Water temperature simulation of rivers in Indonesia

Water temperature has a major influence on biological activity and growth which are measured by the amount of chlorophyll and bacteria present. It also affects water chemistry and water quantity measurements, and governs the kinds of organisms living in water bodies such as rivers and lakes. Higher temperature will increase the rate of chemical reactions. The concentration of dissolved oxygen in warm water is lesser compared to cold water thus affecting the survival of different species of aquatic life. Global News reported that hundreds of thousands of fish have died in Darling River, Australia. On 29 January 2019 New South Wales Department of Primary Industries mentioned that the death is caused by the decrease of dissolved oxygen concentration due to air temperature increase. The aim of this study is to find the water temperature of many rivers in Indonesia, to find the normal temperature for fish life, and to analyze the impact of climate change to the water temperature. Results showed that measured water temperature in 13 rivers varies from 23-32.4°C (upstream) and 25.5-34°C (downstream) that is caused by variation of air temperature, humidity, solar radiation, and wind speed. The normal water temperature for fish species in the downstream region at Opak River such as Barbonymus sp., Puntius binotatus, and Rasbora argyrotaenia varies from 28.6°C to 29.6°C, while water temperature in this study shows increment in the range of 28.92°C to 30°C in the future. However, the location of this study is around 65 km of the upstream side of the location of the previous study. Hence, further study is required to understand the acceptable increment of water temperature for the sustainability of fish life by making direct comparison of the object study. © 2020 22nd Congress of the International Association for Hydro-Environment Engineering and Research-Asia Pacific Division, IAHR-APD 2020: "Creating Resilience to Water-Related Challenges". All rights reserved.