Development of a Synthetic Sediment Graph Using Hydrological Data

A proper and an accurate evaluation of sediment concentration is required for manag-ers and planners for the suitable and effective design of hydraulic structures. The design of most of the soil and water conservation structures is made inaccurately, since the num-ber of studies conducted in the field of sediment temporal distribution is limited. The problem mentioned above is particularly exaggerated in developing countries where more effort is needed in research to achieve appropriate solutions for problems encountered. The main objective of conducting the present research was to develop a model through which the temporal distribution of the watershed sediment i.e. the sediment graph during a storm event can be estimated. The model was developed on the basis of the easily acces-sible hydrological data of the Amameh watershed in Iran comprising an area of ۳۷۱۲ ha. A water discharge rating curve, precipitation-runoff relationship and sediment rating curves were developed for the watershed study for the completion and refinement of the collected hydrological data. From the Sediment Rating Curve (SRC), it was observed that in most of the cases there was more than one value of sediment discharge for the same value of runoff discharge located at the rising and falling limbs of the hydrograph. There-fore, the development of two separate regression equations for these sets of points was at-tempted by using regression and confidence area ellipse approaches. The approach based on the hydrological data was then used for the development of a storm-wise temporal dis-tribution prediction model for sediment yield. Based on the results of factorial scoring, it was found that the model developed on the basis of the concept of Unit Sediment Graph and convolution into direct sediment graph using the sediment mobilized could be sup-posed as an acceptable performed model for the prediction of the sediment graph in the study watershed.

Keywords:

Amameh Watershed (Iran) , Sediment Mobilized , Sediment Rating Curve , Synthetic Sediment Graph , Unit Sediment Graph