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Este trabalho buscou analisar os vales colmatados presentes na Bacia do Riacho Grande a partir dos controles estruturais responsaveis pela criacao de loci deposicionais onde sao estocados materiais coluvio-aluvionares. Para tanto, foram utilizados indicadores morfometricos como lineamentos de relevo e drenagem, relacao declividade-extensao e indicadores morfotectonicos da bacia. A partir dos resultados obtidos podemos destacar que a disposicao geometrica do riacho Grande obedece a uma direcao preferencial para NE-SW. Os processos de sedimentacao se sobrepoem a erosao, com formacao de planicies de inundacao ao longo do canal principal e seus principais tributarios. Essa sedimentacao e controlada pela presenca de diques, que bloqueiam e confinam as drenagens oriundas dos setores de cimeira do macico. Nos setores setentrionais, quebras de patamares se fazem presentes ao longo do curso do rio e estao associadas a anomalias de drenagem do principal curso fluvial dessa area, o riacho Grande. STRUCTURAL CONTROL ON THE VALLEY SEDIMENTATION IN THE RIACHO GRANDE WATERSHED/PB ABSTRACT This paper analyzed the valley fill deposits of Riacho Grande watershed as a result of structural controls. These are responsible for depositional loci creation upon where alluvium-colluvium materials were deposited. The analysis were conducted by means of applying morphotectonic and morphometrical indicators such as relief and drainage lineaments and SL index. The results point to a geometrical disposition of the trunk stream following the NE-SW direction. The sedimentation processes overlaps erosion rates, forming floodplains along the trunk stream and its major tributaries. Sedimentation is controlled by transverse lithological dikes which block up and confine streams coming from the highlands. To the north of the study area, geological conditions are dominated by a sequence of structurally controlled ridges and valleys lacking hillslope colluvial coverage, with sediment accumulation confined to the riverbed. This sector presents morphometric anomalies associated to the presence of knickpoints along the the trunk stream. Keywords : Sedimentation, Structure, Valley Fill. |
