1. introduction current statistical methods may be unable to accurately predict recurrence intervals of rare, large magnitude floods. the usual procedure involves extrapolation from gauged hydrological records documenting 30–40 year records of observed (normally small) floods to the estimation of the quantifies and recurrence intervals of very large, rare floods. this conventional approaches be...

tehran, iran’s capital with a population of more than 10 million is located in the southern foothills of the alborz collision zone. the alborz mountain belt of northern iran results from the collision of a piece of the gondwana with eurasia in the late triassic (sengor et al., 1988). the alborz active mountain range which consists of several sedimentary and volcanic layers, with east-west trend...