River Morphology Modeling at the Downstream of Progo River Post Eruption 2010 of Mount Merapi

Mt.Merapi is one of the most active volcanoes in Indonesia. Some of the rivers that the origin is located at Mt.Merapi have a large amount of sediment resources after eruption in October-November 2010. The total volume of sediment is estimated at 130 million m3.The deposited sediment flows to the downstream area as a debris or bed load transport in high density. Few studies considered downstream change along volcanic rivers due to a high density of bed load transport. Using numerical simulation, the impact of high concentration of bed-load transport is applied in Progo River, Yogyakarta, Indonesia. The results show that the high bed-load transport rate increases the mid-channel bar grow rate and the bed degradation near the bank toe. The increase of bed degradation is an important parameter of bank erosion process. Furthermore, the bed morphology on the downstream after 2010 eruption of Mt. Merapi should be considered intensively.