Brief research history and modern knowledge of the phenomenon of submarine groundwater discharge on the sea and ocean shelves

Abstract

Groundwater is widely spread both on land and under seas and oceans. Today, hydrogeologists and oceanologists recognize the potentially significant contribution of submarine groundwater discharge to coastal areas. The term submarine groundwater discharge (SGD) is commonly used to describe sources below sea level. It should be noted that submarine waters also include the sources located within tidal (littoral) zones, although they get underwater only during high tides. Observation of submarine discharge showed its significant impact on the ecological condition of coastal structures. Along with the percolation of underground water along most of the world’s coastlines, a significant amount of fresh water and substances dissolved in it is spread across large areas. However, the role of such a phenomenon as submarine discharge for coastal communities is practically not considered. The article gives examples from many literary sources, highlighting the importance of submarine discharge sources for local population in their everyday activities for many centuries. This is a source of drinking water, hygienic product, water for agriculture, fishing, shipping, culture, and tourism. In many parts of the world, there are sources of submarine discharge, which have a unique shape and are considered important only because of their exceptional nature and the habitat of freshwater organisms. These examples confirm the uniqueness of such a phenomenon of live activity of coastal communities. As a result, there is a necessity for a comprehensive approach to the study of submarine discharge, which is relevant not only from the point of view of changes in coastal environment but also from the point of view of the global circulation of water and substances on Earth.