The Clear River watershed is located in the middle reaches of the Yellow River. Here, the upper hydrology station has an area of 425 km~2. Ariel photographs taken during various periods show a clearly defined and recognizable forest development pattern.

• 我们使用流域内(黄河中游河龙区清水河流域水文站断面以上425km~2)不同时期航片,判读出森林的动态变化。