In general, the erosion caused by the fluid flow in the vicinity of the moving bed can be called scouring and this occured if the flow conditions exceed the threshold of motion of the sediment particles. Depending on the conditions of scouring, scouring is divided into three categories: general scouring, localized scouring and Tightness scouring. At the bridge piers, the presence of the pier In the flow path reduce the width of channel and causes Tightness scouring. Localized scouring occurs due to flow collisions in the bases. Various methods have been used to control and reduce the scour depth, including the use of a shield layer on bed sediments. On the other hand, riverbeds are often non-uniform granular materials. This makes the creation of an elongated layer as a protective layer against the erosion of the underlying materials. In the present study, numerical modeling of local scouring in elongated substrates has been investigated. For this purpose, a numerical software of SSIIM sediment modeling has been used. The validation of this research was done by Abrahamic laboratory research at Isfahan University of Technology. Ebrahimi conducted his research in a canal with a rectangular section measuring 8.5 meters long and 0.405 meters wide. After verifying the numerical model by different models of experimental results with different substrate conditions, numerical models were designed and implemented. In these models, foundations with 4 pier diameters of 22, 33, 42 and 52 mm and substrate sediments with two uniform layers of layers (uniformly underlying materials protected by a thin layer of coarse aggregates) Different models were designed for two layers. Using the results of these models, graphs were drawn for later and later numbers and referred to the flow mechanism by these diagrams as far as possible. The formation of the upward flow was also evaluated using vertical velocity vectors in the lower base, and it was shown that the upward flow is generated to a suitable lower base. Also, the development diagram of the scouring pit was drawn from a number of these models and compared to the corresponding diagram of the experimental model. The results showed that the ratio of the diameter of the shield layer to the diameter of the lower layer sediments is higher. Software is less accurate in numerical modeling. And also for low cylindrical dies, the results are not very favorabl Key words Numerical Modeling, Scouring, Bridge pier, SSIIM, Verification