GEOGRAPHIC BACKGROUND

Location and Extent.

Valladolid is a city located on the east of the state of Yucatán near the limits of Quintana Roo. Its geographical coordinates are 20º 41´00´´ North latitude and 20º 12´00´´ West longitude, in the Mexican southwest between the Gulf of Máxico and the Caribbean Sea. Valladolid occupies an extension of 945 km2, which represents 2,4% of the states total extension, and it is the second city in importance due to its dynamic economy and its ample regional commercial activity, second to the city of Mérida.

Geology

As far as this area is concerned, there is practically no land elevations but mostly plains with ondulations or irregularities of a few meters. Valladolid underground area is formed by calcaneus layers of marine origin. On the surfacethere are layers  rocks of various thicknesses denominated “Lajas”, There is also an abundance of a whitish material called “Sahcab” which is a calcaneus rock not consolidated. Inner activity has dissolve the lime stone causing in some points the appearance of underground ducts and cavities. On top there is a thin layer of clay mixed with decomposed organic material and small lithified rocks. This layer has a coloring that goes from red to brown and black, and it commonly reaches thicknesses between 20 and 60 cms.

The mayan empirical classification is based on he soil’s color and the presence or absence of rocks and its sizes, all this having an influence on the conservation of humidity and vegetation.

Topography.

            The surface is slightly wavy with some drops from 2 to 10% for Tzequeles soils and in the Chaac-Luum Soils that are predominant in this area.

Vegetation.

            To harvest corn, seventy percent of the original vegetation (primary) has been destroyed and reduced to secondary vegetation, this due to the constant cutting and burning that takes place because of the traditional way to harvest corn also to make pastures for the development of cattle rising and because of the abusive cutting of wood species.

The original forest reaches heights of 15 to 25 mts. tall among which it can be found: cedar, mahogamy and other red and white hard woods common in this area.

The secondary forest is characterized for having a variable height from 5 to 10 mts. It is formed by abundant leguminous resistant to fire, that reproduce easily and have a great capacity for invasion and development. The most important species are:

-Acacia Gaumeri (boxcatzin)

-Acacia Riparoides (ya’ax-katzin)

-Acacia Emarginata (xtha’bim)

-Gymnopodim Antigonoides (ts’its’ilche)

-Nuomillis Ohaugia emarginata (tsaytsa)

-Mimosa Hemiendyta (sac-katzin)

-Pithecolobium Albicans (chimay)

Rain Downfall

The average rain downfall in the municipalities where corn is produced oscilates between 900 and 1,100 millimeters of annual accumulation. The rainy season lasts from May to October and it accounts up to 65% of the annual rain downfall. The months which have the most rainy days are July and September, with high frecuency of rain storms

Hydrology

The great permeability and morphology of the area make possible the existence of a lime stone water acueduct with a level very close to the surface of almost all the area. For Valladolid this depth is of approximately 20 mts. and the hight of the static level in respect to the media sea level is 3 mts.

The waters in the acueducts are resting on top of sea water due to density differences. The contact between the two masses of water, known as “salt interphase” is on a dynamic equilibrium. The depth where the interphase is located in Valladolid’s zone is 120 mts.

Since there are no rivers, the portion of rain not evaporated filters in such a way that everywhere where there is rainfall constitute the charging zones of the acueduct.

This filtered volumes correspond to the almost simultaneous discharges towards the sea in similar quantities.

The media annual rainfall in the area of Yucatan’s peninsula is 1,050mm. The value of real evapo-tranpiration is calculated in 900 mm.

The wells on the area, specifically those of the thermoelectrical plant of the Federal Electric Commission (C.F.E.) water is extracted simultaneously in amounts up to 85 lts. per second without causing significant variations on the acueduct layer. This proves the hydraulic potential of our under surface.

The residual waters after being treated and having obtained the precise characteristics stated in the Mexican laws, are deposited by means of absorption wells back to the salt mantle that is located below the interphase already mentioned (past 120 mts. deep). The design of the absoprtion wells will depend on the company’s characteristics.

Water’s physical and chemical characteristics:

Climate

The climate, in general, is of tropical rains, very hot, with predominant trade winds most part of the year, charged with humidity and coming from the Gulf of México. The temperature oscillates between 15 and 28ºC. The south east is the largest area of rain downfall.

Temperature

 The media annual temperature is uniform, with variations from 24 to 26ºc with a low thermal oscillation. Frecuently the highest temperature exceeds 37ºC. From November to February there is a very definite season with daily temperatures from 7 to 10ºC.

Relative Humidity

The relative humidity is high and oscilates between 75 to 89% during the year. This high humidity prevents thermal oscillations to reach great variations during the year.

Nearby Littorals, Ports and Islands

Valladolid, is located near the northern coast and at 103 km. from Yucatan’s coast in the Gulf México. To the east, at 157 km. from the Caribbean sea.

There is communication with all the near and most important ports and islands located in national territory. On the Gulf of Mexico with Celestún, Sisal, Dzilam Bravo, Río Lagartos, San Felipe and El Cuyo in Yucatán; Lerma and Escárcega in Campeche; Coatzacoalcos and Varacruz in Veracruz and Tampico Madero in Tamaulipas.

On the caribbean sea with Puerto Juárez, Cancún, Puerto Morelos, Playa del carmen,Cozumel island and Chetumal in Quintana Roo.

On the Pacific ocean with Salina Cruz in Oaxaca which is approximately 1250 kms. away by road or train.

The closest most important ports and islands of international level are on the Gulf of  México, New Orleans, Tampa and Miami; on the Caribbean sea, Cuba and Belice.

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