مرکز منطقه ای اطلاع رساني علوم و فناوري - بررسي نتايج برآورد رسوب با استفاده از مدل اصلاح شده PSIAC (مطالعه موردي حوزه آبخيز نوژيان )

چكيده لاتين :

The research studies in Iran have shown that the MPSIAC model for estimating erosion and sediment yield in watershed level, is one of the most common empirical models which has been widespreadly used in comparison to the other models on ungauged watersheds of Iran. A reason for use of this model is only because of the accuracy of the obtained result. In this study, erosion and sediment yield rates was estimated by MPSIAC model using geographic information system (GIS) in the Nojian watershed basin. In order to run the model, the watershed area was divided to 527 homogenous units and the nine factors used in model, were assist in each unit. The results of this study indicate that amount of sediment yield in the study area is about 489372 Tn y-l. Considering the amount of the observed sediment yield of the watershed, which is about 812410 Tn y- I, the amount of estimated sediment yield is significantly differs by 323038 Tn y-l. The observed difference can not consider as this mean that the model should or should not be employed in watershed projects. It seems that there must be a rational reason(s) for difference between the observed and estimated amount of sediment yield. The results of the evaluation on the observed difference were shown that it should has the root in structure of the model as well as its related tables for rating and weighting of the factors included in the model. Because it appears that, the tables of the model used for rating and weighting of the included factors are not complete and can not be used in areas were the characteristics of given watershed are not similar to the development area of the model. It can be concluded that in order to accept or reject the result of the sediment yield estimation using the MPSIAC model with high confidence, the model first should be calibrated based on the existing condition of the Iranʹs watershed.