sentences:  The river forms a small part of the international border between Niger and Nigeria.There are concerns about changes in the river flow, economy and ecology due to upstream dams, the largest at present being the Tiga Dam in Kano State, with plans being discussed for the Kafin Zaki Dam in Bauchi State.Notable towns near the river include Gashua, Geidam, and Damasak in Nigeria, and Diffa in Niger.