Anew paper published in Environmental Research Letters has some warning news for-组卷网

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A new paper published in Environmental Research Letters has some warning news for people living in the lower 48 states: You may be at risk from river flooding and not even know it until the water starts to rise.

In fact, the study, estimates of present and future flood risk in the United States, found that 41 million U. S. residents are at risk from flooding along rivers. That’s three times more than current estimates based on the flood maps produced by the Federal Emergency Management Agency (FEMA) , which primarily maps the areas at risk for 1-in-100-year floods in populous (人口众多的) river basins.

Why does the big difference come into being? As always, it’s all about the data. Generally, FEMA prioritizes risk-assessment areas based on their population; reserving expensive field-work methodologies (研究方法) for the more populous river basins, but many other rivers have not yet been mapped at all.

The size of the USA means that flood maps made in this way are incomplete. It would be too expensive and time-consuming to survey every river basin in America. The national-scale flood maps produced by FEMA leave the flood risk of many parts of the country unaccounted for.

For this research, scientists from The Nature Conservancy adopted a pioneering methodology that avoids the defects of the FEMA approach, where individual catchments (流域) are studied by making use of big data. The study used a new high-resolution model, produced by the flood-mapping organization Fathom, which copies floods on all rivers across the entire continental United States.

“We were all surprised by how many people are actually exposed to freshwater flooding in the USA,” said Oliver Wing, lead researcher on the study and a PhD student at the University of Bristol. “It’s particularly worrisome considering that most of these people aren’t even aware of the risk they face. This study helps fill that critical information gap.”

【小题1】What did the new paper intend to tell readers?

A．The mistakes made by FEMA.

B．The serious situation of the flood.

C．The populous river basins of the USA.

D．The unseen risk of the flood in the USA.

【小题2】Why is the map produced by FEMA incomplete?

A．It’s dangerous to research all the rivers.

B．The size of the USA is too big.

C．It ignores less populous rivers.

D．The efficiency of making it is low.

【小题3】What does the underlined word “defects” in paragraph 5 mean?