Anthropological and Climate Change Effects in the Hydrology of the Po Valley

Watershed hydrology is determined by the state of soil surface. Different degrees of soil covering as well as soil exploitation can cause different processes of weather precipitation division into the watershed area. The anthropical evolution due to the expansion of urban areas is having a significant impact on the hydrological responses within the catchment area. In addition to that, the change in precipitations intensity can affect the formation of flood discharge. Using data collected over a time period of over one century, we have analysed both the changes in soil covering due to anthropical developments throughout the Po Valley – which have caused a remarkable expansion of urban areas – as well as any variation in precipitation intensity that may have occurred due to climate change. What can be observed is that the anthropologic effects on the catchment hydrology are very important and not negligible. In fact, the top monthly levels of flood discharge have been getting higher over time, in spite of the fact that the total values for yearly rainfall have been getting lower. Land Use Planning can be therefore considered as an important tool in catchment hydrology. Urbanization diminishes the capacity of soils to absorb precipitation, and as a consequence of that, unless proper “countermeasures are taken” throughout the catchment area, an increase in discharge volumes and a decrease in hydrological response time all over the area will ensue. Such a concurrence of events would lead to more frequent flood episodes for equal peak flows or, conversely, to higher flows and volumes for equal expected frequency.