from India . The entire watershed of the river is the most fertile agricultural zone . The upper course of the river is famous for crops like ginger , medicinal herbs and fruits like oranges , pomegranates etc . The middle course comprises production of tea and corn dominated while the long course is dominated by rice , jute and tobacco . The bamboo and the mat sticks are cultivated in the lower basin . The river enters Bangladesh at Ghoksadanga district to meet the Brahmaputra or the Jamuna . Subansiri River : Subansiri is the largest tributary of Brahmaputra and originates in the Himalayas from the Tibet Autonomous Region of China at an altitude of 5340 m . It flows east and southeast into Arunachal Pradesh of India and then south to the Assam Valley , where it joins the Brahmaputra River in Lakhimpur district . The length of the river Subansiri from its source of origin to the point of confluence with the river Brahmaputra is 520 km . with a drainage basin 32,640 square kilometers . It contributes 7.92 % of the Brahmaputra ' s total flow . Its discharge is huge ; maximum observed discharge was 18,799 cubic metres per second . Throughout its journey from the Central Himalayas to the Arunachal foothills , the river Subansiri receives the water discharge from numerous mountainous streams . It is the life line
Newsletter No . 63 ; IRBMS of the downstream inhabitants . It plays an important role to the distribution of terrestrial as well as aquatic biodiversity , agricultural diversity and socio economic aspects of local communities which live in the downstream of the Subansiri River , whose local economies are linked with the river system and the it ’ s associated wetlands ( bils ).
A large dam is under construction of 2000 MW capacity known as Lower Subansiri Hydroelectric Power Project by NHPC on the Subansiri river close to the Assam-Arunachal Pradesh border town of Gerukamukh in Dhemaji district of Assam . The height of the dam is proposed to be 116 metres and there will be 8 turbines of 250 MW each in the power station . The total downstream floodplain of the river Subansiri from the dam site at Gerukamukh to its confluence with the mighty river Brahmaputra is approximately 130 sq . km . This hydroelectric project can have serious impact on survival of some species that live and depend on the Subansiri river ecosystem . All the systems in the Subansiri River are delicately balanced and interrelated . Therefore , disrupted food chains and other systems will have serious impacts , affecting both the terrestrial and aquatic species . Reservoirs created by the dam can also block animal migrations towards upstream . Besides , the total aquatic habitats will also be destroyed . The downstream areas of the river Subansiri is
6
Integrated River Basin Management Society