Such programs are much needed because in many aridlands there is only a vague idea of the extent of groundwater resources.
这样的计划是非常必要的，因为在许多干旱地区，我们并不清楚其地下水资源的范围。
2
Regularly flowing rivers and streams that originate within aridlands are known as "endogenous".
起源于干旱地区的流动性河流和溪流通常被称为“内源河流”。
3
The United Nations Environment Programme and the World Bank have funded attempts to survey the groundwater resources of aridlands and to develop appropriate extraction techniques.