Water resources are those sources of water that are essential for human regular use. The use of water is essential for all aspects of human life, including agriculture, industry, domestic use and environmental protection, and what is essential for all these uses is purified pure water. The three main sources of water are rain water, surface water and groundwater. Pollution occurs in all of these cases. Surface water is more sensitive or relatively easily affected than groundwater, since groundwater is naturally protected from surface activity. But the water is now increasing the risk of death due to multi-faceted pollution. People are suffering from various complex and deadly infectious diseases including diarrhea, cholera, jaundice, typhoid, hepatitis, kidney and liver due to drinking contaminated water. The crisis of pure water is manifesting day by day. In a developing country like Bangladesh, the situation is even direr.
About 98.5% of the world’s water is saline and only 2.5% is pure. Two-thirds of this small amount of pure water is solid. Most of the remaining liquid water is groundwater and very little water is available in surface water bodies. Groundwater is more convenient and less polluting than surface water. So, it is usually used for public water supply. Groundwater, for example, is the largest source of usable water in the United States, and among all states, California draws the highest amount of groundwater per year. Groundwater reservoirs hold much more water than all lakes and reservoirs, including the Great Lakes in the United States. Most of the urban water supply is derived from groundwater.
About 100% of the rural people in Bangladesh depend on groundwater for drinking water. Even in urban areas, water supply is mainly dependent on groundwater. More than 7 percent of the total water supply in the capital Dhaka comes from groundwater, the rest comes from groundwater treatment. Groundwater is also widely used for irrigation. According to 1995 estimates, 82% of the total irrigation water is extracted from groundwater, which is a lot. According to a 1989 survey by the Master Planning Agency, Bangladesh has 2,565 crore cubic meters of groundwater reserves, of which 166 million cubic meters is not extractable. The remaining 90 crore cubic meters can be used for household and industrial production and a maximum of 1261 crore cubic meters for agriculture. According to a report by the World Health Organization, 2.5 million people die each year from waterborne diseases in developing countries. It is also said that there is a shortage of 100 million liters of pure water per day in the country. The capital needs 220 to 300 crore liters of water per day. Although about Tk 50 crore has been spent on groundwater in the last three decades, the provision of clean water has not been ensured. At present, about 32 million people across the country are suffering from water crisis every year. It is not possible to meet the daily demand of potable water in the country from groundwater. Due to unplanned water abstraction, the groundwater level is going down every year. As the water level goes down, harmful heavy metals and contaminants are coming up in the tube wells with the underground drinking water. As a result of drinking, people are constantly suffering from various diseases.
Every drop of water is an invaluable resource. Researchers say the water level is falling by about 10 feet every year. The amount of water that is being accumulated underground from the rivers and other reservoirs around the capital to fill this gap is much less than the extraction. Moreover, the toxic water of these water bodies which have been polluted for a long time is going down and polluting the first level of ground water. The second level is at risk. And although the third level is still safe, there are fears about the future. Meanwhile, researchers are noticing the presence of nitrate, sulphate, mercury, lead, arsenic and various organic particles in the first layer of groundwater in Dhaka city. Although the first level water is extracted from the pressure mill, the pure water is extracted from the third level through the second and deep tube well through the motorized shallow tube well. Scientists have been thinking about the issue of groundwater pollution. WASA authorities are not relieved. Officials see the protection of potable water as a challenge. The idea is that Dhaka could become uninhabitable in a few decades due to the lack of potable water if the rivers are not de-polluted.
Groundwater contamination occurs when contaminants mix with groundwater from the soil. This type of contamination can occur naturally due to the presence of small and unwanted substances, contaminants in the ground water, in which case it is better to refer to it as impurity rather than contamination.
Excessive use of groundwater lowers the water level, upsetting the balance in the natural environment or ecosystem. The direct problem is that as the water level continues to fall, the cost of pumping increases and the availability of water decreases, and even the risk of contamination of groundwater may increase. Second, the risk of landslides increases if excess water continues to be pumped from the ground. We all know about both types of risks. That is why the use of water from various surface sources is emphasized in all countries by reducing the use of groundwater. Dhaka WASA is also well aware of this. The agency has long said that the groundwater level in the capital, Dhaka, has dropped at an alarming rate, making the installation of deep tube wells at risk. Shortly after taking over as managing director of Dhaka WASA a decade ago in 2009, he told the media that steps would be taken to reduce the use of groundwater and increase the use of river water. It is necessary to take initiative to implement this directive at all levels of government and non-government. This will reduce the dependence on groundwater to some extent.
According to the IEDCR and CDC program sources of the Department of Health, water is increasing the risk of natural imbalances. As a result of rapid population growth and urbanization, residential areas, hat bazaars, roads, factories, sewerage centers are being built. Toxins such as metals, oily substances, lead, mercury, zinc and chromium are also released into rivers and seawater from sources such as oil tankers. In the last few years, liquid waste from the textile industry, leather industry, refineries, printing presses and large industries has been one of the causes of pollution. On the other hand, when villagers become aware of surface water pollution and start using tube well water, they are exposed to arsenic. In addition, the use of excess pesticides contaminates surface water. These pesticides contain nitrogen, potassium and phosphorus. Excessive use of pesticides poisons the water in the soil. The level of water pollution in urban areas has reached a critical level.
It is mandatory to set up a refinery or effluent treatment plant (ETP) with each industry. Excessive use of pesticides on agricultural land should be reduced. The government should take effective steps to conserve groundwater. At the same time, everyone should be careful not to throw garbage anywhere. Everyone needs to be motivated to throw dirt in a certain place. To prevent wastage of water, use as much as is needed. Keep in mind that groundwater is limited. In particular, dependence on groundwater in agriculture needs to be reduced. Care should be taken to collect rain water so that it can be used in future. Only then can we easily meet the demand for water and prevent groundwater pollution.
(Zannatul Mouwa Naz is a student, Environmental Science and Engineering, Jatiya Kabi Kazi Nazrul Islam University. Email: [email protected]).
