Assessment and geospatial distribution mapping of fluoride concentrations in the groundwater of Al-Howban Basin,Taiz-Yemen

Groundwater is one of the most important natural resources of drinking water on the earth planet. In rural areas of Yemen, groundwater is the main resource for drinking as well as for domestic purposes. According to the World Health Organization, one of the most important elements that has to be found in drinking water is fluorine (fluoride) but within the range of concentration of 0.5 up to 1.5 mg/l. Otherwise, any concentration of fluoride out of that range may cause serious diseases in human’s body such as fluorosis, kidney chronic disease, and/or nephrotoxicity. Taiz City, the third important and largest city in Yemen, has been suffering from dental fluorosis for a few decades. The main resource for drinking water in this city and adjacent areas is Al-Howban Basin (the study area) from where 33 groundwater samples were collected from 33 stations. These samples were preserved and then chemically analyzed according to the American Public Health Association Standards. The results reflected high levels of fluoride concentrations up to 3.6 mg/l in groundwater of many stations. GIS mapping was used to produce a geospatial distribution map of fluoride concentrations using ArcGIS-inverse distance weighted (IDW) tool. As a result, three zones of risks were identified in the study area: mild risk zone which covers the major part of the study area, moderate risk zone, and zone of no risk (optimum level zone). The last two zones occupy small portions of the study area. Consequently, dental and skeletal fluorosis, kidney, and/or nephrotoxic diseases are highly expected to be detected in the study area. Groundwater treatment measurements and health precautions are strongly recommended to be taken by local authorities in the near future.