ABSTRACT
Sedimentation in reservoirs, in addition to reducing water storage capacity, causes serious environmental impacts including intensification of river erosion. Detection of sediment origins plays a determining role in control and prevention of sedimentation. Nowadays, with the help of studies on sedimentation and erosion, sediment origins can be detected with high accuracy. This research integrated geographic information system (GIS) and remote sensing (RS) techniques to detect the primary source of sediment to Taleghan Dam in northern Iran. After collecting samples of sediment from the basin outlet, they were divided into two parts. One part was sent to the Mineralogy Laboratory in order to determine the percentage of each mineral in the samples using X-ray. A few were sent to the Spectroscopy Laboratory to determine their spectral signature using the spectrometer. The laboratory test results determined the wavelength of the minerals. In the next step, those spots on the satellite image whose spectral reflectance fell within the spectral signature of the minerals were detected and enhanced by mixture-tuned matched filtering (MTMF) method. These spots were overlapped with the map of geological formations. Accordingly, the origin of the minerals was detected. The greatest proportion of trace minerals was found in sample 4 including 6% of Illite trace mineral, while sample 2 contains only 2% of trace minerals. Accordingly, the origin of the minerals was detected. The obtained results revealed that mudstone, red siltstone, and conglomerate formations, Karaj formation in section Poldokhtar, acidic tuffs, alcanic lavas of Karaj Formation, mudstone and gypsum of upper red formation, and Cambrian dolomites were recognized as the most possible origins of the dam sediments. These formations are vulnerable to erosion and should be conserved so as to substantially prevent the volume of sedimentation in the reservoir.
