The Role of Geological Formation and Provincial Contribution To Sediment Yield in the Shahid Abbaspour Reservoir Dam (Karon 1 Catchment)

Construction of reservoir dams and increasing its lifespan in the upper catchment of large rivers play an important role in the sustainable development of the dry and desertified lands of the central basin of Iran. Water scarcity, erosion and sedimentation in dam’s reservoir are the major problems of dry and desertified regions in Iran. Generating sediment yield in a watershed area is normally influenced by different geological formation and climatological agents. Among them, the role of erodible formations is very important when compared with other factors. In this study the influence of erodible formations was investigated by feiznia’s methodology (1995) using the geological maps and GIS technology for surrounding provinces of the Karon 1 basin including: Chahar-Mahal and Bakhtiari, Esfahan, Kohkiloyeh and Boyer-Ahmad, Khouzestan and Fars. The contribution of these provinces to Karon river discharge are 168.1, 50.1, 64.7 and 8.5 m3/sec respectively. The results of regression analysis show that sediment load is correlated to watershed area, water discharge and the area of the erodible formation exist in the region. The regression coefficient of this correlation was 0/97 and significant at 0/01 probability level. Finally the contribution of each province- geological formation to sediment discharge was then calculated based on the factors responsible for sediment load at Karon- river outlet.Erodible formation in the drainage basin are: Agha-Jari(MJ), Razak-Gachsaran(Mr-Mgs), Amiran(Kaf), Gurpi-Pabdeh(Kg-Ep), Kazhdumi(KK) and Hormoz(PEh) formations. It was concluded that Chahar-Mahal and Bakhtiari with 47/9%(the highest rate of sediment) and Fars province with 2/1%(the lowest rate) contributed to the sediment yield of the Karon 1 basin.