[地下水]以各种形式存在于地壳岩石或土的空隙(孔隙、裂隙、溶洞)中的水.按照存在的形式,可分为气态水、吸着水、薄膜水、毛细管水、重力水和固态水等.按照埋藏条件,又可分为上层滞水、潜水和承压水三个基本类型.每一类型又根据地下水赋存的形式再分为孔隙水、裂隙水和岩溶水(溶洞水)三类以及一些过渡类型(如裂隙—岩溶水等).地下水一方面可作为居民生活用水、工业用水以及农业灌溉用水的水源,含有特殊组分或有较高温度的地下水还可用于医疗、热能利用和提取有用元素.另一方面,在某些情况下,它又能淹没矿坑或引起土壤盐碱化等,具有危害作用.[水文地质学]研究地下水的学科.它主要研究地下水的形成、分布与运动规律以及它的物理性质与化学成分等.目的是寻找地下水、合理开发利用地下水、防 [Groundwater] Water that is present in various forms in the voids (pores, fissures, caves) of crustal rocks or soils and can be divided into gaseous water, sorption water, membrane water, capillary water, gravity water and solid Water, etc. According to the burial conditions, it can be divided into three basic types: upper water stagnation, submersion and confined water, each of which is subdivided into pore water, fissure water and karst water (cave water) according to the form of underground water. Three categories and some transitional types (such as fissures - karst water, etc.) Groundwater on the one hand can be used as domestic water, industrial water and agricultural irrigation water, containing special components or groundwater with higher temperature can also be used for medical treatment, thermal energy Use and extract useful elements.On the other hand, in some cases, it can submerge the pit or cause soil salinization, etc., have a harmful effect.HydrogeologyThe groundwater research discipline, which mainly studies the formation of groundwater, Distribution and movement law as well as its physical properties and chemical composition, etc. The purpose is to find groundwater, reasonably develop and utilize groundwater, prevent