Diyala River is one of the important rivers that provide water for the Governorate of Diyala. In this research, the morphology and sediment transport of this river were studied using HEC-Ras software. The selected length of the river in the present study is 193 km and extended from Diyala Weir to the confluence of Tigris River and Diyala River. The fieldwork period extended from June 2020 till August 2020, where suspended-load and bed-load samples were collected and surveyed some cross-sections. The one-dimensional sediment transport model has been calibrated for five years, from 2014 to 2019. The results were compared with the measured cross-sections in 2019, and the suitable value of (maximum depth) was 120 cm for five years. The result of invert change from the simulation of the sediment model for real condition of the river from 2018 to 2019 ranged from0.2 m to 0.6 m. Moreover, the daily and yearly sediment discharge was equal to 227.7 tons/day and 83531.93 tons/year, which were previous studies carried out on this river. While the simulating results of the imposed period as five successive flood years give an invert change values varied from -1.25 to 1.4 m. The river's capacity was improved by rising the riverbank level for parts of the reach and/or training of cross-sections for other parts.
