Roof Water Research Articles

Study and Evaluation of Stored Drinking Water Characteristics Using Three Types of Roof Water Tanks in Kirkuk Governorate, Iraq

The scarcity of safe drinking water is one of the problems faced by the majority of cities in the world. Kirkuk city is one of these cities, which suffer from a shortage of drinking water. People have adopted the use of different rooftop tanks to overcome this problem. This research focuses on studying the effect of storage time on the five main characteristics of drinking water, which include, acid index (pH), electrical conductivity (EC), total suspended solids (TSS), total dissolved solids (TDS), and turbidity (Tr). Three types of tanks were used predominantly (galvanized metal, plastic, and aluminum tanks). By analyzing the results, the characteristics of three samples of municipal source water obtained. Three samples were taken from each tank at different periods (4, 8, and 12 days). The results showed that the storage time affected the characteristics of drinking water. These characteristics differed from one tank to another. Metal tanks showed an increase in total dissolved solids, due to the evaporation process, even as plastic and aluminum tanks showed an increase in pH. The properties of all storage water tanks changed with times, but overall, the results were within the Iraqi limitation for drinking water. It was not easy to only depend on the results of this study to believe that any one type of water tank was better than the other, as the values of most of the variables studied had varied from one type to other. However, many studies have indicated a number of health risks, and most significantly with regard to plastic tanks, which are said to contain dangerous organic compounds that can be transferred to water. Metal tanks can cause zinc leakage, caused by a number of environmental factors at high levels. Aluminum tanks also can have an effect on the water in tanks.

Assessing mine water quality using a hierarchy fuzzy variable sets method: a case study in the Guojiawan mining area, Shaanxi Province, China

It is essential to assess mine water quality before this resource can be comprehensively utilized. The objective of this paper was to develop an integrated approach that can be applied for mine water quality assessment. An improved analytic hierarchy process (IAHP) method was used to calculate the weights of evaluation parameters, while fuzzy variable sets were used to determine the classification of mine water quality. Guojiawan mining area in Shaanxi Province, China, was chosen as the study area for this research and concentrations of total dissolved solids, chemical oxygen demand, chloride, sulfate, fluoride, and arsenic, as well as pH were utilized as water quality assessment factors. A total of 16 water samples, 13 samples from Guojiawan coal mine and three samples from Beiniuchuan River near the mine, were collected. The results show that four of these samples belonged to class III (roof water and river water) and encompass 25% of the total, and it can be used for domestic drinking, irrigation and industrial purposes, directly. While three belonged to class V and were derived from the auxiliary and main haulage roadways as well as the 51140 face cutting. They can be used for some industrial purpose after corresponding treatment. This latter group of samples accounted for 18.75% of the overall total, while the remaining nine were evaluated as class IV, encompassing 56.25% of the total, and they can be used for irrigation directly and domestic drinking after proper treatment.

Rooftop and natural springs water harvesting for promotion of vegetable cultivation in drought prone Morni Hills of Haryana State

The Shivalik hill region of Haryana faces acute shortage of water limiting scope of high value vegetable crops in spite of good rainfall and favorable climate. The natural spring water (SW) tapping and roof rainwater (RW) harvesting was not attempted earlier for drought proofing and hence attempted in this study. Seven brick masonry water storage tanks for (SW) and eight for roof water (RW) harvesting were constructed @Rs 1.2 lakh each including accessories having 6mx4mx1.8m size. The economic gains by the cultivation of vegetable crops with supplemental irrigation were analyzed for three samples of SW harvesting and five for RW harvesting. In case of SW harvesting, the traditional maize-mustard sequence generated net saving of Rs. 9, 900/-but net gain over the traditional crops was Rs. 47, 800, Rs. 51, 000 and Rs. 1, 38, 000/acre/yr by the first, second and third beneficiary farmer, respectively. In case of RW harvesting, water of five tanks was shared by seventeen farmers. The area under tomato increased from 8 to 12.2, cucumber from 2.6 to 4.7 acres and new crops of chilies and coriander were introduced over 2.1 and 1.47 acres. The total increase in gross and net income from five tanks was Rs. 14.86 and Rs. 5.94 lakh/yr over control. The aim of crop diversification, more crops per drop or doubling the income of farmers was realized by this initiative having good scope of replication.

Evaluation of rainwater harvesting performance for water supply in cities with cold and semi-arid climate

Abstract In this study, the performance of rainwater harvesting (RWH) was assessed in terms of potential applicability for rainwater saving and non-potable water supply. Rainwater collecting from roofs of buildings was simulated in two cities with cold and semi-arid climate, namely Qazvin and Sanandaj. Rainfall statistics, information on the storage tank size, building roof areas and water demand (non-potable) were obtained. Buildings with roof areas of 100 m2 to 300 m2 were considered for the present study. It can be concluded that for cities located in cold and semi-arid climates, at least 60% of non-potable water can be supplied from roofs with a large area, a minimum 16% and maximum 70% for a low roof area, a minimum 8% and maximum 44% of the days per year from harvested rainwater. It is also found that for cities located in cold and semi-arid climates, it is possible to achieve at least 70% of non-potable water from large surface roofs. For the studied cities, with increasing tank size (1,000 to 5,000 L) rainwater saving was tangible for the same roof areas.

Hönnun og virkni léttra gróðurþaka við íslenskar aðstæður

Green roofs are increasingly being installed cities in Europe as a part of sustainable stormwater systems. The goal of this research was to assess the hydrological efficiency of different configurations of extensive green roofs in Iceland and present suggestions for successful design of such roofs based on local materials and weather conditions. International literature and best design practices were reviewed. Runoff from five test roofs was monitored for 11 months, in conjunction with snowdepth, rainfall, wind and air temperature. Green roof water retention measured highest 85% in June and July in accordance with other studies in cold climates. Water retention measured, however, somewhat lower during the winter (<20%). Significant delay of runoff's center of mass and lowering of peak runoff was measured in all green roofs except during the largest runoff events. Average event water retention was correlated to air temperature, cumulative rain, rain 14 days before event and wind speed 7 days before event. Roofs with moss and sedum turf demonstrated good hydrological efficiency, good appearance and needed little maintenance. Grass turf roofs retained slighlty more water, but were less drought resistant and looked poorly during early summer. Wild, water resistent plants like moss and sedum performed better overall.

Computer aid for roof water harvesting systems analysis in rural areas of Mexico

Abstract Lack of sufficient good quality water to fulfill the rural population's needs in many countries, such as Mexico, has become one of the main issues governments have to cope with to provide adequate living conditions. The situation has worsened due to rainfall pattern variability influenced by climate change. Water harvesting is an ancient practice that provides an additional water supply for different uses. The lack of sufficient readily available decision tools within these environments has hindered adequate decision-making. The computer aid presented in this paper serves the purpose of a decision tool for use in marginal rural areas where a water harvesting system is to be implemented. Input variables are easily obtained and the system has preloaded information for use in the water balance. The interface is user-friendly, enabling users to plug local information in to obtain outputs on which to base a decision. Input variables can be changed as needed to achieve an acceptable output. The system generates rainfall amounts stochastically enabling posterior analysis to be used in terms of designing roof water harvesting under different runoff occurrence probabilities.

Evaluating the Quality of Mine Water Using Hierarchical Fuzzy Theory and Fluorescence Regional Integration

The quality of mine water samples from Hongliulin, Shaanxi Province, China was comprehensively evaluated. The inorganic fraction was analyzed by an analytic hierarchy process, while the main types of dissolved organic matter (DOM) were identified and quantified using fluorescence regional integration. Of the eight samples evaluated, those collected from surface water as well as one coal roof water sample (from the no. 52 seam) were classified as type I. These samples had much lower fluorescence integral values than their counterparts. One water sample from the no. 42 coal face and one from the no. 52 coal haulage roadway were type V, with much higher fluorescence integral values. All of the other water samples evaluated were classified as type II, with intermediate fluorescence integral values. This study showed that sedimentation can improve water quality from type II to type I, allowing it to be safely used for both human consumption and agricultural production. This strategy also reduced DOM by 37.17%.

On prevention and mechanism of bed separation water inrush for thick coal seams: a case study in China

Bed separation can occur in overlying strata, especially in hard and soft interbedded roof strata. If these strata prone to form bed separation are rich aquifers, water can accumulate into bed separation and maybe cause a serious water hazard under the condition of water inflow passages existence. Therefore, studying these types of roof water inrush mechanisms, forecasting roof water inrush, and formulating preventive and control measures in advance are extremely important to a mine. In this paper, we takes the typical case of water inrush in the workface number 1121 at Hongliu coal mine as an example, and study the mechanism of water inrush in detail. Primarily, field drilling with water leakage and color TV observations showed that the maximum height of the water conducting fractured zone was 12.50 times the thickness of the coal seams, which spread to the overlying coarse-grained sandstone aquifer. Secondly, the numerical simulation indicated that bed separation storage space was prone to form under the combination of coarse-grained sandstone and mudstone geological structure. The detection using UWTEM revealed that the groundwater accumulated in this bed separation and formed a water bag (bed separation water). When the water bag reached a certain degree, water bursting happened with the main roof collapsing. Finally, prevention, effective drainage methods, and successful experiences with bed separation water have been summarized, and it will have a major significance to coal mines suffering from bed separation water inrush.

Analysis on the Stability of the Inclined Water-Resisting Roof Layer While Mining Under the Confined Aquifer

Water inrush from the mine roof greatly threats mine safety. In this paper, in order to predict whether a roof water inrush accident will occur during the mining process, we considered the inclined water-resisting roof layer of mine as a rectangular thin plate with four clamped edges, and obtained critical water inrush criterion based on the principle of minimum potential energy and Mohr–Coulomb yield criterion, in which the linear increasing water pressure and the supporting force of fractured rock mass were considered. For a specific project, the stability of water-resisting layer was analyzed by Flac3D based on the fluid structure interaction method, and then the effectiveness of critical water inrush criterion was verified. These results provide valuable guidance for the prevention of water inrush from roof of working face under similar geological conditions.

Comparison of the chemical quality of rainwater harvested from roof and surface run-off systems

Despite numerous studies, little is known about the quality of rainwater harvested (RWH) from roofs or overland flow by smallholder farmers of Africa. Thus, the main objective of this study was to compare the physical and chemical quality of the rainwater harvested from both dwelling roofs and yards situated in a smallholder community in KwaZulu-Natal (South Africa). Rainwater samples were collected at 51 households during a dry period for assessment of the concentration of specific chemical elements. The water harvested from metallic roofs and yards did not meet the World Health Organization (WHO, 2011) guidelines for drinking water, as it exceeded recommended levels of Se, Al, B and Cd in at least 75% of the roof water samples, and of Al in the case of yard RWH. Compared to yard water, RWH from metallic roofs exhibited higher B, Se, Ni, Pb, Cu, As, Cd, and Cr but lower dissolved organic carbon (DOC), NO3-, Fe, SO42-, Na, Mg, Ca, K, Fe concentrations. The content of nutrients and DOC in the water harvested from the surface correlated with the number of pigs per household (with r=0.78 for SO42-, r=0.74 for DOC and r=0.52; NO3-). These results are expected to inform improved design and implementation of RWH. Further investigations should consider both physicochemical and microbiological aspects of water quality to provide a more holistic understanding of potential health risks.

RWRE–A WEB BASED OPEN SOURCE GIS TOOL FOR ROOF WATER RUNOFF ESTIMATION

In rural areas of low rainfall, roof top rainwater harvesting is an ideal method for collecting rainwater because it helps not only in meeting at least a part of the water requirement but also prevents storm runoff and flooding during heavy rains. Individual houses and buildings are the best units for collecting the roof water. In this work an interactive web-based GIS tool named RWRE (Roof Water Runoff Estimator) has been developed to estimate the runoff from the rooftops of the buildings. REWE tool was designed using open source geospatial development tools like Geoserver and OpenLayers. The developed tool provides a polygon drawing tool to delineate the rooftop of individual buildings. The area of rooftop of each building is listed. The runoff coefficient for each building is also taken as input. The annual average rainfall is required to calculate the total amount of water available from the rooftops of all the delineated buildings. For the testing and development of RWRE, the municipal area of Bhopal city of Madhya Pradesh was taken. This tool can be configured to be used for any rural or other area and can be of great help in planning and designing of the roof water harvesting structures as it quickly and accurately estimates the volume of water available from the buildings.

Study of a roof water inrush prediction model in shallow seam mining based on an analytic hierarchy process using a grey relational analysis method

Mining-induced water inrush is a sudden and destructive underground disaster caused by a mining disturbance. This disaster occurs frequently in the northern region of Shaanxi province in China due to overburden fractures in shallow seam mining, which pose a great threat to residents’ safety. It is therefore essential to construct an accurate prediction model. This study first applies selection hierarchy analysis to the main controlling factors of roof water inrush to study their weights using an analytic hierarchy process (AHP) including five factors: surface water catchment features, wateriness of the aquifer, water-resistant characteristics of aquiclude, combined influence of overburden, and mining disturbance characteristics. The grey relational analysis (GRA) method is used to calculate the correlation degree of each water inrush. The AHP-GRA method presents a comprehensive evaluative model combining the advantages of both approaches to analyze mining safety. Qualitative and quantitative indicators of the roof water inrush prediction model in shallow seam mining are established. Secondly, risk prediction of roof water inrush points and comprehensive water inrush is determined using engineering examples from the Hanjiawan coal mine. Results indicate that during safety mining, water inflow data are consistent with our prediction, thereby substantiating the model’s accuracy and providing a new method for predicting roof water inrush in shallow seam mining.

Life Cycle Assessment (LCA) for Water re use System of a Green Roof

In urban contexts climate change and urbanization alter the correct management of outflows. The need to reduce CO2 emissions and increase the green areas presence is linked to forecast targets to facilitate the correct management of urban risks. To achieve these objectives the new technologies are available, such as green roofs, which are useful for reducing the impacts of climate change in urban areas and for the proper management of outflows, indeed, the green roofs can be connected to rainwater reuse systems. The collection and reuse water system can be studied using the Life Cycle Assessment (LCA) methodology. In this paper a sustainability estimate of the green roof and reuse water system is proposed in the Urban Hydrological Experimental Park at the University of Calabria (Italy).

The application of grey water recycling at Gayanti City Apartment, South Jakarta

This planning is aim to design the plumbing system at Gayanti City Apartment with a separate system or grey water recycling system so that the efficiency cost of the recycling system will be known. Clean water system from PAM JAYA DKI and recycle water system from grey water that distributed to Waste Water Treatment Plant (WWTP) to be treated and reused for flushing closet and watering plants are designed for this apartment. The amount of the clean water needed is 116.6 m3/day and the amount of the recycle water needed is 18.64 m3/day. Water supply system that applied to this apartment is roof tank system. Calculation of water consumption's fluctuations to determine the capacity of reservoirs and pumps are using Four Winds Apartment, Bellagio Apartment, Thamrin Residences Apartment, and Karet Kuningan Apartment as a comparison with the same criteria as the designed apartment. The capacity of the clean ground water tank is 123.5 m3and the recycle ground water tank is 12 m3. Transfer pumps work for 12 hour/day (1 time pause) and the capacity of clean roof water tank is 31.5 m3and the recycled one is 6.7 m3. Based on the chosen alternative in design, Gayanti City Apartment is using the first water supply system alternative that needs 18 stand pipes of clean water and 18 stands pipes of recycle water with 4 PRVs mounted on each stand pipes and booster pump installed for the top 6 floors. The amount of clean water needed is 116.6 m3/day and recycle water is 18.64 m3/day. Waste water produced is equal to 93.28 m3which 80% of it is the grey water that will be treated in Waste Water Treatment Plant into recycle water. Total amount of clean and recycled water investment and reservoir constructions is Rp. 1,637,227,201,- and percentage of clean water that can be saved from the application of recycling system is 18% with total efficiency cost Rp 233,932/day or Rp 7,017,960/month.

Laboratory Tests of Substrate Physical Properties May Not Represent the Retention Capacity of Green Roof Substrates In Situ

Green roofs can be used to reduce the volume of polluted stormwater that is generated by cities. Modelling rainfall retention is critical, but green roof water balance models often rely on the physical properties of substrates. In these models, substrate water holding capacity (WHC) determines the depth of water which can be stored before runoff is generated; whereas, the permanent wilting point (PWP) limits evapotranspiration. The WHC and PWP, as well as plant available water (PAW; where PAW = WHC − PWP), as determined from laboratory tests, may not truly reflect how substrates perform on green roofs. We therefore ran a simulated rainfall experiment on green roof modules to (i) compare the rainfall retention of vegetated and non-vegetated substrates with different WHC and PAW, and (ii) relate retention to substrate storage capacity, as calculated from laboratory measures of WHC and PAW. We found that the PAW of a substrate is a better indicator of evapotranspiration and retention when compared with WHC. However, we also found that substrates always retained less water than their calculated storage capacity would suggest, most likely being due to their high permeability. Our results indicate that using laboratory-derived measures of WHC and PAW in green roof models may be over-estimating both evapotranspiration and rainfall retention.

An improved method for determining the position of overlying separated strata in mining

Abstract Water bursts and flooding from overlying separated strata are new types of roof water hazards in coal mining in China. Over the past decade, there have been several major outbursts of water from overlaying separated strata. Accurate determination of the location of separated strata is a prerequisite for preventing and controlling such outbursts. The traditional method of determining the location of separated strata is based on the composite-beam principle, but it still has theoretical defects. To address the shortcomings of this method, we propose an improved method for determining the location of the separated layers, namely, the stepwise comparison combination method (SCCM). SCCM can be used to determine the location of separated strata by comparing the curvature between adjacent rock layers at the same level and dividing the composite beam accurately at each level. The improved method not only considers the interaction of all strata and the influence of any rock stratum on the overall deformation of overlying strata, but also considers local interactions between adjacent strata. By stepwise comparison and combination, the actual combined status of the overlying section can be determined, and the calculated position of separated strata is more accurate. The traditional method and the improved method were used to calculate and determine the location of separated strata in a real mining example. Field explorations confirmed that the results from the improved method described in this paper were more accurate.

A-27 屋上緑化利用水および利用可能な雑用水の水質調査

A-27 屋上緑化利用水および利用可能な雑用水の水質調査

A modelling study of the event-based retention performance of green roof under the hot-humid tropical climate in Kuching.

The influences of climate on the retention capability of green roof have been widely discussed in existing literature. However, knowledge on how the retention capability of green roof is affected by the tropical climate is limited. This paper highlights the retention performance of the green roof situated in Kuching under hot-humid tropical climatic conditions. Using the green roof water balance modelling approach, this study simulated the hourly runoff generated from a virtual green roof from November 2012 to October 2013 based on past meteorological data. The result showed that the overall retention performance was satisfactory with a mean retention rate of 72.5% from 380 analysed rainfall events but reduced to 12.0% only for the events that potentially trigger the occurrence of flash flood. By performing the Spearman rank's correlation analysis, it was found that the rainfall depth and mean rainfall intensity, individually, had a strong negative correlation with event retention rate, suggesting that the retention rate increases with decreased rainfall depth. The expected direct relationship between retention rate and antecedent dry weather period was found to be event size dependent.

Roof Water Harvesting in Hills - Innovations for Farm Diversification and Livelihood Improvement

The north eastern region (NER) of India receives bountiful rains (>2000 mm) annually. However, there is extreme water scarcity during post- and premonsoon season (November-March). In such a situation, roof water harvesting (RWH) holds promise for multiple livelihood opportunities. RWH unit with polyfilm lined water collection tank of 37 m 3 storage capacity (i.e. 5.5 x 4.5 x 1.5 m 3 ) was demonstrated at 11 farmers fields mostly on hill tops in the Ri-Bhoi district (Meghalaya). The average demonstration area was 500 m 2 /farmer in the vicinity of homesteads (kitchen gardens). Volume of water harvested in a collection tank was about 53 m 3 including about 16 m 3 harvested during dry season due to seasonal replenishment. The cost of water harvesting was estimated at about Rs 144 and Rs 119/m 3 considering lifespan of five and ten years respectively. Farmers used harvested water for diversified activities such as raising crops [maize, broccoli, French bean, laipatta ( Brassica juncea ), tomato, etc.] and livestock (pig or poultry) in addition to domestic use. The farmers without RWH could use land only during rainy season for crop cultivation. On an average, the net income from each RWH based model (500 m 2 demonstration area) was Rs 14,910 for crop + piggery and Rs 11,410 for crop + poultry farming which was 261 and 176% higher, respectively than the normal farmers' practice. Similarly, employment and water use efficiency enhanced by 221 and 586%; and 168 and 218% under crop + piggery and crop + poultry based farming respectively.

Developing water resources management strategies for South Sikkim District, India

Abstract This study was an effort to analyse the problems and prospects of water resource management and for suggesting strategies to meet the perceptive demand of 410 L of water per family during the winter period in South Sikkim district of Sikkim state, India. The district is of hilly terrain with an average rainfall of 1,500 mm per year, yet the district faces acute water shortage during the winter period. The hydro-geological and meteorological characteristics of the sub-watersheds were also studied. The district had very poor soil depth (<50 cm), low water holding capacity of soils (27–28%) with mostly sandy-loam texture. The sub-watersheds were found to have more than 70% first-order streams, higher bifurcation ratio (3.31), higher drainage density (3.99 km/km2) and higher stream density (8.65/km2). Sub-watersheds are mostly elongated with average form factors of 0.21. The rainfall pattern, soil type and morphometry of sub-watersheds indicated poor in situ moisture storage and limited possibility of stream water harvesting. To mitigate the scarcity of water in South Sikkim, the only option left for the planners is to promote household roof water harvesting so that water demand can be met during the average consecutive dry period of 30 days.