Diagnóstico físico-conservacionista da bacia hidrográfica do Açude Jatobá, Patos - PB.

Abstract

This project has as objective to rise a physical-conservationistic diagnosis in the watershed of the Açude Jatobá, Patos-PB. It was developed, using Digitalized Planialtimetric Chart, paper of Patos-PB, in scale 1/100,000, obtained with image of satellite CBERS, sensor “HRC”, and Digital Terrain Model (DTM). Using the IDRISI 15.0 (Andes) and AutoCAD 2004 (v.0.86) had been digitalized the drainage net and the perimeter of the watershed in study, and made the determination of area, perimeter, length of the net and density of drainage. Using the resources of the IDRISI was made a digital classification of image HRC, for obtainment of the map of soil occupation with the following typology: Closed Arboreus Shrubs Caatinga; Open Arboreus Shrubs Caatinga; Cattle; Agricultural Tillage and Water Bodies. At next was made divisions of the basin in 15 compartments, with limit of minimum area on 2,500 km². For the diagnosis, the average declivity and the drainage density of each compartment had been used as parameters to calculate the Ruggedness coefficient (RN), that was used to define the 4 classes soil use in the 15 compartments: A Class: appropriate lands for agricultural/urbanization; B Class: appropriate lands for cattle/urbanization; C Class: appropriate lands for cattle/forests; D Class: appropriate lands for forests. The results had shown the existence of conflicts in the soil use in the compartments 11 to 15, on the total of 107.5 hectares, due the use of agriculture in improper places, however, these compartments have average declivity of 19.39%. However, it follows that the watershed of the Açude Jatobá presents an average degradation of 3.85%, indicating that is being used adequately, that is, in equilibrium with the agricultural capacity of the ground, whereas the physical-conservationistic diagnosis indicates a favorable situation in 96.15% totality of the study area.