256 The Barcelona Region’s land mosaic
drop, and in a seasonal wetland may remain below ground level for a pro-
longed period most years. The fluctuating water levels support wetland plants
and wildlife (Boada and Capdevila2000), including rare ones in the region. Typ-
ically some of the water absorbed in the wetland moves through the soil which
filters out many toxic substances that currently flow through sewage-treatment
facilities into the stream. So, the fish and other aquatic organisms ‘‘like” this sep-
arate stormwater system and its many wetlands dispersed across the GBRegion.
Along-lost heritage returns.
Apparently a few neighborhoods currently have dual drainage systems. Sev-
eral areas are identified as highest priorities to begin the process of separating
stormwater and sewage flows: (1) all new urbanization projects; (2) all towns
in the Tordera River Valley; (3) municipalities along the Llobregat River from
Sant Vincenq del Castellet to El Prat; and (4) municipalities upstream of the El
Foix and Ter River reservoirs. This is an extremely effective way to accomplish
multiple ecological and human goals, and see results quickly.Wetlands
Long ago wetlands were doubtless scattered across the region, espe-
cially on floodplains and near the bases of mountains. Today a small handful
remains mainly in the Lower Tordera floodplain and in the Llobregat delta (Color
Figure43)(Acebillo and Folch2000). Wetlands include open ponds and marshes
where groundwater is at or near the surface, but most restored wetlands would
be shrubby or wooded swamps where the watertable is somewhat lower. Open
areas have more water birds and wooded areas more songbirds, both apparently
appreciated by the public.
The most important factor in successful wetland restoration is to get the
hydrology right (Mitsch and Gosselink2000,France2002,Formanet al.2003). For
an extended period during the year, the input of water to a depression (e.g., with
clay in the bottom) needs to roughly equal water output due to percolation down-
ward,runoff from the surface, and evaporation upward. On most floodplains,
which normally have year-round groundwater, wetland species will quickly arrive
and visible success will be obvious. The only places where large wetlands are
feasible are the Lower Llobregat and Tordera floodplain/deltas. Small and tiny
wetlands could be produced throughout the region, for instance, as depressions
at the ends of stormwater drainage pipes and as basin parks by streams and
rivers.Streams, rivers, and blue-green ribbons
Blue-green ribbons (stream corridors) are wide natural-vegetation strips
that protect a stream or river, provide for wildlife movement, and include a