Background As an important engineering measure for soil and water conservation and ecological construction, silt dam has good economic and social benefits. Therefore, it is very important to quantify the benefits of operating silt dam after water storage.

Methods This paper takes the large and medium-sized typical silt dam after water storage in Jingbian county as the research system, collects data from the statistical yearbook, water resources bulletin, and field research from 2018 to 2022, and analyzes the emergy streams of the research system based on the emergy analysis method (renewable resource emergy R, non-renewable resource emergy N, input emergy I, and output emergy O) as well as the four indexes (emergy investment ratio (EIR), net emergy output ratio (EYR), environmental load ratio (ELR), and sustainability index (ESI)) were evaluated.

Results 1) The output emergy O of the research system in 2018-2022 was (4.57 − 5.46) × 10¹⁹ sej, of which the emergy of mud retention benefit was (0.99 − 1.85) × 10¹⁹ sej, accounting for 21.77% − 33.94%; the emergy of flood control benefit was (1.20 − 1.53) × 10¹⁸ sej, accounting for 2.36% − 2.81%; siltation benefit emergy was (2.19 − 2.57) × 10¹⁸ sej, accounting for (4.55% − 5.62%; irrigation benefit emergy was (2.82 − 3.09) × 10¹⁹ sej, accounting for (53.80 − 67.50)%; and farming benefit emergy was (0.89 − 2.94) × 10¹⁸ sej, accounting for 1.92% − 5.76%. 2) From 2018 to 2022, the EIR was 1.2544 to 1.5515; the EYR was 1.6445 to 1.7972, which were in the reasonable range of 1 to 6; the ELR was 1.9261 to 2.3365, which were all less than 3; the ESI was 0.7109 to 0.9331, which were all < 1.

Conclusions From the EYR results, the development level of the research system is generally on an upward trend, and the output emergy after compensating emergy inputs is still surplus and shows strong competitiveness; from the ELR results, the operation of the research system has a low impact on the local ecological environment in general; from the ESI results, which indicates that the research system is more dependent on the input of input emergy, and the harmonization with the ecological environment needs to be improved.