Between 13th and 16th July 2021, low-pressure system Bernd caused heavy flooding in parts of eastern Belgium, western Germany, and north-eastern France. In many of these areas, the 24 hours rainfall amounts exceeded the mean monthly precipitation (T. Junghänel et al. 2021). With at least 220 reported fatalities and insured loss estimates ranging between 10 and 13 EUR billion, it is one of the most devastating natural catastrophes in the central-European region of the last decades (GDV 2021). Given the relevance of this event, a detailed reconstruction of the flood footprint would be of interest for both earth scientists and the insurance industry. For this purpose, a reconnaissance field trip was organised between 1st and 3rd November 2021 to affected municipalities in the German states of North Rhine-Westphalia, Rhineland-Palatinate, and the Belgian province of Liège. Remaining flood marks in buildings and other infrastructure were measured for over 200 locations, and water depths were inferred from them. In addition, information was collected on the degree of damage to buildings, as well as on the stage of reconstruction and clean-up. The focus was on areas that did not get much media attention back in July 2021, smaller ungauged streams, and, in general, any location where the flood depths and damages could not be easily inferred from other sources. The information collected during this field trip, combined with updated E-OBS precipitation data, river discharge gauge data, satellite imagery, as well as media and authorities’ reports was used to input, calibrate, and validate the different components of the RMS in-house flood model chain. In particular, the depth measurements from the reconnaissance trip were useful to calibrate the inundation model in municipalities affected by flash flooding from small to medium-sized ungauged streams, or by pluvial flooding. These point measurements allowed for a more detailed and comprehensive reconstruction of the flood depths over the entire affected area, beyond the better monitored larger river systems. T. Junghänel, et al. (2021) Hydro-klimatologische Einordnung der Stark- und Dauerniederschläge in Teilen Deutschlands im Zusammenhang mit dem Tiefdruckgebiet „Bernd“ vom 12. bis 19. Juli 2021, DWD Geschäftsbereich Klima und Umwelt, https://www.dwd.de/DE/leistungen/besondereereignisse/niederschlag/20210721_bericht_starkniederschlaege_tief_bernd.pdf GDV (2021) Hochwasserkatastrophe: Versicherer zahlen bereits über drei Milliarden Euro, https://www.gdv.de/de/medien/aktuell/hochwasserkatastrophe-versicherer-zahlen-bereits-ueber-drei-milliarden-euro--73798

Alterations in gonad morphology are widespread in wild fish populations. Whitefish (Coregonus spp.) from Lake Thun, Switzerland, display a high prevalence of macroscopical gonad malformations including fusions to the musculature, segmented gonads and intersex condition. The aim of the present study was to evaluate whether the gonad morphological changes in Lake Thun whitefish are caused by genetic factors, environmental factors (water, diet) or “gene × environment” interaction. We performed two independent experiments of a three-year duration in which we reared whitefish from fertilization until adulthood and tested the possible causative factors using a matrix design: (i) genetics—comparing the prevalence of gonad malformations in whitefish of different genetic origin reared under identical environmental conditions (same diet, same water, same experimental facility); (ii) environment—comparing the prevalence of gonad malformations in whitefish of the same genetic origin reared in different water sources and/or fed with different diets; and (iii) gene-environment interaction—comparing the prevalence of gonad morphological alterations in relation to the combinations of genetics and environmental factors. Two diets were used for the rearing experiments: either zooplankton collected in Lake Thun which represents the natural diet of whitefish, or an artificial dry food which was used as control. The key finding of this study is that the inducing factor of the gonad malformations is contained in the zooplankton of Lake Thun. Fish fed with this diet developed a significantly higher prevalence of malformations than fish from any other treatment, irrespective of the genetic origin and/or the water source. This result could be repeated in the two independent experiments. Importantly, the prevalence values observed in the experimental fish fed with Lake Thun zooplankton were similar to the prevalence values recorded in free-ranging whitefish in the lake. The findings of this study advance the understanding of the causes of gonad morphological alterations in wild fish populations.

Surface water floods (SWFs) that lead to household losses are mainly localized phenomena. Research on describing the associated precipitation characteristics has previously been based on case studies and on the derivation of local rainfall thresholds, but no approaches have yet been presented on the national scale. Here, we propose a new way to overcome this scaling problem. We linked a gridded precipitation dataset based on both rainfall gauges and radar data with geolocated insurance claims for all of Switzerland. We show that the absolute thresholds vary markedly over complex terrain, and we thus propose basing early warning systems for predicting damage-relevant SWF events on local quantiles of maximum intensity and the total sum of event precipitation. A threshold model based on these two parameters is able to classify rainfall events potentially leading to damage-relevant SWF events over large areas of complex terrain, including high mountains and lowland areas, and a variety of geological conditions. Our approach is an important step towards the development of impact-based early warning systems. Weather warning agencies or insurance companies can build upon these findings to find workarounds for issuing user-targeted warnings at national scale or for nowcasting purposes.

In Switzerland, almost every second flood damage claim is likely not associated with a fluvial flood, but with a surface water flood. With increasing population and wealth along with climate change, we can expect that damages caused by surface water floods will increase further in the future. Nevertheless, relatively little is known about the drivers and influencing factors of this highly relevant natural hazard.

Surface water floods (SWFs) do not only increasingly threaten cities, but also affect rural areas. So far, little research has been dedicated to the prediction of SWFs in rural environments, although in practice the process is already being considered in deterministic flood hazard assessments. To test the validity of such assessments, we select four raster-based models with differing complexity and evaluate whether they reliably predict inundated areas by SWF in rural areas. The uncalibrated models are first applied to four artificial surfaces and second, to eight case studies covering manifold geographical and meteorological settings. For the case studies, the models' prediction skills are assessed based on inundated areas inferred from various sources. The models’ performance is rather low for all case studies, which highlights the necessity for calibration and/or validation of such models. Moreover, the case studies provide more general conclusions concerning the modeling of SWFs in rural areas.

surface water floods are felt as an increasing problem in intensively settled areas more and more and demand for research on this theme is increasing. Thus, the paper gives significant contribution on objectifying the discussion on losses due to natural hazards like surface water flow (SWF) and matches the scope of NHESS. 2. In addition the paper presents a new way to interpret insurance data in terms of natural hazards. 3. Tools, methods, results are up to international standards. 4. Results of the investigations strongly support the interpretation and the conclusions drawn in the paper. 5. Desicription of data and methods used is sufficient except three points (pages 3, 9 and 12, see further comments below). 6. The title clearly describes the main concern of the paper 7. Title and abstract are clearly presented and easy to read 8. Connex to previous and related research is sufficently described in chapter 1 9. Number of references should be enlarged in chapter 5. The results of the presented project should be discussed more in context of supranational and international studies (see further comments below) 10. Presentation of the paper is structured well and clearly presented except parts of chapters 2 and five (see further comments below) 11. Length of the paper seems adequate 12. Figures and tables are clearly presented, except figures 12 and 14 (some symbols are hard to distinguish) 13. Technical and english language are of good quality, fluently presented and understandable for an interdisciplinary audience

Surface water floods (SWFs) have received increasing attention in the recent years. Nevertheless, we still know relatively little about where, when and why such floods occur and cause damage, largely due to a lack of data but to some degree also because of terminological ambiguities. Therefore, in a preparatory step, we summarize related terms and identify the need for unequivocal terminology across disciplines and international boundaries in order to bring the science together. Thereafter, we introduce a large (n = 63 117), long (10–33 years) and representative (48 % of all Swiss buildings covered) data set of spatially explicit Swiss insurance flood claims. Based on registered flood damage to buildings, the main aims of this study are twofold: First, we introduce a method to differentiate damage caused by SWFs and fluvial floods based on the geographical location of each damaged object in relation to flood hazard maps and the hydrological network. Second, we analyze the data with respect to their spatial and temporal distributions aimed at quantitatively answering the fundamental questions of how relevant SWF damage really is, as well as where and when it occurs in space and time. This study reveals that SWFs are responsible for at least 45 % of the flood damage to buildings and 23 % of the associated direct tangible losses, whereas lower losses per claim are responsible for the lower loss share. The Swiss lowlands are affected more heavily by SWFs than the alpine regions. At the same time, the results show that the damage claims and associated losses are not evenly distributed within each region either. Damage caused by SWFs occurs by far most frequently in summer in almost all regions. The normalized SWF damage of all regions shows no significant upward trend between 1993 and 2013. We conclude that SWFs are in fact a highly relevant process in Switzerland that should receive similar attention like fluvial flood hazards. Moreover, as SWF damage almost always coincides with fluvial flood damage, we suggest considering SWFs, like fluvial floods, as integrated processes of our catchments.

Flood impact modelling requires reliable models for the simulation of flood processes. In recent years, flood inundation models have been remarkably improved and widely used for flood hazard simulation, flood exposure and loss analyses. In this study, we validate a 2D inundation model for the purpose of flood exposure analysis at the river reach scale. We validate the BASEMENT simulation model with insurance claims using conventional validation metrics. The flood model is established on the basis of available topographic data in a high spatial resolution for four test cases. The validation metrics were calculated with two different datasets; a dataset of event documentations reporting flooded areas and a dataset of insurance claims. The model fit relating to insurance claims is in three out of four test cases slightly lower than the model fit computed on the basis of the observed inundation areas. This comparison between two independent validation data sets suggests that validation metrics using insurance claims can be compared to conventional validation data, such as the flooded area. However, a validation on the basis of insurance claims might be more conservative in cases where model errors are more pronounced in areas with a high density of values at risk. (C) 2017 Elsevier B.V. All rights reserved.

The triggering mechanism and the temporal evolution of large flood events, especially of worst-case scenarios, are not yet fully understood. Consequently, the cumulative losses of extreme floods are unknown. To study the link between weather conditions, discharges and flood losses it is necessary to couple atmospheric, hydrological, hydrodynamic and damage models. The objective of the M-AARE project is to test the potentials and opportunities of a model chain that relates atmospheric conditions to flood losses or risks. The M-AARE model chain is a set of coupled models consisting of four main components: the precipitation module, the hydrology module, the hydrodynamic module, and the damage module. The models are coupled in a cascading framework with harmonized time-steps. First exploratory applications show that the one way coupling of the WRF-PREVAH-BASEMENT models has been achieved and provides promising new insights for a better understanding of key aspects in flood risk analysis.

The triggering mechanism and the temporal evolution of large flood events, especially of worst-case scenarios, are not yet fully understood. Consequently, the cumulative losses of extreme floods are unknown. To study the link between weather conditions, discharges and flood losses it is necessary to couple atmospheric, hydrological, hydrodynamic and damage models. The objective of the M-AARE project is to test the potentials and opportunities of a model chain that relates atmospheric conditions to flood losses or risks. The M-AARE model chain is a set of coupled models consisting of four main components: the precipitation module, the hydrology module, the hydrodynamic module, and the damage module. The models are coupled in a cascading framework with harmonized time-steps. First exploratory applications show that the one way coupling of the WRF-PREVAH-BASEMENT models has been achieved and provides promising new insights for a better understanding of key aspects in flood risk analysis.

Several case studies in Switzerland highlight that many buildings which are damaged by floods are not located within the inundation zones of rivers, but outside the river network. In urban areas, such flooding can be caused by drainage system surcharge, low infiltration capacity of the urbanized landscape etc. However, in rural and peri-urban areas inundations are more likely caused by surface runoff formed on natural and arable land. Such flash floods have very short response time, occur rather diffusely and, thus, are very difficult to observe directly. In our approach, we use data records from private, but mostly from public insurance companies. The latter, present in 19 out of the total 26 Cantons of Switzerland, insure (almost) every building within the respective administrative zones and, in addition, hold a monopoly position. Damage claims, including flood damages, are usually recorded and, thus, data records from such public insurance companies are a very profitable data source to better understand surface runoff leading to damages.

A simple distributed hydrologic model was developed in MATLAB, based on water balance principles, and applied to a mesoscale rainfed watershed in Andhra Pradesh. The results show a relatively good performance for surface and subsurface flow that is sufficient for planning purposes, especially given the coarse (monthly) time step and the simple representation of the hydrological processes. Although performance testing was not extensive with many uncertainties because of the limited validation performed, it has also been previously tested at a microscale watershed against a calibrated SWAT model. "Simple" in formulation, the model aims to offer a tool that is as generic as possible, requires minimal data, and can eventually be taken up by relevant nonexpert users from government and nongovernment agencies to support the planning and evaluation of watershed development programs.

A programme to eradicate bovine viral diarrhoea was launched in Switzerland in 2008 with the aim of eradicating the causal virus. During the first year of the programme, the entire population of 1.6 million cattle were tested for the presence of the virus; in the following three years an additional 1.8 million calves were tested. The complexity of information generated during the eradication programme, together with a tight schedule, made computerised data management a necessity. To organise, coordinate and supervise the programme, extensions were made to the computerised information system ISVet, of the Swiss Veterinary Service, which provides automated documents for both the Veterinary Service and private veterinarians. Specific data are accessible by user groups via the BVD-Web platform, ISVet and the Swiss animal movement database. The functionalities of the structure and the reports needed to control the progress of the programme are described in detail. The authors also discuss the major advantages, disadvantages and pitfalls when planning an eradication programme using a national centralised database over a distributed computer network.

Swiss aquaculture farms were assessed according to their risk of acquiring or spreading viral haemorrhagic septicaemia (VHS) and infectious haematopoietic necrosis (IHN). Risk factors for the introduction and spread of VHS and IHN were defined and assessed using published data and expert opinions. Among the 357 aquaculture farms identified in Switzerland, 49.3% were categorised as high risk, 49.0% as medium risk and 1.7% as low risk. According to the new Directive 2006/88/EC for aquaculture of the European Union, the frequency of farm inspections must be derived from their risk levels. A sensitivity analysis showed that water supply and fish movements were highly influential on the output of the risk assessment regarding the introduction of VHS and IHN. Fish movements were also highly influential on the risk assessment output regarding the spread of these diseases.

A high number of whitefish, Coregonus lavaretus , from Lake Thun, Switzerland, display gonad malformations. We tested the hypothesis that exposure to sediment-borne contaminants during the embryonic life results in the development of malformed gonads later in ontogeny. The investigated contaminants were 2,4,6-trinitrotoluene (TNT), which may leak from residues in the lake sediments as consequence of former ammunition dumping into Lake Thun, as well as sulfonated naphthalene formaldehyde condensates (SNFC), which are introduced into the lake from wastewater disposals of a nearby tunnel construction site. Experimentally, whitefish eggs were exposed during 52 days from fertilization until hatching to a) an artificial sediment (control), b) an artificial sediment spiked with TNT (0.5mg·kg -1 dry weight), c) SNFC compounds dissolved in water (3µg·l -1 of each naphthalene-1-sulphonate, naphthalene-2-sulphonate, naphthalene-1,5-disulphonate, naphthalene-2,7-disulphonate), and d) sediment from Lake Thun sampled in an ammunition dumping area. To mimic in situ exposure of the eggs to the sediment-water-interface under laboratory conditions, we developed a novel contact incubation technique. After hatching, fish were reared in tap water for three years until they reached sexual maturity, and were then examined for the presence of gonad malformations. No malformations were observed in the control, in the TNT and SNFC treatment groups. In fish incubated during the embryonic stage on Lake Thun sediment, 2 out of 117 adult males (1.7%) displayed malformed gonads, which is significantly lower than levels of gonad malformations in wild whitefish from Lake Thun (on average 29% in males, 12% in females). The results from our experiment provide no evidence that sediment contamination with TNT or SNFC compounds is a causative factor for the induction of gonad malformations in Lake Thun whitefish.