Abstract
The article focused on the method of terrain roughness calculation in mountainous areas serving for flood flow estimetion to reservoirs; using remote sensing data to determine Manning's roughness distribution using in hydrological modelling on river basins by land cover analysis.
For steep-mountain areas, land cover is the factor that causeed rapid and strong flow. Terain roughness is affected to water storage, infiltration, overland runoff as well as sediment separation and erosion.
Since terrain roughness is often small compared to digital elevation or digital suface models that can be divided into four different types: (1) fine grains of roughness, determined mainly by soil type; (2) random roughness, related to soil aggregates; (3) directional roughness, described to topographically systematic variation; and (4) high roughness, represented by elevation variation in the field.
To caculate upstream flow, random roughness is the main object to determine surface roughness and hydraulic roughness coefficient. The accurate estimation of hydraulic roughness coefficient is important for understanding flow mechanisms, especially in flood flow determanation.
Proposed method are really useful to simulate flood flow scenarios to reservoirs serving for management and decision support in cases of natural disasters