Geoenvironmental Map

Introduction

Geoenvironmental mapping is a source of data for macrodraining programs, urban growth, areas restricted for certain uses and areas that will be potentially used in the municipality of Aracaju State of Sergipe) –SE, as a city planning tool.

The geoenvironmental concept is closely related with the results derived from cross-referencing different themes spatially represented in a same proportion, which then yields a spatial databank that will guide and provide data to the planning process, be it urban, rural and/or environmental.

Given that the task at hand is mapping, the adopted methodology is based on building themes from the pre-established spatial occupation and environmental quality scenario, which will be created at different depths in the future, always supported by geological/geotechnical and environmental potentiality occupation patterns.

Data will be integrated via mapping techniques, resulting in practical documents for carrying out the diagnostics and assessment of the area at hand.

Methodology

Geoenvironmental unit representations are associated with causes of imbalance that can have different origins, but which frequently are related to the anthropization of the natural environment.

Hence, this methodology requires a basic study of relief
representation, watersheds, surface, subsoil and soil draining, and land use that will yield thematic cartographic products for an integrated analysis proposing the cross-reference of mapped themes via a GIS computer system that uses a matrix of possibility as the diagnostics base.

Erodibility Assay Sample Collection

A representative sample is collected from each unit of mapped soil for analysis, with the purpose of identifying the grade of textures observed and soil erodibility, via stability tests.

Water Level (Na) Information

Manmade wells, ditches, artesian wells and other types are assessed for ground water flow and their implications derived from urban enterprises.

Hydrologic Studies

The diagnostics of how rivers behave under different water regimens and mapping problems areas, i.e. floodlands, and erosion-potential areas in water courses, and guidance for draining catchment areas are part of the hydrologic studies, which will focus on:

Watershed boundary marking

As a planning unit, the boundaries of major watersheds located within the municipality will be marked based on the map bases and that will enable subdividing them according to the requirement for works and services to regulate water courses, water allocation and distribution, water pollution control, in compliance with fundaments, goals and guidelines set forth in the Water Resources National Policy.

Maximum flooding

To define flood-risk areas, a survey is carried out with dwellers to learn about maximum flooding and areas already affected by floods, relating those cases with rainfall in certain periods and their spatial distribution over watersheds. Relevant agencies responsible for watershed surveillance also carry out a survey, as well as the interference of tides, as this is a coastal environment.

Steepness

Catchment steepness analysis will identify the distribution of slopes on land relief surfaces, which is a major feature when performing land use and occupation analysis, as well as torrential surface flow and ensuing erosion processes and dislodging of sediments to watersheds and other bodies of water. Steepness grade of the land is classified according to the client’s priority before mapping the land.

Soils

Pedological classification proposed will determine general soil mapping units and identify land support capacity depending on certain occupation patterns.

Land Use and Occupation

Identifying land use and occupation is an important feature in environmental study and planning; an updated study of one site will help identify, among other things, agents that are responsible for certain conditions.

The requirement of a land use classification is based on the socioeconomic and cultural behavior, as well as spatial occupation of a given area.

Environmental Legislation

Environmental Legislation-related information applicable to the area is presented under spatial schematics in maps, taking into account legal and overall considerations, mainly related to the Brazilian Forestry Code for the Protection of Natural Resources and Conservation Units set up in the municipality. The product is the result of the inclusion of the compilation of relevant legislation applicable to a city area.

Geoenvironmental

Geoenvironmental representation is obtained via the integrated analysis of elements from the natural physical environment, which are obtained form cross-referencing land steepness, soil, environmental and hydrological legislation, and land use themes.

Thus, geoenvironmental mapping is a land management and organization tool, subdivided into watersheds and characterized for enabling the integrated analysis of an unlimited number of themes ensuing from the natural or social environment, which provides major contributions to environmental discussion, and to the planning structures it aims at taking on.

Concepts

We propose to generate a model associated with a databank derived from anthropic, biotic and physical systems that is subdivided into themes (abovementioned), and distributed spatially over the same cartographic base, which are governed by a matrix of possibilities.

Decision Matrix

A decision matrix provides feasible possibilities that will be interpreted and mapped, as well as enables cross-referencing situations involved in the mapping. Hence, decision matrix classifies and prioritizes values involved in the proposed issue.

Crossed Information

Information is integrated into a GIS-specific software databank that enables associating spatially represented information and cross-referencing the different mapped classes of all the themes interpreted.

Recommendations

All cartographic interpretations, cross-referencing and decision making are carried out by a multidisciplinary technical team in cooperation with the relevant governmental agent involved, and will prepare a recommendation report to provide guidance and to foster the city’s guidelines.