75% of the sites met WHO standards. At these sites, end-users reported that they cleaned systems at least twice a year. Where training on system maintenance had been carried out, end-users reported more regular cleaning and maintenance of systems. Sanitary surveys highlighted an absence of first-flush or pre-filtration as the most prevalent ROC. Overall, we found that both access to technical specialists and capacity-building activities led to well-maintained RWH systems that provide acceptable water quality at both a household and community level.

Combining Hydrologic Analysis and Life Cycle Assessment Approaches to Evaluate Sustainability of Water Infrastructure: Uncertainty Analysis

The goal of this research is identifying major sources of uncertainty of an environmentally-sustainable urban drainage infrastructure design, based on hydrologic analysis and life cycle assessment (LCA). The uncertainty analysis intends to characterize and compare relative roles of unreliability, incompleteness, technological difference, and spatial and temporal variation in life cycle impact assessment (LCIA) data, as well as natural variability in hydrologic data. Uncertainties are analyzed using a robust Monte Carlo simulation approach, performed by High Throughput Computing (HTC) and interpreted by Morse-Scale regression models. The uncertainty analysis platform is applied to a watershed-scale LCA of rainwater harvesting systems (RWH) to control combined sewer overflows (CSOs). To consider the watershed-scale implications, RWH is simulated to serve for both the water supply and CSO control in an urban watershed in Toledo, Ohio, USA. Results suggest that, among the studied parameters, rainfall depth (as a hydrologic parameter) caused more than 86% of the uncertainty, while only 7% of the uncertainty was caused by LCIA parameters. Such an emphasis on the necessity of robust hydrologic data and associated analyses increase the reliability of LCA-based urban water infrastructure design. In addition, results suggest that such a topology-inspired model is capable of rendering an optimal RWH system capacity as a function of annual rainfall depth. Specifically, if the system could capture 1/40th of annual rainfall depth in each event from rooftops, the RWH system would be optimal and, thus, lead to minimized life cycle impacts in terms of global warming potential (GWP) and aquatic eco-toxicity (ETW). This capture depth would be around 2.1 cm for Toledo (given an 85 cm/year rainfall and 200 m2 typical roof area), which could be achieved through an RWH system with 4.25 m3 capacity per household, assuming a uniform plan for the entire studied watershed. Capacities smaller than this suggested optimal value would likely result in loss of RWH potable water treatment savings and CSO control benefits, while capacities larger than the optimal would likely incur an excessive wastewater treatment burden and construction phase impacts of RWH systems.

Rainwater harvesting system for a sustainable water supply for the poor on Merbau island

Difficulty in meeting one’s basic daily needs such as clean water in order to fulfill a healthy, clean and productive life is a significant problem for people living on remote islands. Rainwater is the only source of clean water for the community on Merbau Island because of the low quality of the surface and groundwater resources. The majority of Merbau Island is covered by peat and lowlands; hence the rainwater that falls on the land surface is generally contaminated with peat water, which tends to be more acidic. Frequent rainfall at the location produces an abundant volume of water that is sufficient enough to meet the collective household daily demand for clean water. However, the community is not able to provide a large rainwater harvesting facility that can minimize the loss of rainwater into the rivers or seas. This study aimed to obtain data on the field conditions used as the basis for planning RWH systems for domestic needs so as to meet the need for sustainable clean water on Merbau Island. The results show that the highest rainfall recorded in 2013 was 3,164.3 mm. Such an amount of rainwater can fulfill the daily clean water requirements for each household on Merbau Island. The population of poor people on the island is approximately 44%, which results in around 73% of people not having an adequate rainwater harvesting system. The average roof area data, the number of family members and the type of roof, being 213 m2, 6 people and zinc (0.9) respectively, using the Rain Cycle v2 software, obtained the result that a 12 m2 tank is needed to meet the need for clean water throughout the year.

Enhancing Stormwater Management Benefits of Rainwater Harvesting via Innovative Technologies

AbstractRainwater harvesting (RWH) systems provide the dual, but often opposing, benefits of acting as alternate water supply sources and providing detention/retention of roof runoff that would otherwise become stormwater runoff. A major challenge that exists when using a RWH system to simultaneously accomplish stormwater and water-conservation benefits in nonarid regions is that these systems are often underutilized, thus remaining full a large portion of the time. For a system to mitigate stormwater runoff, however, there must be sufficient room available in the tank to store a runoff event. Two novel approaches were implemented to improve the ability of RWH systems to serve as both water-conservation practices and stormwater-management practices: an active release technology and a passive release technology. Two locations in Craven County, North Carolina, had RWH systems installed to capture roof runoff and store it for nonpotable uses. One system was equipped with the passive release mechanism, which ...

Environmental analysis of a domestic rainwater harvesting system: A case study in France

Life cycle assessment methodology along with water footprint analysis was used to assess the environmental impacts of a domestic rainwater harvesting system (RWH) in France. Firstly, the relevance of substituting drinking water (DW) with rainwater in a private individual household was studied. Secondly, the effect of several parameters namely construction of infrastructures, building scale and disinfection were evaluated. The quantification of environmental impacts was performed using Ecoinvent inventory data and Impact 2002+ evaluation method. The water footprint was assessed through the water stress indicator (WSI). From an environmental standpoint, the RWH system has only slightly higher impact than the DW system. The consumption of electricity for pumping generates the strongest impact. The analysis of the WSI showed that the RWH system can relieve a stress on water resources where it exists. Consideration of infrastructures and disinfection turns environmental impacts significantly higher in all impact categories. Setting up the RWH system at bigger scale, i.e., building scale, is a bit less favoured than the RWH system at household scale. This study aims at pointing out areas of improvement which need to be further studied to make RWH systems more sustainable.

Effects of Climate Change on Urban Rainwater Harvesting in Colombo City, Sri Lanka

Cities are becoming increasingly vulnerable to water-related issues due to rapid urbanization, installation of complex infrastructure and changes in rainfall patterns. This study aims at assessing the impacts of climate change on rainwater harvesting systems (RWH) in the tropical urban city, Colombo, Sri Lanka. The future climate change projections are downscaled from global circulation models to the urban catchment scale using the Long Ashton Research Station Weather Generator (LARS-WG), described in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), coupled with Inter Comparison Project (CMIP3) model results. Historical rainfall data from 1981–2010 is used to simulate long-term future rainfall data from 2011–2099. The percentage change of the rainfall is calculated. The rainfall patterns are analyzed based on the daily, monthly, seasonal and annual time scales. Water requirements are calculated based on the selected scenario types. Rainfall and water demand data are incorporated into a water balance model. Climate change impacts for the selected RWH scenarios are calculated based on the water security analysis for each scenario. Analysis of the future rainfall data of Colombo reveals that several extreme weather events with very heavy rainfall may occur in the future. However, the frequency of these big events may not occur too often. Most of the selected global circulation models (GCMs) in this study predict that there will be more rainfall towards the end of this century (2080-2099). Residential RWH systems will be more affected than non-residential systems. RWH systems in Colombo should include potential future climate changes in their future design and planning and be prepared for excess runoff and additional measures against potential overflow and urban floods.

Assessment of Water Harvesting System for a Smart Building Considering Climate Change

With climate change now a reality rather than speculated possibility, the future change of rainfall pattern will affect the demand for potable water. Forth coming regulatory changes will mean that over 90% of UK homes will have their water usage metered, making consumers more and more aware of how expensive the commodity of common or garden water has become. In this paper the design of different rainwater harvesting systems (RWH) is evaluated for three residential properties of different roof areas. The design considered climate change effect and change in future rainfall for three periods 2020s, 2050s and 2080s under the high (AIFI) and low (B1) SRES scenarios in NW of England. The RWH systems were shown to fulfill between 25% and 85% of WC, washing machine and outdoor use demand making the system more valuable as a sustainable solution.

Plugrisost: a model for design, economic cost and environmental analysis of rainwater harvesting in urban systems

In the context of transition to sustainability, one of the main challenges facing societies today is the supply of water. By integrating different methodological tools and studies we developed the innovative software program Plugrisost® (rainwater, greys and sustainability), a simulation model, that facilitates the economic evaluation and the potential environmental impact of alternative water supplies (rainwater harvesting [RWH] and greywater systems) at different scales of urban planning. This modelling tool contributes to urban water planning for smart cities development. Plugrisost® analyses the optimal design variables, cost and environmental performance of RWH and greywater systems, using tap water production as a reference system for comparison. The use of economic and environmental indicators can make the optimal size of a rainwater tank more restrictive when it is compared to the results regarding the satisfaction of the demand for rainwater. Economic and environmental analysis can help avoid oversizing tanks for rainwater and thus obtain greater benefits. Plugrisost includes estimated cost and Global Warming Potential, as well as other life cycle impact indicators for this purpose. A case study analyzing the implementation of a RWH system in a single-family house in Aveiro, Portugal is included, showing the importance of rainwater availability and demand for the successful operation of simulated systems.

A Real Option Perspective to Value the Multi-Stage Construction of Rainwater Harvesting Systems Reusing Septic Tank

Recently, rainwater harvesting systems have received increased attention due to their capability for adapting to water scarcity and climate change. However, a key obstacle to the implementation of rainwater harvesting systems is that they are often not financially feasible given difficulty in determining optimal system size. A key premise of previous studies was that all rainwater harvesting systems are constructed in a single construction event even though it is possible to construct a system in multiple stages. This assumption limits managerial flexibility in the construction of rainwater harvesting systems, which is particularly valuable in scenarios where it is difficult to forecast future rainfall patterns. Therefore, we propose a multi-stage system expansion strategy for the implementation of rainwater harvesting systems using decommissioned septic tanks under scenarios of uncertainty in rainfall from a real option perspective as a means to improve the financial feasibility of implementing rainwater harvesting systems. We tested this strategy by evaluating a proposed rainwater harvesting system for a midsize apartment complex in Jeonju, South Korea. The multi-stage expansion strategy generated an option value of 9,896 USD. This study will help to improve the financial feasibility of rainwater harvesting systems by adding the value of managerial flexibility through a sequential expansion of RWH systems as new information becomes available.