In this research, all of existing hydrometric stations are investigated in the part of large central watershed

of Iran and the main physiographical characteristics of these stations are extracted. Then, independent

parameters and homogeneous watersheds were recognized by using factor analysis and clustering

analysis, respectively, and were tested by using discriminate analysis. Regional analysis is evaluated by

using flood index. The results showed that there are three homogeneous areas in central watershed and the

best discharge index is one that have two- year return period. Furthere more, other parameters as well a

area can't improve the accuracy of results.