Spatial Variability Model for Water Quality Assessment of the Physicochemical Parameters and the Water Quality Index of Laguna Lake and its Tributaries

Abstract

Assessment and mapping of quality of surface water are essential because chemical and physical characteristics of the water determine its suitability for domestic, industrial, and agricultural usages. Geographic information system (GIS) is an effective and efficient technique in problem-solving where spatial data are essential. Six Physicochemical parameters; Biological Oxygen Demand, Minimum Dissolved Oxygen, Level of Acidity or pH, Nitrate, Phosphate, and Ammonia from Laguna Lake and its tributary rivers were examined from the year 2016 to 2019. Ordinary Kriging and Universal Kriging were used as the spatial interpolation methods that carried out the estimation of the concentrations of the parameters at the unsampled location. It showed that Ordinary kriging performed better compared to Universal Kriging. This paper attempted to obtain the water quality index (WQI) from the year 2016 to 2019. Results showed that Laguna Lake has a WQI rank of marginal to excellent. The WQI of its tributary rivers is mostly poor. The physicochemical parameters indicated that the life of the lake and its tributaries are in threat. Rehabilitation must be given attention and must be suitably planned and executed. The national government and the responsible authorities must collaborate for the effort in rehabilitating and cleaning.