“…Based on three factors (natural environment, administrative area, and economic relationship), this study divides the Songhua River into three parts: the upstream including Jilin, Changchun, Songyuan, and Baicheng municipalities; the midstream including Daqing, Suihua, and Harbin municipalities; and the downstream including Hegang, Yichun, and Jiamusi municipalities (Figure 1). Czakó et al [31] divided the Danube River into three parts according to the location of the river's partition: the upper part of the river (e.g., South German States, Austrian regions); the middle part of the river (e.g., Slovakian, Hungarian regions); and the lower part of the river (e.g., Romania, Bulgaria). Qin and Li [32] argued that three factors-natural environment, administrative area, and economic relationship-should be considered in watershed segmentation.…”