Hydrographic Basin

It is the contour or boundary of the basin that drains water to a common point. Hydrographic basins, also known as river basins, are parts of the earth's surface from which waters and the runoff of precipitations that end up being dumped or deposited in a main stream flow. REVISAR ORIGINAL Generally, a river basin comprises three characteristic sectors: high, medium, and low. Depending on the topographic characteristics of the region, they can influence its hydro-meteorological processes and resource management .

It is important to clarify and define two concepts that refer to this subject, although they are different from each other, namely:

1. Hydrographic basin.
2. Hydrological basin.

In hydrography, there are two types of hydrographic basins that are classified according to their exit patterns towards the main stream. On the one hand, there is the endorheic basin, named so because its exit point is within the limits of the basin, which is usually a lake. On the other hand, there is an exorreic basin, which refers to the basin whose exit point is within the basin itself, but this, in turn, falls or flows into another stream or into the sea. A hydrographic basin influences terrestrial ecosystems such as jungles, forests, scrub lands, and grasslands, among others, and aquatic ecosystems such as rivers, seas, and wetlands. In addition, hydrographic basins influence the human settlements located in them. This is why a hydrological basin is usually understood as a unit for the management that takes place in the hydrographic basin. Humans have identified the importance of water as a vital resource and its value in all anthropic activities. Given its function as a system, hydrographic basins must be preserved entirely to ensure the continuation of the water cycle and the quality of hydric resources.

Characteristics

The components that characterize a hydrographic basin are :

• Basin: A system made up of several sub-basins or micro-basins.
• Sub-basin: A group of micro-basins draining to a single stream with a flow that fluctuates depending on rainfall, but is permanent.
• Micro-Basin: A micro-basin is when the drains from an area end up in the stream of a sub-basin.
• Creek: Any area that drains directly to the main stream of a micro-basin.

Hydrographic basins are also characterized by the division of their total area into:

• Upper Basin: Includes mountainous areas or headlands of hills limited at the top by the watershed.
• Middle Basin: It’s where waters accumulated from the upper parts fall and the river or main stream maintains its permanent course.
• Lower Basin or Transitional Zones: Area where the river flows into larger rivers or lower areas such as wetlands and estuaries.

Zoning of the hydrographic basin

Hydrographic basins are also divided into zones, since classifying them in this way allows for the analysis of the behavior of the different components of the hydric balance.

• Headland Zones: It is where hydrological currents are born. They are located in the highest parts of the basin, and they represent the most important places for the collection of water and therefore require greater conservation.
• Catchment and Transport Areas: It is the area of the basin responsible for capturing most of the water that enters the system. The water captured from the headland is also transported in this area, causing water bodies with different physical-chemical characteristics to mix here.
• Emission Zone: It is the area that emits water coming from the headwaters and catchment areas toward a larger stream.

Importance of hydrographic basins and their functioning as a system

Different natural ecosystems interact in hydrographic basins, whose complexity and variability increases in relation to their area. Ecosystems are made up of elements such as air, climate, soil, subsoil, water, vegetation, landscape, and fauna, among others. Together they form the natural sustenance base, which is important to know in order to provide an integrated management of the hydrographic basin . A hydrographic basin works as a system because a great diversity of its elements interact. For example, if the upper part is greatly deforested, mass movements and floods may occur in the lower part in rainy seasons. Also, if waters are polluted in the upper or middle part, the fauna and flora of the lower ecosystems and human settlements are affected. In ecology, it is of great importance to know the meaning of hydrographic basins, their functioning, components, zones, and classification to provide a holistic management of all its territorial area. Water is much more than a resource or commodity. It has a symbolic value and is considered in many cultures as the origin of life. In addition, it is irreplaceable, and its vital need causes access to drinking water to be considered as a human right by many governments and international organizations. Even more, many legislations consider it as a public asset. Colombia has extensive hydrographic basins. Considering the ecosystemic treasures found in them, they must be considered as protected areas or areas intended for conservation, given the need to maintain a balance in the relationship between human beings and the environment. Thus, populations may continue to benefit in terms of their supply, on which the socio-economic activities in cities and other populated centers depends. Defining the concept of a hydrographic basin in Colombia has been very relevant to geographical and environmental studies, as it is the fourth country in the world with the highest annual precipitation figures, mostly of rainfall, together with huge reserves in lakes and other aquiferous bodies. Given the situation of Colombia in the equatorial zone, always humid, located between two oceans, crossed by large rivers, possessing extensive marshes and low and flooded territories, mountainous terrains with valleys of all shapes, sizes, and soils, micro-climate zones with sustained high humidity occur all along the year . In the soil, low intensity but long-lasting rains produce greater infiltration, a small part of which is retained by the ground and the rest descends to deeper layers of the earth, unlike intense rains that produce runoff. Runoff is water that does not infiltrate the ground. Rather, it flows on the surface and becomes part of streams, rivers, and lakes which in turn make part of a hydrographic basin whose behavior depends on the geographical characteristics of the area of the basin itself. Hydrographic basins cross vertically and longitudinally along the entire Colombian territory. Several of them flow into the Pacific and Atlantic oceans or into territories of neighboring countries. This characteristic also highlights the spatial position of the country on the continent. Between the Eastern mountain range, formed in its northern sector by the mountain chains of the Motilones and the mountains of Oca, and the Mérida mountain range in Venezuela, lies the hydrographic basin of the Catatumbo River, which drains into Lake Maracaibo .

See also

• Hoya hidrográfica

References

5. ↑ Guhl, E. (2009). El dilema del agua: cambio o sed. Bogotá, Colombia: Quinaxi Institute, Exhibition: WATER, a heritage that circulates hand in hand, p.33 6. ↑ Guhl, E. (2009). El dilema del agua: cambio o sed. Bogotá, Colombia: Quinaxi Institute, Exhibition: WATER, a heritage that circulates hand in hand, p. 245 7. ↑ Guhl, E. (2009). El dilema del agua: cambio o sed. Bogotá, Colombia: Quinaxi Institute, Exhibition: WATER, a heritage that circulates hand in hand, p. 150

Related links in Banrepcultural

• Cauca River Basin between Sabanalarga and Bolombolo • Geological formations of the middle basin of the Tunjuelo River. Photo 9 • The Basins and Water of the Andes

Credits

1. April 2022. Research and text: Federico Paz, for the project Río: territorios posibles (The River: Possible Territories) Banrepcultural