Submarine groundwater discharge (SGD) is an important pathway of nutrients into coastal areas. During the last decades, interest of researchers in SGDs has grown continuously. However, methods applied for SGD research usually focus on the aquifer or on the mixing processes on larger scales. The distribution of discharged water within the water column is not well investigated. Small remotely operated vehicles (ROV) equipped with environmental sensors can be used to investigate the spatial distribution of environmental parameters in the water column. Herein, a low-cost multi-sensor platform designed to investigate the spatial distribution of water quality properties is presented. The platform is based on an off-the-shelf underwater vehicle carrying various environmental sensors and a short-baseline localisation system. This contribution presents the results of SGD investigations in the area of Woodman Point (Western Australia). Various potential SGD plumes were detected using a skiff equipped with a recreational echo sounder. It was demonstrated that this inexpensive equipment could be used to detect and investigate SGDs in coastal areas. In addition, the low-cost multi-sensor platform was deployed to investigate the spatial distribution of environmental parameters including temperature (T), electric conductivity (EC), dissolved oxygen (DO), oxidation-reduction potential (ORP), pH, and dissolved organic matter fluorescence (FDOM). Three ROV surveys were conducted from different skiff locations. Analyses of the spatial distribution of the environmental parameters allowed the identification of nine potential SGD plumes. At the same locations, plumes were identified during the sonar surveys. In addition, fuzzy logic was used for the fusion of salinity, DO, and FDOM readings in order to enhance SGD detection capability of the designed multi-sensor system. The fuzzy logic approach identified 293 data points as potential within a SGD plume. Average minimum-distance between these points and the identified SGD plumes was 0.5 m and 0.42 m smaller than the minimum-distance average of the remaining data points of survey one and three respectively. It was shown that low-cost ROVs, equipped with environmental sensors, could be an important tool for the investigation of the spatio-temporal behaviour of SGD sites. This method allows continuous mapping of environmental parameters with a high spatial and temporal resolution. However, to obtain deeper insights into the influence of SGDs on the nearshore areas, this method should be combined with other well-established methods for SGD investigation, such as pore water sampling, remote sensing, or groundwater monitoring.

中文翻译：

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使用低成本多传感器平台研究海底地下水排放的时空特性

海底地下水排放（SGD）是营养物质进入沿海地区的重要途径。在过去的几十年中，研究人员对 SGD 的兴趣不断增长。然而，应用于 SGD 研究的方法通常侧重于含水层或更大规模的混合过程。排放水在水柱内的分布没有得到很好的研究。配备环境传感器的小型遥控车 (ROV) 可用于研究水体中环境参数的空间分布。在此，提出了一种旨在研究水质特性空间分布的低成本多传感器平台。该平台基于一个带有各种环境传感器和短基线定位系统的现成水下航行器。本文稿介绍了伍德曼角（西澳大利亚州）地区的 SGD 调查结果。使用配备娱乐回声测深仪的小艇检测到各种潜在的 SGD 羽流。事实证明，这种廉价的设备可用于检测和调查沿海地区的 SGD。此外，还部署了低成本多传感器平台来研究环境参数的空间分布，包括温度 (T)、电导率 (EC)、溶解氧 (DO)、氧化还原电位 (ORP)、pH 值和溶解有机物荧光（FDOM）。从不同的小艇位置进行了三项 ROV 调查。环境参数的空间分布分析允许识别九个潜在的 SGD 羽流。在同一地点，在声纳调查期间发现了羽状物。此外，模糊逻辑用于融合盐度、DO 和 FDOM 读数，以增强设计的多传感器系统的 SGD 检测能力。模糊逻辑方法将 293 个数据点确定为 SGD 羽流中的潜在数据点。这些点与确定的 SGD 羽流之间的平均最小距离分别比调查一和三的其余数据点的最小距离平均值小 0.5 m 和 0.42 m。结果表明，配备环境传感器的低成本 ROV 可以成为研究 SGD 站点时空行为的重要工具。该方法允许以高空间和时间分辨率连续映射环境参数。然而，