Agriculture and Its Demands for Water: a Challenge

Agriculture is undoubtedly one of the most important economic activities in Mexico, generating a large number of jobs in the country. Millions of people also depend on agriculture for their primary food products.

In 2017, the sector registered its highest-ever level for gross domestic product (GDP) per capita. Additionally, the sector's exports registered a very high value. It is worth mentioning that primary GDP is made up of agriculture (63.4 percent), livestock (30.6 percent), forest harvesting (3.1 percent), fishing (2.6 percent) and related services (0.3 percent).

The importance of this activity stands out because it is in charge of supplying food, raw materials and labor to the agro-industrial and services sector. In addition, it demands a large number of industrial products for its production, such as fertilizers, herbicides, pesticides, and machinery. According to the Ministry of Agriculture and Rural Development, agriculture has brought social benefits to the country and has allowed some Mexicans to take root, as it supports their families.

The most important agricultural activities in our country are developed in "irrigation districts" and in "irrigation units." According to data from the National Water Commission (CONAGUA), there is an area of ​​6.5 million hectares (ha) under irrigation, of which 3.3 million correspond to 86 irrigation districts and the remaining 3.2 million having more than 40,000 irrigation units. 

According to a study from the Center for Sustainable Rural Development and Food Sovereignty (CEDRSSA), the differences between an irrigation district (DR) and an irrigation unit (UR) is in their dimensions. DR usually have superior surfaces 2,000ha, while the UR are less than 500ha; the ownership of the infrastructure is federal in the case of the DR and private and/or ejido (communal land) in the UR; DRs are organized by civil associations through limited liability companies and URs by civil associations and nonformal societies, organized for the concession of water; and DRs are permanently supervised by CONAGUA and URs are eventually supervised by this same commission.

The organization of DRs and URs in the country is carried out based on the 13 CONAGUA Basin Organizations, whose sphere of competence is the hydrological-administrative regions (RHA), which in turn are formed by groups of basins, which are the basic units for the management of water resources in Mexico. A relevant aspect is that the limits of the RHA are not based on natural limits defined by the natural hydrographic basins, but by municipal limits, which on many occasions has been questioned by researchers and specialists in water resources.

 Based on hydrological balances carried out by CONAGUA and published in a document called "Statistics on Water in Mexico," (2018), the country has an annual renewable water volume on the order of 451,585 million cubic meters per year (Figure 1).

Unfortunately, as can be seen in Figure 2, the geographical distribution of this annual volume of renewable water is not in accordance with the contribution to national GDP. The greatest contribution to GDP is in the areas of the country with only 33 percent of the 451 billion cubic meters of renewable water, while 67 percent of this water is located where there is only a 17 percent contribution to GDP. This shows that the greatest economic activity is carried out where there is less availability of water, which is a serious problem for development.

This situation is closely related to the distribution of rainfall in the country, as shown in Figure 3, where there is a close correlation between the distribution of annual rainfall and economic development.

These problems related to the scarcity of water resources are transferred in the same way to agricultural activities. The location of the DR and UR encourage the main use of water in arid and semi-arid regions for agricultural use; Figures 4 and 5 show the location of these large areas of irrigation that, as mentioned before, add up to around 6.5 million hectares.

If the location of the DRs and URs is compared with the distribution of the average annual rainfall in Figure 3, it is possible to understand the problems related to the scarcity of water resources used for agriculture for other economic activities supplying the population.

The relevance of commenting in this article on the challenge that Mexico faces in relation to its water resources, so that in the future it can continue to develop economic activities, taking agricultural activities as a reference axis, is related to the amount of water that this use demands. As can be seen in Figure 6, of the total water that after being used does not return to the environment where it was collected (consumptive use), 76 percent is linked to agriculture.

The way in which these water requirements by activity are distributed in the hydrological-administrative regions (RHA) is observed in Figure 7.

As can be seen, in the entire Mexican Republic, agricultural use demands the most water, which also does not return to the environment from which it was taken, be it a dam, river or an aquifer. Of these RHAs, the ones marked with the red arrows represent large areas of the national territory where, in its entirety or in a large part, the rainfall is less than 500 mm per year.

These water requirements for agricultural use have led to the extraction of more water from the aquifers than is recharged, so that at least 105 overexploited aquifers exist and that some of these have seawater intrusion and/or soil salinization, as well as brackish groundwater.

All of this leads to the conclusion that in 2020, the continuity of agricultural activities is exposed to a serious problem of water supply and that the Mexican economy and the people dedicated to these tasks are also in the same situation. Additionally, the high demand for water from agriculture puts industrial activities, the water supply to the population and the water required by ecosystems, which together depend on the same amount of renewable water as shown in the Figure 1, at risk.

This situation becomes more alarming when we take into account that we are experiencing climate change. According to 2018 Water in Mexico statistics, in terms of fresh water, it is expected that during the 21st century renewable surface and groundwater will be reduced in most dry, subtropical regions, which will increase competition among users.

Research carried out by Sosa-Rodríguez, F.S. (2020), in which “The Water Crisis in the Valley of Mexico Basin Facing the Challenges of Climate Change is Studied. Mexico: UAM,” has established that the variation of the percentage of precipitation in the country, in the most arid and semi-arid regions of Mexico, will see rainfall decrease by 2-6 percent as can be seen in Figure 9, which will further aggravate the lack of resources to cover the water demands of agricultural activities and of all users in general.

In summary, we know that the water supply problem exists and we must start acting as soon as possible. But how? Helping the public administration to find solutions in which we all participate is vital, because in the face of the political and social situation that the country is experiencing, it is very difficult for CONAGUA or any other institution to do it alone. Instead of strengthening them, they are being weakened, their budget is being reduced, and highly experienced specialists are being fired, replaced with others who are not qualified to occupy these positions. 

What solutions can be viable so that with the water resources that Mexico has, it can face this problem? Some of these may be the following:

1. Because 76 percent of the water is being used in agricultural activities, it is very important that crop changes be made by others who consume less water and offer the same yield. An example is to stop intensively growing alfalfa for livestock consumption, as occurs in the lagoon region, for another crop with the same energy capacity. Another important action is to provide incentives and support to farmers, so that they can make irrigation more technical, but this support must be conditioned to the fact that by using a smaller volume of water for their crops, they do not increase the area they cultivate and accept a reduction in volumes of water assigned to them in their concession titles. For this to be a feasible solution, users must be made aware of and condition the support, which includes those who pay a very low rate per cubic meter. The previous action must be accompanied by an exchange of water rights between users, giving priority to the use of water for the supply of urban areas and rural populations. All of the above must have a legal basis and support.

2. Substantially increase the use of treated wastewater, in all possible areas, among others in industrial and agricultural activities, for which it is important to reach agreements with water operating agencies and provide in-kind support (water concessions), as well as promoting and favoring the interaction between DR, UR and industrialists, with the operating organisms, so that the exchanges of water rights can become a reality. Support investment in the construction of treatment plants at the tertiary level, looking for technical schemes in which its effluents are used for public-urban use, after conducting to aquifers (artificial recharge) or to dams or other bodies of water, to avoid the rejection of the inhabitants to their consumption. Take advantage of the experiences of other countries like the United States of America.

3. Using rainwater, which is currently posing serious problems in large areas of the country, even in semi-desert areas, where there have been large volumes of precipitation in short periods; in most cases, these waters are led to the drainage networks of the cities and are lost. There are studies carried out by Mexican researchers of the economic and environmental benefits of using these resources; for example, research conducted by Dr. Fabiola Sosa of the Universidad Autónoma Metropolitana (Sosa-Rodríguez, et al., 2020).