Applying Grey Systems and Inverse Distance Weighted Method to Assess Water Quality from a River

Abstract

The Cañete River basin, in Peru, has suffered an increase in pollution due to various causes, among the main ones being the lack of knowledge, culture of individuals and municipal authorities, economic activities, among others. We analyze this degree of pollution reflected in the upper part of the Cañete river basin through the Grey Clustering method, based on grey systems, which is presented as a good alternative to evaluate water quality in a comprehensive way, making use of Historical data from the monitoring program for the years 2014 and 2015 with nine monitoring points carried out by the National Water Authority (ANA), 6 parameters were defined to evaluate: Hydrogen potential (pH), Biochemical oxygen demand, Chemical demand of Oxygen, Total Suspended Solids, Total Manganese and Total Iron based on the PRATI index. For the spatial distribution, interpolation surfaces of the clustering coefficients were created, using the Spatial Analyst extension of the ArcGIS software, which provides tools to create, analyze and map data in raster format or surfaces. The interpolation method used is Inverse Distance Weighted (IDW). The results of the evaluation showed that in 2014 the monitoring points determined, through the Grey Clustering method, a level of contamination "Uncontaminated" at each point except for point P7 which gives us an "Acceptable" level according to the PRATI indices, while for the year 2015 points P1 and P2 indicate a level of contamination "Moderately contaminated", point 3 an "Acceptable" level, after points P4 to P9 they present a level of "Not contaminated". Finally, the Grey Clustering analysis method will determine the water quality in the 9 monitoring points of the upper-middle basin of the Cañete River in the years 2014 and 2015. Allowing to observe the reduction of water quality in points P1 and P2 for the period of the years 2014 and 2015 respectively, being crucial to achieve water resource management among local governments that can insert awareness and sustainable development policies.