曾经给这些井提供水源的蓄水层已被宣告枯竭。
The aquifer which had once fed the wells was pronounced dry.
不渗透的岩层都称为隔水层。
可以从中抽取水的地下蓄水层被称为含水层。
A groundwater reservoir from which water can be extracted is called an aquifer.
水的开采取决于含水层的两个性质：孔隙度和渗透性。
Extraction of water depends on two properties of the aquifer: porosity and permeability.
砂岩通常是良好的含水层，而细粒泥岩通常是不透水的。
Sandstones generally make good aquifers, while finer-grained mudstones are typically impermeable.
"大多数沙石中较浅的蓄水层贮水量少，但可以迅速再生。
Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged.
这些含水层在一万多年前就饱和了，现在不再重新补充水分了。
These aquifers became saturated more than 10,000 years ago and are no longer being recharged.
这些水源的一个问题是，深水区的含盐量也比浅水层的含盐量高。
One problem with these sources is that the deep water also has a higher level of salt than shallower aquifers.
在印度、中国、美国等地，地下含水层被抽离的速度比自然补给还要快。
Groundwater aquifers are being pumped down faster than they are naturally replenished in parts of India, China, the USA and elsewhere.
水在含水层中并不是静止不动的，而是会从泉水中渗出，或渗入其他含水层。
Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers.
这种情况在德州最为严重，那里气候最干燥，抽水量最大，含水层含水最少。
The situation is most critical in Texas, where the climate is driest, the greatest amount of water is being pumped, and the aquifer contains the least water.
大部分的石灰岩和砂岩的蓄水层都是深而广的，但可能含有不可再生的地下水。
Most limestone and sandstone aquifers are deep and extensive but may contain groundwaters that are not being recharged.
地下水的矿物含量通常随深度的增加而增加，但即使很浅的蓄水层中可能含盐量也很高。
The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.
总之，这些花粉化石，还有含水层和岩画，这三样东西都证明了撒哈拉沙漠曾经比现在绿得多。
Anyway, it's this fossilized pollen along with the aquifers and the rock paintings, these three things are all evidence that the Sahara was once much greener than it is today.
沉积岩——地表附近最常见的岩石类型——也是最常见的储水层，因为它们可以装水的空间最多。
Sedimentary rocks—the most common rock type near the surface—are also the most common reservoirs for water because they contain the most space that can be filled with water.
大多数石灰岩和砂岩的蓄水层很深并且规模很大，但是它们含有的地下水可能是当前无法再生的。
Most limestone and sandstone aquifers are deep and extensive, but may contain groundwaters that are not being recharged.
这个含水层被命名为奥加拉拉含水层，以曾经居住在这个地区的奥加拉拉-苏族印第安人的名字命名。
This aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region.
地下含水层位于地下1000到3000英尺之间，这意味着抽水成本很高，还有其他接踵而来的问题。
The aquifers range from 1,000 to 3,000 feet below the ground, which means that pumping will be expensive and there are other concerns.
斯坦福大学的研究小组对这一深度以下的地下蓄水层进行了调查，发现蓄水量或许是先前所预想的三倍。
The team at Stanford investigated the aquifers below this depth and found that reserves may be triple what was previously thought.
尽管发达国家的人口、工业产出和经济生产率还在飙升，但人们从含水层、河流和湖泊取水的速度已经放缓。
Although population, industrial output and economic productivity have continued to soar in developed nations, the rate at which people withdraw water from aquifers, rivers and lakes has slowed.
撒哈拉沙漠下面是巨大的含水层，基本上是一片淡水的海洋，那可能是经过岩石层过滤的，已经有一百万年历史。
Beneath the Sahara are huge aquifers, basically a sea of fresh water, that's perhaps a million years old filtered through rock layers.
奥加拉拉含水层是一个砂岩地层，位于从德克萨斯州西北部延伸到南达科他州南部，约583000平方公里土地的地下。
The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to southern South Dakota.
农民们脚下的含水层损耗同样严重。
Just as serious is the depletion of the aquifers on which farmers depend.
而且约有280个地下蓄水层横跨国界。
盖洛说，如果地球是一只苹果，水层比苹果皮还要薄。
If the Earth was an apple, Gallo said, the water layer would be thinner than the fruit's skin.
喷雾能形成防水层，也就是说，只需用水就能洗净它。
The spray forms a water-resistant layer, meaning it can be cleaned using only water.
输油管线沿途经过富饶农田和重要的蓄水层。
The pipeline route crosses rich farmland and important aquifers.
钻进机据说能钻破岩层进入含水层，但看起来不行。
The machine that promises to break bedrock into the aquifer seemingly can't.
它在海洋暖水层和冷水层之间的温度差中获取能量。
It harvests that energy by exploiting the difference in temperature between the warm surface of the sea and its cold depths.
每年将有几个亿加仑的水从当地的地下蓄水层抽取上来。
Afew hundred million gallons of water will also be pumped out of the local aquifer each year.
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