An evaluation method for the survival rates of gully control measures in the Black Soil Region of Northeast China based on the number and intensity of damage

Objective Addressing issues such as the lack of quantitative standards and high subjectivity in surveys of the survival rates of gully control measures in the Northeast Black Soil Region, this study developed a reproducible and quantifiable method for surveying and evaluating survival rates. Methods Based on the two dimensions of the number of damaged structures and the severity of damage, we proposed a standardized method for determining the survival rate grades of six typical remediation measures: gully head protection, check dams, continuous willow drop structures, bank protection, backfilling and restoration, and vegetation measures. Results Three investigators with different professional backgrounds reached complete agreement on the survival rates of three control measures in a single gully across a total of nine assessments. Additionally, the relative deviations in the measured values for each indicator were all less than 8%, and these deviations did not result in changes to the assessment ratings. This indicates that this method possesses good reproducibility and inter-rater reliability. Furthermore, this method was applied to survey 235 controlled erosion gullies in 15 typical counties in the Northeast Black Soil Region. The results showed that the average survival rate for all types of engineering control measures exceeded 75%, with backfilling and restoration having the highest survival rate at 92.5%, while the survival rates for continuous willow drop structures and check dams were relatively low at 77.9% and 76.6%, respectively; the average survival rate for vegetation control measures was 73.9%. Conclusions This study established an evaluation method for assessing the survival rate of gully control measures, shifting from subjective judgment to an assessment based on functional retention. This method demonstrates good reproducibility in surveys of typical gullies and can serve as a reference for evaluating the effectiveness of control measures in black soil regions.