Priorização de bacias hidrográficas pelo método Weighted Sum Analysis: estudo de caso da bacia do Rio Piquiri

Abstract

The Piquiri Watershed (BHP) is one of the largest in the State of Paraná and is vulnerable to environmental and socio-environmental issues The present work aimed to define a prioritization hierarchy of sub-basin stretches (TSBs) for BHP, in order to assist in decision making and management actions. BHP has a population of approximately 549 thousand inhabitants, its area covers 71 municipalities with 24,171.7 km2. The remnants of native forest occupy 5.69% of the area and the predominant soil type are: Latosol, Argisol and Nitossolo. Weighted Sum Analysis (WSA) was the method applied to determine the priorities of the TSBs, which depends on the Spearman correlation analysis applied to the morphometric parameters of each TSB. In terms of quantitative characterization, the morphometric parameters considered were: Stream frequency (Dh), bifurcation ratio (Rb), drainage density (Dd), drainage texture (Rt), circulatory ratio (Ic), form factor (F), elongation ratio (Re), compactness constant (Kc) and basin shape (Fb). The parameters Dh, Dd and Fb are practically uniform across the basin. Re, it ranged from 0.54 to 0.844 and the closer to the value 1 its shape gets closer to a circle. For F, Ic and Kc, which ranged from 1.788 to 2.549, they indicate that the sub-basin sections have an elongated format and are not prone to flooding. Rb varied between 1.641 and 3.809, depending on the number of water sections of different orders. Rt, ranged from 0.316 to 1.18 for all stretches and was classified as distant water courses. With the parameter values, the WSA method was applied to generate the prioritization classification that identified areas TSB1, TSB6, TSB2 and TSB4 as the priority areas. These are small areas in relation to the other stretches and are located close to the outlet. With these results, it is expected that they will help in decision-making and management actions at BHP.