comparison of ajichai basin instability indices with the standards of air instability and developing a model for the catchment

this paper presents a model of a catchment area in northwest of iran. the researchers have studied ajichai basin which is located in the east part of orumiyeh lake, located at the longitude of 47 52’ e to 45 32’ e and the latitude of 37 26’ n to 38 30’ n. the researchers have chosen the data from tabriz upper air station which is the only one in the area. the research data are seven instability indices including: si, k, v.t, c.t, t.t, sw and li taken from the above mentioned station and seventy one floods reported from 1966 to 2004 in the ajichai catchment area. in this research, the above mentioned indices are compared with the standards of air instability. the results show contradiction between the observed and predicted values ( i.e. for si in six days, k in one day, v.t in two days, c.t in fifteen days, t.t in three days, li in forty eight days and sw in thirty five days). the results also show that the following values can be used for the ajichai basin instability indices. si= =14.3 c.t>=11.5 v.t>=24.7 t.t>=41.8 sw>=11.65 li=<6.79