Utilização do modelo hidrológico SWAT (Soil and Water Assessment Tool) para estudos hidrológicos na microbacia hidrográfica do arroio Olaria - rio Uruguai

Abstract

This work aimed to apply the Water and Soil Management Tool (SWAT + in English) to evaluate the hydrological cycle of the Arroio Olaria basin, which contains most of the urban area of the city of Itaqui, RS. A cutout of the 30m resolution SRTM digital elevation model was used to define the drainage network and sub-basins in the study area, using the algorithms contained in QSWAT+. Following the theoretical methodology for calculating the SWAT runoff, the CN number 87 of the basin was calculated as a weighted average of the CN numbers for existing soil uses, as well as its corrections for dry soil, with normal and saturated moisture in the field capacity, and those due to the effect of the slope. These values were applied to the daily runoff flow calculations for the month of January 2019, reaching a maximum value close to 80 mm / day. The contributions of the urban drainage network, estimated by two methods, were also evaluated, staying in the order of 0.3 mm / day of flow from the urban supply, in addition to a maximum of 2 mm / day of flow capacity of the installed pipe. The base flow was measured in times of low urban consumption, around 3 mm / day, mainly from underground contributions. The results can be used as a comparison of the software outputs of the SWAT + model once the preparation of the necessary input data for modeling is completed.