Chihuahua, Chih.- Of the 61 aquifers that correspond to the state of Chihuahua, more than half are in conditions of overexploitation, 23 of them collapsed due to extraction which, on average, is 84 percent more than what they manage to recharge annually.
The most current data from the National Water Commission (Conagua) establishes that the groundwater tables together have an average recharge per year of three thousand 899 cubic hectometers, but six thousand 556 cubic hectometers (hm3) are extracted from them, an annual deficit of three thousand 312 hm3.
Each cubic hectometer is equivalent to one billion liters. For reference, the total surface water storage capacity of the La Boquilla dam, the largest in the state, is 2,903 hm3.
Thus, Chihuahua’s annual subsoil water consumption is greater than more than two full fills of La Boquilla, while the annual recharge is little more than one full fill of that reservoir, located in the most relevant tributary of the state, the river Conchos, which crosses a large part of the entity’s territory, from its highest parts to its mouth into the Río Bravo.
The state faces a serious deficit of surface water due to its climatic conditions, which has led to the overexploitation of groundwater being exacerbated, according to what Víctor Quintana and Martín Solís, consultants at the subregional headquarters of the Economic Commission for America, state. Latin America and the Caribbean (ECLAC) in Mexico – in the “Analysis of different types of agriculture for the conceptualization of a new rurality. The Chihuahua case.
“Groundwater has been the great reserve for Chihuahuan agriculture, but its overexploitation represents a great problem,” say the researchers, who observe a critical situation that makes rural activity unsustainable, due to an intensive growth of agriculture through pumping irrigation.
“This means that the water, especially in the subsoil, that producers have for different crops, is in the process of being exhausted and future generations will have less and less access or no access to it,” they warn.
While the area irrigated with surface water in the districts and irrigation units has remained the same since 2004, there has been a very significant increase in the hectare irrigated by groundwater. Although there is a difference between the data provided by various government agencies, the surface area irrigated with subsoil water increased by 189,253 hectares between 2004 and 2021.
“The reason is that in all those years the hectare planted with surface water did not increase, which is already at its maximum limit,” they state.
This increase was concentrated in 10 of the state’s 67 municipalities, which represent 149,688 hectares of the 189,253 hectares of the increase in surface area irrigated with pumped water between 2004 and 2021, 77 percent. Of these municipalities, seven are in the Desert region (Ahumada, Ascensión, Buenaventura, Chihuahua, Galeana, Janos and Ojinaga), and three in the western region (Cuauhtémoc, Guerrero and Namiquipa).
“In all these municipalities there are many Mennonite farmers, who have expanded from their original establishment in the municipality of Cuauhtémoc, first to Namiquipa and Guerrero and since the beginning of this century to the municipalities of the desert,” they say.
Overexploited aquifers… by a few
Overexploitation for profitable Mennonite production and the exaggerated growth of walnut trees that has been documented throughout the state are the main factors in the depletion of groundwater tables.
“As a conclusion to the analysis of the gap in terms of access to water for agricultural irrigation, it can be noted that access to surface water seems not to be so monopolized in Chihuahua and seems to have already reached the capacity limit of the state’s surface water resources. . Even with climate change, the availability of surface water is declining,” they consider, but warn: “on the other hand, access to subsoil water, which has increased disproportionately, is reserved for medium and large agricultural entrepreneurs, especially ”.
Regarding subsoil water, the analysis indicates that there are a total of 69 aquifers, of which 61 are awarded by the National Water Commission to the state of Chihuahua itself; five to Sonora and three to Sinaloa, according to data from the 2018 State Water Plan.
Since 2000, the area planted with subsoil water has increased. By 2012, although Chihuahua already had concessions of 2,750 hm3 per year, which was enough to irrigate an average of 275,000 hectares, the reality was that in that year approximately 417,000 hectares were already planted with groundwater, which implied the extraction of a very large volume. higher than that officially granted.
Chihuahua is the state that has the highest percentage of overexploited aquifers. It is certainly the one with the most aquifers due to its territorial extension, but also one of the ones that uses the most subsoil water for agriculture.
“All this demonstrates the seriousness of the situation of the aquifers in Chihuahua; More than half of them are overexploited and it is very difficult for them to recover, let alone in the medium term.
For example, it is estimated that the water in the desert aquifers has been deposited for at least 100 thousand years and, when it is extracted at high speed, as in several cases, it will be exhausted in a few years, as is already happening in some Mennonite farms,” they point out.
“The water, especially from the subsoil, that producers have for different crops, is in the process of being exhausted and future generations will have less and less access to it”
Experts
Collapsed aquifers
The 2020 and 2021 data from Conagua, presented in the analysis, show a great disparity between the concessioned volume, effective extraction, estimated annual recharge and the number of agricultural hectares in each region, which results in deficit balances of the aquifers, mainly in 23 of these, which cover the large productive regions of Chihuahua.
The Los Juncos aquifer – covers areas of the neighboring states of Chihuahua and within this the municipalities of Camargo, Julimes, Ojinaga, Aldama and Coyame – has a negative balance of 697.8 hm3, given that its estimated annual recharge is 133.6 hm3, while its expenditure is 831.1 hm3, used to irrigate around 57 thousand hectares.
The Laguna de Santa María aquifer, in the northern portion of the state, in the municipalities of Nuevo Casas Grandes, Ahumada, Ascensión and Buenaventura, has a recharge of only 45.2 hm3, but an extraction of 461.8 hm3, that is, a deficit of 419.8 hm3, used in pumping for almost 40 thousand hectares.
Another one that shows the greatest imbalance is the Tarabillas Lagoon mantle, in the central part of the entity, between Ahumada and the capital, it shows a deficit of 287 hm3, given that 323.5 hm3 are extracted and has an estimated recharge of just 36.4 hm3.
Similar cases of deficit can be seen in the desert and plain portions of Chihuahua, as well as in the aquifers located in the most populated urban areas.
The Meoqui-delicias aquifer, which covers these municipalities as well as that of Rosales, is one of those with the highest annual recharge, of 211.2 hm3, while its expenditure is 376 hm3, which results in a deficit of 165 hm3; In addition to comprising large urban areas, medium-sized cities, this is the area with the largest cultivable area after Cuauhtémoc, with more than 85 thousand hectares, which are irrigated by both surface and subsoil waters.
In the northern area of the entity, the Conejos-médanos aquifer, has an annual recharge of less than 20 hm3, but an extraction of 120.9 hm3, that is, more than 100 hm3 of deficit, basically for human consumption.
The Juárez Valley aquifer, where there are barely 17 thousand cultivable hectares, has a greater recharge, of 125.9 hm3, but a cost of 202.6 hm3.
In the central region that includes the state capital, the Chihuahua-Sacramento aquifer has an extraction of 125.3 hm3, with a recharge barely greater than 56 hm3, with less than four thousand cultivable hectares; while El Sauz-encinillas, with a recharge of 62.4 hm3, has an extraction of 121.1 hm3, with barely 12 thousand hectares of arable surface, but a high demand from the urban area.
Unsustainable agricultural consumption
“There are several factors that aggravate the overexploitation of aquifers and sustainability. The first is the water requirement for the main crops. The second, the over-concessions of volumes by Conagua, the pirate wells to extract water from the subsoil and the clandestine intakes in agriculture of surface waters, as well as the administrative failures and even corruption in the water administration bodies,” Quintana and Solís consider in their analysis.
“Firstly, there is the water requirement for the majority crops in pump irrigation. The most frequent crops in the pump irrigation regime are alfalfa, walnut, apple and peach, among the perennials, and cotton, corn and chili among the annuals.”
The irrigation sheets used for the seven main crops in Chihuahua represent 7 million 270 thousand 396 hm3, well above the total volume granted for agriculture, which is 4 million 796 thousand hm3 annually, 151 percent more.
Another way to calculate the overextraction of subsoil water for agricultural irrigation is based on electricity consumption.
“In addition to overextraction or overconcession of groundwater, there are pirate wells, without a concession or with a concession from another aquifer. Despite their irregularities, the CFE connects them to the electricity supply,” they maintain.
Thus, it is estimated that in Chihuahua there are approximately 2,000 wells without a concession in the closed areas and about 5,000 in the free-flow areas, factors that affect the collapse conditions in which most of the aquifers in the region are found. entity.
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