Redesigning and monitoring groundwater quality and quantity networks by using the entropy theory

Abstract

This study aimed at re-designing and monitoring the groundwater network of Naqadeh plain in the southwest of Lake Urmia to examine the number and position of optimal wells for the salinity information transfer (EC) and survey of groundwater level at aquifer. In this regard, groundwater level data (35 wells) and electrical conductivity values (24 wells) were used during a 10-year period (2002-2012). In the first stage, simulation was conducted using the multivariate regression method and quantitative and qualitative values and the interaction of wells was observed. In the next stage, number of different classes was considered for clustering quantitative and quantitative values. The results of studying different classes of data clustering showed that the 12-class cluster had more accurate results based on the root mean square error and coefficient of determination. The root mean square error was improved by about 40, 21 and 15 percent, respectively, compared to the 3, 5 and 9-classe clusters. Finally, by choosing proper cluster of data, entropy indicators were investigated for quantitative and qualitative values at the aquifer level. The results of entropy indices at the aquifer showed that there was a severe shortage of information in terms of salinity in the Northwest of the aquifer, which necessitates drilling a new well in this area to accurately monitor the EC values. However, since more than 90 percent of the basin area is in surplus and approximately surplus conditions in terms of transferring information, the studied area has a good dispersion for qualitative monitoring. Information transfer index for the quantitative groundwater network monitoring showed that piezometers near Lake Urmia were faced with a lack of information, which according to piezometers ranking, is ranked last in terms of value of maintaining or keeping the network. Eastern areas of aquifer are also faced with shortage of piezometers accounting for about 3% of the total area. The results of survey of surplus wells in the aquifer showed that 9 and 6 surplus wells are in the aquifer for the qualitative and quantitative network, respectively. There were also wells in which information transfer was not well done and their information could not be assured. Finally, based on the conditions, a new arrangement of wells and a new optimal network were proposed.