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.(水的開采取決于含水層的兩個性質(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.(這個含水層被命名為奧加拉拉含水層，以曾經(jīng)居住在這個地區(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.(在這個干旱區(qū)域，這些沒有用在刀刃上的水正是那些農(nóng)民極度渴望的。)