Abstract: In the Loess Plateau, the construction of a silt dam is an essential component of erosion management. The goals of the research presented in this paper are as follows: providing technical data for dynamic assessment of silt dam stability and operation management; developing measurement methods that are efficient and accurate for technical indicators of silt dams; and mastering the changes that occur in technical parameters due to the complex operating environment of silt dams. Based on the field-of-view principle, this paper builds four types of mathematical geometric models of silt dams, such as length, area, height, and slope, and designs feature image acquisition and screening, feature target interpretation, and data extraction schemes to carry out an example measurement study of silt dam technical indicators. The maximum error of the measurement method developed in this paper is -3.48%, and the measurement accuracy of different types of indicators varies. The average measurement error for dam crest length, dam crest width, water transfer culvert, and siltation elevation is less than 1%; the average error for spillway and open channel is less than 2%; and the average error for dam height, siltation area, and dam slope ratio is less than 3.5%. The silt dam technical index measurement method proposed in this paper is well-designed, with small measurement errors and efficient and accurate measurement characteristics.

Key words: silt dam, field of view, RTK differential technology, mathematical geometry model