Inland Delta Building Activity of Kosi River

Despite attempts by several investigators to diagnose the instability of the Kosi River flowing in the Bihar state of India, a complete understanding of the river behavior had never been accomplished. The movement of the river, approximately 70 miles in 230 yr, could be explained by the understanding of the phenomenon of the inland delta building activity of the Kosi. The rate of building of the conical delta and of the westward movement of the river, estimated by using this approach, agree well with observed rates. Other characteristics of the river such as sudden change in the slope and systematic changes in the courses can also be satisfactorily explained. To provide relief to the areas affected by the river, the Kosi project consisting of 150 miles of flood embankments, construction of a barrage, provision of irrigation of 2,600,000 acres and power generation of approximately 20,000 kw, has been completed. Prediction of future trends of river regime is attempted and precautionary measures for safety of the project works are indicated.