Author(s): Maria Diaz-Redondo; Miguel Marchamalo; Felipe Morcillo
Linked Author(s): Miguel Marchamalo Sacristán
Keywords: No Keywords
Abstract: As is the case of most rivers in large cities, the Manzanares River in the city of Madrid was channelized with riprap and stone walls to allow for intensive urban development. Moreover, nine small control dams were built for aesthetic reasons so as to maintain a view of a large river. At the ecological level, the margins were disconnected from the channel by artificial structures, and the longitudinal connection of flows, sediments and species between upper and lower sections virtually disappeared. The opening of the urban dam gates, at the beginning of2016, was the first step towards the renaturalization of the river. Renaturalization objectives include recovering the key function of the river as ecological corridor (connecting the river sections upstream and downstream of the city) and enhancing the landscape and social value of the river within its urban context. The first ecological effects of the longitudinal reconnection of 7.5 km of urban river can be assessed in terms of partial recovery of hydromorphological dynamics. Firstly, by eliminating water retention, water depths have lowered from around 4m average to 0.3 m, allowing for more natural water flows, shallower and with different velocities within the channel. Secondly, sediments, mainly sands, from upstream tributaries are entering the fluvial system and are being deposited in the channelized section, creating bars and islands. The case of the Manzanares River can help in understanding how an urban river can evolve with a non-intensive intervention focused on self-forming dynamics recovery.