Pages: 8-24

Abstract

Rivers are considered as one of the main sources of surface water and important habitant of aquatic animals from effective inland ecosystems. River water, in addition to participation in Earth’s climate cycle, is considered as one of the most important factors in the erosion of the planet Earth. In recent decades, significant progresses have been achieved in the engineering science. But in some cases, such as sediment transport, turbulent flows, flood control, and river response to environmental factors, engineers’ society are still looking forward to precise method for calculating. The river network is defined as set of waterways that, in the basin level , discharges surface flows. Some of these waterways are as perennial rivers, and seasonal rivers, and some other as watercourse that only during rainfall, a flowing body of water follows. In order to provide mathematical model in determining Manning’s roughness coefficient for mountainous range on the basis of existing field data, hydraulic and geotechnical information for 20 American river and 75moiuntain ranges related to Mr. Jarrett researches were collected. This is considered in choosing mentioned rivers that the sections have been placed on the mountainous range of the river, and the slope of the river at that location is more than 1%. The results obtained from the study, suggests that unlike Jarrett’s proposed relations, soil mechanics factors are also have significant effects on the accuracy of the Manning’s roughness coefficient, which is directly tangible in the results.