, 18, 2012 6 Observation of bedforms in the downstream reach of Rumoi River by using a brief acoustic bathymetric system 1 2 3 Ryosuke AKAHORI, Yasuyuki HIRAI, Mineo KONDO 1 Ph.D. ( 062 8602 1 3 ) 2 ( 062 8602 1 3 ) 3 ( 003 0021 2 8-30) In this study, a brief bathymetric system which was designed for observing bedform evolution under flood conditions was proposed. The system consists of a RTK-GPS system and a commercially available fish finder, and it was installed on a radio-control air boat. The proposed system is able to be built at a very low price comparing to existing systems employing other professional acoustic bathymetric instruments or multi-beam bathymetric systems. Also, the system is expected to improve the safety of observation of bedforms under flood conditions by using a radio control platform. The proposed system was applied to observe the river bed topography in Rumoi River in Hokkaido, Japan. The result shows that the bed topography observed by the proposed system is qualitatively accurate, and the results of the wavenumber analysis of the observed bed elevation along the downstream direction shows good agreement with that by using the existing multi-beam survey data. Key Words : acoustic bathymetry, bedform, GPS, GIS 1. 2. 1) 2) 1 KP-2/0 300m 2 2011 4 2011 9 29 12 28 20mm/h 9-137 -
1 2 10 21 12 8 2 ADCP 0.75m/s 12 8 12 14 3. (1) 3 GPS ADCP Lowrance HDS-8HDS-8 50/200kHz Structure Scan GPS HDS-8 GPS IKKI-RS GPS GPS GPS RTK-GPS Nikon Trimble5700 RTK-GPS KP0.2 HDS-8 RTK-GPS HDS-8 RTK-GPS GPS 3) RC 4) Structure Scan - 455/800kHz 4 RC 5) 6) - 138 -
Lowrance HDS-8 a b RTK-GPS : Trimble 5700 A B C Structure Scan: LSS-1 : HRS / Dsub9 : RS232C A: SONER B: PWR/DATA C: ENET a: ENET1 b: SONER : HDS-8 GPS Receiver: IKKI-RS : Structure Scan RTK-GPS Ground-based reference station: Trimble 5700 300m 2.6m 100m 1.3m 3 50m 50m 5 RC 4 RC 6 (2) HDS-8 1 RC 1 2 5 1 1 300m 2 2 3 1 1 2 1 2 RTK- GPS 6 RTK-GPS GPS HDS-8 GPS GIS ESRI ArcGIS10-139 -
2011 12 8 HDS-8 12 14 HDS-8 30cm GPS KP0.2 30cm 4. (1) 12 8 2 1 7 HDS-8 GIS : Inverse Distance Weighted (IDW) : 0.2m 8 12 14 : 0.2m GIS x RMS =0.078 9 7 GIS 10 8 HDS-8 HDS-8: 1.9m 1.3m : 0.2m HDS-8 (2) 150m 12 8 HDS-8 2 0.2m 12 14 0.2m 1 1 11 80m 1 12 HDS-8 0.2m 1.9m 0.2m 11 HDS-8 1 2 12 5 HDS-8 11 12 MS Excel 11 13 12 14 13 HDS-8 1 2 HDS-8 14 2 1 HDS-8-140 -
図 7 HDS-8 による観測結果 2011 年 12 月 8 日第 2 セッ ション 測線が横断方向に密に分布 を基に IDW 法 を用いて補間することで得られた河床標高コンター 図 9 HDS-8 による観測結果 2011 年 12 月 8 日第 2 セッ ション 測線が横断方向に密に分布 を基に IDW 法を 用いて補間することで得られた標高値に対する陰影図 図 8 留萌開発建設部によるマルチビーム測量観測結果 2011 年 12 月 14 日 に対する河床標高コンター 図 10 留萌開発建設部によるマルチビーム測量観測結果 2011 年 12 月 14 日 の標高値に対する陰影図 - 141 -
z(m) -1-1.5-2 -2.5 1214 multibeam 1208 HDS-8 session1 1208 HDS-8 session2-3 0 20 40 60 80 100 120 140 160 distance(m) 11 150m z(m) -1-1.5-2 -2.5 1214 multibeam 1208 HDS-8 session1 1208 HDS-8 session2-3 0 5 10 15 20 25 30 35 40 45 50 distance(m) 12 80m amplitude 1 0.1 0.01 0.001 0.0001 multibeam HDS-8 session1 HDS-8 session2 0.00001 0.01 0.1 1 10 k: wavenumber 13 11 FFT amplitude 1 0.1 0.01 0.001 multibeam 0.0001 HDS-8 session1 HDS-8 session2 0.00001 0.01 0.1 1 10 k: wavenumber 14 12 FFT 5. GIS FFT 1) 33 pp. 439-444 1989 2) Akahori, R., Shimizu, Y.: Bedforms in the Kushiro River: wavenumber analysis of a high-resolution DEM obtained from a multi-beam survey, Proceedings of the 7th IAHR Symposium on River, Coastal and Estuarine Morphodynamics, pp.1987-460, 2011. 3) 4 60 pp. 4-261 2005 4) 3 pp. 43-50 1997 5) RC 1 pp. 215-220 1993 6), 50, pp. 95-96 1995. (2012. 4.5 ) - 142 -