Identificação de áreas hidrologicamente sensíveis por meio de modelagem hidrológica e da distribuição espacial de solos e vegetação em ambientes hidromórficos

This paper presents a methodology based on hydrogeomorphological process dynamics and the related soil-vegetation to establish the hydrological sensitivity limit of the landscape and identify hydrologically sensitive areas in the Pequeno River watershed, PR (104 km2). Hydrologically sensitive areas (HSA) are defined as areas in a watershed that have a greater probability of reaching soil saturation and generating runoff via variable source areas. HSAs are spatially delimited by the definition of a hydrological sensitivity limit. TOPMODEL was used to simulate the rainfall-runoff process on a daily scale from 08/01/1993 to 11/30/2010. The simulation indicates that variable source areas are extremely dynamic and sensitive to climate conditions, with a rapid response to rainfall and abrupt recessions in short periods of drought. In this paper, hydrologically sensitive areas were defined as the riparian zone of a watershed, identified by the presence of hydromorphic soils covered by hydrophilous or hygrophilous forest. As this area presented a saturation probability equal or superior to 90%, this value was defined as the hydrological sensitivity limit. The HSA identified by this limit consists of 20.5% of the watershed’s total area. The results of this paper permit us to establish a way of delimiting the HSA considering the integration of natural features in the landscape.