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Laser Doppler flow measurements and Monte Carlo simulations on small blood perfusion flow models at 780 nm are presented and compared. The dimensions of the optical sample volume are investigated as functions of the distance of the laser to the detector and as functions of the angle of penetration of the laser into the sample. The effects of homodyne and heterodyne scattering are investigated.

After the catastrophic flooding of New Orleans due to hurricane Katrina, plans have been developed for the improvement of the flood protection system of the city. In this paper, we apply the principles used in the Netherlands for risk‐based design of flood protection systems to the New Orleans metropolitan area. In this so‐called economic optimization, the incremental investments in more safety are balanced with the reduction of the risk to find an optimal level of flood protection. Although the analyses are preliminary and not yet fully realistic, the presented outcomes indicate that for densely populated areas, such as the central parts of New Orleans, it could be justified to choose a higher protection level than the currently proposed level of 1/100 per year. The results of the economic optimization can be considered as technical advice that can be used as input for the (political) decision‐making.

Abstract. In this paper, a database of water-related insurance damage claims related to private properties and content was analysed. The aim was to investigate whether the probability of occurrence of rainfall-related damage was associated with the intensity of rainfall. Rainfall data were used for the period of [2003][2004][2005][2006][2007][2008][2009] in the Netherlands based on a network of 33 automatic rain gauges operated by the Royal Netherlands Meteorological Institute. Insurance damage data were aggregated to areas within 10-km range of the rain gauges. Through a logistic regression model, high claim numbers were linked to maximum rainfall intensities, with rainfall intensity based on 10-min to 4-h time windows. Rainfall intensity proved to be a significant damage predictor; however, the explained variance, approximated by a pseudo-R 2 statistic, was at most 34 % for property damage and at most 30 % for content damage. When directly comparing predicted and observed values, the model was able to predict 5-17 % more cases correctly compared to a random prediction. No important differences were found between relations with property and content damage data. A considerable fraction of the variance is left unexplained, which emphasizes the need to study damage generating mechanisms and additional explanatory variables.