The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to southern South Dakota.(奧加拉拉含水層是一個(gè)砂巖地層，位于從德克薩斯州西北部延伸到南達(dá)科他州南部，約583000平方公里土地的地下。)

Extraction of water depends on two properties of the aquifer: porosity and permeability.(水的開(kāi)采取決于含水層的兩個(gè)性質(zhì)：孔隙度和滲透性。)

Two million years ago, a cave-studded aquifer lay beneath an undulating plain of shallow, wooded valleys and rolling hills.(200萬(wàn)年前，在樹木叢生的谷地和波狀丘陵地帶的起伏平原之下，是洞穴密布的地下蓄水層。)

This aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region.(這個(gè)含水層被命名為奧加拉拉含水層，以曾經(jīng)居住在這個(gè)地區(qū)的奧加拉拉-蘇族印第安人的名字命名。)

A groundwater reservoir from which water can be extracted is called an aquifer.(可以從中抽取水的地下蓄水層被稱為含水層。)

But switch the source to a river or an aquifer, and the cost of a cubic meter of water can plummet to 10 to 20 cents, and farmers often pay far less.(如果從河流或地下取水，每立方米的成本可大幅降至10至20美分，農(nóng)業(yè)用水的成本甚至更低。)

The aquifer which had once fed the wells was pronounced dry.(曾經(jīng)給這些井提供水源的蓄水層已被宣告枯竭。)

Geologists eventually realized that the cause was Houston's withdrawal of fresh water from the aquifer located under the city.(地質(zhì)學(xué)家最終認(rèn)識(shí)到導(dǎo)致海平面上升的原因是，休斯頓從城市地下的含水土層抽取淡水。)

This discovery forced city officials to use nearby Lake Houston and Lake Conroe for municipal water instead of the aquifer.(這項(xiàng)發(fā)現(xiàn)迫使城市官方用鄰近的休斯頓湖和康羅湖代替含水土層，成為該市主要水源。)

Tapping the drought-prone region's aquifer for nonessential uses diverts water from farmers who need it desperately.(在這個(gè)干旱區(qū)域，這些沒(méi)有用在刀刃上的水正是那些農(nóng)民極度渴望的。)