THE SAINT RIVER (RIO SANTA).

Peru is the third largest country by area in South America (1'285,000 km2), after Brazil and Argentina.
Peru has 3 very distinct climatic regions: a very arid Western coastal zone, a Central High Mountainous zone (Andean region), and a humid Tropical Jungle zone (dense Amazonian rain-forest) to the East.
With its population concentrated in the dry coastal zone, the availability of water is critical to the local population as glacier retreat has become extensive.
The Andes control Peru's climate; Atlantic air masses, blocked by the mountains, provide a warm, humid climate in the East, and the cold Humbolt Current creates a dry climate along the Pacific coast.
The annual oscillation of the inter-tropical convergence zone causes annual dry (May to October) and wet (November to April) seasons.
Nearly all the water that is available in the coastal region comes from Rivers of glacier origin on the Western slopes of the Andes.
The Saint River (Rio Santa) Basin is located in the Ancash Region of Peru about 400 km North of Lima. Its source is the Lake Conococha (4,080 above sea level), which is fed by small streams of the Black mountain range (Cordillera Negra) and Lake Macar in Tuco River originating in the glaciers of Tuco Nevado in the White mountain region (Cordillera Blanca). It has the second largest flow of the Peruvian coastal rivers. Twenty of the twenty-three tributary streams arise from the glaciers.
The water from the Saint River supplies a large area of mostly agricultural activity between 2,000 and 4,000 m elevation; a hydrolelectric plant representing 5% of Peru's total energy production capacity; a large scale of intensive commercial agriculture in the coastal area; and a large part of the drinking water to 2 major urban areas on the coast, Chimbote and Trujillo.
The White mountain range, located approximately 180 km from the Peruvian coast where the Nazca plate dips below the South American continental plate, is relatively a recent intrusion. Large-scale uplift has produced the current White and Black mountain ranges with the Huaylas Aisle in between them forming the Saint River Basin. Mount Huascaran has a height of 6,780 m rising 2,500 m above the Saint River Valley in less than 15km. This great height, plus global cooling periods, has led to major and repeated glaciation of the region. Variations in climate affect glacial advance and recession and the length of the seasons
The Saint River (Rio Santa) runs North from Lake Conococha between the White and the Black mountain ranges (Blanca and Negra Cordilleras), forming the Huaylas Aisle (Callejon the Huaylas).
Further downstream, after passing the Duck Canon (Canon del pato), at the confluence with the Rio Manta, the River turns West and finally arrives at the coast near the city of Chimbote and outlet at the Pacific Ocean.
The White mountain range (Cordillera Blanca) is the most extensively glaciated tropical region in the World with more than 30 peaks in excess of 6,000 m above sea level. The Highland areas of the Saint River Basin feature extensive rural subsistence farming and grazing. The middle Basin supports irrigated farming and is home to the Duck Canon (Canon del Pato) hydroelectric facility, one of the largest in Peru. It is one of the hardest hit regions of the World in terms of Floods from glacial Lakes and large ice avalanches.
The glacially-dominated Saint River Basin now faces unique challenges in adapting to recent and continuing climate change, including projected reduced dry season flows and increased threats of glacial lake Floods. As glaciers have melted in the Andes, new glacier lakes have been created or enlarged presenting the risk of glacial lake outburst Floods.
The White mountain region has a long history of glacier-related catastrophes that has been recorded since 1725. A notable example is the 1941 Lake Palca'Cocha disaster in Huaraz, Peru that killed nearly 6,000 people within minutes. Events such as the 1941 prompted the creation of the Glaciological Unit in Huaraz that has developed methods to successfully drain and control 35 Lakes throughout the range.
Nevertheless, these precautions have not fully addressed the threat of glacial lake outburst Floods.
On April 12, 2010 following an extremely warm year, an ice avalanche the size of several football fields, fell into a Lake and caused extensive flooding downstream, destroying at least 50 homes.