HYDROGRAPHY OF MEXICO: RIVERS, OCEANS, LAKES - GEOGRAPHY - 2025

The hydrography of Mexico has a significant number of hydrological sources, whose flows vary depending on their location. The country has a water network more than 600 kilometers long.

This wide network includes rivers and surface sources, as well as hydrological basins (groundwater) that occupy about 60% of the national territory. The main sources of fresh water are represented by its rivers, lakes and lagoons. However, 95% of it comes from groundwater, which contributes 75% for human consumption.

On the other hand, due to the constitution of the relief, river flows can vary throughout the year depending on the season (dry or rainy season). At this point the conditions of the land also influence the irrigation system towards other areas of the territory.

For example, to the north, near the desert and arid areas, the rivers are characterized by sporadic flow. On the other hand, towards the south there is a greater presence of rains and precipitations due to having a geography more of the tropical type.

One of the most important problems facing the country is the distribution of drinking water. Because the main source comes from groundwater through rainfall, the region has been affected by deforestation, which causes soil erosion and affects the seepage of the liquid thanks to surface runoff.

As a result of this situation, groundwater has not been properly used, which has represented a significant inconvenience when it was distributed to populations farthest from urban centers.

Rivers: slopes

In general terms, it is understood that it is possible to group rivers from three main slopes:

- Del Pacífico, located in the west.

- The Gulf and the Caribbean, located in the east. It gathers those that flow into the Gulf of Mexico and the Caribbean.

- Some scholars include the internal slopes that flow into different points throughout the territory.

Thanks to the aforementioned, the country has a great variety of hydrological and hydrographic sources, constituting a network through which more than 50 main rivers cross. The most important rivers are described below, according to the previous classification:

Western or Pacific slope

Balsas River

With a length of 771 km, the Balsas River is home to a number of important hydroelectric plants.

Lerma River

It finds its origin in the Nevado de Toluca and flows into Lake Chapala. Thanks to its length of more than 900 km, it runs through several important towns in the country.

Mayo River

It originates in the Chihuahua mountains to flow into the Gulf of California. In the vicinity is Alamos, a city famous for its silver mines.

Yaqui River

It leaves from the Sierra Madre Occidental to flow into the municipality of Guaymas. The Yaqui, together with the Mayo, are part of a set of rivers that enrich the land and make it ideal for agriculture.

Colorado River

It originates from the Rocky Mountains, which is why it runs through part of the United States. Likewise, it is considered as an international boundary between the two nations. It passes through Sonora and Baja California.

Eastern slope or the gulf and the Caribbean

Bravo River

Considered one of the longest, since it has a length of more than 3000 km. It has its origin in the Rockies (as in the case of the Colorado River), so it shares part of the territory in the United States (there it is called the Rio Grande). It empties into the Gulf of Mexico.

Pánuco River

Originally he was known as Moctezuma and was born in the eastern part of the country, precisely from the Anáhuac plateau. It also empties into the gulf.

Papaloapan River

It is another of the largest as it has a length of 900 km and passes through several areas of the country: from the Sierra de Ixtlán to the Sierra Madre Oriental, to finally flow into the Gulf of Mexico.

Isthmus River

It is considered one with a greater flow, since it is fed by several hydrological sources. It is born in Sierra Atravesada and ends in Coatzacoalcos.

Tonalá River

With more than 300 km in length, this river also acts as a boundary between the states of Veracruz and Tabasco.

Usumacinta

It is considered the most abundant and, in addition, it is presented as an international border with Guatemala. In turn, it makes anchorage with the Grijalva river (the second largest), as they join up to the plains in Tabasco.

Both cover a length of more than 600 km and, due to their powerful flow, hydroelectric plants have been built for use in the generation of electricity.

Internal slopes

They receive this name because rivers do not flow into seas or oceans; instead, they do so in geographic structures called pockets. These waters are used for distribution to the cities that are nearby. Among the most important are the following:

Nazas River

It is located in the state of Durango and flows into the Mayrán lagoon.

Aguanaval River

Together with the previous tributary, the Aguanaval is located in the states of Zacatecas, part of Durango and Coahuila. Although it has little flow, it represents an important source of fresh water.

Rio del Carmen

Originally it was known as the Santa Clara River. Due to a series of changes, it is now part of other rivers.

Oceans

Due to its geographical location, Mexico has an eastern coast made up of the Gulf of Mexico and the Caribbean Sea. In addition, both are part of the Atlantic Ocean. To the west, Mexico borders the Pacific Ocean.

The Mexican coastline can be divided as follows:

Pacific Coast

It is comprised of the peninsula and the Gulf of California. On this coast it is possible to appreciate an important variety of ecosystems and maritime geography. In total it covers more than 7000 km in length.

Atlantic coast

With almost 4000 km of extension, it is included by the Gulf of Mexico, the mouth of the Rio Grande and part of the Yucatan peninsula.

Furthermore, 16 states are considered to be located in the vicinity of these coastlines.

Lakes and lagoons

Most of the lakes and lagoons in Mexico are the main sources of water for irrigation and for the production of electricity, although most of them are not large. In the country there are several types of lagoons and lakes:

Volcanic lakes

They are found in the craters of volcanoes or by the path drawn by the flow of lava in previous eruptions. Those formed in Nevado de Toluca, Cuitzeo and Pátzcuaro stand out.

Kartic lakes

They were created from a series of depressions such as those found in Yucatán and Chiapas.

Lakes formed by landslides

Due to the movements of the earth, a kind of natural dam is formed, enclosing the waters. An example of this is Lake Metztitlán, in the state of Hidalgo, which was originated by a strong earth movement during the Quaternary.

Currently, the authorities are obliged to regulate the flood to prevent flooding in surrounding areas.

Artificial lakes

They originated thanks to the construction of dams. These include Tequesquitengo, Valle de Bravo and Thousand Islands.

Some of the most important lakes and lagoons in Mexico are:

- Lake Chapala, considered one of the most important that is close to disappearing due to its overexploitation.

- Lake Pátzcuaro.

- Lake Cuitzeo.

- Lake of Parras.

- Lake Zirahuén.

- Lake Santa Ana.

- Tamiahua Lagoon.

- Laguna de Catemaco.

- Guzmán Lagoon.

- Lagoon of Terms.

- Laguna de Santa María.

- Laguna de Palos.

- Laguna de Tlahualilo.

- Bag of Mapimí.

- Mayran Lagoon.

- Lagoon of Palomas.

Groundwater

Groundwater is stored in geological formations or reservoirs that are found below the earth's surface. In most cases, this accumulation of liquid is obtained through precipitation.

As previously mentioned, groundwater plays a vital role in the distribution of the liquid in the main urban centers, especially in the Federal District.

Its main sources are found in the wells of the Valley of Mexico and the Lerma river basin. However, there are a series of problems that prevent the correct use of these waters:

Overpopulation

Only in the capital are more than 18 million people, which indicates a challenge for the supply of the vital liquid.

Environmental problems

Due to logging and burning of forests, the soil has been affected, compromising its levels of porosity and permeability. Due to erosion, it becomes more difficult for water to leak into aquifers.

Extraction speed

The speed of the extraction affects the recharge. In general, the recharge of aquifers is more or less slow. This, coupled with the speed of extraction, leads to overexploitation and the potential loss of freshwater sources.

Contamination

It is related to the previous point. The intervention of man in extraction activities -as well as others of an industrial nature- has compromised the quality of the water thanks to the presence of heavy minerals. On the other hand, other polluting elements have been found, such as the inclusion of saline water or wastewater.

The consequences of these actions have produced the regularization of the service in some cities of the country such as Mérida and Monterrey, as well as the decline of important basins such as the Lerma River, which has forced the use and treatment of well water.

Another warning sign is that, thanks to the presence of waste and harmful substances in lakes, lagoons and aquifers, the balance of existing ecosystems has also been endangered.

Humidity

Mexico has a varied climate, since there are arid areas, tundra and even tropical environments where rains abound. Therefore, humidity will vary by region.

For example, some areas whose temperatures are between 10 and 20 ° C have mostly snow and sleet, typical of mountainous cities.

On the other hand, in areas that are rather hot-humid, it is normal to encounter rainfall almost all year round.In general, the following characteristics can be listed:

- Mexico has a rainy season from May to October.

- The humidity will depend on the location of the area.

- It is estimated that there is an average of 60 days of rain.

- Cold and warm-tropical areas present a significant degree of humidity. In the case of coastal areas, there is also the influence of the winds that bring seawater with them (as in the case of Baja California).

Precipitation

The distribution of rain is different across the country, so this is also related to climate and humidity. These characteristics are conditioned by the country's location in the Tropic of Cancer and near the equator. Therefore, we have the following:

- The rainiest areas are found in the central and southern part of the country, especially those that are adjacent to the Gulf of Mexico. Likewise, they also perceive the humidity of the winds that come from the sea. This increase is due in particular to tropical cyclones.

- On the Pacific side, the scenario is different. There is not as much rainfall as in the gulf, except in exceptional cases such as the Sierra Madre de Chiapas. In case of rains, these will be noticeable in summer.

- In the coldest areas, present in the peaks such as Malinche and Nevado de Toluca, rainfall can occur in the form of snow or sleet due to the drop in temperature.

- To the north, the area is arid and dry, due to the fact that it is surrounded by mountains that prevent its contact with the seas, so there is a maximum of 300 mm of annual rainfall. This strip extends towards the border with the United States and next to the Colorado River.

- Another area recognized for its low rainfall is that found in Baja California, although in the higher areas there may be the presence of rains in the summer.

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