Effects of Climate Change on Water Quality and Countermeasures in Lake Kojima

Abstract

To understand the effects of climate change on lake water quality, we quantitatively determined long-term changes in water quality by simulating future water quality predictions for Lake Kojima in Okayama Prefecture, Japan. For future meteorological data, we used data from two scenarios, Shared Socioeconomic Pathways (SSP) 1-2.6, which has a small degree of climate change, and SSP5-8.5, which has a large degree of climate change. As a result of simulating the current 5 years and the next 30 years until 2050, there is a period in which the concentration of COD increases significantly, and the magnitude of the concentration change is equivalent to 5% of the average of the current period. This degree is about the same as the improvement target in the lake water quality conservation plan, and it is considered that the effects of the water quality conservation measures by the local government will be offset. In addition, regarding chlorophyll a, which represents the amount of phytoplankton, the number of days when the concentration of Chl.a exceeds 70 μg L^–1 will be larger than that in the current situation.