Roughness Characteristics Of Kut-Hay Reach Of The Gharraf River And Its Impact On The Hay Regulator

Abstract

Represent the study  of this research is the problems of water levels fluctuation for different discharges in downstream Gharraf regulator for Gharraf river of the reach kut-Hay  along 58.3 km . Compute Manning roughness coefficients which has not been determined before and investigate rating curve by back water curve during study period to be used simulation of HEC-RAS model. the roughness coefficient is one factors which effect on flow depth in the rivers. Many researchers have made to estimate the river roughness coefficients, Because of its importance. Among them. Absolutely, the above methods cannot be applied for each river reach due to differences in the factors affecting the roughness coefficient as (backwater curve , flood plain ,sediment ,routing  etc.) . These study are important due to the diversity and irregularity of natural rivers. Field measurements were carried out during period(2016-2017) along reach included 22 across section surveys and hydrological measurements. It is found that the value n  for Gharraf river which shows good agreement between observed and computed hydrographs is(0.026). The results show that effect of Al-Hay regulator on upstream reach because of backwater curve .When was gate opening less than (0.5)m for all available discharges, gate opening, (0.65 - 0.9)m for discharge more than(175 m3/sec), gate opening (0.9 - 4)m for discharge more than (210 m3/sec), and gate opening(4 - 5.8)m for discharge more than(350 m3/sec) at upstream reach.