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Water harvesting.

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Water harvesting It means capturing rain where it falls or capturing the run off in your own village or town. And taking measures to keep that water clean by not allowing polluting activities to take place in the catchment. Therefore, water harvesting can be undertaken through a variety of ways * Capturing runoff from rooftops * Capturing runoff from local catchments * Capturing seasonal floodwaters from local streams * Conserving water through watershed management These techniques can serve the following the following purposes: * Provide drinking water * Provide irrigation water * Increase groundwater recharge * Reduce stormwater discharges, urban floods and overloading of sewage treatment plants * Reduce seawater ingress in coastal areas. In general, water harvesting is the activity of direct collection of rainwater. The rainwater collected can be stored for direct use or can be recharged into the groundwater. Rain is the first form of water that we know in the hydrological cycle, hence is a primary source of water for us. Rivers, lakes and groundwater are all secondary sources of water. In present times, we depend entirely on such secondary sources of water. In the process, it is forgotten that rain is the ultimate source that feeds all these secondary sources and remain ignorant of its value. Water harvesting means to understand the value of rain, and to make optimum use of the rainwater at the place where it falls. How much water can be harvested? Urban scenario The total amount of water that is received in the form of rainfall over an area is called the rainwater endowment of the area. Out of this, the amount that can be effectively harvested is called the water harvesting potential. Water harvesting potential = Rainfall (mm) x Collection efficiency The collection efficiency accounts for the fact that all the rainwater falling over an area cannot be effectively harvested, because of evaporation, spillage etc. ...read more.


Construction of smaller reservoirs for fire protection not only provided increased resistance for forest fires due to their microclimatic effects, but also make available additional water for use during extreme droughts. Disadvantages Reservoirs create extensive land-use changes, wherein agricultural bottomlands are inundated and habitat is disturbed. Such disturbances lead to potentially severe environmental impacts depending on the size of the impoundment, including changes in the microclimate in the vicinity of large impoundments and both terrestrial and aquatic ecological disturbances. Because they are artificial structures, reservoirs can both add and detract from the aesthetic value of landscapes, depending on their design and construction. Cultural Acceptability Generally, impoundments are an acceptable technology. However, because of the land-use changes inherent in dam-building technology, cultural and social problems occur within the communities directly impacted by the construction process Further Development of the Technology Future dam construction will be subject to intense environmental scrutiny, focussing not only on direct, in-basin impacts but also hydrological optimalization, including in stream flow regulation. Notwithstanding, the dam construction technology is a well-established technology. 2.Collection And Reuse Of Stormwater Technical Description In developing urban areas, stormwater can be gathered in separate stormwater sewers and reused after simple treatment for washing streets, cooling, watering of gardens, and other purposes requiring nonpotable water. In addition to providing this reuse potential, this technology makes possible the treatment of urban runoff before it enters waterbodies. The simplest form of stormwater treatment consists of open or closed sedimentation basins, retention ponds, or storm sewer, in-line separation chambers for capturing oil products. Stormwater management technologies include provision of grit chambers and swirl separators within sewer mains, and skimmers which capture floatable solids and oil products from the water surface of basins. Infiltration ditches also can be used for filtration of oil products. Operation and Maintenance Regular inspections during rainy weather should be conducted to minimise the occurrence of blockages within the collection system. ...read more.


The models can be used to simulate current and future conditions within a distribution system under various conditions, to plan operation and repair activities, and to assess changes in the system and required improvements due to the reconfiguration or enlargement of the network. Disadvantages These models are data intensive, requiring well-documented system information that may not be readily available or correct. Cultural Acceptability This technology is largely an hidden technology used by the system engineers. However, provided the level of computerization is adequate for the operation of this type of model, systems modelling is well-accepted. Further Development of the Technology Better data collection, organization, and data base creation, as a standard procedure in system design, construction and operation, would enhance the ability of municipalities and water utilities to implement this technology effectively. 4.Lake Rehabilitation Technical Description Lakes are important resources not only landscape features, but also as recreational venues for fishing, boating, and swimming, all of which are very popular outdoor activities Lakes also serve life-sustaining functions such as provision of flood protection, drinking and irrigation water, and fish. Lake usage must be balanced between the desires of people to exploit lake-based resources and the capacity of the lake to satisfy these desires. Problems arise as a result of limitations on these uses that can reasonably be prevented or corrected with proper management. Thus, lake and reservoir management is an active process that considers how the various components of a lake ecosystem and its tributary watershed work and fit together, and, through this understanding, identifies the effects of various lake management interventions on these different components, both positive and negative. Lake management techniques include both watershed-based interventions, such as land use planning and pollution control technologies, and in-lake interventions, such as nutrient inactivation. The combination of measures is site specific, and, typically, a number of complementary measures should be used. 5. Desalination Evaporation ponds are comparatively low cost method for removing salinity. Evaporation pondsare most appropriate for smaller volume flows and for regions of relatively high evaporation rates, level topography and low land costs. 1 ...read more.

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