Abstract: “This study concerns using Multivariate statistical analysis to handle the large complex datasets in lakes and use water quality index factor to estimate the water quality in lakes.This study investigated the seasonal and spatial variations of water quality parameters in Burullus Lake in Egypt as a case study. Significant seasonal changes (p < 0.05) were observed in temperature,pH and phosphate (PO4-P), whereas significant spatial differences (p < 0.05) were detected in pH, salinity, dissolved oxygen (DO), ammonium-nitrogen (NH4-N), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), PO4-P, silicate (SiO4) and Chlorophyll-a (Chl-a). The water quality index (WQI) estimated using the inputs of: salinity, DO, NH4-N, NO3-N, PO4-P, and Chl-a. The (WQI) of the lake was rated as Bad to Very bad. Based on principal component analysis (PCA), the first principal component (PC1: 38.78%) represented high loadings on NH4-N: 0.46, NO3-N: 0.45, and PO4-P: 0.45, indicating that the lake was mainly infl”

Keywords: Dendrogram; Principal component analysis; Spatiotemporal variability; Water quality index.