Monitoramento fluviométrico de duas bacias hidrográficas vizinhas: comparação de vazões em períodos concomitantes.

Abstract

Estimation of median and minimum flows in small watersheds is a complex process due to the heterogeneity of physical characteristics for each location. The proposed work intends to demonstrate this hypothesis, defining two surrounding watersheds with equivalent areas. A hydrological monitoring was obtained at both watersheds by using level sensors and hydraulic structures for metering flow. The two small watersheds present same conditions of precipitation because they contain similar physiographic characteristics. The land use in one watershed is 100 % rural and in another watershed is 50 % urban and 50 % rural. The results found for water flow were different from conventional predictions mainly due to hydrogeology. Medians and lower minimum flows in the watershed with urbanization were expected according to the characteristics of groundwater flow - naturally is a higher infiltration rate for rural watershed that increases the groundwater reserves, which could be used for periods of drought. However, this study presented opposite results. In rural small watershed the value found for Q95 was null and for Q50 was 1.29 L/s. For small watershed with urbanization the values found were 6.72 and 19.78 L/sfor Q95 and Q50, considering an identical monitoring period. This fact is due to the peculiarity of complex hydrogeological place. In this case the groundwater from rural small watershed does not supply the watershed’s mouth, but it supplies the surrounding watershed