水文地質學是研究地下水的數量和質量隨空間和時間變化的規律，研究地下水的分布、運動和形成規律，地下水的物理性質和化學成分，地下水資源評價、開發及其合理利用，地下水對工程建設和礦山開采的不利影響及其防治等。

       在不(bu)同(tong)(tong)(tong)環境中地(di)(di)下(xia)水(shui)(shui)(shui)的(de)埋藏、分(fen)布、運動和(he)組(zu)成(cheng)成(cheng)分(fen)均不(bu)相同(tong)(tong)(tong)。查明上述各方面(mian)狀況，可為(wei)科學(xue)(xue)(xue)地(di)(di)利用或防(fang)治地(di)(di)下(xia)水(shui)(shui)(shui)提供根據。水(shui)(shui)(shui)文(wen)地(di)(di)質(zhi)學(xue)(xue)(xue)對地(di)(di)下(xia)水(shui)(shui)(shui)的(de)研(yan)(yan)究，著(zhu)重自然歷史和(he)地(di)(di)質(zhi)環境的(de)影響，同(tong)(tong)(tong)主要用水(shui)(shui)(shui)文(wen)循(xun)環和(he)水(shui)(shui)(shui)量平衡(heng)原理(li)研(yan)(yan)究地(di)(di)下(xia)水(shui)(shui)(shui)的(de)地(di)(di)下(xia)水(shui)(shui)(shui)水(shui)(shui)(shui)文(wen)學(xue)(xue)(xue)關系密切，只是研(yan)(yan)究的(de)側重點稍有不(bu)同(tong)(tong)(tong)。

      隨著科學(xue)(xue)的發展(zhan)和(he)生產(chan)建設的需要，水(shui)(shui)(shui)文(wen)(wen)地質(zhi)學(xue)(xue)又分為區域水(shui)(shui)(shui)文(wen)(wen)地質(zhi)學(xue)(xue)、地下(xia)水(shui)(shui)(shui)動(dong)力學(xue)(xue)、水(shui)(shui)(shui)文(wen)(wen)地球化(hua)學(xue)(xue)、供水(shui)(shui)(shui)水(shui)(shui)(shui)文(wen)(wen)地質(zhi)學(xue)(xue)、礦床水(shui)(shui)(shui)文(wen)(wen)地質(zhi)學(xue)(xue)、土壤改良水(shui)(shui)(shui)文(wen)(wen)地質(zhi)學(xue)(xue)等分支學(xue)(xue)科。

      水(shui)文(wen)(wen)(wen)地(di)質(zhi)學(xue)與(yu)地(di)熱、地(di)震、環(huan)境地(di)質(zhi)等(deng)方面的(de)研究相(xiang)互滲透，又形成了若(ruo)干新(xin)領域，如(ru)環(huan)境水(shui)文(wen)(wen)(wen)地(di)質(zhi)學(xue)、地(di)下水(shui)資源管理、同位素水(shui)文(wen)(wen)(wen)地(di)質(zhi)學(xue)等(deng)。