Análise da fragilidade ambiental de paisagens semiáridas do Rio Grande do Norte, Brasil

Abstract

In the environment Semi-arid the attempts of use models to analyze erosive processes its against with own characteristics of this environment that the erosive processes make relation with the very strong rainfall and wiht the intricics chacacteristics of the soil the shows the erodibility of its. Besides that, the use of variables that were chosen it made tha analysis subjective, that proves the necessity of the methodological contribution that can to consider landscape attributes that point to each variable it can contribute in a degree of fragiity in the landscape unit. In this way, the objective of this job is to analyze the unity semi-arid landscapes in the municipality of Currais Novos with the prospect of to understand the fragility in erosive processes. To make the objective viable, review was carred out in the compartmentalization of the landscapes unit of the study area through geoprocessing techniques, then it sought to know the soil erodibility the was representative of each landscape unit that were defined through of aggregate analysis and the knowledge about the soil chemical physical attributes. After this, statistical analysis techniques were applied with correction and linear regrassion in order to assign weights to variables of the landscapes related to the erosion susceptibility to, in the end, establish relationships between fragility and the landscape erosion that are typical of the semi-arid. When referring to water erosion, the landscapes elements who obtained higher weights to compose a fragility calculation in the semi-arid that were the attributes of the soils in relationship between carbono/nitrogen (C/N), the organic carbono, the clay contente and the remaining phosphor (P-rem), the holding capacity of the water in the soil, beyond the relief aspects. In the wind erosion the elements landscapes that obtained higher weights were the clay contente, the cation exchange capacity, the remaining phosphor (P-rem) and the holding capacity of the water in the soil. The equation results that made use of the elements above and the related assigned weights shows that the action of the water agentes is bigger than the wind agente in the erosion process in the researched environment. In addition, it was possible to associate the results of surface erosion and cumulative potential with the result of water erosion fragility. Besides that, when considering surface structures of landscape units it have the following hierarchical order, from less susceptibility to greater susceptibility the runoff erosion Flat top plateau, Borborema residual massif, Borborema plateau on the eastern slope, Borborema plateau on the western slope, isolated pontoons of the Borborema plateau, Chapada erosive escarpment, Sandy fields in Borborema quartzitic relief, Acauã's interplanaltic depression, exceptional semi-arid floodplain, semi-arid floodplain. When referring to wind erosion, the hierarchical order to the superficial horizons from less susceptibility to greater susceptibility the erosion in a semiarid landscape unit is as follows: the grouped and isolated pontoons of the Borborema plateau, the exceptional semi-arid floodplain, semi-arid floodplain, the chapada erosive escarpment, sandy fields in busy Borborema relief, the residual massif of Borborema, the Acauã's interplanaltic depression, the Borborema plateau encosta oriental, the flat top plateau, the Borborema plateau encosta ocidental.