Dataset on onshore groundwaters and offshore submarine spring of a Mediterranean karst aquifer during flow reversal and saltwater intrusion

This dataset was generated to study the behavior of a Mediterranean coastal (Thau lagoon, southern France) karst aquifer for which the flow reversal phenomenon has occurred several times in the past through a submarine karst spring located at -29.5 meters below the lagoon level. Since the 1960s, seven flow reversal phenomena have occurred, the last one occurring between 11/28/2020 and 03/14/2022. During these phenomena, which can last from a few weeks to several months, the salty water is absorbed from the lagoon to the conduit of the submarine spring, which leads to the salinization of the underlying karst aquifer. The equipment and the monitoring of the submarine spring constitute a key element of the research project to understand of the hydrogeological functioning of the karst system during regular conditions, when fresh groundwater flows out of the submarine spring, as well as during disruptive events, when flow reversal and salty water intrusion through the spring occur. The submarine spring flow dataset is contained in the Vise_Submarine_Spring.xlsx file, which contains three excel sheets. The first sheet named "Flow" contains the data of the hourly averages of the flow rates measured at a time step of 5 minutes between 06/26/2019 and 12/31/2022. During regular flowing conditions (i.e. groundwater flows out of the spring), the flow rate is positive. During flow reversal periods, the flow rate becomes negative. The "Comments" column is used to qualify this flow context. The second sheet named "SpC" and the third sheet named "Temp" contain, data of the hourly averages of water specific conductivity and temperature data, respectively, measured at a 5 minutes time step between 06/26/2019 and 10/13/2022. During flow reversal periods, the specific conductivity and temperature measured are those of the lagoon water, these measurements make it possible to qualify the physico-chemical properties of the salty water infiltrated by the karst spring during disruptive events. The lagoon water level dataset is contained in the Thau_Lagoon.xlsx file. The sheet named “WaterLevel” contains the hourly data of the lagoon water levels measured at the H-lagoon site. The data is expressed in meters above sea level. Measured lagoon water level fluctuations were repeatedly checked at the reference point using a manual water level gauge. The groundwater dataset is contained in the Thau_karst_groundwater.xlsx file, which has 9 sheets, one for each of the following stations referenced to the BRGM groundwater database (BSS number with hypertext links). Each sheet contains piezometric data (expressed in m.a.s.l) between 01/01/2017 and 12/31/2022 for the longest time series. The sheets also provides the groundwater temperature and specific conductivity data (with the exception of point BSS002JEKD). Information on the depth of the measurement probe is indicated into the metadata section of each excel sheet.本数据集专为研究地中海沿岸法国南部泰奥潟湖（Thau lagoon）喀斯特含水层（karst aquifer）的水文行为而构建，该含水层曾多次通过一处位于潟湖水位以下29.5米的海底喀斯特泉（submarine karst spring）发生水流反转（flow reversal）现象。自20世纪60年代以来，该区域已发生7次水流反转事件，最近一次发生于2020年11月28日至2022年3月14日期间。此类现象的持续时长从数周至数月不等，在此期间咸水会从潟湖渗入海底泉的导水通道，进而导致下方喀斯特含水层发生盐化。针对该海底泉的设备布设与监测工作，是本研究项目的核心组成部分，用于厘清该喀斯特系统在常规工况（即地下淡水从泉眼涌出）与极端扰动事件（即发生水流反转及咸水通过泉眼入侵）时的水文地质运行机制。海底泉流量数据集存储于Vise_Submarine_Spring.xlsx文件中，该文件包含3个Excel工作表。第一个工作表命名为"Flow"，收录了2019年6月26日至2022年12月31日期间、以5分钟为时间步长测得的流量小时均值数据。常规涌流工况下（即地下水从泉眼流出），流量为正值；水流反转时段内，流量则转为负值。"Comments"列用于标注当前的水流工况。第二个工作表命名为"SpC"，第三个命名为"Temp"，分别收录了2019年6月26日至2022年10月13日期间、以5分钟为时间步长测得的水体比电导率（specific conductivity）与温度小时均值数据。水流反转时段内测得的比电导率与温度即为潟湖水体的参数，这些数据可用于表征极端扰动事件中海底泉入侵咸水的物理化学性质。潟湖水位数据集存储于Thau_Lagoon.xlsx文件中。该文件内名为"WaterLevel"的工作表收录了H潟湖站点测得的潟湖水位小时级数据，单位为米海拔（meters above sea level, m.a.s.l.）。实测潟湖水位波动已通过手动水位计在参考点处完成多次校核。地下水数据集存储于Thau_karst_groundwater.xlsx文件中，该文件包含9个工作表，每个工作表对应法国地质矿业研究局（BRGM）地下水数据库中的一处测点，各测点均带有超链接形式的BSS编号。对于最长时间序列而言，每个工作表均收录了2017年1月1日至2022年12月31日期间的测压水位数据，单位为米海拔。各工作表同时提供地下水温度与比电导率数据（BSS002JEKD测点除外）。每个Excel工作表的元数据部分均标注了测量探头的埋设深度。