Development of snowmelt runoff prediction system based on distributed snowmelt runoff model and airborne laser profiler snow depth observation

本研究的主要目的是利用新的机载激光扫描技术和我们的分布式融雪模型，开发一种预测流域内积雪数量和分布的新方法。作为一项新技术，GPS技术和激光扫描技术的进步使0.5m空间分辨率的测量成为现实。本研究尝试通过两次激光扫描获取积雪深度，一次是在无雪季节，一次是在有雪季节。通过机载激光扫描仪获得的数字积雪深度数据和数字高程模型覆盖了三个流域，即Echigo Hillside Park流域、Tone河流域内的八泽河流域和Shinano河流域内的Saguri河流域。结果表明，机载激光剖面仪是进行大范围积雪深度观测的有力工具。分析了积雪深度的分布特征及其与多种地形因子的关系为了比较激光观测得到的积雪深度，建立了一维积雪模型，该模型考虑了积雪本身重量对积雪的粘性压缩作用，并将其应用到分布式融雪径流模型中。在比较之前，首先研究了降水调节。事实证明，观测到的降雪量被严重低估了。为了维持年水量平衡，既要调节水位，又要调节海拔高度。然后将考虑这些调整的计算积雪深度与观测值进行比较。结果表明，计算得到的雪深分布与实测值基本吻合，但在谷线上被低估，在山脊线上被高估。在一个小山坡上使用便携式激光扫描仪进行的地面观测表明，几次降雪事件的降雪量没有明显差异。这意味着，盆地内的暴风雪和局部雪崩可能导致重新分配的重要性。较少

The main purpose of this study is to develop a new method to predict the amount and distribution of snow within a basin using new airborne laser scanning technology and our distributed snowmelt model.As a new technology, the progresses in GPS technology and laser scanning technology make the survey with spatial resolution of 0.5m practically available. In this study, it is tried to obtain snow depth by two laser scanning, one in snow free season and one in snow covered season. Digital data of snow depth as well as digital elevation model derived from airborne laser scanner over three river basins, namely the Echigo Hillside Park, the Yagisawa river basin within Tone river basin and the Saguri River basin within Shinano river basin. It is shown that the airborne laser profiler can be a powerful tool to make observation of the snow depth over a vast area. And also the characteristics of the distribution of the snow depth, and their relationship with many topographical factors are analyze … More d.In order to compare snow depth derived from about laser observation, an one-dimensional snowpack model talking into account of the viscous compression by the weight of the snowpack itself is developed and implemented into our distributed snowmelt runoff model. Prior to the comparison, precipitation adjustment is studied first. It turned out that the observed snowfall is significantly underestimated. In order to maintain the annual water balance, both gauge adjustment and altitudinal adjustment are necessary. The calculated snow depth considering these adjustments is then compared with the observed ones. It is shown that the calculated snow depth distribution can basically represent the observed one though it is underestimated along the valley lines and overestimated along the ridge lines.And also ground based observation by using a portable laser scanner over a small hillside slope showed no significant differences of the snowfall for several snowfall events. This implies the possible importance of re-distribution caused by blizzards and local avalanches within the basins. Less