Continuous and Unpolluted Flow in Ganga River : Hydrological Research Needs

[C. P. Kumar]

Ministry of Water Resources, River Development and Ganga Rejuvenation (Government of India) has prioritised rejuvenation of Ganga river with the objectives of taking comprehensive measures for restoration of the wholesomeness of the Ganga ecosystem and improvement of its ecological health, with due regard to the issue of competing water uses in the river basin. 

The wholesomeness of the river can be grasped in terms of four defining concepts: "Aviral Dhara" (Continuous Flow), "Nirmal Dhara" (Unpolluted Flow), Geologic Entity, and Ecological Entity. The goal is effective use of the water resources to optimise national welfare and Ganga Rejuvenation with guiding philosophy of equity, sustainability, stakeholder involvement, mass awareness and local capacity building.

Aviral Dhara (Continuous Flow)

For a given geological-climatic setting, alluvial rivers achieve stability through long-term balance between various parameters such as water and sediment flow rates, temporal variations of flow, terrain gradient, and seepage flow rates. "Aviral Dhara" emanates from this long-term balance of rivers. A direct violation of Aviral Dhara is due to dams and barrages, which snap the longitudinal connectivity in rivers and alter river water and sediment flows. However, since National River Ganga Basin (NRGB) is hydraulically connected by groundwater flow, water withdrawals/recharges from different regions of the basin also affect the river. Thus, while longitudinal connectivity in rivers is a pre-requisite for Aviral Dhara, maintaining Environmental Flows (or E-flows) needed for the sustenance of rivers also depends on judicious management of the basin’s waters. Available data indicate that human water use has been increasing rapidly of late, and probably increasing beyond the renewal capacity of the basin. Hence, either (i) water availability in the basin must be increased through increased storage, preferably by "distributed storage" in locally manageable and ecofriendly water bodies and aquifers, and/or (ii) water demands must be reduced through more efficient water use. These issues call for both technical interventions and changes in government policies on NRGB’s water resources. For dams and other structures that disrupt or change river flows, the maintenance of E-flows in the river network is essential, besides fulfilling other safety criteria. The estimated E-Flows for select locations in the Upper Ganga reach – which has many existing and potential hydropower sites – have been presented to enable their inclusion in the design and operation of these dams and barrages.

Nirmal Dhara (Unpolluted Flow)

The Ganga river’s present-day water quality is abysmal due to anthropogenic wastes polluting the river network in various ways. The main approach in Ganga River Basin Environment Management Plan (GRBEMP) has been to identify the types of pollutants, their sources of generation, and the feasibility of collecting and treating them to the degree needed for reuse and/or safe environmental disposal. Urban and industrial wastewaters are major point sources of pollution that need immediate remediation. For municipal wastewaters it was found that it is economically feasible to treat them to the point where they can be re-used for noncontact purposes, the cost of such additional treatment being only about 1 paisa per litre at 2010 price levels. It is therefore recommended that all Class 1 Towns of NRGB immediately embark on such treatment through competent service providers under the Design-Build-Finance-Operate model, whereby the service provider receives remuneration for providing reusable-quality water over a reasonably long contract period. It is also recommended that all fresh water withdrawals from the basin be priced at least 50% higher than the recycled water, considering the minimum costs of full treatment in nature. For major polluting industries (such as tanneries, pulp and paper units, distilleries and dyeing units) in NRGB, the cost of treatment for reuse purposes are higher, but these costs are much less than the damage caused to NRGB otherwise, justifying the expenditure on such treatment.

Geological Safeguarding

Modern human activities – such as underground explosions, excavations, tunneling, rock fracturing, mining, and operation of large reservoirs – can damage the geological formations supporting the basin’s aquatic systems. Overwithdrawal of groundwater from confined/ semi-confined aquifers may also create unbearable overburden pressures, causing land subsidence. Geomorphologically, rivers and wetlands are vulnerable to various land-use stresses. Land-uses needing immediate control are deforestation, construction activities on riverbanks and fragile slopes, agricultural practices that increase soil erosion, sand mining from river beds, urban, industrial and infrastructure projects that adversely affect drainage patterns, and local flood control works and river bank modifications.

Ecological Restoration

The ecological balance in the Ganga river network has been critically affected in recent times, with major indicator species (such as Dolphins, Trouts, Carps and Hilsa fishes) having dwindled or disappeared. The analyses indicate that the ecological status can be largely restored by adhering to the principles of "Aviral Dhara" and "Nirmal Dhara" by ensuring unpolluted E-flows and variable flow regimes, protection of spawning and breeding grounds of native species, elimination of competing exotic species from the Ganga river network, and protection from human encroachments.

It would be necessary to list/elaborate specific hydrological studies (dealing with the above concepts) required to support the decision making process for rejuvenation of Ganga river. Any ideas or suggestions are welcome.

Thanks & Regards

C. P. Kumar

=====================================================

C. P. KUMAR

Scientist 'F' 

National Institute of Hydrology

Roorkee - 247667 (Uttarakhand)

INDIA

Web Page: http://www.angelfire.com/nh/cpkumar/ 

          https://in.groups.yahoo.com/groups/cpkumar/ 

=====================================================