How to coordinate cross-regional water resource relationship by integrating water supply services flow and interregional ecological compensation

Ecosystem service (ES) flow reveals the transregional benefits transferred from service supply areas (SSAs) to service benefiting areas (SBAs), which correspond to the sellers and buyers of interregional ecological compensation, respectively. However, current ecological compensation policies usually ignore this close connection. This study took the water supply services (WSSs) with the most obvious flow characteristics as an example and established a universal framework for interregional ecological compensation by combining WSSs flow simulation and regional disparity. The simulation process was programmed with Interactive Data Language (IDL) and analyzed with ArcGIS. Most regions serve as a dual role in the WSSs flow process, the water suppliers and users are relative and scale-dependent. Taking Ningxia as an example, As water benefiting areas (WBAs)/buyers, the total material inflow to Ningxia was 135.86 × 108 ~ 294.22 × 108 m3 from 2000 to 2015 and the value inflow ranged from 1077.39 × 108 ~ 2333.16 × 108 CNY, requiring 101.64 × 108 ~ 293.51 × 108 CNY ecological compensation paid by Ningxia. As water supply areas (WSAs)/sellers, the total material outflow from Ningxia was 72.83 × 108 ~ 200.46 × 108 m3 from 2000 to 2015, and the value outflow was between 577.54 × 108 CNY and 1589.65 × 108 CNY, requiring 63.80 × 108 ~ 112.34 × 108 CNY of ecological compensation to be paid by the downstream basins, especially the Shizuishan – Hekou Town subbasin. Overall, Ningxia was a beneficiary area of WSSs flow and the payers of interregional ecological compensation, with a net payment amount of 37.84 × 108 ~ 181.16 × 108 CNY. This study provides a direct spatial-visualized reference to water resource management for policy-makers and promotes the integration of ES flow and interregional ecological compensation. Furthermore, it can improve the public recognition of interregional ecological compensation with the spatial mapping of the levy and allocation and conducive to the sustainable provisioning of ESs ultimately.