Assessment of the Impacts of Inter-Basin Water Transfer on the Bed River Morphology in the Origin Basin (Case study: Zab River Basin)

In recent years, in order to revive the Urmia lake and preventing the negative environmental impacts, the water transfer project from Zab River to Urmia Lake has being studied and implemented. In this paper, it is tried to assess the possibility of morphological changes of Zab River due to implement of project at the downstream of Kanisev dam. The research method is mainly analytical method.The data of this study include Geological map of 1/100000 scale, areal photographs, LANDSAT 8 (ETM sensor) satellite imagery, GDEM images of ASTER with resolution of 15 meter, meteorological data and hydrological surface water of the under study area. The data were collected using libraries and referred to agencies and organizations, web sites and field surveys.Results showed that after water impoundment of Kanisev dam and transferring water to Urmia Lake, the average of the Zab River discharge in the hydrometric station of Grzhal will decrease from 1464.72 to 653.42 million cubic meters per year and the bed river at downstream will decrease drastically. So that in September and October. Zab bed river from dam wall to the Abkhorah tributary will be dried approximately. The decline of flow will cause changes of the morphological indexes such as cross-section and longitudinal-section and hydrological features similar to depth and velocity of flow. With reduction of discharge at the downstream of Kanisev dam, at A section, the flow of river will pass of the deepest bed river in which new terraces, narrowing cross-section, remove the side vegetation or retreat to far from will occur. At B section, the power of flow will focus toward the side of the river and also cut-off them, finally lead to fill the pothole using deposition. At the last section, C, with increasing distance from Kanisev dam and enhance sediment load rather than transport capacity, both depth and width of the bed river due to creation the point bars along flow and sedimentation at the sides will decrease.