It is believed that life originated in water before it invaded the land. Water is, in fact, a precondition for life and essential for the sustenance of all forms of life, food production, economic development and for general well being.
The primary source of fresh water on the Earth is precipitation that comes in the form of rain and snowfall. The rivers are the main outlets or sources of this freshwater, which is then termed as surface water.
Apart from the water available in the various rivers, the ground water is also an important source of water for drinking, irrigation, industrial uses, etc.
Over-utilization of Surface and Groundwater
Worldwide the largest use of water is for irrigation.
Secondly is for industries, and the third is for direct human use.
Given existing status of the water resources and increasing demands of water for meeting the requirements of the rapidly growing population, the need of the hour is to conserve and manage our water resources. We have to safeguard ourselves from health hazards, to ensure food security, continuation of our livelihoods and productive activities and also to prevent degradation of our natural ecosystems. Over-exploitation and mismanagement of water resources will impoverish this resource and cause an ecological crisis that may have serious impacts on our lives.
Consequences of Over Exploitation of Surface Water Resources
To trap and control flowing surface water, dams and reservoirs are build. The stored river water along with rainwater in a dam or a reservoir is used for irrigation, electricity generation, water supply for domestic and industrial uses, flood control, recreation, inland navigation and fish breeding.
These dams and reservoirs have enormous ecological impacts. When a river is dammed, valuable fresh water habitats are lost. Sometimes the river’s flow is diverted to cities or croplands, which affects the fishes and other the aquatic organisms. The wildlife that depends on the water or the food chains involving aquatic organisms is also adversely affected. Sometimes fishes swim up river from the ocean to spawn are seriously affected by reduced water level. The reservoirs, which are created on the floodplains, also submerge the existing vegetation and soil leading to its decomposition over a period. Due to a diversion of the river’s flow, estuaries are also affected because less fresh water enters ad flushes the estuary. Consequently, salt concentration increases profoundly affecting the estuary’s ecology.
Consequences due to Depletion of Groundwater
If the groundwater withdrawals exceed its recharge, the water table falls. When the water table falls, the springs and seeps start drying up and even the stream and the rivers are affected. Thus, surface water diminishes and this creates the same results as the diversion of surface water. Over the ages, groundwater has leached cavities in the ground. The water fills these spaces and helps support the overlying rock and soil. Due to fall in water table, this support is lost and there may be gradual settling of the land, known as land subsidence.
Land subsidence may cause building foundations, roadways and water and sewer lines to crack. In coastal areas, this phenomenon may cause flooding.
Another problem resulting from dropping water tables is saltwater intrusion. In the coastal areas, the springs of overflowing groundwater may lie under the ocean. Thus, wells in the coastal areas have fresh water. Lowering of water table at a rapid rate reduces pressure in the aquifer and thus permitting salt water to flow into the aquifer and hence into wells.
Water Conservation and Management
Water resources can serve more people by wise and good management. Every human being has the responsibility to conserve water used in various activities. Several approaches to conserve and manage the water resources are:
- Avoid polluting-Pollution makes water unfit for use. Renewing takes time and nature may not be able to renew it if the pollution is bad. Properly dispose off oil so it does not get into water. Use pesticides sparingly and do not use excess of detergents and soap.
- Dispose off properly- Proper disposal of wastewater helps protect natural supplies. Wastewater can be partially renewed in treatment plant facilities.
- Install conservation processes- Many approaches can be used to conserve water supplies and quality. Approaches that conserve soil also conserve water. Terraces, ponds, and mulches can be used to reduce water runoff. Factories can seek efficient ways of using water.
- Have good equipment- Pipes, pumps, and other facilities should be free of leaks. Leaky equipment wastes water. It also costs more to operate a leaky system because more water must be pumped just to have enough to do what is needed. More energy is needed to power the pumps.
- Reuse-Water used for one purpose can often be used for other purposes before it is released. The additional uses may help clean the water. An example is using wastewater to raise fish and grow non edible plants. Both activities remove nutrients in wastewater from food manufacturing operations.
- Renew used water- Renewing wastewater is helping nature do its job. it may involve filtering to remove solid materials. In holding reservoirs, it might include promoting the growth of microbes so processes occur, such as the nitrogen cycle.
- Efficient use of water- Everyone can make better use of water by consuming a little less water for the daily chores.
Water Harvesting for Conservation
From the ancient times, there exists an extraordinary tradition of water harvesting system. People have in depth knowledge of rainfall regimes, and soil types and thus have developed various techniques to harvest rainwater, ground water, river water and the flood water in keeping with the local ecological conditions and their water needs. In hills and mountainous regions, people build diversion channels like the ‘kuls’ of the Western Himalayas for agriculture. Roof top rainwater harvesting is commonly practiced to store drinking water. Huge underground tanks are constructed inside the main house or courtyard and are collected to the sloping roofs of the houses through a pipe. Rainwater falling on the rooftops flows down into the tanks through the pipes.