Abstract: With global warming, extreme rainfall events are increasing, leading to frequent disasters in small watersheds in mountainous regions and threatening severely the safety of people's lives and property. A small watershed can adopt various forms of disaster prevention and reduction, among which the combination of ecological engineering measures and geotechnical engineering measures can not just fully utilize the disaster reduction effects of the two measures at different periods, but also increase the overall disaster reduction effectiveness. At present, the principle of collaborative disaster reduction between ecological and geotechnical engineering measures is unclear, and their evaluation methods are also unclear; so, it is extremely difficult to combine the two organically or conduct a comprehensive disaster reduction benefit assessment. On the basis of natural solutions, this paper establishes a principle of coordinated ecological-geotechnical measures for reducing disasters in small watersheds in mountainous regions. Specifically, a stable step-deep pool structure using ecological and geotechnical engineering measures should be formed through collaboration of both fields, slope protection, and channel regulation, so as to achieve collaborative disaster reduction. Then, we give a quantitative method for evaluating the effectiveness of synergistic disaster reduction by small watershed ecological and geotechnical engineering measures based on energy reduction planning, thus laying a basis for design, species selection, and integration with geotechnical engineering strategies.

Key words: small watershed, Natural based solution (NBS), energy reduction, ecological-geotechinical engineering coordinated disaster reduction