Three geographical problems

1. It can be seen that there was a spring flood in March, when the river flow increased slightly, but the river sediment concentration did not increase significantly. The "sand" in the river mainly comes from soil and is formed in the process of rain erosion. In March, the temperature on the mountain was low enough to melt the glaciers. It can be seen that the water source of spring flood is snow melt water.

The main flood season of this river is July and August. At this time, the river flow increases and the sediment volume increases rapidly, indicating that short-term heavy precipitation is the main factor causing the flow increase. However, the heavy precipitation in July and August is mainly convective heavy precipitation brought by cold front.

3. It can be seen that although the river exists in spring, it is not obvious (it must not be a southern river), but in summer, the river has a large amount of sediment (it must not be a northeast river), so it can only be a river in North China.