Abstract

Sediment oxygen demand (SOD) is believed to be an important process affecting dissolved oxygen (DO) concentrations and has become an integral part of modeling dissolved oxygen (DO) in surface water bodies. Because no SOD data are measured at specific study sites, it is common for researchers to take SOD values from the literature for use in DO modeling. This paper focuses on an approach for measuring sediment oxygen demand in the laboratory using undisturbed sediment core samples in the Yuan-Yang Lake (YYL) of north-central Taiwan. The measured SOD values among six sampling stations were within the range of 0.06 to 4.50 g/m²/day at a temperature of 20°C. The ordinary kriging method was then applied to map the spatial distribution of the monthly average SOD values, which were incorporated into a three-dimensional water quality model for simulating the dissolved oxygen distribution of the lake. The simulation results accurately reflect the field-measured DO concentrations. Model sensitivity analyses were also conducted with increasing and decreasing 30% SOD values based on the monthly average SOD in the spatial distribution. The simulated results reveal that SOD had a significant impact on the DO concentrations in the lake. The present work, with its field measurements and numerical modeling, will provide assistance in lake water quality management.

Key words: Sediment oxygen demand, dissolved oxygen, measurement, water quality model, kriging, Yuan-Yang Lake.