Rivers and lakes on Grande Terre

Rivers and lakes

Streams are well developed only on Grande Terre. Aside from the Diahot and the upper valley of some rivers (Ouaième), all run perpendicular to the central range axis. Their upper course is mountainous with numerous water falls. Their lower course is quiet with meanders on the West Coast where flat lands are more extensive than on the East Coast. Rivers estuaries are fringed with mangrove particularly on the West Coast. In the ultrabasic massif red lateritic soils, streams becomes reddish when floods occur, but they very quickly revert to extraordinarily clear water when the flood is over. These waters are very poor in nutrients and they have very few fishes.

Upstream, river basins are virgin and devoid of human settlement and agriculture. Water from creeks and rivers may be safely drunk or you can swim in them without any risk of catching disease.

There are few natural lakes and they are rather small but in the South in the swampy area of Plaine des Lacs. The only artificial lake is Yaté. It is also the largest fresh water lake on the island.

Picture to the left : waterfall on river Neba (East Coast North of Yaté). Neba river is only about 10 km long. Upstream it runs among rugged mountains. This river is in the ultrabasic massif of the south with reddish laterite soils.

The rocky bed width, clean of vegetation, shows how powerful floods can be with heavy tropical and cyclonic rainfalls. Water then floods entirely the rocky area.

Less than 2 km downstream from this waterfall, the river spreads quietly in a coastal plain.

Its profile is typical of New Caledonian rivers. A small river on the East Coast, the downstream course of Neba is only shorter than the one of the large rivers, in particular on the West Coast.

Mangroves

Mangrove areas are widespread on the West Coast and in the Northern end of Grande Terre. They cover large shore areas and follow deeply the main water streams, in particular along the Diahot and in its mouth the Harcourt bay.

The picture shows mangrove at Pointe, in Harcourt bay.

Mangroves are important systems for the ecological equilibrium of the lagoon. They shelter many juvenile forms of the lagoon fauna. Sediments trapped by roots prevent cloudy water silting adjacent lagoon.