Analysis of Factors Influencing the Trophic State of Drinking Water Reservoirs in Taiwan

Cheng-Wei Hung,Lin-Han Chiang Hsieh

doi:10.3390/w13223228

Abstract

Eutrophication is an environmental pollution problem that occurs in natural water bodies. Regression analyses with interaction terms are carried out to identify the factors influencing the Shimen, Mingde, and Fongshan Reservoirs in Taiwan. The results indicate that the main factor influencing these reservoirs is total phosphorus. In the Shimen and Mingde Reservoirs, the influence of total phosphorus, when interacting with other factors, on water quality trophic state is more serious than that of total phosphorus per se. This implies that the actual influence of total phosphorus on the eutrophic condition could be underestimated. Furthermore, there was no deterministic causality between climate and water quality variables. In addition, time lagged effects, or the influence of their interaction with other variables, were considered separately in this study to further determine the actual relationships between water trophic state and influencing factors. The influencing patterns for three reservoirs are different, because the type, size, and background environment of each reservoir are different. This is as expected, since it is difficult to predict eutrophication in reservoirs with a universal index or equation. However, the multiple linear regression model used in this study could be a suitable quick-to-use, case-by-case model option for this problem.

Highlights

Constructing reservoirs is one of the most effective ways of storing water in Taiwan
This study lists the descriptive statistics of the Shimen, Mingde, and Fongshan Reservoirs (Table 2)
The concentration of chlorophyll a (Chl-a) is calculated as 3926.5 mg/L. This means that the unit value of Chl-a increases when other variables are fixed and total phosphorus (TP) and ammonia nitrogen (AN) are both increased by 1 unit (Equation (14)). These results show that when evaluating the water quality trophic state, time-lag and the additive relationship of interactions between factors should be taken into account to evaluate more accurately the potential for water eutrophication

Summary

Introduction

Constructing reservoirs is one of the most effective ways of storing water in Taiwan. Eutrophication, the most challenging water pollution problem in water bodies, will eventually become an issue in many reservoirs [1]. Eutrophication negatively affects the water quality, safety, ecological integrity, and sustainability of global water resources [2,3,4]. Population density, urbanization, and agricultural activities are factors that influence the water quality of freshwater systems [6,7,8,9,10]. Since the 1940s, a substantial population increase, land-use intensification, and the use of agricultural fertilizers from developed countries [11], as well as the use of detergents containing phosphate compounds since the 1950s, have accelerated the eutrophication of waterbodies [12]

Objectives

Methods

Conclusion