CPGB in collaboration with IIT Guwahati, organized an International meeting at Guwahati on December 18-19, 2010. The title of the meeting was “Seeking Sustainable Solutions for the Brahmaputra: Challenges and Solutions”. The meeting was sponsored by the Government of Assam and invited 200 Professionals, Professors, Private Consultants and Engineers from the Water Resources Department (WRD), Government of Assam attended the meeting. The meeting was successful with 34 technical papers which were presented in six following topics and sessions:
Out of above diverse important issues discussed, the Flood and River Bank Erosion of the Brahmaputra was considered as the most important issue. A group of Engineers under Dr. Arvind Phukan’s chairmanship, met at the end of the meeting on December 19, 2010 and Dr. Phukan presented about the CPGB’s comprehensive review of the severe river bank erosion of the Brahmaputra River that occurred at numerous locations in Assam during past six decades. Then, he identified mitigation of chronic River Bank erosion of Majuli Island as a “Piot Project”. Accordingly, a Majuli proposal had been prepared by a group of CPGB Engineers under Dr. Phukan’s leadership and submitted to the Secretary, Ministry of Water Resources Department (MoWRD), Govt. of India on March 25, 2011. After six years of meetings and reviews with MoWRD, the CPGB’s original proposal titled “Sustainable Design Solutions for Mitigation of Flooding and River Bank Erosion of Majuli Island of Brahmaputra” was revised and being submitted to the MoWRD, River Development and Ganga Rejuvenation, Govt. of India by IIT Guwahati in collaboration with CPGB on May16, 2017.
The IITG-CPGB proposal has been prepared with input and significant contributions from internal four working groups. They are given below:
Once the IITG-CPGB team is entrusted, the Project Team will arrange meetings to prioritize the data and information that are needed for the design and the mathematical modeling. The following pictures show typical River bank erosion of the Majuli Island at various locations.
Photo. 1: Typical View of Eroded River Bank at Kumar Gaon, Observed by CPGB Team during the field trip on Match 23-24, 2011
Photo. 2: Typical View of Eroded River Bank at Kumar Gaon, Observed by CPGB Team during the field trip on Match 23-24, 2011
Photo. 3: Typical View of Eroded River Bank at Molual Gaon Observed by Dr. Phukan during the field trip on Match 23-24, 2011
Photo. 4: Typical View of Eroded River Bank at Upstream of Spur #1, Observed by CPGB Team during the field trip on Match 4-24, 2016
Photo. 5: Typical View of Eroded River Bank at Downstream of Spur #4, Observed by CPGB Team during the field trip on Match 4-24, 2016
The Purpose of the sustainable design solution task is to design flood and erosion prevention measures as well as mitigation to reduce flooding and erosion on the Majuli Island caused by the Brahmaputra River.
Prevention of flooding and mitigation of the erosion problem must be selectively developed with the most efficient solutions possible while considering the available resources and construction capability. The solutions for the erosion measures can be broken down into structural and non-structural solutions. The design team will evaluate the results of the inventory of available resources as well as the fluvial geo morphologic information and the numerical hydrodynamic modeling results. This information will be used as the basis for formulating sustainable design solutions to the flooding and the bank erosion problem. It is recognized that each strategic location may require a combination of measures to mitigate each identified erosion problem instead of applying one solution to solve all problems.
The extensive frequent floods from the Brahmaputra River inundate areas of the Majuli Island imposing severe distress and costs on the region. As a result of this, flooding needs to be managed to improve economic development.
Historically, the causes of the flooding have been from high flows in the Brahmaputra River, synchronized with high flows from many tributaries, and from heavy rainfall on the floodplains combined with insufficient slope for depressed areas to drain by gravity to the river.
It is to be recognized that the complex braided channel pattern including the erratic shifting nature of the Brahmaputra River have important implications of flood control by embankments. Given the high rates of channel migration and bank erosion in many places along the Brahmaputra River, unprotected embankments cannot be expected to remain immune to river erosion for many years, even if they are initially set back some distance from the banks. Also, the shifting channel pattern means that at many locations, flood flows can strike the banks or embankments at severe angles of attack, producing deep scour in the river bed and there by undermining the banks causing erosion.
The primary recommendations for river bank protection and mitigation will be structural recommendations. Non-structural recommendations, where appropriate will form a support and backup role to reduce impact and induce siltation.
These measures can comprise of techniques that have a long history of success locally and throughout the world. These techniques may include:
There are many factors contributing to the web of erosion problems that are associated with the Majuli Island within the Brahmaputra River. Sediment from upland reaches of the flood plain is carried by surface water run of land to a lesser extent, wind-blown. In addition to structural strategies of infrastructure to mitigate flood and river bank erosion non-structural measures can provide short-term reduction of erosion during construction and long-term mitigation of erosion. The IITG-CPGB team will present a holistic approach for mitigating flood and river bank erosion to include in its design non- structural recommendation.
The non-structural approach would provide a variety of proven erosion control measures through strategic establishment of native plant species and site specific or condition specific land management recommendation. Native plants have the advantage of being naturally adapted to environmental conditions within the region and sub-regions along the Brahmaputra River and more specifically the dramatic bank erosion occurring at Majuli Island. Improving the management of upland soils such as agricultural lands as well as the application of best management practices for reducing surface water run-off will be included in the design recommendations.
Proposed Project Team consisting of well qualified and experienced Professional (Bringing total 300+ years), is presented in the following organization chart.