Urbanization increases regional impervious surface area, which generally reduces hydrologic response time and therefore increases flood risk. The objective of this work is to investigate the sensitivities of urban flooding to urban land growth through simulation of flood flows under different urbanization conditions and during different flooding stages. A sub-watershed in Toronto, Canada, with urban land conversion was selected as a test site for this study. In order to investigate the effects of urbanization on changes in urban flood risk, land use maps from six different years (1966, 1971, 1976, 1981, 1986, and 2000) and of six simulated land use scenarios (0%, 20%, 40%, 60, 80%, and 100% impervious surface area percentages) were input into coupled hydrologic and hydraulic models. The results show that urbanization creates higher surface runoff and river discharge rates and shortened times to achieve the peak runoff and discharge. Areas influenced by flash flood and floodplain increases due to urbanization are related not only to overall impervious surface area percentage but also to the spatial distribution of impervious surface coverage. With similar average impervious surface area percentage, land use with spatial variation may aggravate flash flood conditions more intensely compared to spatially uniform land use distribution.

Abstract:We analyze economic perspectives of forest adaptation to risk attributes, caused mostly by climate change. We construct a database with 89 systematically chosen articles, dealing simultaneously with climate, adaptation, risk and economy. We classify the database with regard to 18 variables bearing on the characteristics of the paper, the description of the risk and the adaptation strategy, the topic and the corresponding results. To achieve a "high level-of-evidence", we realize a multiple correspondence analysis (MCA) to identify which variables were found in combination with one other in the literature and make distinct groupings affecting adaptive decisions. We identify three groups: (i) profit and production; (ii) microeconomic risk-handling; and (iii) decision and behavior. The first group includes economic costs and benefits as the driver of adaptation and prioritizes simulation, and a mix of theoretical and empirical economic approach. The second group distinctly involves risk-related issues, in particular its management by adaptation. The third group gathers a large set of social and behavioral variables affecting management decisions collected through questionnaires. Such an approach allows the identification of gaps in the literature, concerning the impact of owners' preferences towards risk and uncertainty regarding adaptation decisions, the fact that adaptation was often reduced in an attempt to adapt to the increasing risk of wildfire, or the existence of a regional bias.

<p>In Canada, floods are the most common and most costly natural disaster. Floods threaten lives, properties, and the environment and these risks are only expected to increase alongside expected population increase and impacts from climate change. Flood early warning systems (FEWs) can help mitigate the impact of floods by helping inform the public when and where a flood may occur, identifying infrastructure that may be impacted, and disseminating evacuation routes that avoid flooded roads. FEWs have been shown to save lives and mitigate flood impacts. However, many existing FEWs are limited in terms of their forecast horizon and geographical coverage, and also require precise hydraulic models and substantial computing.</p> <p>This paper develops a flood preparedness application for all of Canada to help prepare Canadians for future and imminent floods. This Canadian flood preparedness application addresses limitations associated with many of the developed FEWS in Canada by matching predicted river flows to predetermined return periods for developed global (or country-wide) flood inundation maps. By matching predicted river flow to return periods of predetermined inundation maps, complex computation is avoided reducing response time, and improving geographical coverage (by using a Canada-wide model). Lastly, using the static map approach, the public and emergency personal can help prepare for floods well in advance, identifying their own flood risk and as well as evacuation and muster locations strategies by identifying roads that would likely be flooded under various flood return periods. Overall the Canada-wide flood preparedness application will help protect and better prepare Canadians as flood risks continue to rise by increasing forecast horizon and geographical coverage and minimizing computation. The new approach of using global (or country-wide) static flood inundation maps to inform FEWS may be applicable in other countries where detailed hydraulic models are unavailable or too time consuming to calculate on a continuous or as needed basis.</p>

Key message By calibrating and validating a forest growth model for seven species in Germany and coupling it with a wind damage simulator, we specifically estimated the impact of wind damage on the net present value of Norway spruce and European beech in mixture and monoculture. Under risk, the net present value of spruce managements saw the sharpest declines, although the highest end net present value was still obtained through a heavily thinned spruce monoculture. Context Wind damage is one of the most important risks to Central European forests, and adaptation measures are essential. Aim Adaptive management strategies should simultaneously account for forest production and wind risk. We simulated the effect of adaptive measures on wind-risk in German forests. Methods A process-based forest growth model, “3-PG Mix”, was recalibrated and coupled with the storm damage risk model “Lothar”. We investigated the effect of thinning regimes on wind risk in monoculture and mixed species stands. The net present value of the simulated regimes was calculated and compared (risk vs. no risk). Results Spruce regimes achieved the highest net present values when risk was not considered. Considering risk in spruce and beech mixtures and monoculture, all regimes reached values below 3000 € ha−1 by year 120. The exception was a heavily thinned spruce monoculture at 4507 € ha−1, being the most profitable regime under risk. Conclusion We conclude, on the basis of this modelling study, that heavy thinning reduced storm risk and maintained a higher net present value in spruce. Species mixture of beech and spruce saw net present values levels remain more constant under risk, while beech monoculture increased.