shallow layer

基本解释

According to the results in analysis of the sample water quality, it evaluates the shallow-layer groundwater quality in the urban planning area.
根据水质取样分析结果，对区内浅层地下水水质进行评价；
The results of shallow-layer apparent density mapping reveal that: ① The crustal density in Sichuan basin is higher than that in Songpan-Ganzi orogenic zone;
浅层重力异常的密度填图表明①四川盆地地壳密度较高，松潘—甘孜造山带密度较低；
The groundwater resources in Suzhou Urban Planning Area are abundant, but previous application and study are related to the deep-layer groundwater more than the shallow-layer groundwater.
苏州城市规划区内地下水资源丰富，但是以前相关的应用、研究主要是针对深层地下水，而浅层地下水较少涉及。

The thinking is that you could bury a small reactor in a shallow layer of bedrock, perhaps 30-50 meters underground.
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