Investigation of chemical and physical properties of neogen marls effects on the forms and intensity of erosion in Varamin area, southwest of Tehran province

Marls produce the highest deposits in the catchment areas among lithological units. This property of marls can cause the reduced useful life of dams, river, and sedimentation of water channels, the destruction of road, utilities, and ultimately desertification phenomenon. Hence, understanding the characteristics influencing the erodibility and marls divergence can be a priority. In this thesis, marls located in the south of Tehran (south of Hassan Abad- Varamin) were evaluated in terms of shape and intensity of erosion, physical, chemical, engineering and divergence features. Marl unit studied includes the onshore marl of Upper Red Formation unit M3 and Pliocene marl of unit Plm. Sampling in the unit of red upper geology and Pliocene was conducted in slopes 5%, 20% and 40%. Tests such as gradation, Atterberg limits, chemical analysis such as cations and anions, SAR, TDS, EC and dual Hydrometry and pinhole were carried out to achieve the predetermined goals. Granulation distribution showed no significant difference in different slopes. Comparing the plasticity index among the different forms of erosion, it can be seen that the surface erosion plasticity index is greater than other forms of erosion .it is a factor in the postponement of erosion. But overall, it's not much different from many other forms of erosion. The cation exchange capacity in the samples is between 14/2 to 25/88 meq per liter. The mean of this variable is further in the stream erosion .the range of this variable in samples is between 0.9 to 2.17 meq per liter. The mean of this variable in the erosion of stream and ditch is more than the rest of upper red formation units. The results of the double hydrometer tests on 20 samples indicate the high non-divergence. The sample collected from Station 1 (in the form of gully erosion) and station 5 with a gradient of 5% (with stream erosion) shows the average divergence. According to the pinhole experiment conducted at different stations, station 5 (with single stream erosion M3) and station 7 (with a form of gully erosion M3) showed a moderate divergence.