ZERO-ORDER CHANNELS

CONTRIBUTIONS TO MANAGEMENT IN THE PIAVA RIVER ENVIRONMENTAL PROTECTED AREA, UMUARAMA, PARANÁ

Abstract

The Piava River Watershed Station, in Umuarama (Paraná) is the only source of public water supply for the municipality, benefiting more than 100,000 people and thus assuming a fundamental role in the city’s sustainability. Although strategically important for regional water security, the watershed is under the influence of anthropogenic pressures related to urban expansion, predominant livestock production, soil compaction,  riparian vegetation removal, and the intensification of erosive processes. Zero order channels play an environmentally relevant role, as they are areas of convergence of surface and subsurface flows are often associated with temporary zones of water saturation, wetlands, and the onset of incision erosive processes. The aim of the study was to evaluate the use of geotechnologies and morphometric indices for identifying these channels in the Piava River Environmental Protection Area (APA), particularly through the Topographic Wetness Index (TWI) and the Maximum Flow Index (MFI) – the latter derived from the Digital Terrain Model processed in QGIS and SAGA GIS. Differences were observed between official topographic maps at the 1:50,000 scale and what was represented through geoprocessing and field validation, highlighting the underestimation of naturally vulnerable sites. It is concluded that the inclusion of zero-order channels in environmental planning is crucial for reviewing vegetative margins, for the mitigation of siltation and for the consolidation of integrated watershed management.