Optimization framework for eco-hydrological connectivity schemes based on graph theory and waterfront accessibility

Zhengzhou section of the Jialu River. In this study, the Zhengzhou section of the Jialu River was chosen to construct a watershed river network graph model based on graph theory, and this model could describe water volume distribution at diversion nodes and water balance relationships, which aimed to maximize the ecological landscape area. Considering residential aggregation along riverbanks, a waterfront accessibility matrix was used to derive an optimized water system connectivity scheme based on flow allocation at diversion nodes. In the optimized scheme, flow distribution from 5 diversion nodes to downstream river sections ranged from 0.2 to 0.8, resulting in significant changes in the landscape area of 20 river segments. The ecological landscape area under the optimal scenario was 31.06 km 2 , which was 0.03 km 2 more than the worst-case scenario. The water system connectivity allocation remained consistent before and after considering waterfront accessibility, and the optimal weighted landscape area was 12.69 km 2 with waterfront accessibility in mind. Considering the accessibility of waterfront areas, the center of gravity of the water system connectivity scheme shad undergone a significant change before and after. The research results could provide theoretical support for the construction of regional ecological civilization. • Constructing the river network model based on graph theory. • Determine water system connectivity using landscape area as an indicator. • Optimize the connectivity plan considering waterfront accessibility.