Document Type : Research Paper

Authors

• Mahmood Arabkhedri ¹
• Hamzeh Noor ²
• Ali-Akbar Abbasi ³

¹ Assoc. Prof. Soil Conservation and Watershed Management Research Institute, Agricultural Research, Education and Extension Organization, Tehran, Iran.

² Assistant Proposer, Soil Conservation and Watershed Management Department, Khorasan Agricultural and Natural Resources Research Centre, Mashad, Iran

³ Retired Associate Proposer, Soil Conservation and Watershed Management Department, Khorasan Agricultural and Natural Resources Research Centre, Mashad, Iran

Abstract

Soil erosion and sedimentation measurements and evaluation of the temporal and spatial data thus obtained are crucial for advancing the knowledge on soil erosion, evaluating relevant models, and designing soil erosion experiments. Extensive temporal changes in erosion and sediment yields, particularly in small watersheds, require special technical provisions to ensure accurate records. Based on the existing records, maximum events, or even a single one (with a high return period), play an important role in altering average sediment yields in river basins. It is, therefore, necessary to collect long-term data in order to derive a reliable average value for sediment yield under natural conditions. The present paper explores such technical considerations in measuring sediment yields in small experimental watersheds. For this purpose, two simple and automatic sediment samplers and a flow divider are introduced for measuring suspended sediments. It is also shown that concrete tanks and small reservoir dams need to be constructed at the outlets of the experimental watersheds. Finally, different methods used for measuring total load (including bed and suspended loads) are described.

Keywords

• Experimental watershed
• Sediment measurement
• Maximum event