Key Laboratory of Marine Environment & Ecology, Ministry of Education, Ocean University of China
Shandong Provincial Geological Survey Institute
Hainan Geological Comprehensive Exploration and Design Institute

滨海地区普遍存在向海倾斜的承压含水层,但含水层底板的倾斜角度对海水入侵的影响程度仍不清楚。本研究利用室内砂箱试验,并应用显色示踪技术,综合分析不同底板倾斜角度承压含水层海水入侵的动态过程,探究海平面高度、地下淡水流量和含水层岩性对向海倾斜的承压含水层海水入侵的影响。研究发现,底板倾斜角度对承压含水层的海水入侵有显著影响。在咸淡水界面稳定时,底板倾斜角度与咸水楔长度之间存在指数函数关系,咸水楔长度随倾斜角度的增加而减少。在定水头条件下,底板倾斜角度的增加导致地下淡水排泄量减少。在定流量边界条件下,尽管底板倾斜角度的变化不影响地下淡水排泄量,但咸水楔面积却随倾斜角度的增加而减小。当含水层岩性从粗砂变为细砂时,由于其渗透系数降低,咸水楔长度减少,尤其是在定流量条件下,其缩短更为显著。研究表明,对于向海倾斜的承压含水层,底板倾斜角度较小时,海平面升高和地下淡水流量减少对海水入侵的影响更加显著。

In coastal regions, there is a widespread presence of confined aquifers sloping seaward, but the impact of the aquitard’s bottom slope angle on seawater intrusion remains unclear. In this paper, laboratory sandbox experiments employing color tracing technology were first conducted to analyze the dynamic process of seawater intrusion into confined aquifers under various bottom slope angles. The impact characteristics of sea level height, the amount of subterranean freshwater discharge, and aquifer lithology on seawater intrusion into seaward sloping confined aquifers were then investigated. The results demonstrate that the bottom slope angles significantly affects seawater intrusion into confined aquifers. When the interface between saline and freshwater during seawater intrusion stabilizes, there exists an exponential function relationship between the bottom slope angle and the length of the saltwater wedge: the length of the saltwater wedge decreases as the slope angle increases. Under constant head conditions, the discharge of subterranean freshwater decreases with the increase of the bottom slope angle. Under constant flow boundary conditions, although changes in bottom slope angles have no impact on subterranean freshwater discharge, the area of the saltwater wedge consistently decreases with an increase of the slope angle. When the lithology changes from coarse sand to fine sand in inclined aquifer, the length of saltwater wedge shortens as the hydraulic conductivity of the aquifer decreases, and the shortening becomes the greatest under constant-flow conditions. For confined aquifers sloping seaward, the smaller the bottom slope angle is, the greater the impact of sea level rise and subterranean freshwater discharge on the degree of seawater intrusion becomes.

国家重点研发计划“大气与土壤、地下水污染综合治理”重点专项(2023YFC3709002);山东省自然资源厅地质勘查项目(鲁勘字(2022)3号)