This study reports a new and significantly enhanced analysis of US flood hazard at 30 m spatial resolution. Specific improvements include updated hydrography data, new methods to determine channel ...depth, more rigorous flood frequency analysis, output downscaling to property tract level, and inclusion of the impact of local interventions in the flooding system. For the first time, we consider pluvial, fluvial, and coastal flood hazards within the same framework and provide projections for both current (rather than historic average) conditions and for future time periods centered on 2035 and 2050 under the RCP4.5 emissions pathway. Validation against high‐quality local models and the entire catalog of FEMA 1% annual probability flood maps yielded Critical Success Index values in the range 0.69–0.82. Significant improvements over a previous pluvial/fluvial model version are shown for high‐frequency events and coastal zones, along with minor improvements in areas where model performance was already good. The result is the first comprehensive and consistent national‐scale analysis of flood hazard for the conterminous US for both current and future conditions. Even though we consider a stabilization emissions scenario and a near‐future time horizon, we project clear patterns of changing flood hazard (3σ changes in 100 years inundated area of −3.8 to +16% at 1° scale), that are significant when considered as a proportion of the land area where human use is possible or in terms of the currently protected land area where the standard of flood defense protection may become compromised by this time.
Plain Language Summary
We develop a method to estimate past, present, and future flood risk for all properties in the conterminous United States whether affected by river, coastal or rainfall flooding. The analysis accounts for variability within environmental factors including changes in sea level rise, hurricane intensity and landfall locations, precipitation patterns, and river discharge. We show that even for a conservative climate change trajectory we can expect locally significant changes in the land area at risk from floods by 2050, and by this time defenses protecting 2,200 km2 of land may be compromised. The complete dataset has been made available via a website (https://floodfactor.com/) created by the First Street Foundation in order to increase public awareness of the threat posed by flooding to safety and livelihoods.
Key Points
First complete high‐resolution flood hazard analysis of conterminous US flood risk from all major sources (fluvial, pluvial, and coastal)
In validation tests the model achieved Critical Success Index scores of 0.69–0.82, similar to many local custom‐built 2D models
By 2050, flood hazard increases for the Eastern seaboard and Western states, but decreases or changes little for the center and South‐West
In India, the debate surrounding climate change centres around the need for the country to eradicate poverty and provide basic necessities for its citizens, while simultaneously deliberating on the ...need for the country to curb emissions voluntarily through the use of new and efficient technologies. Accordingly, while India commits to take responsibility for its current greenhouse gas emissions and takes steps to reduce them, its international negotiation position is based on the principles of historical responsibility. With the developed world responsible for 70–80 per cent of the current stock of carbon dioxide in the atmosphere, it is not hard to understand this position. The question that is often asked is “should the peoples of the developing countries like India be asked to forego their quest for their basic necessities and needs, merely because the developed and affluent countries have over the years degraded the atmosphere in pursuit of affluence and luxury?”Nevertheless, as the discussions for the post 2012 Kyoto regime progress, pressure is bound to build on the emerging economies of China, India, and others to take up time bound emission reduction targets. In 1995, developing countries contributed 27 per cent of the total world emissions. It was estimated that by 2035, they will be contributing 50 per cent. The indications, however, are that this will happen sooner rather than later as China alone is now releasing 24 per cent of global greenhouse gases and has overtaken the United States as the world's largest emitter. With Indonesia quickly jumping to third place, India is now the world's fifth largest emitter.Under pressure for increasing emissions due to sustained industrialization, India's stand on carbon emissions can be summed up by Prime Minister Manmohan Singh's commitment at the last G8 summit at Heiligendamm: “India is prepared to commit that our per capita carbon emissions will never exceed the average per capita emissions of developed industrial countries. Moreover, as developed countries take measures to bring down their per capita carbon emissions, our threshold would come down too”. Accordingly, the Indian Government is promoting the concept of convergence of per capita emissions, whereby developed countries are asked to bring down their emissions as developing countries make a conscious effort not to increase their per capita emissions to that of developed countries levels.
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