Rain water harvesting - Need of the era
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Rain water harvesting - Need of the era
- 1. Rainwater Harvesting Presented To- Sh. Sunil Khichar Sir Presented By-Nitin Chhaperwal Class-X Roll No. 1013 .ppt (1)
- 2. Rain Water Harvesting?. • Rain Water Harvesting RWH- process of collecting, conveying & storing water from rainfall in an area – for beneficial use. • Storage – in tanks, reservoirs, underground storagegroundwater • Hydrological Cycle
- 3. What Is Rainwater Harvesting? RWH technology consists of simple systems to collect, convey, and store rainwater. Rainwater capture is accomplished primarily from roof-top, surface runoff, and other surfaces. RWH either captures stored rainwater for direct use (irrigation, production, washing, drinking water, etc.) or is recharged into the local ground water and is call artificial recharge. In many cases, RWH systems are used in conjunction with Aquifer Storage and Recovery (ASR). ASR is the introduction of RWH collected rainwater to the groundwater / aquifer through various structures in excess of what would naturally infiltrate then recovered for use .ppt (3)
- 4. Why Rainwater Harvesting? Conserve and supplement existing water resources Available for capture and storage in most global locations Potentially provide improved quality of water Supply water at one of the lowest costs possible for a supplemental supply source. Capturing and directing storm water (run-off) and beneficially use it Commitment as a corporate citizen - showcasing environmental concerns Public Mandate (India) Replenishing local ground water aquifers where l owering of water tables has occured .ppt (4)
- 5. Why Not RWH? Not applicable in all climate conditions over the world Performance seriously affected by climate fluctuations that sometimes are hard to predict Increasingly sophisticated RWH systems (ASR) necessarily increases complexities in cost, design, operation, maintenance, size and regulatory permitting Collected rainwater can be degraded with the inclusion of storm water runoff Collected water quality might be affected by external factors Collection systems require monitoring and continuous maintenance and improvement to maintain desired water quality characteristics for water end-use Certain areas will have high initial capital cost with low ROI .ppt (5)
- 6. Condensation Let’s take a look at Precipitation The Water Cycle Evapotranspiration Evaporation Infiltration Grou n dw Surface Runoff Consumption Surface Water ater Sea water intrusion .ppt (6)
- 7. Condensation Rainfall Definitions Intensity – Quantity per time of the rainfall event (mm/hour) Precipitation Duration – period of time for the precipitation event Grou Consumption ndw Average Annual and Monthly Precipitation – Average rainfall over one year period and monthly intervals and usually based on 30 or more years of data ater Surface Water .ppt (7)
- 8. Rain Water as Source Water Design Considerations 1 2 Typical Diagram Recomendation 3 4 5 6 Raw water tank or Aquifer 1 Roof 2 Screen 3 Discharge of water 7 4 Pre-filter 5 Storage tank 6 Flow meter 7 Storm water discharge .ppt (8)
- 9. Ground Water Recharge Under natural conditions it may take days to centuries to recharge ground water by rain water. As we need to replenish the pumped water, Artificial Recharge of Ground water is required at some locations. .ppt (9)
- 10. Appropriate Technology Water conservation and groundwater recharge techniques Water harvesting cum supplementary irrigation techniques in Jhabua
- 11. Ground catchments systems channel water from a prepared catchment area into storage. Generally they are only considered in areas where rainwater is very scarce and other sources of water are not available. They are more suited to small communities than individual families. If properly designed, ground catchment systems can collect large quantities of rainwater. .ppt (11)
- 12. Storage • Storage devices may be either above or below ground • Different types include Storage Tanks Water Containers Lagoons or Lined Ponds Infiltration Ponds Size based on rainfall pattern, demand, budget and area .ppt (12)
- 13. Percolation Pit To divert rainwater into an aquifer, The percolation pit is covered with a perforated concrete slab The pit is filled with gravel/ pebbles followed by river sand for better percolation. The top layer of sand must be cleaned and replaced at least once in two years to remove settled silt for improving the percolation .ppt (13)
- 14. RWH – Methodologies • Roof Rain Water Harvesting • Land based Rain Water Harvesting • Watershed based Rain Water harvesting • For Urban & Industrial Environment – • Roof & Land based RWH • Public, Private, Office & Industrial buildings • Pavements, Lawns, Gardens & other open spaces
- 15. Recharge Wells The runoff water from rooftops or other catchments can be channelized into an existing /new well via sand filter to filter turbidity and other pollutants Abandoned wells can also be used Cost-effective process, which not only conserves rainwater for immediate use but also helps to enhance the local ground water situation .ppt (15)
- 16. Operational Procedures and Design Considerations • Storage tank – dark materials to exclude light and algae formation • Corrosion resistant materials • Tank in protected shaded area – lower temperature • For multiple storage tanks – design for frequent turnover • Regional wind direction and industrial activity – Lead, Mercury, other heavy metals .ppt (16)
- 17. RAIN W ATER HARVESTING FOR OFFICES – Developing a GREEN BUILDING in Nairobi, Kenya RAIN W ATER ACCUMULATION IN LIEU OF STORM W ATER ATTENUATION POND GREEN ROOF GREEN ROOF MANICURED LAWN GARDEN Co nc e p t & De s ig n Princ ip le s POROUS PARKING BACKUP MUNICIPAL SUPPLY OZONATION FILTRATION OVERFLOW GROUND WATER REPLENISHING WELLS .ppt (17)
- 18. PRINCIPLES OF A GREEN BUILDING - WATER SYSTEM OF RAIN WATER HARVESTING AND GREY WATER ARE COMBINED TO ACHIEVE THE FOLLOWING: • 25% OF POTABLE WATER CONSUMPTION REDUCTION • 100% OF POTABLE WATER PROVIDED BY RAIN • 50% REDUCTION OF SEWER QUANTITIES .ppt (18)
- 19. W ater harvesting structures in India .ppt (19)
- 20. Not new to India Rainwater storage reservoir at Dholavira (Rann of Kutch) – Harappan civilization (2500-1900 BC)
- 21. Centuries old ‘Kul irrigation’ in the Western Himalayan mountainous rain-shadow regions like Spiti valley Glacier melt is diverted into the head of a ‘kul’ or a diversion channel These ‘kuls’ channel the water over many kilometers They lead into a tank in the village from which water flow is regulated
- 22. Inundation channel Bengal Flood plains Floodwater entered the fields through the inundation canals The waters brought in rich silt and fish Em ba nk m en t The fish fed on mosquito larva and helped check malaria in this region. er iv R Fields Ka n a/ N adi Fields
- 23. Khadins of Jaisalmer (harvesting structures for agricultural fields) Designed by the Paliwal Brahmins of Jaisalmer, in 15th century Similar system also practised in Ur (Iraq), the Negev desert, and in south west Colorado An embankment prevents water from flowing away. Collected water seeps into the soil. This water saturates land, which is then used for growing crops
- 24. Johads of Rajasthan (provide water for domestic use) Earthen or masonry rainwater harvesting structure, for providing water for domestic use to the communities. Photo by L R Burdak
- 25. Johads of Rajasthan (provide water for domestic use) Photo by Farhad Contractor, taken in Alwar district of Rajasthan Read about revival of Johads in ‘Reviving India’s water harvesting systems’
- 26. Tankas of Bikaner, Barmer, Phalodi - Rajasthan Pipes from the rooftop lead rainwater into the tanka catchment Note the slope provided for the rainwater (palar pani) to flow into the tanka
- 27. Tankas for storing drinking water Thar desert region of Rajasthan (Barmer, Bikaner, Pallodi) Unique underground structures of various shapes and sizes to collect rain water for drinking purposes Sometimes used to store drinking water brought from far off wells in case the rainwater gets exhausted Constructed in court yards or in front of houses and temples, Built both for individual households as well as for village communities
- 28. Tankas of Bikaner, Barmer, Phalodi - Rajasthan Main source of drinking water in these areas People protect and maintain them Just before the on-set of the monsoon, the catchment area of the Tanka is cleaned up to remove all possible pollutants Human activity and grazing of cattle in the area is prohibited First spell of rain not collected
- 29. Tankas of Bikaner, Barmer, Phalodi - Rajasthan Provide enough drinking water to tide over the water scarcity during the summer months even though average annual rainfall is as less as 200 mm to 300 mm. In many cases the stored water lasts for the whole year. These simple traditional water harvesting structures are useful even during years of below-normal rainfall.
- 30. Bamboo drip irrigation in Meghalaya
- 31. Bamboo drip irrigation in Meghalaya 200-year-old system Used by tribal farmers of Khasi and Jaintia hills Bamboos divert water from perennial springs on hilltops to the lower reaches by gravity Used to irrigate the betel leaf or black pepper crops 18-20 litres of water entering the bamboo pipe system per minute gets transported over several hundred meters and finally gets reduced to 20-80 drops per minute at the site of the plant. Attempts made to introduce modern pipe systems but farmers prefer to use their indigenous form of irrigation.
- 32. Rainwater harvesting today Collection (Catchment) Flat / sloping roofs Transportation: Downtake pipes Leaf and grit filter, First flush device Storage in tanks Recharge into open wells / borewells / percolation pits / trenches
Notes de l'éditeur
- Narration: The hydrologic or water cycle is the continuous flow of water between reservoirs at or near the earth’s surface. As water falls to the ground as precipitation, it may develop as surface runoff into nearby surface waters or infiltrate into the ground and become stored as groundwater. Water stored in open areas, know as surface water, can evaporate into the atmosphere. In addition, water used by plants for normal growth or transpiration is also returned to the atmosphere. Once in the atmosphere water can condense into clouds and precipitate as rain or snowfall, initiating the cycle over again. Water is a renewable resource that, managed properly, can sustain the activities in the watershed for an indefinite period of time. Animation: shows water cycle
- Narration: The hydrologic or water cycle is the continuous flow of water between reservoirs at or near the earth’s surface. As water falls to the ground as precipitation, it may develop as surface runoff into nearby surface waters or infiltrate into the ground and become stored as groundwater. Water stored in open areas, know as surface water, can evaporate into the atmosphere. In addition, water used by plants for normal growth or transpiration is also returned to the atmosphere. Once in the atmosphere water can condense into clouds and precipitate as rain or snowfall, initiating the cycle over again. Water is a renewable resource that, managed properly, can sustain the activities in the watershed for an indefinite period of time. Animation: shows water cycle
- The collection device usually represents the biggest capital investment of an RWH system. It therefore requires careful design- to provide optimal storage capacity while keeping the cost as low as possible. While above-ground structures like tanks are easily purchased or made with a variety of designs, and water extraction is in many cases by gravity; they also are expensive, require more space and are prone to attack from the weather. Below-ground structures like cisterns, lagoons etc. are generally cheaper due to lower material requirements and unobtrusive. However, water extraction often requires a pump, contamination is more common, and present a potential danger to children and small animals if left uncovered.
- Whenever the depth of clay soil is more, recharge through a percolation pit with bore is preferable. This bore can be at the centre of the pit, which is filled with pebbles. The top portion is filled with river sand. The pit itself is covered with a perforated concrete slab. If the area is prone to flooding, it is advisable to provide an air vent to the percolation pit to avoid air locking. Roof water and surface water from buildings can be diverted to percolation pits. It is advisable to have at least one percolation pit in every house with open area for every 20 square metres.
- Existing structures such as defunct bore wells, unused/dried up open wells, unused sumps, etc. can be very well used for RWH through this technology of recharge wells instead of constructing recharge structures to reduce the total cost
- The Harappan civilisation (2500-1900 BC) comprised a number of urban centres. Dholavira, in the great Rann of Kutch (in present-day Gujarat, western India), is one of them. The city was built in a semi-arid region averaging 260 mm rainfall annually. There were no perennial water sources. Subterranean water was saline, potable water scarce. How did Dholavira manage? Two storm water channels, Manhar (north) and Mansar (south) flanked the city. The city was laid out on a 13 m gradient (higher in the east to lower in the west), ideal for reservoirs. It seems the planners knew this. They made a series of 16 reservoirs between the inner and outer walls of the city to collect the monsoon runoff from the channels, which amounted to 250,000 cu.m. of water. Inside the citadel (inner city), there are large storm drains with apertures. These were not for wastewater, as archaeologists first thought, since they were not connected to housing or bathing platforms. These were for rainwater. The air-apertures ensured easy passage of rainwater. Source: http://www.rainwaterharvesting.org/Solution/History_tour0.htm accessed November 2008 To the casual visitor, the most striking feature of Dholavira is its water management system. One gets the sense that every drop of water had to be saved. About 25 of the city's 250 acres are occupied by 16 rock cut reservoirs of various sizes. Linked by channels and dams, the reservoirs are quite spread out and must have added to the aesthetic appeal of this planned city. Source: http://blog.shunya.net/shunyas_blog/2008/08/dholavira-a-har.html accessed November 2008 In one of the older water harvesting systems, about 130 km from Pune along Naneghat in the Western Ghats, a large number of tanks were cut in the rocks to provide drinking water to tradesmen who used to travel along this ancient trade route.
- KulKuls are water channels found in precipitous mountain areas. These channels carry water from glaciers to villages in the Spiti valley of Himachal Pradesh. The Spiti area of Himachal Pradesh is a cold desert. Villages in the Spiti subdivision are located between 3,000 m and 4,000 m, which means they are snowbound six months a year. Rainfall is negligible in Spiti because it is a rainshadow area. The soil is dry and lacks organic matter. Spiti’s lunar-like terrain was transformed into an agrarian success story by an ingenious system, devised centuries ago to tap distant glaciers for water. This unique system is called kul irrigation, which utilises kuls (diversion channels) to carry water from the glacier to the village. The kuls often span long distances, running down precipitous mountain slopes and across crags and crevices. Some kuls are 10 km long, and have existed for centuries. The crucial portion of a kul is its head at the glacier, which is to be tapped. The head must be kept free of debris, and so the kul is lined with stones to prevent clogging and seepage. In the village, the kul leads to a circular tank from which the flow of water can be regulated. For example, when there is need to irrigate, water is let out of the tank in a trickle. Water from the kul is collected through the night and released into the exit channel in the morning. By evening, the tank is practically empty, and the exit is closed. This cycle is repeated daily. The kul system succeeds because Spiti residents mutually cooperate and share. The culture also is instrumental in maintaining the carrying capacity of the surrounding cultivable land. However, this system, carefully nurtured through the centuries, now runs the risk of being upset through government intervention. In the Jammu region too, similar irrigation systems called kuhls are found Source: http://www.rainwaterharvesting.org/methods/traditional/kuls.htm accessed November 2008
- Bengal once had an extraordinary system of inundation canals. Sir William Willcocks, a British irrigation expert who had also worked in Egypt and Iraq, claimed that inundation canals were in vogue in the region till about two centuries ago. Floodwater entered the fields through the inundation canals, carrying not only rich silt but also fish, which swam through these canals into the lakes and tanks to feed on the larva of mosquitoes. This helped to check malaria in this region. According to Willcocks, the ancient system of overflow irrigation had lasted for thousands of years. Unfortunately, during the Afghan-Maratha war in the 18th century and the subsequent British conquest of India, this irrigation system was neglected, and was never revived.According to Willcocks, the distinguishing features of the irrigation system were:1.) the canals were broad and shallow, carrying the crest waters of the river floods, rich in fine clay and free from coarse sand;2.) the canals were long and continuous and fairly parallel to each other, and at the right distance from each other for purposes of irrigation;3.) irrigation was performed by cuts in the banks of the canals, which were closed when the flood was over. Source: http://www.rainwaterharvesting.org/Rural/Traditional2.htm#beng accessed November 2008
- A khadin, also called a dhora, is an ingenious construction designed to harvest surface runoff water for agriculture. Its main feature is a very long (100-300 m) earthen embankment built across the lower hill slopes lying below gravelly uplands. Sluices and spillways allow excess water to drain off. The khadin system is based on the principle of harvesting rainwater on farmland and subsequent use of this water-saturated land for crop production. There are as many as 500 big and small Khadins in Jaisalmer district, which are productive, even with 40 mm rainfall. Rocky-hill-terrain around a valley including the valley slopes, constitute the catchment area of a Khadin. Stony gravels, wasteland with gentle slope in the form of valley can also form the catchment area of such structures.
- Tankas are usually built using locally available materials. While some structures are built in stone masonry with stone slab coverings, others are built with only rudimentary plastering of bare soil surfaces of the tank with cement or lime and covering with Zizyphus Numularia thorns. Tankas that are accommodated inside a house/courtyard are typically made of chiseled blocks of stone, in lime mortar and are made waterproof by an indigenous herbal mix, which seals minor cracks and prevents bacteriological growth inside the tanka. The size of the tanka is large enough to store sufficient drinking water for a family for six to eight months. An average storing capacity of the tanka is around 25,000 litres and a tanka can be as large as 20 feet x 60 feet x 12 feet. The tanka feeds on the rainwater collected through roof runoff. Inlet holes are provided in the convex covering at the ground level to facilitate entry of rain water into the tank. The wall of the tanka is kept projecting above the ground to provide inlet holes. When the owner is certain of the cleanliness of rainwater (done by constant visual testing and actual tasting of water) the tanka inlet is opened. Tankas have a hatch cover, which is kept closed except for the time when water is needed. Some tankas have a fish marked on the inside. Water is usually not filled above this level as the hydraulic pressure inside may exceed the retaining capacity of the tanka wall. The tanka water is stored to be used long after the rains have stopped. The clean conditions of collection and storage makes the tanka water a most precious resource in the hot summer months. When required to be cleaned, tankas must be emptied manually, they are large enough for people to enter and work inside. The tanka floor slopes into a sump right under the point from where the water is drawn out. http://www.unescoparzor.com/tankakyoto.html
- Tankas are usually built using locally available materials. While some structures are built in stone masonry with stone slab coverings, others are built with only rudimentary plastering of bare soil surfaces of the tank with cement or lime and covering with Zizyphus Numularia thorns. Some Kuccha structures have a convex covering of local wood with mud plaster. Inlet holes are provided in the convex covering at the ground level to facilitate entry of rain water into the tank. In case of Pacca structures (called tanka) the wall of the tank is kept projecting above the ground to provide inlet holes.
- Bamboo pipes are used to divert perennial springs on the hilltops to the lower reaches by gravity. The channel sections, made of bamboo, divert and convey water to the plot site where it is distributed without leakage into branches, again made and laid out with different forms of bamboo pipes. Manipulating the intake pipe positions also controls the flow of water into the lateral pipes. Reduced channel sections and diversion units are used at the last stage of water application. The last channel section enables the water to be dropped near the roots of the plant. Bamboos of varying diameters are used for laying the channels. About a third of the outer casing in length and internodes of bamboo pieces have to be removed while fabricating the system. Later, the bamboo channel is smoothened by using a dao, a type of local axe, a round chisel fitted with a long handle. Other components are small pipes and channels of varying sizes used for diversion and distribution of water from the main channel. About four to five stages of distribution are involved from the point of the water diversion to the application point. Source: http://www.rainwaterharvesting.org/Rural/nehr_tradi.htm