The hydrological significance of mountains: from local to global aspects

Most of the major rivers on our planet originate from mountain regions. Their freshwater supplies the lower lying areas where a large fraction of the mountain discharge is used for irrigation and thus for food production. Therefore, mountains are often referred to as natural "water towers". Although mountain regions make up only about a quarter of the Earth’s continental surface, the share of the world’s population they supply with water largely surpasses this share. When it comes to quantification of this hydrological significance of mountains, however, there is a good deal of uncertainty in the scientific world. On a global scale, only few measurement series exist for discharge in mountainous regions and the periods they cover are extremely limited