Estimation of Effect of Global Warming on Snowmelt Runoff in River of Snowy District

本文研究了全球变暖对多雪地区河流融雪径流影响的预测问题。我们选择的流域是宫城县的大仓坝流域和富山县的鸟坝流域。我们讨论了这两个大坝所显示的总径流量、融雪径流量、融雪季节和积雪消失日期的影响，并建立了两个情景：情景一考虑到降水量随温度上升而增加，情景二则没有考虑到这一点，结果摘要如下。(1)气温的升高降低了降水量占降雪量的百分比和雪的水当量。此外，融雪季节和积雪消失日期提前。因此，我们可以看到显着的早期融雪径流和减少量。(2)总径流和融雪径流深度在4、5月随气温升高而显著减小，3、2月随气温升高而略有增加。(3)总径流和融雪径流深度在情景II中的减少幅度大于情景I。(4)有没有一个显着的差异大仓坝流域和托里之间的总径流量和融雪径流量减少的百分比。另一方面，Tori大坝流域的总径流和融雪径流的深度明显减少：它比另一个减少了两到三倍。(5)因此，可以预测，全球变暖对雪区河流融雪径流的影响很大。

Our research deals with the forecast of the effect of global warming on snowmelt runoff in rivers of snowy district. The basins we select for our research are the Okura dam basin in Miyagi prefecture and Tori dam basin in Toyama prefecture.We have discussed the effect from total runoff, snowmelt runoff, snowmelt season, and snow cover disappearance date that these two dams show, and have also established two scenario : Scenario I takes into consideration an increase in precipitation with the rise of temperature and Scenario II does not.The summary of the results is shown below.(1) The rise of temperature reduced the percentage of precipitation to snowfall and the water equivalent of snow. Moreover, the snowmelt season and the snow cover disappearance date came earlier. Therefore, we can see remarkably early snowmelt runoff and its decrease in volume.(2) The depth of total runoff and snowmelt runoff decreased abundantly, with the rise of temperature in April and May, and, on the contrary, the depth increased a little in March and February.(3) The depth of total runoff and snowmelt runoff showed a greater decrease in Scenario II than in Scenario I.(4) There was not a significant difference between the Okura dam basin and the Tori in the percentage of decrease in total runoff and snowmelt runoff. On the other hand, the Tori dam basin showed a marked decrease in the depth of total runoff and snowmelt runoff : it had two to three times greater decrease than the other one.(5) Thus, it can be predicted that global warming has a large effect on snowmelt runoff in river of the snowy district.