Submarine groundwater discharge: Effects of hydrogeology and of near shore surface water bodies

Abstract. Submarine groundwater discharge (SGD) and its role in marine nutrient cycling are well known since the last decade. The freshwater equivalent, lacustrine groundwater discharge (LGD), is often still disregarded, although first reports of LGD are more than 50 years old. We identify nine different reasons why groundwater has long been disregarded in both freshwater and marine environments such as invisibility of groundwater discharge, the size of the interface and its difficult accessibility. Although there are some fundamental differences in the hydrology of SGD and LGD, caused primarily by seawater recirculation that occurs only in cases of SGD, there are also a lot of similarities such as a focusing of discharge to near-shore areas. Nutrient concentrations in groundwater near the groundwater–surface water interface might be anthropogenically enriched. Due to spatial heterogeneity of aquifer characteristics and biogeochemical processes, the quantification of groundwater-borne nutrient loads is challenging. Both nitrogen and phosphorus might be mobile in near-shore aquifers and in a lot of case studies large groundwater-borne nutrient loads have been reported.

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Faktor Hidro-Oseanografi Terhadap Distribusi Air Tawar Bersuhu Rendah Dekat Pantai Sekitar Lokasi Keluaran Air Tanah Lepas Pantai (KALP) di Perairan Lombok Utara, Indonesia

Oseanologi dan Limnologi di Indonesia ◽

10.14203/oldi.2019.v4i3.157 ◽

2019 ◽

Vol 4 (3) ◽

pp. 145

Author(s):

Ulung Jantama Wisha ◽

Gunardi Kusumah

Keyword(s):

Submarine Groundwater Discharge ◽

Flow Model ◽

Field Survey ◽

Groundwater Discharge ◽

High Tide ◽

The North ◽

Submarine Groundwater ◽

Ambient Water Temperature ◽

Near Shore ◽

Two Parameters

<p><strong>The Influence of Hydro-Oceanography Factors on the Distribution of Near-shore Low-Temperature Freshwater around Submarine Groundwater Discharge (SGD) Area in the North Lombok Waters, Indonesia.</strong> North Lombok coast has lot of resources of Submarine Groundwater Discharge (SGD). The biggest discharge appeared in the Krakas Beach where cold groundwater discharge many spots might trigger anomalies in the ambient water temperature. This study was aimed at determining the distribution of the cold groundwater discharge. A field survey was conducted on March 23th -26th, 2016. Flow model and statistical analysis were employed to determine the transport pattern of temperature anomalies. Vertically, the current direction is in accordance with Ekman spiral that triggers the vertical cold groundwater distribution. The current speed during the displacement toward high tide ranges 0-0.15 cm/s which predominantly moves south-westward. During low tide, tidal current was predominantly north-eastward moving at 0-0.3 cm/s. Temperature variation around the SGD spot fluctuated following sea surface surface elevation dynamics in which these two parameters has a correlation value of 63%.</p>

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