in order to decrease the risks associated with the management of urban watersheds, the use of proper methods is an essential task to estimate the runoff with a high degree of confidence. time of concentration is one of factors that impacts on peak discharge and runoff volume. the objective of this study is to select the best method among the empirical formulas for estimating the time of concent...

evaporation, as a major component of the hydrologic cycle, plays a key role in water resources development and management in arid and semi-arid climatic regions. although there are empirical formulas available, their performances are not all satisfactory due to the complicated nature of the evaporation process and the data availability. this paper explores evaporation estimation methods based o...

Most seismic codes specify empirical formulas to estimate the fundamental vibration period of buildings. Evaluated first in this paper are the formulas specified in present US codes using the available data on the fundamental period of buildings “measured” from their motions recorded during eight California earthquakes, starting from the 1971 San Fernando earthquake and ending with the 1994 Nor...

In the past centuries, water was considered as one of the most important factors to appear the social groups and develop communities. Today, it is emphasized as a necessity to supply the economic and political balance. Regarding to limited water resources and underused plains in the world, to provide the humans needs and prevent to appear the consequences of water shortage, the best strategy is...

In this paper twelve different empirical resistance coefficients expressed in terms of Manning's roughness are used apiece in seventeen known compositing methods. The data obtained from ten different cross-sections of the Sefidrood River, Iran, are used for the evaluation of the empiricalformulas. The present case-study is selected from a reach with gravel bed topology. Then no remarkable bed f...