Estudo dos fatores controladores dos processos erosivos em área urbana:caso da voçoroca na cidade de Bom Jesus das Selvas/MA

Abstract

The research had as objective to present the results obtained in the study of the controlling factors of erosive processes in the urban area of Bom Jesus das Selvas / MA. The analysis of these factors contributes significantly to the knowledge about erosion in the study, relating them to the triggering agents that converge to advance the erosion denominated gully on September 7, where there was the collection of soil samples, infiltration test and activities as registration photographic study area, application of questionnaires and conversations with residents, among others. For the accomplishment of this work, the following environments were used: 1 - Activity in the Cabinet, for bibliographical and cartographic survey, with the search for theoretical reference, as well as data and files for elaboration of maps; 2 - Field activities (whose objective was the collection of soil samples, being collected 8 undeformed samples and 38 deformed to perform the morphological description of the soil, as well as soil density, granulometric and granulometric analysis, samples collected. The results obtained indicated that the September 7 gully is influenced by natural and human control factors, in which the characteristics of the slopes, declivity, land use and cover, hypsometry, and soil typology were evidenced. By indicated that soil particles do not show resistance to exogenous agents, water being the main means of the soil analysis, it was verified that the predominant granulometric fraction in the gull is frank clay, not being a highly susceptible soil to erosion, which indicates that other factors are more significant in action under erosion. In relation to the soil density, the data show a mean compaction, also reflecting a mean porosity. As for particle density, the data natural influencing agente, as well as man as an anthropic agent egarding soil morphology, the results indicate that it is characterized as medium / sandy texture, small size and granular structure; its dry and wet consistency and in relation to the plasticity and viscosity indicated little variation, comprising aspects referring to a soil of medium to clay texture. The susceptibility map indicated the areas with the highest probability of occurrence of erosions, being confirmed in the field, with the presence of several erosive processes. The applied questionnaires indicated that the population understands as the causal agent of the erosion advance, the lack of actions os the public power, not reflecting to a large extent its participation as well as influencing the agent in this advance, nevertheless, affirm that this erosion has a solution and blocking its impact. This work culminated in a sum of efforts in search of data and information, which were scarce in greater detail in the study area, but despite the difficulty, obtained satisfactory results, which corroborates the need for continuous study and deepening in relation to this. report and the final work, to further detail the subject.