Guwahati city is one of the most ecologically endowed urban areas of India. The city boasts of many hills with lush green cover which are inhabited by different forms of wildlife. The city also has two notified wildlife sanctuaries apart from eight other forests reserves. Further, the city also takes pride in the existence of the Deepor Beel – the lone RAMSAR site of Assam. Guwahati is also one of those metropolis of the country where we find lots of natural streams and river channels traversing the entire topography. The Bharalu river, Mora-Bharalu, Basistha and Bahini river, all of them together forms an intricate hydrological network within the landscape of Guwahati city. However, even though this rich ecology seems to be an indicator of being sustainable and eco-friendly, yet there are numerous other reasons because of which people no longer consider this city as habitable. One of such numerous reasons is the rapid degradation of the natural waterbodies including the streams and rivers.
In fact, the Bharalu river, which is one of the south bank tributaries of the mighty Brahmaputra river, is listed as one the most polluted rivers of the country. Since the last four decades the Bharalu river has faced severe degradation owing to severe pollution, alteration of hydraulics, loss of ecological habitat, etc. Rapid and unplanned urbanization across all parts of Guwahati city is at the most the root cause of all problems of Bharalu river. The negative changes that occur to such streams and rivers that drains urban land are collectively known as “urban river syndrome”. Impacts of urbanization on a river system can be multifold. The major categories of elements that can be impacted upon are the catchment processes, flow regime, habitat, water quality, sediment chemistry, aquatic and riparian biodiversity. Some very predominant signs of urbanization and its impact on streams and rivers include the increase in frequency of overland flow, pollution load, magnitude of high flow, rise and fall of storm hydrograph, increased impacts of nutrients (Nitrogen, Phosphorous), toxicants and also the increase in invasive species. On the other hand, decreasing trends are observed in case of infiltration, lag time to peak flow, nutrient uptake and also there is a significant decrease in abundance and diversity of fish, invertebrates and macrophytes. Most of these symptoms are observed in the case of Basistha-Bahini-Bharalu stream network of Guwahati city. The population of Guwahati city is estimated at around 7 lakhs and the population density is 2695.43 per sq.km. as per census 2011, which is very high. So it is very obvious that such a high population will exert tremendous pressure on the natural resources for meeting the needs of infrastructural development as well as for fulfilling basic human needs. The human pressure is evident from the fading green cover from the hills and the conversion of once vibrant natural streams, the Bharalu and Bahini, into putrefying sewage canals. A growing concept among water professionals across the world is that of “River restoration”, which includes all actions aimed at improving the river health. River restoration managers aims not only to improve the health of a degraded river but also to improve the overall ecosystem function and related ecosystem services. River restoration becomes necessary in case of rivers where the system have degraded to a point where they can no longer deliver the expected ecosystem services. However, it is often recognized that urban rivers which are highly degraded and modified, restoring such waterbodies to a pre-development state or to a state wholly resembling a natural system is highly unlikely. At least, this is not hundred percent achievable when considerations are to be made with regards to maintaining the societal function expected from the river system. Yet, river restoration benefits cannot be undermined because such restoration in urbanized settings has helped bring about wider socio-economic benefits as evident in many cases worldwide. This is why a robust restoration and rejuvenation plan must be developed based on sound scientific inputs and thereafter implemented for the entire stream network of Basistha-Bahini-Bharalu of Guwahati city. While considering restoration of our city rivers and streams, there are 3 key challenges before us:
It is a well-known fact that at different times in the last five decades, all these departments and agencies have been engaged or entrusted with some works related to the city rivers or other waterbodies. Lots of money have also been utilised for various kinds of projects, particularly for dredging and cleaning of the Bharalu, Mora Bharalu and Bahini river by the GMDA. But, till date there has been no permanent solution to the problems associated with these rivers. Rather, the problem has been attenuated by many times due to lackadaisical efforts of government agencies and also due to implementation of faulty projects. Therefore, it is important to realise the fact that an integrated strategic approach is the due need of the hour for restoring of Basistha-Bahini-Bharalu river network. To address the challenges mentioned above, a strategic approach shall be required for a complex network of streams like that of Guwahati city. It would require-
Finally, all restoration activities should be manned and executed in such a way that it ensures sustainability of the restoration outcomes. Restoring Basistha-Bahini-Bharalu river network and other smaller streams too, must involve all stakeholders including local communities. Inter-agency collaboration and community participation shall be the key to the success of restoration projects.
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