"非承压含水层" can be translated as "unconfined aquifer" in English.
In hydrogeology, an aquifer is an underground layer of water-bearing permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted. A "unconfined aquifer" specifically refers to an aquifer that is not overlain by an impermeable layer, allowing water to freely rise to the water table under atmospheric pressure.