The Davao River is the third largest river by

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

on the southern

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

in the island of

Mindanao Mindanao ( ) ( Jawi: مينداناو) is the second-largest island in the Philippines, after Luzon, and seventh-most populous island in the world. Located in the southern region of the archipelago, the island is part of an island group of ...

. It drains an area of over with a total length of . Most of the area is uplands. Average flows within the river near to the mouth are estimated at . The climate type is relatively uniform throughout the year with evenly distributed

rainfall Rain is water droplets that have condensed from atmospheric water vapor and then fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. It provides water f ...

and

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

s and humidity (rainfall = 2600mm, Actual Evap 1028mm). The area rarely experiences typhoons.

Stats

* River Length: "Principal River Basins of the Philippines", Published by the National Water Resources Board, October 1976 (p. 12) * Maximum Elevation: * Rainfall Average: Mean annual rainfall is 1800mm. Rainfall is evenly distributed throughout the year.

Topography/Soil Type

Plains and Valley: Parent Material: * San Maguel Silty Clay Loam:

Alluvium Alluvium (from Latin ''alluvius'', from ''alluere'' 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. ...

of igneous * Matina Clay Loam : Alluvium from

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especiall ...

and

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicat ...

s Intermediate Upland: * Tugbok Clay:

Igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...

Andesite Andesite () is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predo ...

s * Faraon Clay: Soft Coralline limestone * Cabantain Clay: Soft shales with mix of weathered gravels and pebbles Hills and Mountains: * Camansa sandy clay loam: Shale and sandstone with weathered gravel and sand * Mountain Soils: undifferentiated : Various igneous and

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, caus ...

Demographic properties

* DRW Population: ~ 800,000 * Average per capita income: 144,039 per family per annum (2000 National average) * Industrial and agricultural gross domestic product: 64.1 Billion Peso for Region XI * Population Below Poverty Line: 45% in rural areas ; 27% in urban areas (for southern Mindanao) * Water Poverty Index parameters: Medium (WPI 56-61.9).

Land uses

The

landform A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, ...

and landcover within the basin is highly diverse. Ranging from lowland urban, agricultural, wetland and

mangrove A mangrove is a shrub or tree that grows in coastal saline or brackish water. The term is also used for tropical coastal vegetation consisting of such species. Mangroves are taxonomically diverse, as a result of convergent evolution in severa ...

to natural riparian, plantations, upland agriculture and mountainous forest including primary forest. The area is classified by DENR as 77.5% forestlands and 22.5% alienable and disposable land. This is not a true land uses (or land cover) classification. Detailed land use is not available. Information is available from several sources including the Comprehensive Land Use Plan of the City, however this data is as yet theoretical and does not represent the realities or suitability of land at the barangay (lowest tier of local government) level. However the City Planning Office is collecting and digitizing data for land use maps.

Water resources and uses in the basin

River discharge measurements taken from 1984 to 1990 indicated an average river flow of approximately 78 cubic meters per second for the period. The main

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, ...

sources for Davao City are in the neighboring Talomo watershed. These sources are under pressure and the Davao River Basin is likely to be required for water abstraction in the near future. The Environmental Management Bureau samples 8 sites from the confluence of the Tamugan river downstream to the mouth of the river. From the Tamugan River confluence with the Davao River down stream to DDF Subdivision, Mandug the water is classified as Class A – Public Water Supply Class II. Downstream of this point to the sea is classified as Class B or recreational water class I. Analyses for

dissolved oxygen Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...

over the past 4 years has indicated no significant change in quality. The current monitoring of water quality is insufficient to monitor and evaluate pollution levels and trends in the river.

References

* D Hearne, crs, proposal to HELP UNESCO, 2004

External links

Basin Properties

" Pictures

Davao Water Partnership
{{Webarchive, url=https://web.archive.org/web/20130506100634/http://finishersnetwork.com/ , date=2013-05-06 Rivers of the Philippines Landforms of Davao del Sur Landforms of Bukidnon