STUDY ON COVER DEGREE OF ALIEN AQUATIC WEEDS AND ENVIRONMENTAL CONDITIONS AFFECTING THE GROWTH OF Egeria densa IN DOWNSTREAM OF THE HAJI DAM, JAPAN

Abstract

The purpose of this study is to elucidate the environmental conditions causing the community of overgrowth of the alien aquatic weed Egeria densa and to construct an appropriate management method.

In this study, unmanned aerial vehicle (UAV) was used to survey to quantify the cover degree of E. densa. In addition, environmental conditions that affect the cover degree of E. densa were explored by using fluid models, geographic information system (GIS)．The results of this study showed that the cover degree of E. densa can be easily quantified by using images taken by UAV and GIS. When the flow velocity was <1.0m/sec and the water depth was <2.0m, a high coverage area was confirmed irrespective of hydraulic conditions.