In this study, in order to investigate the resilience of the area in the catchment of Lake Urmia, in contrast to the destruction of the density of the stream network, a performance function matrix was developed in the probabilistic First Order Reliability Method (FORM). The basis for calculations in the Python programming environment was the changes in the flow accumulation layer, as an important factor in the surface recharge of Lake Urmia. Preparation of flow accumulation layer, based on the digital elevation model of 30 meter’ s altitude of Aster Landsat satellite in the geographic information system environment, and the criterion for its changes, according to the different layers of the stream network density and with certain thresholds of sequential power, has been the natural flow path in the automatic extraction method. The performance function in the FORM method was prepared by estimating the standard deviation, mean and linear correlation between the two categories of current stream network density, with thresholds of 100, 300 and 1000, as well as 1000, 3000 and 10000, and by deducting two sets of coordinate points. The results showed that the failure probability in the catchment area, without taking into account the lake environment, varies between 28% and 72%. For the boundary strip, the lake's vulnerability display is the least resilient in the western, northwestern and southern parts. Vulnerability occurs with the destruction of the stream network in accordance with the FORM method in its maximum value with 86% in the western part of Lake Area.