底板角度对向海倾斜潜水含水层海水入侵的影响研究

Influence of the inclination angle on seawater intrusion in seaward-inclined unconfined aquifer

海水入侵是全球性的环境地质灾害,其入侵程度受地质因素和人为因素的综合影响,而含水层底板倾斜是研究海水入侵不可忽略的地质因素,目前系统分析向海倾斜含水层底板倾斜角度对海水入侵影响的研究还较少。本文通过室内砂槽显色示踪实验,分析了不同水动力条件下潜水含水层中向海倾斜底板角度对海水入侵程度的影响。结果表明:底板倾斜角度与咸水楔长度之间存在指数函数关系。在定流量和定水位淡水边界条件下,随向海倾斜底板角度增大,海水入侵现象减弱,咸水楔长度及面积、达到稳态所需时间均减小,而淡水排泄口增大。当淡水边界流量为15 mL/min,底板倾斜角度由0°增加至10°时,咸水楔长度缩短32.4%,垂向剖面的入侵面积减小35.0%,淡水排泄口增大27.1%,达到稳态所需时间缩短40.7%。此外,咸水楔长度对地下淡水流量的响应最为敏感,其次是淡水水位和底板倾斜角度。研究成果可为定量评价与海水入侵防治提供科学依据。

Seawater intrusion is a global environmental geological disaster,and the degree of intrusion is influenced by both geological and human factors.In the investigation of seawater intrusion,the inclination angle of the aquifer bedrock is a geological issue that cannot be disregarded.At present,there are few researches on the influence of the inclination angle of the aquifer bedrock on seawater intrusion systematically.In this study,a color tracing experiment in an indoor sand tank was used to examine how the inclination angle affected seawater intrusion in unconfined aquifers under various hydrodynamic conditions.The findings demonstrated an exponential function link between the inclination angle of the aquifer bedrock and the length of saltwater wedge.The phenomenon of seawater intrusion weakened with increasing the inclination angle under the conditions of constant-flow boundary and constant-head boundary.While the length and area of saltwater wedge and the time needed to reach steady state decreased and the fresh water discharge outlet increased.The length of the saltwater wedge decreased by 32.4%,the intrusion area decreased by 35.0%,the groundwater outlet increased by 27.1%,and the equilibrium time decreased by 40.7% when the freshwater boundary flow was 15 mL/min and the inclination angle raised from 0°to 10°.Additionally,the length of saltwater wedge was the most sensitive to freshwater discharge,followed by freshwater level and inclination angle.The research results provided scientific basis for quantitative evaluation and prevention of seawater intrusion.