Tidal Current Influence on Distributing Submarine Groundwater Discharge (SGD) Area in the North Lombok Waters, Indonesia

Abstract

Submarine Groundwater Discharge (SGD) has been found in the North Lombok Island. This phenomenon is strongly related to the watershed from Rinjani Mountain permeated in the form of underwater seepages. The largest seepage was observed in Krakas Beach. The emergence of these seepages may affect water quality and nutrient pollution in the surrounding by which the distribution is mainly induced by the tidal current regime. This study aimed to determine the influence of tidal current on low-temperature groundwater distribution and to analyze the environmental issues resulted from this phenomenon. Flow model and statistical analysis were employed to determine the transport pattern of SGD. The tidal current moved southwestward during the high tidal condition ranging from 0-0.15 cm/s. While tidal current flowed northeastward during the low tidal condition ranging from 0-0.3 cm/s. The temperature fluctuation follows the changes of surface elevation around SGD in which the correlation value between those two parameters reached 63 percent. This proves that the cold-water transportation depends on the fluctuation of tidal current (tidal pumping), resulting in the imbalanced ecosystem, especially during the high tidal condition when a greater water mass transport takes place.