Recession Curve Modeling for Diyalah, Greater Zab and Lesser Zab Rivers

Recession curves of yearly stream flow hydrographs are analyzed by a probabilistic approach suggested by (Akosy, H. & Bayazit M, (2001)) and development of a spatial program with advanced language programming (Visual Basic 6) compatible with Microsoft excel for this purpose. Flow of a month on a recession curve is calculated by multiplying the previous month's flow with a value of K smaller than one; K, defined as the ratio of the flows of successive months on the recession curve, was determined from observed monthly flow time series.