Prediction of water resources as snow storage under climate change in the Tedori River basin of Japan

We investigate the effect of climate change on water resources as snow storage (WRSS) using a regional climate model with a 20-km mesh (MRI-RCM20), in the Tedori River basin of Japan. We make four main predictions. First, annual average temperature in Kanazawa is predicted to increase by 2.7 °C by 2081–2100, compared to the period 1981–2000. The smallest predicted temperature difference is 1.1 °C in August, and the largest is 3.4 °C in April and December. The annual average temperature is predicted to change from 14.5 to 17.2 °C. Second, annual average precipitation is predicted to increase by 3.8 %, and precipitation during the snowfall season (December–February) is predicted to decrease by 13.2 %, as a result of increasing temperatures. Third, average WRSS for the period 2001–2100 is predicted by degree-day and tank model analyses. Both the analyses show very similar results. The degree-day analysis shows 200 mm of average WRSS in 2100, and 477 mm in 2050. These values constitute 26 and 63 % of the WRSS value in 2000 (754 mm). The tank model analysis shows WRSS of 260 mm in 2100 and 523 mm in 2050, which are 33 and 67 % of the WRSS (785 mm) in 2000, respectively. Fourth, to examine the effect on irrigation water especially on the paddy paddling period, discharge is predicted and considered under the predicted average WRSS is 520 mm in 2050, 258 mm in 2100, and reaches a minimum of 41 mm in 2100.