Confluence of the Huerva and the Ebro Nature · Cadrete, Comarca Central, Zaragoza Image of Cadrete, not of the place itself. The green corridor of the Huerva river runs through Cadrete, Cuarte de Huerva and María de Huerva before joining the Ebro at Zaragoza. The Huerva rises in the sierra de Cucalón and flows for 128 km to its mouth, with a catchment area of 1,020 km², an average flow of 0.84 m³/s and an annual contribution of 67 hm³. As it passes through the Aragonese capital, in the 1920s and 1930s it was decided to cover its course to make way for the construction of streets. Photo: 19Tarrestnom65 (CC BY-SA 4.0) What to see and do in Cadrete