Exploring the coupling relationship of stormwater runoff distribution in watershed from the perspective of fairness

Urbanization and climate change have led to a large number of stormwater runoff issues. How to deal with stormwater runoff is not only affected by local factors, but also by the surrounding land consumption. Therefore, it becomes particularly difficult to clarify the responsibility for the runoff. This study constructed a guiding planning framework for runoff distribution from the perspective of fairness. This framework established an evaluation method for regional unbalanced development through the coupling relationship between local coupling and telecoupling and multi-regional input-output, and used the evaluation results as a basis for realizing fair distribution of the increment of stormwater runoff, thereby clarifying the attribution of runoff responsibilities. The main conclusions about watershed of Dajiaxi are: (I) Compared with urbanization, climate change is the main factor causing the increase in stormwater runoff. (II) From the perspective of the coupling relationship, the external system needs to share 70.7% of the runoff increment, the midstream and downstream need to share 4.88% and 23.44% of the total runoff, while the upstream only needs to share 1.39% of the total runoff. The results of this study provide a foundation for the medium-scale runoff distribution planning.