Question

    There’s more fresh water hidden below Earth’s surface in underground aquifers (含水层) than any other source besides the ice sheets. That groundwater earns an unshakably important place for rivers worldwide, keeping them running even when droughts bring their waters low.

But in recent decades humans have pumped trillions of gallons out of those underground reservoirs. In a new research, water experts and scientists are taking a global look at where groundwater is already being extracted at such a rate that it has caused water levels to drop so much in rivers and streams that they will slip into the ecological danger zone.

Much of that water is being removed much faster than it can be refilled. That has enormous potential consequences for people and crops in areas that don’t get enough rain. But far before those impacts emerge, the effects will fiercely hit rivers, streams, and the habitats around them. Hundreds of rivers and streams around the world would become so water-stressed that the entire ecological system would hit a danger point, says Inge de Graaf, the lead author of the research. “We can really consider this ecological effect like a ticking time bomb,” she says. “If we pump the groundwater now, we don’t see the impacts until like 10 years further or even longer.”

But the severity of the impacts might still be underestimated. As a baseline, they used the global water demand in 2010 and spun their climate model forward to predict how stresses on groundwater systems might develop. But as populations swell and the demand for food rises, those stresses could skyrocket for reasons other than climate change, speeding along the extraction from underground water sources.

The effects of over-pumping groundwater take years, if not decades, to become visible. Changes in rain have immediate, obvious effects on river flow. When it pours, rivers often rage. But groundwater is hidden and changes don’t always manifest in the place where the pumping occurs and are programmed to “wait for the perfect moment”. That makes aquifer management issues extra challenging. In the meantime, rivers and streams are the signal that says we’re using water in an unsustainable fashion, we need to take a hard look at what we’re doing.”.

1.The underground water is of critical importance to rivers due to the fact that ________.

A.it helps to maintain the same water level of rivers

B.it stops the running of rivers during dry spells

C.it leaves rivers drying out due to droughts

D.it ensures the flow of rivers throughout the year

2.The phrase “slip into the ecological danger zone” (in the second paragraph) suggests that ________.

A.it is thrilling to explore the ecological danger zone

B.pumping underground water is convenient though dangerous

C.the underground water level has dropped to an alarming level

D.the constant drop of water level prevents people feeling secure

3.Why does the author say “the severity of the impacts might still be underestimated” (in the fourth paragraph)?

A.Because the water demand data in 2010 was not accurate.

B.Because the water demand has soared ever since 2010.

C.Because the water demand was not stressful in 2010.

D.Because the water demand prediction didn’t consider climate change.

4.Over-pumping groundwater doesn’t show immediate effect because _________.

A.the changes are waiting for a heavy rain

B.underground water is used sustainably

C.the changes take longer to come to light

D.underground water is inexhaustible

Answer

1.D

2.C

3.B

4.C

【解析】

本文是议论文。气候变化、人口的迅速增加和对粮食需求的增加，引起水需求急剧上升，从而加速了地下水源的开采。地下水过度开采会导致生态系统处于危险境地，而且这种影响要很多年以后才能显现出来。

1.细节理解题。根据第一段“That groundwater earns an unshakably important place for rivers worldwide, keeping them running even when droughts bring their waters low”可知，地下水对世界各地的河流都很重要是因为即使在干旱使河流水位降低的情况下，地下水也能保证河流 继续流淌。故选D项。

2.词句猜测题。根据第二段“…groundwater is already being extracted at such a rate that it has caused water levels to drop so much in rivers and streams”可知，因为地下水的开采速度太快，导致河流和溪流的水位迅速下降，这会使生态环境有危险。故选C项。

3.推理判断题。根据第四段“But as populations swell and the demand for food rises, those stresses could skyrocket for reasons other than climate change, speeding along the extraction from underground water sources”可知，研究者们使用2010年的全球水需求作为基准，预测地下水系统的压力会如何发展。但是自2010年以来，除了气候变化以外，随着人口的迅速增加和对粮食的需求的增加，水需求急剧上升，从而加速了地下水源的开采。研究者可能低估了地下水开采加速的严重性。故选B项。

4.细节理解题。根据第五段“The effects of over-pumping groundwater take years, if not decades, to become visible”和groundwater is hidden and changes don’t always manifest in the place where the pumping occurs and are programmed to “wait for the perfect moment”可知，因为地下水是隐藏的，变化并不总是在抽取地下水的地方表现出来。过度抽取地下水的影响需要数年甚至数十年才能显现出来。故选C项。