On the influence of fissure flow on the landslide activity

Water ManagementCivil Engineering and Geoscience

Effectiveness of communication in climate change and risk research: Is the impact evaluated and where is it presented at scientific conferences?

Water ManagementCivil Engineering and Geoscience

Smartphone applications for communicating avalanche risk information – a review of existing practices (discussion)

Every year, in all mountainous regions, people are victims of avalanches. One way to decrease those losses is believed to be informing about danger levels. The paper presents a study on current practices in the development of smartphones applications that are dedicated to avalanche risk communication. The analysis based on semi-structured interviews with developers of smartphone apps highlights the context of their development, how choices of content and visualization were made as well as how their effectiveness is evaluated. It appears that although the communicators agree on the message to disseminate, its representation triggers debate. Moreover, only simple evaluation processes are conducted but there is a clear awareness that further scientific efforts are needed to analyze the effectiveness of the smartphone apps. Finally, the current or planned possibility for non-experts users to report feedback on the snow and avalanches conditions open the doors to a transition of these apps from one-way communication tools to two-ways communication platforms. This paper also indicates the remaining challenges that avalanche risk communication is facing, although it is disputably the most advanced and standardized practice compared to other natural hazards. Therefore, this research is of interest for the entire field of natural hazards related risk communication.Water ManagementCivil Engineering and Geoscience

Preface: "Hillslope hydrological modelling for landslides prediction"

Water ManagementCivil Engineering and Geoscience

Invited perspectives: Hydrological perspectives on precipitation intensity-duration thresholds for landslide initiation: Proposing hydro-meteorological thresholds

Many shallow landslides and debris flows are precipitation initiated. Therefore, regional landslide hazard assessment is often based on empirically derived precipitation intensity-duration (ID) thresholds and landslide inventories. Generally, two features of precipitation events are plotted and labeled with (shallow) landslide occurrence or nonoccurrence. Hereafter, a separation line or zone is drawn, mostly in logarithmic space. The practical background of ID is that often only meteorological information is available when analyzing (non-)occurrence of shallow landslides and, at the same time, it could be that precipitation information is a good proxy for both meteorological trigger and hydrological cause. Although applied in many case studies, this approach suffers from many false positives as well as limited physical process understanding. Some first steps towards a more hydrologically based approach have been proposed in the past, but these efforts received limited follow-up. Therefore, the objective of our paper is to (a) critically analyze the concept of precipitation ID thresholds for shallow landslides and debris flows from a hydro-meteorological point of view and (b) propose a trigger-cause conceptual framework for lumped regional hydro-meteorological hazard assessment based on published examples and associated discussion. We discuss the ID thresholds in relation to return periods of precipitation, soil physics, and slope and catchment water balance. With this paper, we aim to contribute to the development of a stronger conceptual model for regional landslide hazard assessment based on physical process understanding and empirical data.Water Resource

Smartphone applications for communicating avalanche risk information: a study on how they are developed and evaluated by their providers

Every year, people are victims of avalanches. It is commonly assumed that one way to decrease those losses is to inform about danger levels. This paper presents a study on current practices in the development and evaluation of smartphones applications that are dedicated to avalanche risk communication. The analysis based on semi-structured interviews with developers of six smartphone apps highlights the context of their development, how choices of content and visualization were made and how their effectiveness is evaluated by the developers themselves. It appears that all these communicators agree on the message to disseminate and the general representation concepts (i.e., use of the international avalanche danger scale and of a tiered approach). However, the specific ways this message is presented (e.g., maps, icons) is not uniform. Moreover, only simple evaluation processes (e.g., usage monitoring) are conducted by the developers. However, they are well aware that further efforts need to be made in order to thoroughly analyze the effectiveness of the smartphone apps in terms of their real impact (e.g., increase in awareness or change in behavior). This work also highlighted that the smartphone applications are in transition from being one-way communication tools to becoming two-way communication platforms, with the possibility for non-experts users to report on snow and avalanche conditions. This paper indicates challenges that avalanche risk communication is facing, although it is indisputably the most advanced and standardized practice compared to communication tools for other natural hazards. In addition to being relevant for the avalanche risk communication community, this research is therefore of interest for scientists and practitioners working on risk communication related to natural hazards.Water Resource

Landslide precipitation thresholds in Rwanda

Regional empirical-statistical thresholds indicating the precipitation conditions initiating landslides are of crucial importance for landslide early warning system development. The objectives of this research were to use landslide and precipitation data in an empirical-statistical approach to (1) identify precipitation-related variables with the highest explanatory power for landslide occurrence and (2) define both trigger and trigger-cause based thresholds for landslides in Rwanda, Central-East Africa. Receiver operating characteristics (ROC) and area under the curve (AUC) metrics were used to test the suitability of a suite of precipitation-related explanatory variables. A Bayesian probabilistic approach, maximum true skill statistics and the minimum radial distance were used to determine the most informative threshold levels above which landslide are high likely to occur. The results indicated that the event precipitation volumes E, cumulative 1-day rainfall (RD1) that coincide with the day of landslide occurrence and 10-day antecedent precipitation are variables with the highest discriminatory power to distinguish landslide from no landslide conditions. The highest landslide prediction capability in terms of true positive alarms was obtained from single rainfall variables based on trigger-based thresholds. However, that predictive capability was constrained by the high rate of false positive alarms and thus the elevated probability to neglect the contribution of additional causal factors that lead to the occurrence of landslides and which can partly be accounted for by the antecedent precipitation indices. Further combination of different variables into trigger-cause pairs and the use of suitable thresholds in bilinear format improved the prediction capacity of the real trigger-based thresholds.Water Resource

Integration of observed and model-derived groundwater levels in landslide threshold models in Rwanda

The incorporation of specific regional hydrological characteristics in empirical statistical landslide threshold models has considerable potential to improve the quality of landslide predictions towards reliable early warning systems. The objective of this research was to test the value of regional groundwater level information, as a proxy for water storage fluctuations, to improve regional landslide predictions with empirical models based on the concept of threshold levels. Specifically, we investigated (i) the use of a data-driven time series approach to model the regional groundwater levels based on short duration monitoring observations and (ii) the predictive power of single variable and bilinear threshold landslide prediction models derived from groundwater levels and precipitation. Based on statistical measures of the model fit (R2 and RMSE), the groundwater level dynamics estimated by the transfer function noise time series model are broadly consistent with the observed groundwater levels. The single variable threshold models derived from groundwater levels exhibited the highest landslide prediction power with 82 %–93 % of true positive alarms despite the quite high rate of false alarms with about 26 %–38 %. The further combination as bilinear threshold models reduced the rate of false alarms by about 18 %–28 % at the expense of reduced true alarms by about 9 %–29 % and is thus less advantageous than single variable threshold models. In contrast to precipitation-based thresholds, relying on threshold models exclusively defined using hydrological variables such as groundwater can lead to improved landslide predictions due to their implicit consideration of long-term antecedent conditions until the day of landslide occurrence.Water Resource

Disaster Managers’ Perception of Effective Visual Risk Communication for General Public

Risk communication is one of the measures that should be implemented to increase the awareness and preparedness of the general public in order to attain disaster risk reduction. Among the various forms that can be used in communication campaigns, visualizations are appropriate to disseminate information about spatial phenomena such as natural hazards. In order to be effective, communication campaigns should be designed according to the specificities of the targeted audience. Risk and disaster managers are seen as a source of information about the latter as their tasks put them in direct contact with the general public and they need to communicate risks. Hence it is assumed that investigating their perception on the informative needs of the general public can help to design effective visual risk communication campaigns and to evaluate them.Water ManagementCivil Engineering and Geoscience

Quantifying spatial and temporal discharge dynamics of an event in a first order stream, using distributed temperature sensing

Civil Engineering and Geoscience