The Yangtze River is 6,300 kilometers long
I don't know what you mean by "D" climate regions, but the cooler the climate, the more likely permafrost will be found. If the climate is warmer, permafrost won't be found because it will be thawed out.
The continents that currently have sufficient water to meet the needs of their populations are North America, South America, Africa, and Australia.
The remaining continents do not - and they have to find their water elsewhere in order to provide all people with enough water for their everyday needs.