Statistical Assessment of Water-quality Parameters for Different Flow Regimes

Groundwater and drainage-water sustainability is crucial to water management. Controlling the interaction between the groundwater and drain-water salinity at the watershed level has only been the topic of a limited number of studies. This study statistically compares salt concentration rate across time and four different flow regimes. We sampled water from 2014 to 2018. The study used R software to analyze water-quality parameters utilizing PCA and indices. Multiple water-quality indices were used to test irrigation water. A linear model with TDS as the response was fitted to the data. Another two-factor repeated-measurement covariate model was built. Water-quality indices suggest that measured water from varied flow regimes in the study area is suitable for irrigation. Based on the statistical models, Tukey's adjustment pairwise demonstrates considerable salinity variations between drain water and surface water. However, the main effect of the flow regime on TDS is significant. This indicates that the TDS value varies depending on the flow regime, not on time plus the interactions between these regimes. Keywords: Total dissolved solids (TDSs), Groundwater, ANCOVA, Flow condition, Tile drain, PCA