Search results

Urbanization alters hydrological processes and is often associated with increasing flood risks, which threaten human wellbeing and social and economic development. The conventional paradigm of flood protection relying on structural measures based on hard engineering solutions (e.g., dams, piped systems) has proven insufficient to mitigate floods. Sustainable water management, including solutions to enhance natural processes within urban areas, is a promising approach to enhance flood resilience and address the multiple sustainability challenges faced by cities. However, implementation of solutions based on mimicking natural processes has been slow. Mainstreaming of urban sustainable flood management is inhibited by governance aspects (e.g., limited collaborative governance), and knowledge gaps on effectiveness compared with conventional engineering approaches. The increasing flood hazards driven by growing urban populations and climate change projections of increasing frequency and intensity of large precipitation events demand improvements in spatial planning. This also provides opportunities for sustainable water management mainstreaming in order to complement the relatively limited drainage capacity of conventional systems.

Soil degradation by water is a serious environmental problem worldwide, with specific climatic factors being the major causes. We investigated the relationships between synoptic atmospheric patterns (i.e. weather types, WTs) and runoff, erosion and sediment yield throughout the Mediterranean basin by analyzing a large database of natural rainfall events at 68 research sites in 9 countries. Principal Component Analysis (PCA) was used to identify spatial relationships of the different WTs including three hydro-sedimentary variables: rainfall, runoff, and sediment yield (SY, used to refer to both soil erosion measured at plot scale and sediment yield registered at catchment scale). The results indicated 4 spatial classes of rainfall and runoff: (a) northern sites dependent on North (N) and North West (NW) flows; (b) eastern sites dependent on E and NE flows; (c) southern sites dependent on S and SE flows; and, finally, (d) western sites dependent on W and SW flows. Conversely, three spatial classes are identified for SY characterized by: (a) N and NE flows in northern sites (b) E flows in eastern sites, and (c) Wand SW flows in western sites. Most of the rainfall, runoff and SY occurred during a small number of daily events, and just a few WTs accounted for large percentages of the total. Our results confirm that characterization by WT improves understanding of the general conditions under which runoff and SY occur, and provides useful information for understanding the spatial variability of runoff, and SY throughout the Mediterranean basin. The approach used here could be useful to aid of the design of regional water management and soil conservation measures.