The 2010 eruption of Mount Merapi resulted in huge sediment that flows through tributaries as debris flows which had caused morphological change. Its impact affected on environment and socio-economic condition of inhabitant. It is important to study the effect of debris flow post the 2010 eruption of Mount Merapi on environment and socio- economic inhabitant. The study aims to investigate morphological condition, damage due to debris flow and its impact on inhabitant life as well as environmental change. The study locations were the lower of Pabelan River, the lower of Putih River and Progo River. The Rosgen method was used to determine the morphological characteristic. To calculate sediment transport, Einstein method was used.