Impact of upstream anthropogenic river regulation on downstream water availability in transboundary river watersheds

This article assesses the adverse impact of upstream anthropogenic regulation of a transboundary river watershed on the natural flow regime of the downstream country, by focusing on a case study: the Diyala (Sīrvān) River watershed shared between Iraq and Iran. The article explores transboundary watershed management difficulties in a three-level system called the transboundary three-scalar framework, which helps to sustainably manage water resources. The average rates of reduction in flow between 2004 and 2013 ranged from nearly 24% in February to about 77% in September. The median of the reduction of rates between June and October was 66.4%.