In this section we analyze typical disaster reports, technical documents drawn up locally after extreme weather-related events (intense rainfall, floods, and landslides). They are produced mainly within the activity framework of the Decentralized Functional Centers of Civil Protection (DFCCP) (Table 1). These reports are written with the aim of gathering and summarizing information on the events and are mainly addressed to specialized technicians and experts.
We also considered some DRs drawn up by the National Department of Civil Protection for those regions that lacked a DFCCP at the time of the flood event. In Italy, only in recent years (starting from the end of the 1990s) the civil protection activities are decentralized, that is, managed at the regional and lower levels. Before the creation of the DFCCPs (for example, for the Salerno case study), these occasional reports were included in the Hydrological YearbooksFootnote 1 published by the National Hydrological and Mareographic Service (SIMN − Servizio Idrografico e Mareografico Nazionale). The SIMN was decentralized during the 1990s and its duties, including the publication of DRs, were taken by the DFCCPs. The analysis of the informative content of the DRs highlighted some common features found in almost all DRs, which are summarized below.
Part 1—Description of the Event
A section “Description of the Event” is always found in the reports and briefly accounts for the places, the times, and the duration of the event, its dynamics, as well as the most relevant phenomena. It is generally presented as a foreword.
Part 2—Meteorological Analysis
The section “Meteo Analysis” is almost always included and the attention to detail varies depending on the issuing institution. The section’s size increases according to the importance of the event under discussion. The comparison of the DRs of the first years of the 2000s and the ones written in recent years highlights a growing availability of sources for meteorological data and tools to present the meteorological framework in which the event evolved.
This part provides a description of the meteorological evolution of the event at a synoptic scale, normally by using charts of atmospheric pressure at ground level and geo-potential maps (rarely temperature and humidity). The most used weather forecast models (listed according to the frequency of use), whose output are reported in the DRs, are provided by:
ECMWF (European Centre for Medium-Range Weather Forecasts);
UKMO (United Kingdom Meteorological Office);
NCEP (National Centers for Environmental Prediction);
CNMCA (Centro Nazionale di Meteorologia e Climatologia Aeronautica).
In most cases the source is not explicitly reported. However, it can be deduced from indications alongside the maps.
In order to further document the evolution of meteorological events in DRs, images by EUMETSAT’s Meteosat satellite (in visible or infrared bands) are often included. Alternatively, new yet increasingly common multispectral products represented with band composites, such as Airmass, can be found and the source can be deduced from the features of the images.
Some DRs present maps of the mosaic weather radar reflectivity and of radar estimated rainfall (instantaneous and cumulative) to provide a representation of the areal rain conditions (in other cases, the same map is shown in the “Rainfall Analysis” section). Sometimes it is possible to find a lightning map. Very rarely data from radio sounding can be found (for example, temperature profiles).
Part 3—Rainfall Analysis
The section regarding the analysis of rainfall data is always included in DRs, and it is usually the one that presents the largest amount of collected data. Hourly and cumulative rainfall data are typically published in the form of tables. Often it is possible to find comparisons of precipitation values with an intensity-duration-frequency curve that can highlight the importance (rarity) of the event.
In addition to punctual data, maps of the areal rainfall with isohyets are often available. These are obtained by interpolating the rainfall data (through inverse distance weighting or geostatistical analyses). Information about rainfall, its intensity, and isohyet maps are also always present in the DRs found in the Hydrological Yearbooks.
Some DRs present data from the DEWETRA processing and visualization platform, which operates at the National Department of Civil Protection. DEWETRA provides, through a graphical interface, high resolution and continuously updated information, allowing the user to monitor weather events, build detailed risk scenarios, and evaluate the potential impact of phenomena on communities and infrastructures. Finally, information on rainfall in the days preceding the event and soil moisture estimation (HSAF-H14 model) may also be found in this section, if some additional analyses have taken place.
Part 4—Hydrometric Analysis
The hydrometric analysis is found frequently in DRs. It is omitted in the case that the event did not lead to measurable flooding, for example, in an urban environment. Data collected are typically shown as flood hydrographs recorded at the official gauging stations, with water levels or flow rates often compared to threshold levels. Occasionally one can find the delimitation of the catchment area affected by the event, in which case the exact position of the basin outlet is shown on the map.
In rare cases, a further description is also included regarding the hydraulic operations on dam and reservoir gates (with data of discharge in time) that may have changed the evolution of the event. Information about water levels and peak discharges is also present in the DRs found in the Hydrological Yearbooks.
Part 5—Supplementary Analyses
In order to properly describe the event, DRs occasionally present supplementary analyses, such as a thermometric analysis, zero-degree isotherm maps, a nivometric analysis (with occasional estimates of the snow water equivalent), an anemometric analysis, and the height of sea waves.
Part 6—Ground Effects and Photo Report
The section on the ground effects of the event is not always available as part of DRs, even if it has a strong communicative impact on people. When available, it typically contains photos of the damage caused by the event. These can directly belong to the agency releasing the DR or are obtained from the press or other amateur witnesses. In this section, like in the previous ones, the indication of the location of the damage is provided by using the name of the place rather than using a geographic map. Pictures of the event are also sometimes present in the DRs found in the Hydrological Yearbooks.
Part 7—Reports and Notices Issued
The DR can end (or, more rarely, start) with the alert notices issued before and during the event. This kind of information has become more and more important in Italy after approval of the Civil Protection Directive 10/26/2016 about the standards to use all over Italy for event alerts.