Dear JH: your Spanish rivers beginning with "guad-" pronounced "wad- " reminded me of Arabic "wadi"
wadi
n.,
pl. 3dis or 3dies 5Ar wadj, channel of a river, a river, ravine, valley6 in Arabia, N Africa, etc., a) a valley, ravine, or watercourse that is dry except during the rainy season b) the stream or rush of water that flows through it Also sp. wa$dy, pl. 3dies