Trend Analysis of Groundwater Quality Using Coherence and Cross Wavelet (case study of Khorramabad city)

Today, monitoring groundwater quality and the trend of its changes for drinking, industrial and agricultural uses is very important for the general health of society. Due to changes in groundwater quality that can be due to climatic or human factors, it is necessary to consider and study these resources to maintain their quality. The purpose of this study is to investigate the quality and effective factors in groundwater quality changes in Khorramabad from 2005 to 2018 using the global water quality index (WQI) and coherence and cross wavelet. To achieve this goal, first, the drought assessment of Khorramabad city has been studied according to precipitation data using index (SPI). Then, using the world water quality index (WQI), the groundwater quality of Khorramabad has been studied. The results showed that the quality of groundwater in Khorramabad during the years 2005 to 2018 was in standard condition. Also, the correlation between the chemical parameters of groundwater has been evaluated. The results of coherence and cross wavelet showed that the relative effect of precipitation with a wavelet coherence coefficient of 0.5 has been more compared to other factors in changes groundwater quality Khorramabad city. Therefore, it can be said that the relative impact of climatic factors on changes in groundwater quality in Khorramabad has been more than the other factors. Accordingly, appropriate management strategies for groundwater quality resources and mitigation solutions are imperatively needed to ensure the sustainability of the groundwater resource and the protection of public health in the Khorramabad city.