This probably because that Heihe River Basin was mainly controlled and affected by water vapor of westerlies, and local evaporation was weak in cold season.
黑河流域冷季主要受西风带水汽控制,局地蒸发水汽较弱;
3
This basin is located in north China continental arid and semi-arid climate zones . Low rainfall and strong evaporation, weak ecological environment in general.