Water crisis and rain water harvesting
Thursday, 5 May 2011
Shafiqul Alam
Treating the severely polluted Buriganga is no longer a feasible option to meet the growing needs of water in Dhaka city, according to experts. The government has to spend about US$ 1.0 billion if the Padma and Meghna rivers are to meet the city's water needs. This is because we have been dumping everything in the Buriganga for years and it has become so polluted that the water would not be drinkable even if properly treated. The city's population is increasing rapidly and the issue of supplying adequate water to meet the city's growing needs is one of the most urgent and significant challenges. For sustainable management of freshwater, the government has emphasised on sourcing water from the two rivers. But among the various alternative options to augment freshwater resources, rainwater harvesting and utilisation could be a good solution, which can avoid many environmental problems often caused in conventional large-scale projects. Rainwater harvesting, in its broadest sense, is a technology used for collecting and storing rainwater for human use from rooftops and land surfaces using simple techniques such as jars and pots as well as engineered techniques. It is an important water source in many areas with significant rainfall and a good option in areas where good quality fresh surface water or ground water is lacking. Rain water harvesting systems can provide water at or near the point where water is needed or used. The systems can be both owner and utility operated and managed. Rainwater collected using existing structures (i.e., rooftops, parking lots, playgrounds, parks etc.), has a few negative environmental impacts compared to other technologies for water resource development. Rain water is relatively clean and the quality is usually acceptable for many purposes with little or even no treatment. The physical and chemical properties of rain water are usually superior to sources of ground water that may have been subjected to contamination. There are some other advantages as well: Rain water harvesting provides a water supply buffer for use in times of emergency or breakdown of the public water supply systems, particularly during natural disasters; rain water harvesting can reduce storm drainage load and flooding in city streets; users of rain water are usually the owners who operate and manage the catchment system, hence, they are more likely to exercise water conservation because they know how much water is in storage and they will try to prevent the storage tank from drying up; and rain water harvesting technologies are flexible and can be built to meet almost any requirements. Its construction, operation, and maintenance are not labour intensive. If we consider that we might face water scarcity in Dhaka city in the future then the assumption would be wrong. During summer, the city dwellers have been experiencing the problem for many years not only for the water level but also for load shedding as well as faulty pumps. Water scarcity is becoming a major challenge for the city authorities. The government has to allocate a large amount of funds for supplying pure drinking water in Dhaka and this would be a huge burden for the country. In this context, rain water harvesting, undoubtedly, can be a better alternative to meet the future water needs of a mega-city like Dhaka at a much lower cost than sourcing water from other sources and this will also reduce pressure on ground water. Rainwater harvesting can be a feasible alternative for providing safe drinking water and this practice is nothing new in the country. In arsenic affected areas about 1000 tanks were installed at affordable cost several years back. Dhaka City has been suffering from a variety of problems, mostly due to the unplanned activities. Again, if some long-term plans had been adopted, we would not have faced such insurmountable problems. However, time is not over and still a change is possible. For this, the planners have to be more proactive and search for alternate solutions like rain water harvesting. The writer can be reached at E-mail: shafiqul0032@yahoo.com
Treating the severely polluted Buriganga is no longer a feasible option to meet the growing needs of water in Dhaka city, according to experts. The government has to spend about US$ 1.0 billion if the Padma and Meghna rivers are to meet the city's water needs. This is because we have been dumping everything in the Buriganga for years and it has become so polluted that the water would not be drinkable even if properly treated. The city's population is increasing rapidly and the issue of supplying adequate water to meet the city's growing needs is one of the most urgent and significant challenges. For sustainable management of freshwater, the government has emphasised on sourcing water from the two rivers. But among the various alternative options to augment freshwater resources, rainwater harvesting and utilisation could be a good solution, which can avoid many environmental problems often caused in conventional large-scale projects. Rainwater harvesting, in its broadest sense, is a technology used for collecting and storing rainwater for human use from rooftops and land surfaces using simple techniques such as jars and pots as well as engineered techniques. It is an important water source in many areas with significant rainfall and a good option in areas where good quality fresh surface water or ground water is lacking. Rain water harvesting systems can provide water at or near the point where water is needed or used. The systems can be both owner and utility operated and managed. Rainwater collected using existing structures (i.e., rooftops, parking lots, playgrounds, parks etc.), has a few negative environmental impacts compared to other technologies for water resource development. Rain water is relatively clean and the quality is usually acceptable for many purposes with little or even no treatment. The physical and chemical properties of rain water are usually superior to sources of ground water that may have been subjected to contamination. There are some other advantages as well: Rain water harvesting provides a water supply buffer for use in times of emergency or breakdown of the public water supply systems, particularly during natural disasters; rain water harvesting can reduce storm drainage load and flooding in city streets; users of rain water are usually the owners who operate and manage the catchment system, hence, they are more likely to exercise water conservation because they know how much water is in storage and they will try to prevent the storage tank from drying up; and rain water harvesting technologies are flexible and can be built to meet almost any requirements. Its construction, operation, and maintenance are not labour intensive. If we consider that we might face water scarcity in Dhaka city in the future then the assumption would be wrong. During summer, the city dwellers have been experiencing the problem for many years not only for the water level but also for load shedding as well as faulty pumps. Water scarcity is becoming a major challenge for the city authorities. The government has to allocate a large amount of funds for supplying pure drinking water in Dhaka and this would be a huge burden for the country. In this context, rain water harvesting, undoubtedly, can be a better alternative to meet the future water needs of a mega-city like Dhaka at a much lower cost than sourcing water from other sources and this will also reduce pressure on ground water. Rainwater harvesting can be a feasible alternative for providing safe drinking water and this practice is nothing new in the country. In arsenic affected areas about 1000 tanks were installed at affordable cost several years back. Dhaka City has been suffering from a variety of problems, mostly due to the unplanned activities. Again, if some long-term plans had been adopted, we would not have faced such insurmountable problems. However, time is not over and still a change is possible. For this, the planners have to be more proactive and search for alternate solutions like rain water harvesting. The writer can be reached at E-mail: shafiqul0032@yahoo.com