A river is a natural stream of fresh water fed by rain or melting snow during the monsoon. On its onward journey, many tributaries join in and the river and its tributaries form the drainage basin. The river collects the available runoff and groundwater discharge and flows into an ocean or a landlocked water body at the end of its journey. A perennial river is a living ecosystem, an essential component of the natural hydrological cycle and its continuous flow is an inbuilt character of its health.
The environmental flow is that optimum quantity of continuously flowing water in the river system which is essential for the discharge of its natural responsibility i.e. maintaining the ecosystem, safety or survival of dependent creatures, vegetation, etc. A river system performs its natural functions continuously. While during the rainy season, the flood waters transport sediments, organic matter and dissolved salts, during the dry months, the river flow carries dissolved compounds even though the transportation of rock fragments, soil, etc reduces considerably. Rivers form delta of different shapes and sizes by depositing these fine materials. A river dries when it stops receiving surface water and/or groundwater.
The current approach of the town and country planning department is to build and operate STPs on the main rivers at identified locations only. Without covering the entire basin, all sources and relevant aspects, rivers will be cleaned only partially and their wholesomeness will not be achieved. We also know for certain that a flowing river dilutes impurities and self-cleaning mechanism keeps the water pure. We must remember that the solution to this pollution is not just partial but a wholesome treatment of rivers.
K. G. Vyas is a geologist and a well-known writer on environmental issues. He has served as a consultant for the Rajiv Gandhi Drinking Water Mission in Madhya Pradesh.