Evapotranspiration Estimate in Microscale at Onigi Rice Terraces Using UAV

Life and livelihood of Onigi rice terraces declined by cultivation abandonment and crop conversion in Hasami town. As the rice terraces were developed on the slopes, the area in rice terraces is small and its productivity is lower than flatland paddy fields. Therefore, understanding the conditions of vegetation, the water balance and land uses are important for Onigi rice terraces. Land cover maps are required in many places including rice terraces since 66% of Japan is covered with forests. On the other hand, in recent years, the spread of a UAV progressed rapidly. A UAV is used in many fields. Images of a UAV are higher resolution than aerial photographs of satellites, and the photographs could be repeated easily. Land cover classification of vegetation and water areas can be done from RGB and infrared images. A UAV has automatic navigation functions, and the air dose rate was measured even in places where human intrusion was difficult. In this study, annual analysis of land covers was carried out with a UAV automatic navigation for Onigi rice terraces in Hasami Town. First, a UAV route map of Onigi rice terraces was made with automatic navigation software. Next, in April, June and July of 2017, a UAV flew over the rice terraces. 5-band images of visible range and near infrared were acquired with IR filters. 3D models and orthographic images were created from these 5-band aerial images. Spatial The distributions of NDVI and evapotranspiration were calculated with GIS software from the orthographic images. Their seasonal changes were examined from calculated NDVI and evapotranspiration spatial distributions