River Danube, Niger and Mekong – comparing the sediment status of large rivers

Abstract

The overall aim to analyze large rivers based on a common / standardized and replicable methodology has been developed from the UNESCO IHP World’s Large Rivers Initiative’s (WLRI) vision to improve the knowledge on the status of large rivers, and to better understand developments, synergies and challenges in large river basins holistically. In a first step of a multi-level approach, conceptualized in the frame of the WLRI, three rivers as pilot rivers – Danube, Mekong and Niger – were studied, whereby this contribution focuses on an integrative assessment of the status of the Danube, Niger and Mekong Rivers. By applying a common methodology of analysis to each of the rivers, for the first time, comparable analyses enable a uniform assessment of the respective river and its basin. It became clear that all three rivers are undergoing major changes with different focus. For the Danube, flood protection, navigation and hydropower have been developed for a long time. As a consequence, the sediment regime is totally disturbed with only 10 % of the river length to be in equilibrium, the rest shows erosion or sedimentation. The Niger River is very sensitive to changes in the flow regime. Discharge amount as observed before 1970’s has not been reached in 2001. Climate change impact seems to be apparent. At the Mekong the long-term seasonal discharge within the last 75 showed an increase of dry discharge by 7% and a reduction of wet discharge by -11%. For all three rivers a significant reduction of the suspended load transported to the Delta and the Sea can be observed, however with different temporal and spatial extent. In the contribution also a need for improved monitoring in various topics is elaborated.