Investigation of sediment rating curves error for estimating flood events sediment yield in Gharachay river

Estimating flood events sediment yield and its temporal variation are of the main and basic issues in watershed management strategies. On the other and there are little investigations about sediment yield behavior of the flood events and applicability of the sediment rating curves to estimate sediment load of flood events. In this study in order to investigate bias and errors of the sediment rating curves in estimating sediment load of the flood events, the estimated values of 10 types of rating curves compared by the observed values of some hourly monitored flood events in the Gharachay River of Markazi provinces. By considering accuracy and precision indexes the results shows that in all of treated sediment rating curves underestimated (40-80%) flood hydrograph sediment yield in this case the FAO’s method has relatively closer estimates to the observed data and despite of suitable applicability of the MVUE method in estimating annual sediment yield it could not prove to be applicable in the flood events cases.