Saving the degraded river basin

Assam shows how water needs can be met without disturbing a river’s ecology

By Arup Kumar Sarma
Published: Sunday 11 August 2019

THE STATE of a river basin can be evaluated using parameters such as its water yield, sediment yield, quality and quantity of ground, and surface water, vegetation health, soil productivity and climate resiliency.

The hydrological response and climate resiliency of river basins change due to the variations in precipitation, temperature, topography, lithology, vegetation and other climatic characteristics. While many sub-basins with subtropical climate and montane ecosystems in the Brahmaputra and the Ganga are experiencing increased flooding, other rivers are water stressed due to anthropogenic and climatic factors.

Studies on the impact of climate change on precipitation indicate the possibility of high intensity rainfall of short duration and long dry spells that lead to flood and drought.

A river basin can be called degraded if the natural productivity, water availability and its capacity to absorb impacts of extreme events deteriorate from that of pre-industrial times. To evaluate degradation, one needs to compare the response of the basin with its response before human interventions. But human beings are part of nature and their actions to meet their needs are natural.

With these philosophies, the concept of optimal ecological management practices (EMP) was developed, which aims to revert sediment yield, water yield and water quality parameters of a degraded basin by using ecologically sustainable and economically viable management practices. EMPs include afforestation and are a judicious combination of vegetative and other traditional measures.

To estimate the affordable basin population of flood-prone cities, SAFE (sustainable accommodation through feedback evaluation) carrying capacity was developed. Sustainable approach of rainwater management and application, or SARMA system, helps in climate-resilient rainwater management using multiutility ponds.

It is implemented in tea gardens. Assessment of settlement in ecosensitive areas, or ASEA, assist in understanding settlements in the eco-sensitive wetlands and hills near or within urban areas. ASEA helps in policy making on urban development.

Some of these initiatives were supported by the Union Ministry of Housing and Urban Affairs. The Assam government implemented it in two pilot watersheds with encouraging results. The concepts can well be used to manage all river basins. The Union government’s afforestation efforts can be effective if plantation locations are identified using the EMP concept.

River basin degradation is a socio-economic problem. The challenge lies in finding ways to satisfy our needs without disturbing the ecological balance. As a river basin spreads over many states, a holistic project prepared with a win-win situation to all riparian states can form the basis for political negotiation and can pave the path for a better future.

(Arup Kumar Sarma is a professor at IIT Guwahati)

(This article was first published in Down To Earth's print edition dated August 1-15, 2019)

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