Exceedance probability assessment of bathing water quality standards in lake Van based on a geostatistical analysis

Abstract

Monitoring bathing water quality (BWQ) is highly important in Turkey both for public health issues and tourism income. Lake Van is one of the largest lakes of Turkey and serves as one of the most important tourist attractions in the eastern part of Turkey. This study aims to assess critical bathing sites in Lake Van by using historical BWQ data that was collected twice a month during the swimming season from June 15 to August 31, between the years 2010 and 2020. To avoid public health hazards, it is very important to determine the spatial dimension of inland water pollution and provide visual tools for its presentation. Geostatistical data analysis and the determination of critical locations have been done by a spatial interpolation method, named Probability Kriging (PK) using Geographic Information System (GIS) based software ArcMap 10. Probability maps for exceeding the threshold values identified for the two microbiological water quality parameters of Escherichia coli and intestinal enterococci (IE) were generated, and used for the identification of four critical regions: İskele (4), west side of Gevaş (1), Edremit (3) and Muradiye/Erciş (7). Insufficient wastewater treatment plant capacity serving to high population in these regions may indicate the most pressing issues disturbing the BWQ.