Estimates of maximum rate and water saturation capacity of Upper River Ligeiro watershed, in Pato Branco, PR

O objetivo deste artigo é a estimativa da vazão máxima com o uso do método da curva número desenvolvido pelo Soil Conservation Service (SCS), pelo uso da fórmula racional e da equação de Ven Te Chow, ambos métodos hidrológicos que transformam chuva em vazão, tendo como estudo de caso a bacia hidrográfica do alto do rio Ligeiro (1/3 superior). A bacia hidrográfica localiza-se no município de Pato Branco (latitude 26o09’52” Sul e longitude 52o41’44” Oeste) e apresenta uma área de 68,26 km2. Para obtenção do modelo hidrológico, foi necessária a confecção de mapas temáticos de uso do solo para os anos de 1980 e 2008. Nas condições de umidade normal (NII), tempo de recorrência de 10 anos, a vazão de pico (chuva 0,3h) elevou-se de 59,76 m3 em 1980 para 72,13 m3 em 2008. Essa vazão é consequência da impermeabilização da bacia no período e redução da área de cultivos agrícolas que, consequentemente, reduziram as taxas médias de infiltração da bacia (as áreas cultivadas em 1980 atingiam 70,63% do total da bacia e em 2008 foram reduzidas a um percentual de 51,98%).Palavras-chave: Hidrologia; bacia hidrográfica; rio Ligeiro; vazão e curva número. AbstractEstimates of maximum rate and water saturation capacity of Upper River Ligeiro watershed, in Pato Branco, PR. The aim of this paper is to estimate the maximum flow in Upper River Ligeiro watershed (1/3 higher) using the curve number method, developed by Soil Conservation Service (SCS), by the application of the rational formula and the Ven Te Chow equation, both hydrologic methods that transform rainfall into runoff. This watershed is located in Pato Branco (latitude 26º09'52" S and longitude 52º41'44" W) covering an area of 68.26 km2. In order to get the hydrological model it was necessary the preparation of thematic maps of land use for the years 1980 and 2008. Under normal humidity conditions (NII), recurrence time of 10 years, the peak flow (rainfall 0.3 m) increased from 59.76 m3 in 1980 to 72.13 m3 in 2008. This flow is due to the impermeability of the basin in the period and agricultural crops area reducing, which consequently reduced the average rate of infiltration basin (the cultivated areas in 1980 reached 70.63% of the total watershed and in 2008 were reduced to a percentage of 51.98%).Keywords: Hydrology; watershed; river Ligeiro; flow and curve number.The aim of this paper is to estimate the maximum flow in Upper River Ligeiro watershed (1/3 higher) using the curve number method, developed by Soil Conservation Service (SCS), by the application of the rational formula and the Ven Te Chow equation, both hydrologic methods that transform rainfall into runoff. This watershed is located in Pato Branco (latitude 26º09'52" S and longitude 52º41'44" W) covering an area of 68.26 km2 . In order to get the hydrological model it was necessary the preparation of thematic maps of land use for the years 1980 and 2008. Under normal humidity conditions (NII), recurrence time of 10 years, the peak flow (rainfall 0.3 m) increased from 59.76 m3 in 1980 to 72.13 m3 in 2008. This flow is due to the impermeability of the basin in the period and agricultural crops area reducing, which consequently reduced the average rate of infiltration basin (the cultivated areas in 1980 reached 70.63% of the total watershed and in 2008 were reduced to a percentage of 51.98%)