Lerma Chapala Basin

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Location of larger cities in the Lerma-Chapala basin

The Lerma-Chapala Basin (Spanish: Cuenca Lerma-Chapala ) in Mexico is the hydrological catchment area of the Río Lerma from its origin to the confluence with Lake Chapala . It is one of the most important Mexican river systems and includes parts of 127 parishes in the five states of México , Querétaro , Michoacán , Guanajuato and Jalisco .

The basin is of considerable economic importance. With an area of ​​54,451 square kilometers , it takes up less than 3% of the total area of ​​Mexico, but is home to 9.3% of the entire Mexican population and contributes around 11.5% to the national gross domestic product (GDP) with their economic activity (as of 2009). Against this background, the natural resources in the area, especially water, are of great importance. The basin is a strategic inland region for the development of Mexico, but the dynamism of its socio-economic growth has in the past caused severe problems and conflicts in the area of ​​water resources and a deterioration in the environmental situation.

topography

The Lerma Chapala basin is divided into three main basins and 19 sub-basins. The upper basin covers the region above 2000 m above sea level. d. M., the largest medium basin in terms of area begins below 2000 m above sea level. d. M. and gradually falls down to 1600 m. In this middle basin is the Bajío , a fertile, economically and industrially well developed region. The lower basin is below 1600 m above sea level. d. M. and ends a little below the mean water level of Lake Chapala at 1490 m altitude. About 90% of the pool area is underlaid with basalt rock .

The Río Lerma arises on a high plateau at over 2600 m above sea level. d. M. by the confluence of several brooks, which in the mountains south and east of the Toluca Valley at an altitude of more than 3800 m above sea level. d. M. arise. The Lerma is not a particularly water-rich river, especially in the dry season it has little water. The surface runoff in the period from 1949 to 2005 averaged 4740 hectocubic meters per year, the width of the river rarely exceeds 30 m. Tributaries are the Río Turbio , Río Guanajuato , Río Apaseo , Río Laja , Arroyo Angelo and the Río Duero .

Reservoirs and lakes

There are a number of dams in the Lerma Chapala Basin. The Chapala , Yuriria and Cuitzeo lakes are the three most important natural lakes, but they have been redesigned through hydraulic engineering measures. The lakes Cuitzeo and Pátzcuaro are endorheic . A smaller dam near Poncitlán that drains into the Santiago increases the storage capacity of Lake Chapala, which is the most important water source for the Guadalajara metropolitan area and accounts for almost 75% of the water supply.

history

The development of large-scale irrigation in the Lerma-Chapala Basin began with the arrival of the Spaniards and the resulting colonization of the basin. The discovery of the silver mines in Guanajuato in the 1550s was followed by the rapid settlement of the central Lerma basin and the development of the irrigation industry for wheat cultivation, mostly on private initiative and by monasteries. The increasing demand for grain by the cities led in the 17th and 18th centuries to an expansion of irrigation, which was based on river irrigation systems and the intelligent use of floods, through the construction of so-called Cajas de Agua ("water boxes"). It was a system of interconnected and diked fields of 5 to 200 hectares each, which could be filled with flood water one after the other, mainly from the tributaries of the Río Lerma. Towards the end of the colonial period , the water resources of the Lerma-Chapala basin were already being used intensively, and by 1900 the irrigation potential of the tributaries of the Río Lerma was largely exhausted with around 60,000 hectares.

See also

Presa Solís

literature

Individual evidence

  1. ↑ Lerma Region , Comisión Nacional del Agua (Conagua), accessed January 18, 2020.