Jorge López-Blanco

Delineation of suitable areas for crops using a Multi-Criteria Evaluation approach and land use/cover mapping: a case study in Central Mexico

Abstract The application of a Multi-Criteria Evaluation (MCE) approach to identify suitable areas for the production of maize and potato crops in Central Mexico is presented. Maize and potato are the most important crops in the Rural Development District of Toluca (RDDT). Climate, relief and soil databases were used to integrate GIS raster coverages. Relevant criteria for crops and suitability levels were defined. This information was used to obtain the criteria maps, which in turn were used as input into the MCE algorithm. Several decision support procedures in the Idrisi GIS environment were applied to obtain the suitability maps for each crop. A 1996 Landsat TM image was processed using GIS capabilities by means of a supervised classification to obtain a land use/cover map. These land use/cover and the suitability maps were crossing to identify differences and similarities between the present landuse in the suitable areas for the maize and potato crops.

Evaluating biophysical variables to identify suitable areas for oat in Central Mexico: a multi-criteria and GIS approach

Evaluation of biophysical variables is usually a first step in land use analysis. A multi-criteria evaluation (MCE) approach, within a GIS environment, was used to identify suitable areas for oat (Avena sativa L.) crop production in Central Mexico. Relevant environment-components such as climate, soil, and topography at different spatial and temporal resolutions were considered. Fuzzy membership function was used to generate standardized factor maps. According to the weight-eigen vectors, the results indicated that the most important variables affecting the growth of an oat crop were precipitation, altitude and soil depth. This research provided information at regional level that could be used by farmers to select crop pattern and suitability. The results of this research identified 6663 ha with a high suitability level, which represent 57% more than the territory presently being used for oat cultivation, under rain-fed agriculture in Central Mexico.

Mangrove vegetation assessment in the Santiago River Mouth, Mexico, by means of supervised classification using LandsatTM imagery

This paper presents a mangrove vegetation assessment from 1970 to 1993 of the Santiago River Mouth, Nayarit, West of Mexico. The aims of this work are to describe the plant composition and structure of mangrove in the study area, and to evaluate the deforestation level and its amplitude by means of a retrospective analysis of the cover and distribution area of mangrove species using a LandsatTM image, aerial photographs and oblique video. Mangrove of the study area is dominated by Laguncularia racemosa with the average importance value of 158.18 and 400 ha of plant cover, followed by Avicennia germinans, with an average importance value of 138.52 and 324 ha of plant cover. Mangrove showed seven height and five diametrical classes that include the two dominant species. L. racemosa was the dominant species in six of the eight compass lines. The highest absolute frequencies for both dominant species were found in the second height class frequency, and the first diametric class frequency. Cover area and distribution of mangrove in the study area were mapped using a LandsatTM5 image (April 1993). A supervised classification was applied using the maximum likelihood algorithm, considering ten initial classes. This classification was evaluated by obtaining a classification error matrix and by assessing its accuracy. The mangrove vegetation area reported before, considering the same area for image analysis, resulted to be overestimated in 56% regarding the value obtained in our photointerpretation (1065 ha). From the latter mangrove area, the current cover is 724 ha, which represents a decrease of 32% in a 23-yr period.

Post-Oligocene river incision, southern Sierra Madre Occidental, Mexico

The Sierra Madre Occidental of western Mexico consists of a granitic basement covered by Oligocene ignimbrites that define a reference surface from which to estimate late Cenozoic river incision. A 90-m-grid digital elevation model was used to characterize contemporary topography and interpolate the Late Oligocene surface of the ignimbrite plateau from a surface fit to the highest points in the relatively undissected uplands between major river valleys. Long-term river incision rates calculated from the difference between this reference surface and longitudinal profiles of 11 rivers that flow toward the Tepic-Zacoalco rift zone range from about 0.01 to 0.2 mm year−1. River profiles of this region also show evidence of river capture driven by flexural uplift along the flank of the rift zone. River profile concavity values (θ) in the Sierra Madre Occidental range from 0.22 to 0.63, a range similar to that reported previously for a wide range of environments. In contrast, the empirically constrained ratio of exponents in the stream power model of river incision (m/n) ranges from 0.44 to 0.52, close to the expected theoretical value of 0.5. The wider range of observed θ values may illustrate how θ can differ from the driving values of m/n in non-steady-state bedrock river systems.

Dry vegetation in relation to the physical environment in the Baja California Peninsula, Mexico

Abstract An ordination analysis of vegetation and flora of Los Cabos Region, Baja California Peninsula, Mexico and its relationships with their environment and geomorphic characteristics was studied at 38 sites, selected based on ecoregion mapping units (EMU) previously delineated for the study area. Multivariate methods were used to analyse the relationship between physical characteristics of the environment and the two primary vegetation types, the Dry tropical forest (DTF) and the Xerophilous scrubland (XS), which together represent 83% of the vegetation cover in the study area. Sites were grouped based on both physical characteristics and relative abundance of plant species. The results of the statistical analysis suggest that altitude, rainfall, temperature, and lithology can help explaining differences between these important vegetation types. In the case of XS, the morpho-physiognomic characteristics of vegetation in each site discriminated between two scrub types. Abbreviations: DTF = Dry tropical forest; XS = Xerophilous scrubland.

Delineating boundaries of environmental units for land management using a geomorphological approach and GIS: A study in Baja California, Mexico

A geomorphological approach was applied to delineate environmental terrains in the study area, using a Geographic Information System. Such units were used as main spatial framework to search the land use suitability for landscape sets. A hierarchical structure was developed using ecological considerations with broad to specific scales. Thirty-two landscapes were delineated. The use of GIS for collecting, storing, and processing the spatial database was useful to interpret and determine the boundaries of environmental units, particularly in the interactive process of on-screen digitizing. In this process different thematic information layers were selected and overlaid on the hillshading map generated from a digital terrain model. The landscape units map was cross-tabulated against several thematic maps to obtain a database that describes area and cover percentage of each thematic class for each landscape. The landscape units map and its database led, in further phases, to our interpreting land use suitabilities related to an environmental land management approach.

Development and implementation of an electronic journal for publishing peer-reviewed GIS-based maps on the Web

The fusion of recent Internet and mapping technologies, such as Web Map Services, has made the publication of interactive cartographic products technically feasible, leading to a reduction in production costs and to an increase in the number of map readers. This study examines the scientific role of cartography in relation to the publication, communication and dissemination of geoscientific maps. We analyse the importance of cartography and mapping, including some constraints associated with the decline in the publication of maps in peer-reviewed journals, and present a new electronic journal as an alternative medium for publishing and disseminating cartographic products. Digital Geosciences (http://digitalgeosciences.unam.mx) specializes in the web publication of Earth Science and Physical Geography maps. Its objective is to re-establish the value of cartography by promoting its publication and recognition as a scientific product. This journal publishes peer-reviewed GIS-based maps from any part of the world, although Latin America is the main region of interest. The official languages are Spanish and English. We present the new paradigm used by Digital Geosciences in the publication of interactive cartography. Journal conception and development, operational details and information for international contributions are also discussed. The accepted products are published using Map Servers. The interface uses standard ArcIMS with predesigned HTML pages, enhanced with the advanced cartographic design of the ArcMap Server extension and simple adaptations. We are working on the implementation of Map Server free software, a metadata engine tool, and the full integration of the online peer-review process using Open Journal System, including map notes and map edition capabilities.