Adoption of Rainwater Harvesting: a Dual-factor Approach by Integrating Theory of Planned Behaviour and Norm Activation Model

The objective of the study is to identify the factors that lead to the adoption of rainwater harvesting in enabling sustainable ground water. The Theory of Planned Behavior and Norm Activation Model has been adopted. The sample consists of 400 participants who were either constructing and likely to construct houses have been considered for the study. Structural Equation Modelling was used to analyze the data. The study results exhibited the adoption of rainwater harvesting, and the moderation effect of intention to acquire rainwater harvesting knowledge on the relationship between environmental concern; environmental responsibility and rainwater harvesting. Based on the results, significant theoretical and practical implications have been made.

     

Analysis and Modelling of Stormwater Volume Control Performance of Rainwater Harvesting Systems in Four Climatic Zones of China

Rainwater harvesting has been widely used to alleviate urban water scarcity and waterlogging problems. In this study, a water balance model is developed to continuously simulate the long-term (57 to 65 years) stormwater capture efficiency of rainwater harvesting systems for three water demand scenarios at four cities across four climatic zones of China. The impacts of the “yield after spillage” (YAS) and “yield before spillage” (YBS) operating algorithms, climatic conditions, and storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are analyzed. The YAS algorithm, compared with the YBS, results in more conservative estimations of stormwater capture efficiency of rainwater harvesting systems with relatively small storage tanks (e.g., ≤50 m³). The difference between stormwater capture efficiency calculated using the YBS and YAS algorithms can be remedied by increasing storage capacity and reduced by decreasing water demand rates. Higher stormwater capture efficiency can be achieved for rainwater harvesting systems with higher storage and demand fractions and located in regions with less rainfall. However, the lager variations in annual rainfall in arid zones may lead to unstable stormwater management performance of rainwater harvesting systems. The impacts of storage and demand fractions on stormwater capture efficiency of rainwater harvesting systems are interactive and dependent on climatic conditions. Based on the relationships among storage capacity, contributing area, water demand, and stormwater capture efficiency of rainwater harvesting systems, easy-to-use equations are proposed for the hydrologic design of rainwater harvesting systems to meet specific stormwater control requirements at the four cities.     

Water Management,Rainwater Harvesting and Predictive Variables in Rural Households

Water management in rural domestic households plays an important role in reducing water-related health risks. This study was conducted to examine the relationships between the dependent variable (rural domestic rainwater management) and the independent predictive variables (personal characteristics, tank size, years of water harvest, rainwater harvesting associations, usage instructions including water borne health risk, and tank operation and maintenance) in Uganda. Logistic regression techniques were used on a random sample of 301 respondents to ascertain the influence of predictive variables on rural domestic rainwater management. Analyses of the hypothesised relationship revealed three statistically significant results: years of water harvest, rainwater harvesting associations and usage instructions. Overall, the findings suggest that consideration of usage instructions including waterborne health risks, years of harvest, and local water associations, will improve domestic water management, in combination with progressive measures focused on water quality and quantity. Moreover, medical expenses and time spent in hospitals or health dispensaries will be minimised and saved through utilisation of usage instructions. Experienced harvesting households, those with few years of harvest, and non participants as well in local water associations will easily enrich knowledge of how to minimise contracting water-related diseases.     

Application of HEC-HMS Model for Evaluation of Rainwater Harvesting Potential in a Semi-arid City

Water Resources Management - 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...     

Sustainability of Rainwater Harvesting Systems in Rural Catchment of Sub-Saharan Africa

Sustainability of rainwater harvesting in enhancing water productivity in various biophysical and socioeconomic conditions of SSA is a key in large scale livelihood improvement. A study was undertaken in Makanya catchment of rural Tanzania to assess sustainability of storage type of rainwater harvesting systems including microdam, dug out pond, sub-surface runoff harvesting tank and rooftop rainwater harvesting system. The increasing population in upstream areas of the catchment has forced use of RWH systems for streams and river water abstraction. The agricultural intensification in hillslopes has affected the water availability for downstream uses. Rainfall variability, runoff quality and quantity, local skills and investment capacity, labour availability and institutional support influence sustainability of rainwater harvesting systems.     

Identifying Potential Rainwater Harvesting Sites of a Semi-arid, Basaltic Region of Western India, Using SCS-CN Method

Upper Karha watershed from semi-arid part of Deccan Volcanic Province, India was investigated to identify the potential sites to construct rainwater harvesting structures with the help of remote sensing and geographical information system. Attempt was made to understand the basaltic terrain in spatial context to find out the rainwater harvesting structures like farm ponds, percolation tank, check dams and gully plugs deriving from thematic layers, such as landuse/landcover, slope, soil, drainage and runoff from Landsat Thematic Mapper imagery and other collateral data. Subsequently, these layers were processed to derive runoff from Soil Conservation Service Curve Number (SCS-CN) method using Arc-CN runoff tool. The SCS-CN method shows that the high runoff potential is from water-body, agriculture land (including harvested land) and followed by settlement, open scrub, dense scrub and low for the open forest, dense forest area. Parameters like hydro-geomorphology, geology were considered as per Integrated Mission for Sustainable Development specifications for identification of the structures. The thematic layers overlaid using intersection based on these specifications. Derived sites were investigated for its suitability and implementation by ground truth field verification. In conclusion, the method adopted in present study deciphers the more precise, accurate and ability to process large catchment area than other methods.     

壶关县雨水集蓄利用的可行性探讨

壶关县的水资源严重短缺,文中收集了当地三种蔬菜作物的灌溉制度,计算了其作物需水量和可能集蓄的雨水资源量,进行了供需水平衡分析。结果表明,集蓄雨水资源完全能够满足农作物灌溉的需要。壶关县通过集水窖对雨水资源收集储存,并应用于农作物灌溉上,这一举措不仅可以解决水资源短缺问题,而且对现状缺水靠天吃饭的农村均具有示范作用。     

Optimal Sizing of Rainwater Harvesting Tanks for Domestic Use in Greece

Water Resources Management - Rainwater harvesting gains more and more ground as a modern, relatively inexpensive and simple water-saving technology, and as a sustainable water management practice,...     

Rainwater Harvesting for Urban Areas: a Success Story from Gadarif City in Central Sudan

Gadarif city, in central Sudan, has suffered from a shortage of drinking water for decades. Half of its daily water requirement is met through river water imported over 50 km away and from local salty wells. As a consequence of building a small dam to control seasonal floods, it was found that the dam reservoir recharges groundwater, raising the water table by few a meters. Such experience was repeated and a second dam built in response to this success. This indicates that such a method may be a useful rainwater harvesting technique to provide safe water in water deficit areas in semi-arid regions affected by climate change and population increase.     

Water Quality Monitoring and Hydraulic Evaluation of a Household Roof Runoff Harvesting System in France

The quality of harvested rainwater used for toilet flushing in a private house in the south-west of France was assessed over a one-year period. Twenty-one physicochemical parameters were screened using standard analytical techniques. The microbiological quality of stored roof runoff was also investigated and total flora at 22°C and 36°C, total coliforms, Escherichia Coli, enteroccocci, Cryptospridium oocysts, Giardia cysts, Legionella species, Legionella pneumophila, Aeromonas, and Pseudomonas aeruginosa were analysed. Chemical and microbiological parameters fluctuated during the course of the study, with the highest levels of microbiological contamination observed in roof runoffs collected during the summer. Overall, the collected rainwater had a relatively good physicochemical quality but variable, and, did not meet the requirements for drinking water and a microbiological contamination of the water was observed. The water balance of a 4-people standard family rainwater harvesting system was also calculated in this case study. The following parameters were calculated: rainfall, toilets flushing demand, mains water, rainwater used and water saving efficiency. The experimental water saving efficiency was calculated as 87%. The collection of rainwater from roofs, its storage and subsequent use for toilet flushing can save 42 m³ of potable water per year for the studied system.     

Towards Sustainable Water Quality: Management of Rainwater Harvesting Cisterns in Southern Palestine

Environmental management of rainwater harvesting in southern Palestine is required to reduce the continuously increasing demand for fresh water from limited water aquifers and to reduce the adverse health impact on the people drinking harvested rainwater. This continuously increasing demand for fresh water requires the enhancement of environmental conditions surrounding the cistern owners’ awareness to tackle the mismanagement that contributed to rainwater contamination. In this study, 100 cisterns were sampled and tested for physiochemical and microbiological parameters. Most of the tested physiochemical parameters were within the acceptable limits of WHO and Palestinian standards except turbidity, calcium and magnesium where 24%, 47% and 32% of the samples were non-conforming, respectively. The pH values of the collected rainwater ranged from 7.32 to 8.97 with a mean value of 8.16. The nitrate analysis results range from 1.5 to 7.0 mg/L, with a mean value of 4.2 mg/L. High percentage of cisterns were found to be contaminated with total Coliforms (TC) and faecal Coliforms (FC) with percentages of 95% and 57%, respectively, rendering the cistern water unacceptable for drinking purposes. 78% of samples had a severe degree of contamination for which water needs flocculation, sedimentation then chlorination to become suitable for drinking. On the other hand, based on FC data, none of the tested samples for FC was a “high risk”, but 57% of them were categorized with “simple” to “moderate risk” and 43% were “no risk” cisterns. A cistern owner’s survey was utilized to reveal the roots behind this contamination. Different remediation measures, such as cleaning cisterns and rainwater collection surfaces and discarding water from the first season storm, were recommended to enhance and protect the cistern water quality.     

Modeling the Effect of Cistern Size,Soil Type,and Irrigation Scheduling on Rainwater Harvesting as a Stormwater Control Measure

Urban stormwater runoff could have negative impacts on water resources and the environment. Rainwater Harvesting (RWH) can serve both as a stormwater control and water conservation measure. Cistern size and irrigation scheduling are two of the factors that directly impact the total runoff from a residential unit with a RWH system and the amount of potable water used for irrigation. The effectiveness of RWH was evaluated for four soil types; Sand, Sandy Loam, Loamy Sand, and Silty Clay, with a root zone of 15.2 cm using three irrigation scheduling methods (Evapotranspiration (ET)-based, soil moisture-based, and time-based), and five cistern sizes. Total runoff volumes and total supplemental potable water used were compared among the three irrigation scheduling systems and a control treatment without RWH. A model was developed to simulate the daily water balance for the treatments. Irrigation and runoff volumes were compared for the various scenarios. Silty clay soil resulted with 83 % more runoff than Sandy soil, while Sandy soil required on average 58 % more supplemental water than Silty Clay soil. On average, the 833 L cistern resulted with 41 % savings in water supply and 45 % reduction in total runoff. Results showed that the greatest volumes of runoff predicted were for the silty clay soil Control Treatment using a time-based irrigation scheduling method, while the least volumes calculated were for the sandy loam soil time-based irrigation scheduling treatment with 833 L cistern size. The greatest volumes of total supplemental water predicted were for sandy loam soil Control Treatment, while the least volumes were for silty clay soil ET-based irrigation scheduling treatment with 833 L cistern size. Regression equations were developed to allow for users to select a RWH cistern size based on the amount of water they want to save or runoff to reduce.     

Improvement of Rainwater Harvesting Analysis Through an Hourly Timestep Model in Comparison with a Daily Timestep Model

Water Resources Management - For the analysis of rainwater tank outcomes, some researchers used monthly water balance model, which ignores an important factor such as overflow from the tank....     

Rainwater harvesting and poverty alleviation: a case study in Gansu,China

China faces great challenges to alleviate poverty as it enters the new century. There are still 30 million people living below the absolute poverty line. They are concentrated in the mountainous areas of western China, of which the loess area of Gansu province is one of the driest and poorest. One of the root causes of poverty is water scarcity. Water is the key factor in changing the fundamental conditions for the existence and development of the poor areas. Due to the topographical nature of the area, a major water delivery project would be difficult to build and be economically unfeasible. The most easy-to-use water source with the highest potential is rainwater. Rainwater harvesting (RWH) has been carried out in previous decades and it has been shown that it can serve the poor by supplying water for domestic use and supplemental irrigation, thus ensuring both water and food security. It can create a pre-condition for the modification of agricultural structure, thus promoting income generation. RWH is also beneficial to the recovery of the ecosystem and environmental conservation in the semi-arid northwest region of China. Past experiences show that RWH is an innovative approach for the integrated and sustainable development of the poor areas. It is reasonable to mainstream RWH in integrated water resources management.     

Use of Intercepted Runoff Depth for Stormwater Runoff Management in Industrial Parks in Taiwan

First flush of stormwater runoff plays an important role in water quality management. Since stormwater runoff during the initial period of precipitation events carries a greater portion of pollution loads, appropriate strategies are needed for effectively controlling the non-point source loads (NPS). In the present study, case studies were performed in two industrial parks for correlating the relationship between pollutant mass and the runoff volume. Three precipitation events were used for calibration and verification of a deterministic model, Storm Water Management Model. The model was then used to simulate all rainfall events in a particular hydrological year to determine the relationship between interceptive amounts of initial runoff and their corresponding reduced portion of annual NPS loads. The results indicate that the first 6–8 mm of a storm runoff depth includes more than 60% NPS loads. If the depth is increased to 10 mm, 80% NPS loading can be contained. The interceptive volume for eliminating 80% NPS loading in Guan-Tian and Yong-Kong industrial areas are 7 and 12 mm, respectively.     

Modeling of Surface Runoff in Xitiaoxi Catchment,China

Xitiaoxi catchment is one of the most important catchments in the Taihu basin in China. Due to its significant contribution of surface runoff and associated nutrients input to Lake Taihu, understanding of the processes of surface runoff in this catchment is, therefore, of primary importance in quantifying water and nutrient balances for Lake Taihu. The generation of surface runoff in the catchment is mainly controlled by rainfall and land cover, so the variety of surface runoff in Xitiaoxi catchment is seasonal. Moreover, the annual change of surface runoff is distinct. Because of the diversity of land use and variety of hydrological characteristics, numerical simulation of the generation of surface runoff over this catchment is not straightforward. In this paper, attempts were made in applying the Large Scale Catchment Model (LASCAM) to Xitiaoxi catchment. The Xitiaoxi catchment is divided into 47 subcatchments connected via a river network based on topology. The model was first run in an optimization mode to calibrate the parameters against the observed runoff for the period of 1968–1977, and then was run in a prediction mode to try to reproduce the runoff for the next 10 years from 1978 to 1987. The model indicates that saturation excess runoff is probably the dominant process for the catchment. The modeling results indicate that water storage in shallow soils near the stream has a high correlation with daily rainfall, while the water storage changes in deep aquifers demonstrate an annual change trend, showing a rising level for wet seasons and a declining level for dry seasons. The success in modeling surface runoff leads to confidence in modeling nutrients transport as the next step of modeling work.     

The Working Conditions and Optimisation of a Large Rainwater Harvesting and Treatment System in an Area at a Risk of Erosion

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.

     

北方建筑小区雨水径流水质变化规律与处理利用研究

以阜新北方花园小区雨水工程为研究对象,通过对不同强度降雨时,小区屋面和路面雨水取样监测,得到雨水径流的污染状况和水质特性,探讨了北方缺水型城市建筑小区雨水利用的技术途径,提出了小区雨水利用的工艺流程,并进行了弃流井的弃流量分析和混凝实验研究,为北方缺水型城市住宅小区雨水利用提供可靠的参考依据.     

A New Model for Simulating Supplemental Irrigation and the Hydro-Economic Potential of a Rainwater Harvesting System in Humid Subtropical Climates

Here we have developed a new model to simulate supplemental irrigation and the hydro-economic potential of a rainwater harvesting system in rainfed agricultural areas. Using the model, soil moisture in rainfed crop land, supplemental irrigation requirements, rainwater storage in an on-farm reservoir (OFR) system, and surface and ground water availability were predicted. In an irrigated system, an OFR was used to harvest rainwater during the rainy season, and stored water was applied to cropland as supplemental irrigation (SI). An economic analysis was performed to calculate the benefits due to an OFR irrigation system, and gains from increased crop yield and downstream water availability in the irrigated OFR system were compared with rainfed system (i.e. no OFR). In addition, we calculated the impacts of dry and wet seasons on total value gains (grain and water gains) for irrigated and rainfed conditions and performed a sensitivity analysis to quantify the impacts of model input parameters on total value gains. Analyses showed that the OFR system can produce crop yields three times greater than rainfed agriculture. During a water stress season, the total water use in the irrigated system was 65 % greater than for the rainfed system. Water use efficiency of the irrigated system was 82 % higher than for the rainfed system. In a dry season, the total value gains due to increased crop yield by supplemental irrigation and downstream water availability of the irrigated system were 74 % greater than for the rainfed system, while in a wet season the total value gain of the irrigated system was 14 % greater than for the rainfed system. A precipitation scenario analysis of wet and dry seasons indicated that the benefits of a rainwater harvesting system can be considerably greater in dry seasons than wet seasons.     

Runoff Efficiency and the Technique of Micro-water Harvesting with Ridges and Furrows,for Potato Production in Semi-arid Areas

A field study was conducted to determine runoff efficiency and the effects of different ridge: furrow ratios and ridge-covering materials on tuber yield, soil moisture storage and water use efficiency (WUE) in the ridge and furrow micro-water harvesting system in a dry semi-arid region of China, during two consecutive years of 2002 and 2003. The average runoff efficiency of ridges with compacted soil (SR) was very low (24.6–28.8%) compared to that of ridges covered with plastic film (MR) (91.1–94.3%). The minimal rainfall necessary to produce runoff was 2.76–2.78 mm for SR, only 0.23–0.47 mm for MR. The field experiments using potato as an indicator crop showed that tuber yields in the MR system were significantly higher than that in the flat planting (control), with an average increase of 158.6–175.0% during 2 years. In the SR system, the average increase was valued of 14.9–28.4% during 2 years. Regression analysis between tuber yields and ridge widths indicated the optimum ridge: furrow ratio for MR was 39: 60 cm in 2002 and 48: 60 cm in 2003 respectively. The WUE values of potato in MR were 1.50 times greater than that of the controls in 2002 and 1.62 times greater than the controls in 2003. No differences were found in the WUE between the SR and the controls on average of 2 years. Due to the different runoff efficiency between two ridge-covering materials and absence of runoff occurrence in the controls, the soil water content in the MR was higher than that in the SR, both of which were greater than the controls. With the soil crust development, the distribution of soil water at the bottom of the furrow, at the side of the furrow and at the top of the ridge, is similar between the SR and the MR.