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.
How things change with time
In ancient times, the demand for water was very low. Barring a few exceptions, the river water was seldom used directly and the construction of large dams across rivers was uncommon. Rainwater was collected mostly in village tanks; in south India, village tanks were filled by diverting the partial flow of rivers. Water management was mostly community-owned and water bodies were protected through religious traditions and customs. This approach continued in India till the Mughal period.
A different approach for river water use was introduced by the British rulers in India during their incumbency. In the 20th century, water resources departments made enormous efforts to harness the runoff available from the rivers. This effort increased inland water storage, facilitated food production and made India self-sufficient. Of the inland water storage on the river courses, nearly 690 BCM (billion cubic metre) is utilisable for irrigation of nearly 35 percent area, leaving nearly 65 percent area as rainfed or at the mercy of rainfall. This is due to various topographic constraints and uneven distribution of water.
Under the river interlinking initiative, nearly 173 BCM water is proposed to be transferred from the Brahmaputra river to irrigate about 35 million hectares. This water is proposed to be stored in 16 reservoirs in the Himalayan component and 58 reservoirs in the Peninsular India.
Increasing challenges in river water use
The major challenges of the 21st century in river water use is the increasing pollution in the rivers and the partial failure of the conventional methods of pollution control due to various reasons. The depletion in non-monsoon flow in rivers (more pronounced in peninsular rivers) is enhancing the pollution load and making the situation more difficult. Due to these challenges, the revival of the rivers in a holistic way has become a non-negotiable need of the day.
River science experts and environmentalists lay emphasis on the wholesomeness of a river system which includes components like aviral dhara (continuous flow), nirmal dhara (unpolluted flow), the geologic entity (natural function) and the ecological entity (balance between various living species and the physical environment). These requirements, combined with the probable impacts of climate change, are becoming serious concerns of the 21st century in river water use and planning. Since the central government, as well as many states, are undertaking initiatives to revive the past glory of the Ganga, we need to vividly understand the approach adopted and the future road map of the revival.
Initiatives to revive rivers
The Ganga basin covers 26 percent of landmass and passes through five states. Despite an enormous amount being spent on its cleaning, the river continues to be polluted. Today, pollution can be seen even in those stretches which were clean before. We all know that enough water flows during monsoon to clean the river system. The pollution is the result of the inability of the river flow to dilute after the monsoon and remove pollutants in the holy river, along with insufficient number and capacity of sewerage treatment plants.
In its journey from Gangotri to Diamond Harbor, the Ganga receives 6087 MLD (millions of litres per day) pollutants. This quantity is more than 80 percent of the capacity of the sewerage treatment plants (STPs) installed. Therefore, there is a need for more STPs to be constructed to clean the river. Apart from STPs, other initiatives like riverfront development will facilitate the cleaning programme. It is hoped that since these proposals come after more than two years of brainstorming exercise, the past shortcomings and inadequacies will not hamper the results. Suboptimal functioning and meeting recurrent expenditure will also not be a concern for the local bodies and industries. It is believed that the new initiatives will help achieve the goal and will be replicated successfully in other parts of the country and could become a role model for other states.
The Madhya Pradesh government has prepared a project to establish water plants and STPs in 24 cities where the pollution level is high in the river. The government proposes to use the treated water for agriculture, industries and fire services. Two projects are being finalised--one with the KFW (German mission) and the other with ADB, costing Rs 450 -500 crore and Rs 1500 crore respectively. The projects will be implemented by the town and country planning department. The government’s plan is to clean Narmada river at 14 locations, while the remaining 10 locations are situated on rivers like Betwa, Shivna, Mandakni, Parvati, etc. The projects will get loans from the financial agencies mentioned above, and the state government will bear 30 percent cost from their own internal sources.
All about pollution sources
The rivers always have two distinct sources of pollution. The visible source of pollution is from untreated or partially treated sewer, industrial waste, etc and this pollution reaches the river only when there is sufficient flow in the river. If the flow ceases en route, the pollutants join the groundwater and become invisible. The other sources of invisible pollution are the insecticides, pesticides and fertilisers used in agriculture. Other common substances in the groundwater are sodium, potassium, calcium, magnesium, chloride, carbonate, bicarbonate and sulphate. Apart from these, iron, manganese, fluoride, nitrate, strontium and boron, too are found in small quantities. The river receives invisible pollution continuously from underground water, hence any initiative aiming to clean rivers, must include all possible sources that cause pollution.
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.