Seite - 630 - in Book of Full Papers - Symposium Hydro Engineering

In order to achieve the objectives of the study, the following processes were carried out. The status of the annual water balance of the inflow was analyzed to identify the process. Due to the lack of trend on this scale, the study was conducted on a monthly scale. Afterwards, the total monthly precipitation was investigated to find out the cause of changes in monthly input flow. Considering the lack of trend in the amount of monthly precipitation, attention was paid to the factor of precipitation pattern variation in the region. The best factor that could be taken into account in this snowy area is the monthly temperature and its effects on the precipitation pattern. In other words, the change was in precipitation as snow and thus in the monthly discharge and also in the long-term river discharge pattern of Taleghan river. For this purpose, long-term changes in snow coverage in line with long-term changes of the most influencing and crucial climate parameter, namely temperature, were analyzed. In this regard, Mann- Kendal non-parametric method and non-parametric CUSUM free distribution method was used to determine the beginning time of changes in the precipitation pattern of the region and also the thermal climate of the basin, respectively. To study the statistical accuracy of the analyzes, statistics such as Mean absolute error percentage, Mean absolute deviations and Mean square deviations were applied. Data on precipitation, temperature and inflow of the dam were collected from terrestrial stations and for snow data, satellite images of Terra satellite was used as follows. 2.2 STUDY AREA: The Taleghan Basin, which is one of the important sub-basins of the Sefid Rud waterfall, is located within the study area of Taleghan Alamut. This basin is located on the southern slopes of the Alborz mountains and in the northwestern part of Iran, 120 kilometers from Tehran. In geographical position, the basin is restricted from the north to the Alamut basin, from the south to Zayaran and Samghabad, from the east to the part of the Karaj basin and from the west to Shahroud Basin. Figure 1: Location of Taleghan Basin 2.3 DATA 630