How important is sediment graph development in Iran?

A careful measurement and analysis of sediment data is a basic pre-requisite for the successful planning and design of any soil and water conservation programme. However, the proper evaluation on the aptness of available measurement and estimation techniques is rarely made worldwide. The problem is much more complicated and neglected in developing countries like Iran. The present paper aims to review the soundness and applicability of available procedures of infrequent and irregular suspended sediment sampling and estimation of total sediment yield by using sediment rating curves. The results of the existing and oft-applied method were then compared with those obtained through developing the sediment graphs on the storm basis. The study was formulated based on data intensively collected for some study watersheds in Iran. The results of the study verified the inapplicability of sediment rating curves for giving accurate estimation of suspended sediment yield in the study areas. The results of sediment graph analysis not only proved its aptness to estimate sediment yield in the study areas, but it could also mirror all changes made in the watershed which had been masked at the time of applying sediment rating curves. These findings clearly verified the necessity of sediment graph development in a country like Iran governed by very natural and changing anthropogenic conditions.