Investigating the Effect of Drinking and Sanitary Water Separation on the Quality of Drinking Water and Preparing a Groundwater Quality Map (Case study: Bajestan Watershed)

In order to supply the drinking water for inhabitants of arid areas always have several challenges. The main source of fresh water supply in these areas is groundwater, but in recent years, increasing harvests and declining aquifers have increased salinity. Bajestan watershed is no exception of this issue and the main source of drinking water and sanitation is groundwater sources from the Playa, which is of very low-quality water. By decreasing the quality of groundwater resources has created the project to separate drinking water and sanitation by creating “The Government Drinking Water Stations”, since 2014. The purpose of this study is to investigate the rate of realization of this project implementation in order to quality drinking water supply. For this purpose, some of water samples was taken from the network and drinking wells, then the samples were compared with National and International standards and prepared the groundwater resources quality map.

In this study, at the first stage, the water samples taken from drinking wells and distribution network in the same period (2014-2019) were collected and compared with National and International standards. These standards included the standard of the Industrial Research Organization of Iran (1053 Report), WHO, the United States Environmental Protection Agency (EPA), the European Union (EU) and Schuler diagram. Then, Prepared the maps based on 1053 and Schuler diagram (The most common drinking water quality standards in Iran) which were selected by choosing the best interpolation method in the field of Geostatistical by choosing the lowest value of RMSE.

The results of this research showed that all of the quality parameters of distribution network’s water samples were within the standard condition, the values ​​of all the quality parameters were equal or even lower than the standard value of the indicators, So the conditions are optimal. While the water quality parameters in drinking water supply wells were of unfavorable quality according to the values ​​of the standards used in the research; These are EC, TH, TDS, Na, CL ​​in the water samples obtained from the wells on the Playa were 4 to 6 times and in other wells on the plain were 1.5 to 2 times the values ​​found in the standard indices. The results of the interpolation of the quality parameters of the plain's groundwater showed that the Co-Kriging method has the lowest Error in the main parameters of water quality determination, including EC, TDS and TH, which shows the high correlation of the parameters, there was a high correlation of groundwater in the plain with each other.

Comparison of the samples in the two parts of the wells and the drinking water distribution network showed that the current plan has sufficient usefulness to providing the quality the drinking water. Also, based on the map of the quality of the groundwater resources of the plain, the playa has the lowest quality of water resources and the wells located in the plain area have better quality.