土壌が凍結する積雪寒冷地流域における異常融雪出水メカニズムの解明

土壤冻结的雪寒地区盆地异常融雪排水机制的阐明

• 批准号: 06750537
• 负责人: 早川 博
• 金额: $ 0.58万
• 依托单位: Kitami Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Encouragement of Young Scientists (A)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 无数据
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06750537/
• 关键词: 凍土; 融雪流出; 川水温; 地温; 流出率; 不浸透域; 降雨流出; 融雪災害

北海道東部地域(北見・帯広)は,他の地域に比べ積雪が少なく寒さが厳しいために流域の土壌が凍結し,晩秋期あるいは融雪期に異常出水を引き起こす一因になっている.本研究はこの土壌の凍結と融雪出水の関係について,1.十勝川水系士幌川など4河川の水文・気象資料を用いた融雪出水に及ぼす凍結土壌の影響の定性的な評価,2.北見市郊外富里ダム流出試験地(流域面積8.4ha)の'93,'94年融雪期の観測結果を基にした土壌が凍結した流域の融雪出水機構の解明,を目的としている.以下に,その検討結果を要約する.1.十勝川水系諸河川の水文資料による解析流域の土壌凍結が流出に及ぼす影響は,定性的には流出率で評価できる.夏期の降雨-流出の流出率と比較すると,融雪期の同程度の降雨による流出率が約5割増となり,土壌凍結による流域の不浸透域の増加,すなわち一時的な流域の都市化現象と見なすことができる.2.富里ダム流出試験地の観測(1)厳冬期に流域の土壌は,日平均気温が0℃を下回る頃から凍結を始め,積雪深が落ち着く2月初旬まで凍結深は増大した.しかし,河道の近傍はほとんど凍結せず,最大でも10cmを越えることはない.土壌中を浸透してくる湧水からの熱の供給を受けるためと考えられる.(2)融雪期に入ると,融雪の進行とともに河川水の水温が次第に上昇を始めた.融雪水(水温0℃)が河道に直接流入する場合は,逆に水温が低下すると考えられるので,融雪水が地中に一旦潜って地熱で暖められてから河道に流出してくるメカニズムを想定した.また,土壌の凍結は,積雪が消失した6月中旬まで存在していた.(3)上述の流出機構をモデル化した融雪出水モデル(並列タンクモデル)を構築した.(4)'95年融雪期(現在)は河道近傍と斜面部の2カ所で地温を詳細に観測中であり,融雪水の水温をトレーサにして(2)で仮定した流出経路の特定を行う予定にしている.

Hokkaido eastern region (Kitami·Keihiro), other areas than the snow cover is less, cold, middle, river basin soil is frozen, late autumn, middle, snowmelt period abnormal water is caused by a cause. This study focuses on the relationship between soil freezing and snowmelt runoff. 1. A qualitative evaluation of the effects of snowmelt runoff and frozen soil runoff on the use of hydrological and meteorological data from the Tokachi River system; 2. A preliminary study of the snowmelt runoff mechanism in the '93 and'94 snowmelt period at the Fuli River Outflow Test Site (8.4 ha) in Kitami City. 1. Hydrological data of rivers in Tokachi River system, analysis of soil freezing outflow and its impact, qualitative evaluation of outflow rate. The runoff rate of rainfall in summer is about 5%, the runoff rate of rainfall in the same degree in snowmelt period is about 5%, the increase of impermeability area in the basin due to soil freezing, the urbanization phenomenon in the basin due to soil freezing is about 5%, and the runoff rate in the basin due to soil freezing is about 5%. The snow is deep and falling. It is freezing in early February. The river is frozen near the river, and the maximum is 10cm. The soil is saturated with water and the heat is supplied. (2)The snowmelt period begins, and the temperature of the river rises. Snowmelt water (water temperature 0℃) directly flows into the river channel, but when the water temperature is low, the snowmelt water flows out of the river channel once it is submerged in the ground. The earth freezes and snow disappears in mid-June. (3)The outflow mechanism is constructed in parallel with the snowmelt outflow mechanism. (4)During the snowmelt period of '95 (now), the ground temperature of the slope part near the river channel was measured in detail, and the temperature of the snowmelt water was measured in detail.