ドローン熱画像撮影による砂州における伏流水湧出場の検出

Abstract

To detect hyporheic outflows and understand topographic characteristics of the outflows around gravel bars, thermographic images were taken by drone at downstream reaches of Saigo Dam in Mimi River and a reach in the Kizu River. Spatial heterogeneity in water surface temperature was evident between main-flow and secondary flow (fed by hyporheic outflow), and middle and periphery of each flow. Hyporheic outflow (upwelling flow) can be determined according to the distribution (planar shape) of distinct temperature zones. Many of the hyporheic outflow showed a tapered shape from edge to middle of flow, while stagnant water affected by sunlight and air temperature showed a band along edge. Temperature in the secondary flow fed only by hyporheic outflow changed longitudinally by inlet of hyporheic outflows with different temperatures.