Digital Terrain Data:

Digital elevation data with 30-arcsecond resolution (approximately 1-km) for the Central America region was obtained from the United States Geological Survey’s GTOPO30 database (a public domain global database).  This data is used to delineate stream networks and watershed boundaries through GIS processing.  The elevation data is shown in the figure below for regions of Honduras, El Salvador, and Nicaragua, with the delineated streams and watershed boundaries also given in the figure.  The black lines represent the delineated stream networks and the blue polygon shapes represent the watershed boundaries.

Digital hydrographic features (including locations of streams, lakes and reservoirs) were also obtained from the Digital Chart of the World (DCW).  The data is useful for verification of the GIS delineation processing.

Land Cover Data:

A global land cover dataset with 1-km resolution is publicly available through the University of Maryland’s Global Land Cover Facility.  The digital data covering the Central American regions is shown in the figure below.   Primary land cover figures for the region are woodland or wooded grasslands (along the western portions of the region), evergreen forest (primarily along the eastern portions of the region), and a large region of deciduous forest in the northern regions of Guatemala.  Characterization of the land cover is necessary in the soil moisture analysis to aid in estimation of evapotranspiration.

Soil Properties Data:

The Food and Agriculture Organization (FAO) of the United Nations has produced a digital database of soils and terrain properties.  The data was obtained for the Central American region, which included geo-spatial and relational databases for soil and terrain characteristics.  The soil characteristics can be related to soil texture classifications, and to subsequently obtain derivative soil hydraulic properties and their variation across the region.  One example of the saturated hydraulic conductivity, in units of m/hr, is given in the figure below.  The variation of hydraulic conductivity is significant, with large regions of low hydraulic conductivity (e.g., < 0.006 m/hr), and localized area with relatively high hydraulic conductivity (e.g., > 0.03 m/hr).