The hydrographic network of the city of Caracas is made up of the Guaire river basin which is a sub-basin of the Tuy river. This basin crosses the valley where the city is located from West to East (Las Adjuntas - Petare). It covers about 655 square kilometers, about 45 km. long and about 15 km. wide, has a rectangular shape. The basin is formed by the Caracas Valley, which is relatively high, narrow and long, surrounded by the high and steep Cordillera de la Costa, which runs parallel to the Litoral.