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Ajichai watershed is located on north western part of Iran and 64.5 percent of this area is mountainous and hills, and 15.9 percent of it is plateaux and upper terraces. This watershed has men annual discharge of 15 m3/sec,and its final destination is Orumieh lake with 260 kilometers distance.
PSIAC method was used for determining erosion and sedimentation. Intensity of sedimentation was classified in 5 slasses. For salinity studies samples were collected from 24 saline streams of Ajichai watershed and BC and PH were measured in these samples.
Relation between discharge and BC in each stream was also calculated to determine the effect of each stream on salinity o Ajichai in Vaniyar hydrometry station.
Study of soil erosion indicated that sediment yield and specific erosion in Vaniyar hydrometry station watershed are 228 and 1940 T/km2/Y respectively. Study of results showed that surface erosion has little effect on salinity increase of the river. The main reason for salinity of the river is atributed to infiltrated water which is the main cause of dissolutin of salts which finally joins to main river or minor bifurcations