Fig. 5
From: Assessing the water quality hazard and challenges to achieving the freshwater goal in Sri Lanka
Spatially interpolated gridded maps of groundwater quality and hydraulic parameters across Sri Lanka. a chloride; b alkalinity; c nitrate; d nitrite; e fluoride; f phosphate; g total dissolved solids (TDS); h hardness; i total iron; j sulphate and k aquifer types and distribution in Sri Lanka. Data source: values are interpolated from variable data points (maximum number is 688) water-point locations available within the National Water Supply and Drainage Board (NWSDB) database. The location of data points for each parameter is also shown on the maps as black cross. Ordinary Kriging and Inverse Distance Weighting (only for nitrate) interpolation methods are used for creating these maps in ArcGIS Desktop (v. 10.8) from available point observations for each parameter (points also shown on these maps).
