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Observation of incomplete particle hops in imaging-based experiments with bed-load transport does not just occur with hops that are longer than an area of observation. Even short hops can be in fact incompletely measured if they cross the boundaries of the focus area. Experimental censorship biases the statistical distribution and moments of bed-load particle hops. This paper presents: a theoretical quantification of an expected effect of experimental censorship; based on this quantification, a method to correct the statistical distribution of hop lengths; an application of the method to experimental data. Applying the correction leads to significantly different values of the mean hop length, compensating the biasing effect of censorship. By contrast, nothing can be done for experimental truncation that is associated with hops longer than an applied area of observation. Experimental truncation must be avoided a priori, by appropriate design of the measurement method.

Disaster forensic investigation analyses the unfolding of a disaster and attempts to identify its multiple causes of damage which can lead to (i) improved disaster prevention and management from lessons learnt, and (ii) more effective mitigation measures in the aftermath of a disaster. The way in which damage data are collected after a flood event as well as the types of collected data influences their usability within forensic investigations. In order to explore whether or not existing data can be used for disaster forensic analysis, the European Project IDEA (Improving Damage assessments to Enhance cost-benefit Analyses) is investigating existing gaps in damage information so as to identify possible paths towards improving data quality. This paper focuses in detail on a forensic analysis of the interlinked damage to economic activities and infrastructure in the Severn floods of 2007 in the UK. Besides investigating the usability of existing data, this research investigated: (i) the relative weight of direct and indirect costs to business and infrastructure companies; (ii) to what extent damage to infrastructure has impacted on indirect damage to businesses. Finally recommendations for improving the data for use in forensic investigation are offered.