Global map

Only saline groundwater at depths less than 500 meters below surface level is considered (shallow and intermediate depths). It is assumed that at these depths most of the human groundwater extraction is taking place and the groundwater is interacting with eco-systems. In this inventory the lower limit of 1,000 mg/l, TDS is used. Thus, when talking about saline groundwater, this tacitly includes brackish groundwater and brines as well.

According to our inventory, the total area with high groundwater salinity at shallow or intermediate depth approximates 24 million km2. This is about 16% of the total land area on earth. The generic type evaporation of shallow groundwater (B1) and dissolution  (B2) or a combination of the two contribute most to this saline groundwater area with respectively contributions of 20, 26 and 13%. No significant groundwater salinity occurrences caused by membrane effects are found in this study. In addition, the effect of anthropogenic pollution on the TDS-content of groundwater is not significant on this scale. In the Basins of West and Central Asia, the largest area with high groundwater salinity is found. It contributes 14% to the total groundwater salinity area. The lowlands of South America, lowlands of Europe, mountain belt of central and eastern Asia and Eastern Australia all contribute individually for about 6-7 % to the total groundwater salinity area.

According to this study, about 1.1 billion people live in areas with groundwater salinity at shallow and intermediate depths. The generic types contributing most to the amount of groundwater salinity ‘affected' people are irrigation (C1, 25%), lateral seawater intrusion (A4, 17%), dissolution (B2, 17%) and igneous activities (15%). It is not surprising that the first two generic types affect most people since it are these very same people who are the drivers for these salinisation processes (with high numbers of people living in fertile agricultural areas and along the coast and in deltas this seems logical). The areas in the world with highest population density contribute most to the groundwater salinity affected people: lowlands of eastern China (15%) the plains and deltas of Ganges and Brahmaputra rivers (13%) and the Northwestern Pacific margin (13%). Whether people living in the groundwater salinity affected areas are really being affected by the salinity is very much dependent on their groundwater use.

The draft map with the global overview of saline groundwater occurrence and genesis can be downloaded.