同位体トレーサーと数値モデルを併用した流域滞留時間推定手法の開発とその検証

提出了一种方法来估计时变MTT和TTD使用五层坦克模型与同位素示踪剂，并在富士河流域，日本中部进行了测试。通过对比水平衡和同位素平衡的观测结果和模拟结果，对用于渡越时间估算的水箱模型进行了标定和验证。控制MTT时间变异性的主要因素是沉淀量。沉淀的发生改变了TTD，增加了年轻的成分，并缩短了MTT。长期MTT值与平均坡度，覆盖中生代砂岩/页岩，森林覆盖，蒸发，拦截和存储每个集水区。所有这些都与地下水储量有关，山区地下水储量较小，平原地区地下水储量较大。

An approach to estimate the time-variant MTT and TTD using a five-layer tank model with isotopic tracers was proposed and tested within Fuji River catchment, central Japan. The tank model used for the transit time estimation was calibrated and then validated by comparing observed and simulated results of not only water balance but also isotope balance. Predominant factor controlling temporal variability of MTT is precipitation amount. Occurrence of precipitation alters TTD, with increases in younger components, and shortens the MTT. Long-term MTT values correlated with mean slope, coverage of Mesozoic sand stone/shale, coverage of forest, evaporation, interception and storage for each catchment. All of these are related to the amount of groundwater storage, which is smaller in mountainous areas and greater in plain areas.