Changing the Flow: Impact of transferring river water

Dr R.N. Sankhua, Chief Engineer (South), National Water Development Agency

The National River Linking Project (NRLP) water transfers aim to reduce the impact of recurring flooding in Eastern India while easing water shortages in western and southern India. Once the NRLP is completed, In­d­ia’s utilisable water resources are expected to grow by 25 per cent, and the disparity bet­ween the water resources in various regions will decrease. The issue of India’s limited per capita storage is expected to be resolved by the inc­reased capacity. It is currently only 200 cubic metres (cum) per person, compared to 5,960 cum in the US, 4,717 cum in Australia and 2,486 cum in China.

Water transfer from one state to another would also require enormous storage facilities, which have a significant negative environmental impact. By changing the dynamics of water flows, the interlinking project is expected to ha­ve an impact on all the ecosystems in ecological hotspots such as the Western Ghats, the Gan­ge­tic plains and the Sundarbans. Water is a state subject and the interlinking of river (ILR) plan exacerbates the existing water distribution and management issues in the riparian states. Some ILR programmes have global repercussi­ons, which could lead to strained relations with nei­gh­bours such as Bhutan, Nepal and Banglade­sh. Given the fundamental significance of w­a­ter for both life and the economy, such diversions do undoubtedly raise the most serious concerns with respect to inter-basin transfers, frequently sparking demonstrations and opposition in the supplying region.

Surplus water presumptions in ILR

According to a recent study of water availability using space inputs by the Central Water Commission, the major donor rivers such as the Brahmaputra and the Barak river system (528.27 bcm of yield against utilisation of only 24 bcm), the Ganga (526.09 bcm) and the Teesta in the NRLP have surplus river flows under various environmental management co­nditions. Under slightly altered environmental conditions, the Mahanadi and the Godavari can have surpluses. However, they are able to manage them under somewhat altered environmental flow conditions due to inter-basin transfers to the Mahanadi and ultimately the Go­davari. The primary necessity, if these surpluses are to be transferred somewhere else, is to protect their environmental flow requirements during the months with low flow.

Costs and benefits of transferring irrigation water

The NRLP suggests requirements for the volume of water transfers and the returns on irrigation investments in specific linkages as the major concerns. However, given the high-value agricultural production patterns and the interdependent links envisioned in the NRLP, the advantages of irrigation may outweigh its disadvantages. It is also important to evaluate how certain benefits will affect the economy, such as how drought and floods will be somewhat mitigated, as well as how fishing, picnicking and amusement parks will generate more cash. Irrigation is intended to benefit most fr­om the NRLP water transfers. New irrigated crop­lands totalling 34 million acres will be added.

Impact on monsoons and climate change

Even without ILR in place, India has reasons to be concerned about climate change, such as the around 40-day delay in the monsoon’s retreat. Any negative impact on water availability brou­ght on by glaciers, reduced precipitation, or increas­ed flooding in some areas would endanger food security, and cause the extinction of speci­es vital to rural households’ livelihoods. This will have a negative effect on the coastal system due to the rising sea levels and an increase in extreme weather events. Besides this, it would be detrimental to attaining important national development goals relating to other systems such as habitats, health, energy demand and infrastructure investments. Non-climatic factors also have an impact on systems and industries directly or indirectly by altering climate factors such as reflected sun radiation and evaporation.

Increased water storage in its various for­ms, such as soil moisture, ponds, groundwater, small and large reservoirs, and their combination through ILR, should be used to combat the anticipated increase in variability in water availability due to climate change. This will reduce the salinity of groundwater and the river channels. States should be given incentives to im­prove their water storage capacity, which sh­ould involve, among other things, restoring old­er water harvesting systems and waterbodies. In addition, ILR would increase water conservation and precipitation.

Hydropower development

At present, the share of hydropower is only about 25 per cent of the total power generation since our hydropower development is only about 28,000 MW out of the total potential of about 84,000 MW. Merely 2 per cent of the potential of the Northeast has been developed so far, although 45 per cent of the country’s total hy­dro­­power potential lies there. The proposed grid, especially the Himalayan component, is go­ing to provide 34,000 MW of additional hy­dro­po­wer for peaking purposes and for increasing the desired share of hydro to about 40 per cent.

Water supply for drinking and industrial use

In light of the irregular rainfall patterns, the fulfilment of domestic water needs to be given top priority in our water policy. In addition, India’s water strategy should place a high premium on safeguarding rain-fed farmlands. The idea behind the interlinking project is to transfer water from surplus rivers to deficit rivers, thereby ending human suffering caused by droughts and water scarcity.

Further, sanitation needs to be the country’s top priority, especially in rural India where basic sanitation facilities are still lacking. In order to meet the demand by 2050, the projected National Perspective Plan (NPP) of the Ministry of Jal Shakti calls for supplies of clean drinking water and water for industrial usage of 90 bcm and 64.8 bcm respectively. This will ease the current suffering, especially for rural women who travel long distances each day to collect water for domestic use and drinking. Also, no industrial expansion is possible without a reliable supply of water.

Out of the 3,880 bcm of average annual rainfall, about 1,166 bcm of fresh water is wasted and flows out to the sea. The main challenge is to divert water causing devastation and running waste into the sea (especially from the Brahmaputra and Ganga) for productive use in the drought-prone areas in the south and the west so that the country gets rid of the current flood-drought-flood syndrome. The NPP is envisaged to give the benefit of 25 million hectares (ha) of irrigation from surface waters and 10 million ha through the increased use of groundwater, raising the ultimate irrigation potential from 140 million ha to 175 million ha.

Environmental and ecological concerns

The major concerns include the fundamental limitations of socio-economic viability, environmental effects, human displacement and rehabilitation, the difficulty of resource mobilisation and geopolitical restraints. Unfavourable effe­cts include salinity intrusion, pollution concentration increased methane emission from reservoirs, changes in the river regime, aquatic and terrestrial biodiversity, groundwater recharge, diversion of forest areas and submergence of land leading to deforestation and soil erosion. It is impossible to avoid rebuilding and rehabilitating a sizeable population that has been displaced, submerged large areas of forest, agricultural land, and non-agricultural land, and suffered psychological harm due to cultural alienation as a result of the resettlement of the local indigenous tribal community.

River linking may bring consequential changes in the physical and chemical compositions of the sediment load, river morphology and shape of the delta formed at the river basin. Damming India’s east-flowing rivers will prevent downstream flooding, but the sediment load could destroy delicate coastal habitats and lead to delta erosion. Sediment management raises serious issues, particularly for the Himalayan system. Transferring water from the surplus Himalayan rivers to the deficit regions in the southern port of India requir­es factoring in the differential sediment regime defining the flow regimes, which would modify the ecosystem structures in both areas.

Further, interlinking a toxic river with a non-toxic one will have a devastating impact on all our rivers, and consequently, on all human be­ings, fish migration, aquatic biodiversity and wild­life. According to certain environmentalists, the water flowing into the sea is not waste, but a crucial link in the water cycle. With the link broken, the ecological balance of land and oceans, freshwater and seawater, also gets disrupted. There is great trepidation that the diversion of unutilised water from the Brahmaputra (potential of 528.27 bcm) and the Ganga (potential 526 bcm) may result in an ecological setback.

In sum

Aptly planned water resource development and management would be able to alleviate poverty, improve the quality of life, reduce regional disparities and maintain the integrity of the natural environment. It is essential that environmental safeguards such as a comprehensive environment impact assessment and strategic impact assessment are properly implemented in a coordinated manner.