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Presentation on theme: "MK. PSDA PENGELOLAAN DAN PANEN AIR HUJAN"— Presentation transcript:

diabstraksikan oleh: soemarno, psdl.ppsub, juni 2013

2 PANEN AIR HUJAN Rainwater harvesting is the accumulation and storage of rainwater for reuse before it reaches the aquifer. Uses include water for garden, water for livestock, water for irrigation, etc. In many places the water collected is just redirected to a deep pit with percolation. The harvested water can be used for drinking water as well if the storage is a tank that can be accessed and cleaned when needed. Rainwater harvesting provides an independent water supply during regional water restrictions, and in developed countries is often used to supplement the mains supply. Rainwater harvesting systems are appealing as they are easy to understand, install and operate. They are effective in 'green droughts' as water is captured from rainfall where runoff is insufficient to flow into dam storages. The quality of captured rainwater is usually sufficient for most household needs, reducing the need for detergents because rainwater is soft. Financial benefits to the users include that rain is 'renewable' at acceptable volumes despite climate change forecasts, and rainwater harvesting systems generally have low running costs, providing water at the point of consumption (Ferguson 2012). Benefits of widespread rainwater harvesting to the regional reticulated supply system may include reduced treatment, pumping, operation and augmentation costs, reducing peak storm water runoff and storm water processing costs, as well as reduced greenhouse gas emissions due to reduced dependence on pumping and potential augmentation through sources such as desalination (Coombes 2007, White, 2009). Coombes PJ (2007). Energy and economic impacts of rainwater tanks on the operation of regional water systems. Australian Journal of Water Resources 11 (2) 177 – 191. Ferguson M (2012) a 12-month rainwater tank water savings and energy use study for 52 real life installations. Ozwater12 COnference, Sydney, Australia: May 2012. White I (2009). Decentralised Environmental Technology Adoption: The household experience with rainwater harvesting. PhD Thesis. Griffith University. Diunduh dari: ………… 18/1/2013

Teknologi hijau ini adalah memanen dan mengolah air hujan sehingga kualitasnya sesuai untuk penggunaan lain. Jumlah Air Hujan Konfigurasi Atap Panen Air Hujan Bahan Atap Sistem Perlakuan Diunduh dari: ………… 18/1/2013

4 Kualitas Air dan Risiko Kesehatan
PANEN AIR HUJAN KUALITAS AIR HUJAN The concentration of contaminants is reduced significantly by diverting the initial flow of runoff water to waste. Improved water quality can also be obtained by using a floating draw-off mechanism (rather than from the base of the tank) and by using a series of tanks, with draw from the last in series. The stored rainwater may need to be analyzed properly before use in a way appropriate to its safety. Diunduh dari: ………… 18/1/2013 Kualitas Air dan Risiko Kesehatan Rainwater is relatively free from impurities except those picked up by rain from the atmosphere, but the quality of rainwater may deteriorate during harvesting, storage and household use. Wind-blown dirt, leaves, faecal droppings from birds and animals, insects and contaminated litter on the catchment areas can be sources of contamination of rainwater, leading to health risks from the consumption of contaminated water from storage tanks. Poor hygiene in storing water in and abstracting water from tanks or at the point of use can also represent a health concern. However, risks from these hazards can be minimized by good design and practice. Well designed rainwater harvesting systems with clean catchments and storage tanks supported by good hygiene at point of use can offer drinking-water with very low health risk, whereas a poorly designed and managed system can pose high health risks. Diunduh dari: ………… 18/1/2013

PANEN AIR HUJAN PEMASANGAN SISTEM Rainwater harvesting systems can be installed with minimal skills (White , (2009). The system should be sized to meet the water demand throughout the dry season since it must be big enough to support daily water consumption. Specifically, the rainfall capturing area such as a building roof must be large enough to maintain adequate flow. Likewise, the water storage tank should be large enough to contain the captured water. White I. (2009). Decentralised Environmental Technology Adoption: The household experience with rainwater harvesting. (PhD Thesis. Griffith University, Australia). Diunduh dari: ………… 18/1/2013 KOMPONEN SISTEM PEMANEN AIR HUJAN A rainwater harvesting system comprises components of various stages - transporting rainwater through pipes or drains, filtration, and storage in tanks for reuse or recharge. The common components of a rainwater harvesting system involved in these stages are illustrated here. Catchments: The catchment of a water harvesting system is the surface which directly receives the rainfall and provides water to the system. It can be a paved area like a terrace or courtyard of a building, or an unpaved area like a lawn or open ground. A roof made of reinforced cement concrete (RCC), galvanised iron or corrugated sheets can also be used for water harvesting. Diunduh dari: 18/1/2013

PANEN AIR HUJAN KOMPONEN SISTEM PEMANEN AIR HUJAN Coarse mesh at the roof to prevent the passage of debris Gutters: Channels all around the edge of a sloping roof to collect and transport rainwater to the storage tank. Gutters can be semi-circular or rectangular and could be made using: Locally available material such as plain galvanised iron sheet (20 to 22 gauge), folded to required shapes. Semi-circular gutters of PVC material can be readily prepared by cutting those pipes into two equal semi-circular channels. Bamboo or betel trunks cut vertically in half. The size of the gutter should be according to the flow during the highest intensity rain. It is advisable to make them 10 to 15 per cent oversize. Gutters need to be supported so they do not sag or fall off when loaded with water. The way in which gutters are fixed depends on the construction of the house; it is possible to fix iron or timber brackets into the walls, but for houses having wider eaves, some method of attachment to the rafters is necessary. Diunduh dari: 18/1/2013

PANEN AIR HUJAN COMPONENTS OF A RAINWATER HARVESTING SYSTEM 4. Conduits Conduits are pipelines or drains that carry rainwater from the catchment or rooftop area to the harvesting system. Conduits can be of any material like polyvinyl chloride (PVC) or galvanized iron (GI), materials that are commonly available. The following table gives an idea about the diameter of pipe required for draining out rainwater based on rainfall intensity and roof area: Sizing of rainwater pipe for roof drainage : Diameter Of pipe (mm) Average rate of rainfall in mm/h 50 75 100 125 150 200 13.4 8.9 6.6 5.3 4.4 3.3 65 24.1 16.0 12.0 9.6 8.0 6.0 40.8 27.0 20.4 16.3 13.6 10.2 85.4 57.0 42.7 34.2 28.5 21.3 - 80.5 64.3 53.5 40.0 83.6 62.7 mm/ h - millimeters per hour; m - meters Source: National Building Code Diunduh dari: 18/1/2013

8 Source: A water harvesting manual for urban areas
PANEN AIR HUJAN COMPONENTS OF A RAINWATER HARVESTING SYSTEM First-flushing A first flush device is a valve that ensures that runoff from the first spell of rain is flushed out and does not enter the system. This needs to be done since the first spell of rain carries a relatively larger amount of pollutants from the air and catchment surface. Source: A water harvesting manual for urban areas Diunduh dari: 18/1/2013

9 . PANEN AIR HUJAN COMPONENTS OF A RAINWATER HARVESTING SYSTEM 6. Filter The filter is used to remove suspended pollutants from rainwater collected over roof. A filter unit is a chamber filled with filtering media such as fibre, coarse sand and gravel layers to remove debris and dirt from water before it enters the storage tank or recharge structure. Charcoal can be added for additional filtration. Charcoal water filter A simple charcoal filter can be made in a drum or an earthen pot. The filter is made of gravel, sand and charcoal, all of which are easily available. Sand filters Sand filters have commonly available sand as filter media. Sand filters are easy and inexpensive to construct. These filters can be employed for treatment of water to effectively remove turbidity (suspended particles like silt and clay), colour and microorganisms. In a simple sand filter that can be constructed domestically, the top layer comprises coarse sand followed by a 5-10 mm layer of gravel followed by another 5-25 cm layer of gravel and boulders. Source: A water harvesting manual for urban areas Diunduh dari: 18/1/2013

Fasilitas Penyimpanan Air Hujan There are various options available for the construction of these tanks with respect to the shape, size and the material of construction. Shape: Cylindrical, rectangular and square. Material of construction: Reinforced cement concrete, (RCC), ferrocement, masonry, plastic (polyethylene) or metal (galvanised iron) sheets are commonly used. Position of tank: Depending on space availability these tanks could be constructed above ground, partly underground or fully underground. Some maintenance measures like cleaning and disinfection are required to ensure the quality of water stored in the container. Diunduh dari: 18/1/2013

11 PANEN AIR HUJAN KOMPONEN SISTEM PEMANEN AIR HUJAN 8. Recharge structures Rainwater may be charged into the groundwater aquifers through any suitable structures like dugwells, borewells, recharge trenches and recharge pits. Various recharge structures are possible - some which promote the percolation of water through soil strata at shallower depth (e.g., recharge trenches, permeable pavements) whereas others conduct water to greater depths from where it joins the groundwater (e.g. recharge wells). At many locations, existing structures like wells, pits and tanks can be modified as recharge structures, eliminating the need to construct any structures afresh. Here are a few commonly used recharging methods: 1. Recharging of dugwells and abandoned tubewells. In alluvial and hard rock areas, there are thousands of wells which have either gone dry or whose water levels have declined considerably. These can be recharged directly with rooftop run-off. Rainwater that is collected on the rooftop of the building is diverted by drainpipes to a settlement or filtration tank, from which it flows into the recharge well (borewell or dugwell). If a tubewell is used for recharging, then the casing (outer pipe) should preferably be a slotted or perforated pipe so that more surface area is available for the water to percolate. Developing a borewell would increase its recharging capacity (developing is the process where water or air is forced into the well under pressure to loosen the soil strata surrounding the bore to make it more permeable). If a dugwell is used for recharge, the well lining should have openings (weep-holes) at regular intervals to allow seepage of water through the sides. Dugwells should be covered to prevent mosquito breeding and entry of leaves and debris. The bottom of recharge wells should be desilted annually to maintain the intake capacity. Providing the following elements in the system can ensure the quality of water entering the recharge wells: 1. Filter mesh at entrance point of rooftop drains 2. Settlement chamber 3. Filter bed Diunduh dari: 18/1/2013

PANEN AIR HUJAN KOMPONEN SISTEM PEMANEN AIR HUJAN 2. Settlement Tank Settlement tanks are used to remove silt and other floating impurities from rainwater. A settlement tank is like an ordinary storage container having provisions for inflow (bringing water from the catchment), outflow (carrying water to the recharge well) and overflow. A settlement tank can have an unpaved bottom surface to allow standing water to percolate into the soil. In case of excess rainfall, the rate of recharge, especially of borewells, may not match the rate of rainfall. In such situations, the desilting chamber holds the excess amount of water till it is soaked up by the recharge structure. Thus, the settlement chamber acts like a buffer in the system. Any container, (masonry or concrete underground tanks, old unused tanks, pre-fabricated PVC or ferrocement tanks) with adequate capacity of storage can be used as a settlement tank. Diunduh dari: 18/1/2013

PANEN AIR HUJAN KOMPONEN SISTEM PEMANEN AIR HUJAN Recharging of service tubewells. In this case the rooftop runoff is not directly led into the service tubewells, to avoid chances of contamination of groundwater. Instead rainwater is collected in a recharge well, which is a temporary storage tank (located near the service tubewell), with a borehole, which is shallower than the water table. This borehole has to be provided with a casing pipe to prevent the caving in of soil, if the strata is loose. A filter chamber comprising of sand, gravel and boulders is provided to arrest the impurities. Recharge pits – Lubang Resapan A recharge pit is 1.5m to 3m wide and 2m to 3m deep. The excavated pit is lined with a brick/stone wall with openings (weep-holes) at regular intervals. The top area of the pit can be covered with a perforated cover. Design procedure is the same as that of a settlement tank. Soakaways / Percolation pit – Lubang Perkolasi Filter materials in a soakaway Percolation pits, one of the easiest and most effective means of harvesting rainwater, are generally not more than 60 x 60 x 60 cm pits, (designed on the basis of expected runoff as described for settlement tanks), filled with pebbles or brick jelly and river sand, covered with perforated concrete slabs wherever necessary. Filter materials in a soakaway Diunduh dari: 18/1/2013

PANEN AIR HUJAN KOMPONEN SISTEM PEMANEN AIR HUJAN 6. Recharge trenches A recharge trench is a continuous trench excavated in the ground and refilled with porous media like pebbles, boulders or broken bricks. A recharge trench can be 0.5 m to 1 m wide and 1 m to 1.5 m deep. The length of the recharge trench is decided as per the amount of runoff expected. The recharge trench should be periodically cleaned of accumulated debris to maintain the intake capacity. In terms of recharge rates, recharge trenches are relatively less effective since the soil strata at depth of about 1.5 metres is generally less permeable. For recharging through recharge trenches, fewer precautions have to be taken to maintain the quality of the rainfall runoff. Runoff from both paved and unpaved catchments can be tapped. Diunduh dari: 18/1/2013

To collect the runoff from paved or unpaved areas draining out of a compound, recharge troughs are commonly placed at the entrance of a residential/ institutional complex.These structures are similar to recharge trenches except for the fact that the excavated portion is not filled with filter materials. In order to facilitate speedy recharge, boreholes are drilled at regular intervals in this trench. In design part, there is no need of incorporating the influence of filter materials. This structure is capable of harvesting only a limited amount of runoff because of the limitation with regard to size. Source: A water harvesting manual for urban areas Diunduh dari: 18/1/2013

16 KOMPONEN SISTEM PEMANEN AIR HUJAN 8. Modified injection well
PANEN AIR HUJAN KOMPONEN SISTEM PEMANEN AIR HUJAN Modified injection well (Modifikasi Sumur Injeksi) In this method water is not pumped into the aquifer but allowed to percolate through a filter bed, which comprises sand and gravel. A modified injection well is generally a borehole, 500 mm diameter, which is drilled to the desired depth depending upon the geological conditions, preferably 2 to 3 m below the water table in the area. Inside this hole a slotted casing pipe of 200 mm diameter is inserted. The annular space between the borehole and the pipe is filled with gravel and developed with a compressor till it gives clear water. To stop the suspended solids from entering the recharge tubewell, a filter mechanism is provided at the top. Diunduh dari: 18/1/2013

17 Memanen Air hujan dengan Hutan Genangan Air-Tawar
PANEN AIR HUJAN Memanen Air hujan dengan Hutan Genangan Air-Tawar Rain water harvesting is possible by growing fresh water flooded forests without losing the income from the used /submerged land. The main purpose of the rain water harvesting is to utilize the locally available rain water to meet water requirements throughout the year without the need of huge capital expenditure. This would facilitate availability of uncontaminated water for domestic, industrial and irrigation needs. UTILITY OF FRESH WATER FLOODED FORESTS IN INDIA ( N. Sasidhar. : There are vast areas of fresh water flooded forests in Amazon River, Mekong River andMeghna River (Bangladesh) basins. In these flooded forests, the flora & fauna is richer than tropical ever green forests and many tree species grow more than 20 meters inheight. These forests are inundated / submerged by river flood water up to ten metersdepth for 5 to 7 months duration at a stretch. The portion of forest under the water,remain verdant similar to the portion above the water level.Many trees with commercial value yielding fruits, seeds, timber, fodder, herbs, biodiesel,etc are native to flooded forests. In flooded forests, the fish growth is also veryencouraging as they feed on tree seeds, fruits, vegetation, etc Diunduh dari: ………… 18/1/2013

18 PANEN AIR HUJAN Memanen Air Hujan:
The flooded forest plants/trees are very useful in rain water harvesting / ground water recharging anywhere such as house plots, farm lands, forest lands, open areas, river courses, etc. Rain water wherever available and needed are stored in small pits/ponds/tanks by growing ‘flooded forest trees’ which will earn income exceeding that of normalcrops /trees. Recharging rain water in the house compounds: Mmebuat lubang resapan air hujan. Make a pit of 1.5 meters depthwith sufficient storage volume to collect moderate fortnight rain fall. Plant the   ‘flooded forest trees’ in this pond area. When there is rain, the rain water collectsin this pond and slowly percolates in to the ground building up ground water.Thus trees can be grown and the ground water is recharged simultaneously for dryseason drinking water purpose. Meresapkan air hujan pada lahan terbuka di wilayah desa dan kota : Build a check damto store water up to 1.5 meters depth and plant ‘flooded forest trees’ in the water stored area. The entire area becomes woody area in few years and also the groundwater is recharged. 3. Memanen Air Hujan di Lahan PErtanian: Generally the time gap between good rains is 15or more days. It is very useful to store the rain water in a small area of the fieldand use it to water the crop till the next rain. Thus the crop yield is assured evenin erratic rain fall. Create a pond of depth 1.5 meters in 5% area of the field and plant the ‘flooded forest trees’. Thus the pond area land also contributes equallyfor agriculture produce and stores water for the needs of the crop. 4. Memanen Air Hujan di Lahan Hutan: On the small streams in the forest area,construct check dams of nearly 1.5 meters high and plant ‘flooded forest trees’ inwater spread area. The rain water collected by the check dam will enhance water  percolation in to the ground. The subsoil moisture will help the forest in preventing water stress during summer months. Thus the growth of the forest ishealthy. The forest animals also get drinking water and shelter during summer months. Diunduh dari: N. Sasidhar. : ………… 18/1/2013

19 Rainwater Harvesting Basic Components
PANEN AIR HUJAN Rainwater Harvesting Basic Components Rainwater systems come in all shapes and sizes, from simple catchment system under a downspout to large above and/or underground cisterns with complex filtration systems that can store thousands of gallons of water. Most rainwater collection systems are comprised of the following basic components: Catchment surface - rooftop or other raised solid surface. The best catchment systems have hard, smooth surfaces such as metal roofs or concrete areas. The amount of water harvested depends on the quantity of rainfall, and the size of the surface and the slope of the catchment area. Gutters and downspouts - also known as distribution systems that channel the water from the catchment area to a holding container such as a barrel, cistern, planted area, etc. Leaf screens - a screen that removes or catches debris. Roof washers - a device that diverts the "first flush" of rain before it enters the storage tank. Most rainwater suppliers recommend that the "first flush" of water is diverted to an outside area of the storage system, since the catchment surface may accumulate bird droppings, debris and other pollution. Storage tanks - In general, the storage tank is the most expensive component of a rainwater harvesting system. There are numerous types and styles of storage tanks available. Storage can be above-ground or underground. Storage containers can be made from galvanized steel, wood, concrete, clay, plastic, fiberglass, polyethylene, masonry, etc. Examples of above-ground storage include; cisterns, barrels, tanks, garbage cans, above ground swimming pools, etc. Storage tank prices vary based on different variables such as size, material and complexity. To inhibit the growth of algae, storage tanks should be opaque and preferably placed away from direct sunlight. The tanks should also be placed close to the areas of use and supply line to reduce the distance over which the water is delivered. Also consider placing the storage at an elevated area to take advantage of gravity flow. The tank should always be placed on a stable and level area to prevent it from leaning and possibly collapsing. Delivery systems - gravity-fed or pumped to the landscape or other end use areas. Purification/treatment system - needed for potable systems to make the water safe for human consumption. Please check with your local health department for information on filtration systems and certification requirements. Diunduh dari: ………… 18/1/2013

PANEN AIR HUJAN KEUNTUNGAN DAN KERUGIAN Keuntungan Panen Air Hujan Makes use of a natural resource and reduces flooding, storm water runoff, erosion, and contamination of surface water with pesticides, sediment, metals, and fertilizers Reduces the need for imported water (the San Diego region imports between 80%-90% of its water from Northern California and Colorado River) Excellent source of water for landscape irrigation, with no chemicals such as fluoride and chlorine, and no dissolved salts and minerals from the soil Home systems can be relatively simple to install and operate May reduce your water bill Promotes both water and energy conservation No filtration system required for landscape irrigation Kerugian / Kelemahan Panen Air Hujan Limited and uncertain local rainfall Can be costly to install - rainwater storage and delivery systems can cost between $200 to $2,000+ depending on the size and sophistication of the system The payback period varies depending on the size of storage and complexity of the system Can take considerable amount of time to "pay for itself" Requires some technical skills to install and provide regular maintenance If not installed correctly, may attract mosquitoes (i.e.; West Nile Disease and other waterborne illnesses) Certain roof types may seep chemicals, pesticides, and other pollutants into the water that can harm the plants Rainwater collected during the first rain season is generally not needed by plants until the dry season. Once catchment is full, cannot take advantage of future rains. Diunduh dari: ………… 18/1/2013

21 Shivakumar’s wife Suma is used to his eccentricities as a scientist.
Shivakumar offered to take us on a tour of his eco-friendly house Sourabha, in Vijayanagar, to display his advanced rain water harvesting system that makes him completely independent of Bangalore Water Supply and Sewerage Board (BWSSB). Shivakumar’s wife Suma is used to his eccentricities as a scientist. Diunduh dari: ………… 18/1/2013

22 Low Energy House - Rainwater Harvesting - Water Collection
A Rainwater Harvesting System can be installed in a house to reduce mains water usage and maintain water supplies in periods of drought Rainwater Harvesting System Design Rainwater harvesting is a specialised field so when considering an installation it is advisable to takes the advice of a competent installer. The rainwater harvesting system must be designed so that the supply of rain water meets the demand. Rainfall is intermittant so it will be necessary to store enough rainwater to avoid running out in dry spells. Diunduh dari: ………… 18/1/2013

23 How to save 50% on metered water costs
MEMANEN AIR HUJAN How to save 50% on metered water costs The UK practice of using mains water to supply all our water needs is needlessly wasteful, both financially and environmentally. Mains water is expensively purified to drinking water standards - but much of the water is used for non-potable purposes, like flushing toilets, cleaning and gardening. Harvested rainwater can be substituted for mains water, saving money and contributing to the protection of a key natural resource. Diunduh dari: ………… 18/1/2013

Think beyond the rain barrel: This simpler, cheaper approach to rainwater harvesting will help you harvest much more water for your garden! By Cheryl Long. August/September 2012 Read more: Harvesting rainwater to use for growing vegetables makes a great deal of sense. Unfortunately, the most common method of rainwater harvesting isn’t the most effective. Typically, gardeners invest in a rain barrel — which holds only 50 or 60 gallons of water — and then dole out the captured water to plants as needed, hopefully emptying the barrel before the next storm. Read more: Diunduh dari: ………… 18/1/2013

Components - Design - Construction The components of rainwater harvesting systems include:  (1) catchment  (2) conveyance or conduit system  (3) first flush  (4) filters  (5) storage or recharge system  Diunduh dari: 18/1/2013

26 MEMANEN AIR HUJAN Rainwater harvesting involves collection and storage of rainwater for future use. Rainwater can also be discharged into the ground without loss through evaporation or seepage. Rainwater can be recharged into the ground. The main components of a rainwater harvesting system are: The catchment area where the water is collected. The conduits through which the harvested water is carried. Storage and recharge facilities where the harvested water is stored or recharged into the ground. Diunduh dari: ………… 18/1/2013

27 Diunduh dari:………… 18/1/2013
RAIN GARDENS . A rain garden is a planted depression or a hole that allows rainwater runoff from impervious urban areas like roofs, driveways, walkways, parking lots, and compacted lawn areas the opportunity to be absorbed. This reduces rain runoff by allowing stormwater to soak into the ground (as opposed to flowing into storm drains and surface waters which causes erosion, water pollution, flooding, and diminished groundwater). They can be designed for specific soils and climates. The purpose of a rain garden is to improve water quality in nearby bodies of water. Rain gardens can cut down on the amount of pollution reaching creeks and streams by up to 30%. Native plants are recommended for rain gardens because they generally do not require fertilizer and are more tolerant of one’s local climate, soil, and water conditions, and attract local wildlife such as native birds. The plants — a selection of wetland edge vegetation, such as wildflowers, sedges, rushes, ferns, shrubs and small trees — take up excess water flowing into the rain garden. Water filters through soil layers before entering the groundwater system. Root systems enhance infiltration, maintain or even augment soil permeability, provide moisture redistribution, and sustain diverse microbial populations involved in biofiltration. Also, through the process of transpiration, rain garden plants return water vapor to the atmosphere. A more wide-ranging definition covers all the possible elements that can be used to capture, channel, divert, and make the most of the natural rain and snow that falls on a property. The whole garden can become a rain garden, and each component of the whole can become a small-scale rain garden in itself. Diunduh dari: 18/1/2013

28 Diunduh dari:………… 18/1/2013
RAIN GARDENS A rain garden requires an area where water can collect and infiltrate, and plants to maintain infiltration rates, diverse microbe communities, and water holding capacity. Transpiration by growing plants accelerates soil drying between storms. This includes any plant extending roots to the garden area. Simply adjusting the landscape so that downspouts and paved surfaces drain into existing gardens may be all that is needed because the soil has been well loosened and plants are well established. However, many plants do not tolerate saturated roots for long and often more water runs off one's roof than people realize. Often the required location and storage capacity of the garden area must be determined first. Rain garden plants are then selected to match the situation, not the other way around. When an area’s soils are not permeable enough to allow water to drain and filter properly, the soil should be replaced and an underdrain installed. This bioretention mixture should typically contain 60% sand, 20% compost, and 20% topsoil. Existing soil must be removed and replaced. Do not combine the sandy soil (bioretention) mixture with a surrounding soil that does not have high sand content. Otherwise, the clay particles will settle in between the sand particles and form a concrete-like substance. Deep plant roots also create additional channels for storm water to filter into the ground. Microbial populations feed off plant root secretions and break down carbon (such as in mulch or desiccated plant roots) to aggregate soil particles which increases infiltration rates. A five year USGS study indicates that rain gardens in urban clay soils can be effective without the use of underdrains or replacement of native soils with the bioretention mix. Pre-installation infiltration rates should be at least .25 in/hour, however. Type D soils will require an underdrain paired with the sandy soil mix in order to drain properly. Diunduh dari: 18/1/2013

29 Perlunya tumbuhan pada suatu RAIN-GARDEN
As we all know, freshwater is becoming increasingly scarce due to pollution despite its increasing necessity. Thankfully, rain help garden reduce pollution and preserve our water system by keeping clean and fresh rainwater out of the sewer system. It can capture the runoff and hold not only thousands of gallons of rainwater that can be used in your own garden and yard but all of the pollutants that contaminate our waterways. After that, the water will infiltrate deep into the ground so that it can be used by nearby plants and trees. Saving the earth may sound like a grand and complicated work which should be assigned to ecologists. However, just by planting a rain garden and spreading the words, you can improve the community the world you live in. Will this be enough of an reason for you to plant a rain garden? Oh and also, rain garden is quite beautiful. You can impress your neighbors not only by its gorgeous look but also by its function as a habitat fo birds and beneficial insects. Diunduh dari: 18/1/2013

30 RAIN GARDENS: One size fits all
When planning the garden’s construction, the first principle to remember is that any sized rain garden is better than no rain garden at all. However, if you want to take a scientific approach to minimize rooftop runoff, start by calculating the size of your roof. For example, let’s say that your roof is 186 square metres and that rainwater runs to each corner equally. That means that each of the four down spouts drains about 46 square metres of roof. Next (stay with me now!), divide the 46 square metres by 6 (because someone somewhere discovered that was the magic number) to determine the optimum size of garden you need, which in this case is about 8 square metres. The construction is relatively simple. Choose a location that’s not on too steep of a slope (this will eliminate erosion), dig the garden to a depth of 15 cm and ensure that you have well-drained soil—the sandier, the better. A good way to test your soil for drainage is to dig a 15-cm deep trial ‘pit’ and to fill it with water. If it drains within 24 hours, you’re set. If water remains after 24 hours, either replace the soil or amend it with a mixture of coarse sand and loam. The only step that’s left after that is to plant the entire rain garden (not just the periphery) with suitable plants. Diunduh dari: ………… 18/1/2013

31 RAIN-GARDEN di halaman rumah
Slow Down, Soak In & Clean Up Stormwater - Naturally View the Rain Gardens signage placed at Griggs & Hoover Reservoirs How Do They Work? When it rains, a rain garden acts as a basin to capture and absorb water runoff..  Nutrients, oils and other pollutants are then filtered by the soil and plants. Deep roots and pervious soils help to slow stormwater's flow, filtering out pollutants and keeping surface & ground water cleaner. 3. Water Fact: Did You Know? Rain gardens absorb 30% more water than the same size area of turfgrass. 4. Plant A Beneficial Bouquet of Natives Ohio-native plants have deep root systems and tolerate drought. This means less maintainance & watering. They also provide wildlife habitat. 5. Sow the Seeds, Reap the Benefits Plant a rain garden in your yard to protect water quality and: Reduce lawn maintainance Minimize area flooding Recharge groundwater Diunduh dari: ………… 18/1/2013

32 Iowa Rain Garden Design Manual
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33 Concept drawing of example Rain Garden
When using Rain Gardens, it is advisable to: Use more and smaller rain gardens than using few larger ones Contributing catchments should be limited to ~0.1 ha Design as off-line systems Aesthetically designed systems will encourage greater public support and acceptance Diunduh dari: ………… 18/1/2013


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