عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Estimation and allocation of environmental flow are the most effective approach to avoid the negative effects of the regulation of surface flows on the ecosystems. One of the useful approaches in this field is the wetted perimeter method. Determination of critical point in the P-Q curve is an important issue in this method, which is still associated with ambiguity. In this paper, the minimum environmental flow of Kheyr-Abad River, with the average annual flow (AAF) of 34 m3/s, is calculated using the wetted perimeter method based on the slope and curvature techniques for determining the critical point. The results indicated that the slope technique always gives higher values than curvature technique. The calculated values for flow using the slope and curvature techniques were equal to 5.2 and 2.0 m3/s, respectively. By comparing the results of both techniques with the acceptable range of Tennant’s table (10-30 percent's of AAF), it is specified that the results of slope method (15.3% of AAF) are located in this range, while the results of the curvature technique (6.0% of AAF) don’t lie in the acceptable range. The results indicated that the curvature technique cannot be a suitable choice for determining the critical point in the curve and the slope technique presented acceptable results.