Reinaldo Paul Pérez Machado

The author of "Redefining borders in the contested territory between San Pedro and San Andres Cholula" provides an interesting and comprehensive understanding of the redefinition of borders between two of the municipalities of the Metropolitan Area o...

The Lençóis Maranhenses region, located in the state of Maranhão in northeastern Brazil, constitutes an area that includes a national park and presents extreme physical, geographic and climatic contrasts in addition to economic diversity and emerging tourism. Scattered throughout this portion of the Brazilian territory are local inhabitants whose traditional lifestyles are characterized by agricultural, extractive, fishing and animal husbandry activities. These local residents use guidance systems and mental maps developed through their long history, interaction with nature, and knowledge of the environment in which they live and work. Based on sketches prepared by residents and by Health Agents serving the communities, and with the support of cartographic-based materials produced by the team of the Socioenvironmental Atlas of Lençóis Maranhenses (ASALM, Portuguese abbreviation for Socioenvironmental Atlas of Lençóis Maranhenses), we present a set of digital and interactive cartographic materials that reproduce the movements, uses and practices of the families of these communities as well as the environmental dynamics of this vast region. Such cartography can serve as an instrument of planning, understanding and action, both to safeguard the rights of the local residents and for the handling and management of natural resources. Based on the dialogue between local knowledge and cartography, we present the methods, processes and results of our research project.

Dasymetric mapping is a process of disaggregating spatial data from a coarser to a finer unit of analysis, using additional (or “ancillary”) data to refine the locations of population and achieve greater accuracy. Disaggregating population data reported by census tracts or other administrative or political geographic units can provide a more realistic depiction of actual population distribution and location. This is particularly important in assessing environmental exposures and impacts. Additionally, because exposures can occur in three dimensions (e.g., air pollution is a three-dimensional phenomenon), modeling residential population in three dimensions might produce more reliable estimates of exposure. Population exposure estimates are improved through dasymetric disaggregation and 3D extrusion, using a combination of cadastral data (residential area by property tax lot), building footprint data, and building height data. Population in census units is dasymetrically disaggregated into individual buildings using residential area derived from property tax lots and then extruded vertically based on building height. This 3D dasymetric mapping technique is presented through a New York City–based case study, and contrasted with a case study of São Paulo, Brazil, to demonstrate the possibilities of using this technique in different settings of data availability.