The Estimation of Probable Maximum Precipitation: the case of Catalonia

What is it about?

The spatial distribution with a high spatial resolution (1km x 1km) of the 1-day probable maximum precipitation (PMP) in Catalonia (Spain) was obtained. Despite the general concordance between this spatial distribution and the mean annual rainfall spatial distribution in Catalonia, remarkable differences were found in some zones which can be explained by the meteorological scales involved in each case. In Catalonia, the meteorological situations contributing to high rainfall for monthly or annual periods are very different from those producing the highest daily rainfall. Thus, whereas the synoptic-scale organizations have a greater influence on the annual precipitation distribution, the local and mesoscale factors (e.g., orographical and geographical characteristics, temperature differences between sea and land, distance to sea, and humidity and temperature advections at low levels) have a greater influence on the 1-day PMP map.

Featured Image

Photo by Ricky Rew on Unsplash

Photo by Ricky Rew on Unsplash

Why is it important?

Probable maximum precipitation (PMP) has been defined as “the greatest depth of precipitation for a given duration meteorologically possible for a given size storm area at a particular time of year, with no allowance made for long-term climatic trends”. Hydrologists use the PMP magnitude and its spatial and temporal distributions in the design of hydrologic structures for maximum reliability and safety. The technique applied was useful to assign a numeric value objectively calculated of the PMP to every km² of the Catalonian territory, providing a high spatial resolution of the PMP distribution, and notably improving the estimation that can be made from a map analyzed by hand.