Author(s): Martiwi Diah Setiawati; Pu Jian; Chethika Gunasiri Wadumestrige Dona; Kensuke Fukushi

Linked Author(s):

Keywords: WQI; NSFWQI; Sumida River; Trend detection; Tokyo

Abstract: The Water Quality Index (WQI) is essential for tracking trends, performing empirical studies, and generating sound judgments. It provides a complete picture of the temporal variance in water quality in an area of watershed. Tokyo's water infrastructure and regulation improvements since 1959 greatly enhance water quality within the study area by reducing contamination levels and ensuring safe drinking water for residents. The present research tackles the problem of interpreting temporally monitoring data to assess water quality in riverine ecosystems over time. Our goal was to explore changes in water quality by creating an aggregate water quality index using data from numerous public monitoring system conducted over 50 years within the Sumida River, Tokyo. In total eight water quality parameter data were acquired from the measurement records available through the Tokyo Metropolitan Government webpage. Twenty-seven sampling locations generated 759 monthly average water quality data points spread across four to eight parameters, which were utilized to calculate the index. The aggregate WQI water quality index was derived using a modified National Sanitation Foundation Model of Water Quality Index (NSFWQI) method. The analysis of the WQI over a decade revealed shifts in water quality regardless of station site in the watershed or extent of human involvement. WQI ratings indicate an increase in water quality over the last 50 years. This study shows that integrating data from several observation parameters into a WQI can be utilized to examine long-term water quality changes and patterns in Tokyo's Sumida River. These results significantly affect water management and decision-making in Tokyo in particular in high-level strategic planning, laying the groundwork for implementing appropriate measures to maintain water quality and guarantee water security.

DOI: https://doi.org/10.64697/978-90-835589-7-4_41WC-P1612-cd

Year: 2025