Agriculture Reference
In-Depth Information
CHAPTER TEN
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A gricultural Drought in North-Central
M exico
JO SE ALFREDO RODRIGUEZ-PINEDA,
L ORRAIN GIDDINGS, HECTOR GADSDEN,
A ND VIJENDRA K. BOKEN
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Drought is the most significant natural phenomenon that affects the agri-
culture of northern Mexico. The more drought-prone areas in Mexico fall
in the northern half of the country, in the states of Chihuahua, Coahuila,
Durango, Zacatecas, and Aguascalientes (figure 10.1). The north-central
states form part of the Altiplanicie Mexicana and account for 30.7% of the
national territory of 1,959,248 km 2 . This area is characterized by dry and
semidry climates (García, 1981) and recurrent drought periods. The cli-
mate of Mexico varies from very dry to subhumid. Very dry climate covers
21%, dry climate covers 28%, and temperate subhumid and hot subhumid
climates prevail in 21% and 23% of the national territory, respectively.
About 20 years ago, almost 75% of Mexico's agricultural land was rain-
fed, and only 25% irrigated (Toledo et al., 1985), making the ratio of rain-
fed to irrigated area equal to 3. However, for the northern states this ratio
was 3.5 during the 1990-98 period (table 10.1). Because of higher per-
centage of rain-fed agriculture, drought is a common phenomenon in this
region, which has turned thousands of hectares of land into desert. Though
the government has built dams, reservoirs, and other irrigation systems to
alleviate drought effects, rain-fed agriculture (or dryland farming) remains
the major form of cultivation in Mexico.
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D efining a Drought
In Mexico, there is no standard definition for agricultural drought. How-
ever, the Comisión Nacional del Agua (CNA; i.e., National Water Commis-
sion), which is a federal agency responsible for making water policies, has
coined its own definition for drought. This agency determines whether a
particular region has been affected by drought, by studying rainfall records
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