It makes sense to install grey water systems as well.

The evolution of this river system is closely linked to the system of actors. [© H. Piegay]

Together they form the largest inland waterway system.

The railway network in Iran is not very extensive.

The São Francisco River system, which includes 168 tributaries, is the fourth-largest river system in South America.

The hydrology and biology of the river system would change fundamentally.

Iraq has an extraordinary river system, the most extensive in the Middle East.

The Luangwa River, the most intact major river system in Africa.

In fact, the Luangwa River is the most intact river system in the whole of Africa.

The main river system of Bilbao is the also hydrological artery of Biscay.

Together, these form the longest river system in North America.

The main river system of Bilbao is also the hydrological artery of Biscay.

Taken together, they form the largest river system in North America.

Ghana has a vast river system with an array of tributaries.

In Ghana there is an extensive river system with a set of inflows.