Page - 493 - in Book of Full Papers - Symposium Hydro Engineering

 Traces of events that happened in the observation period including forming relevant statistics  Changes in the riverbed and its contributories The fact that quality and resolution of images has changed over time has to be compensated. Software for change detection is readily available. Nevertheless, plausibility checks are always recommended. Rock falls and all kinds of sliding events receive priority in operational risk assessment. 3. CLIMATE CHANGE, INFLUENCE ON FLOOD AND RAINFALL Flood risk and, generally speaking, disasters due to natural disasters is constantly increasing. Vulnerability itself tends to change over many areas, due to a range of climatic and non-climatic impacts whose relative importance is site- specific. Climate-driven changes in future nature-caused disaster frequency are complex, because they depend on the generating mechanism. In many places, for instance, flood risk is likely to grow, due to a combination of anthropogenic and climatic factors. Recent modelling studies show that plausible climate change scenarios project future increases of both amplitude and frequency of natural- disaster events. It is very likely that there will be an almost ubiquitous increase in precipitation intensity in the warming world. Decreasing flood magnitudes, for instance, can be expected in many areas where floods are generated by spring snowmelt. However, global warming may not necessarily reduce snowmelt flooding everywhere. Several ongoing land-use changes, such as urbanization, deforestation, and reduction of natural storage (floodplains, wetlands), can be regarded as adverse from the viewpoint of safety from nature-caused disasters. Furthermore, human encroachment into unsafe areas has increased the potential for damage. Societies become more exposed, developing disaster-prone areas (maladaptation). In such a global change, mitigation of the risk disasters calls for a change from reactive to an anticipatory stance. The warning point is that climate change will perhaps not change the real nature of natural disasters, but their intensity and frequency, thus increasing the risk itself (IPPC,2017). As a matter of reference, we include the following picture which shows the shows an extreme heavy rainfall event that took place on Aug 15th, 2015 in the area of Eastern Tibet. 493