Floodplains of the Eria River Nature · Castrocalbón, La Bañeza, León Image of Castrocalbón, not of the place itself. The Eria waters fertile, tree-lined flood plains between arid alluvial terraces and hills patched with holm oak, oak and steppe scrub. The municipality receives some 477 millimetres of rain a year and its average temperature is around 11.7 degrees. Photo: Antramir (CC BY-SA 3.0) What to see and do in Castrocalbón