Bathymetry and photogrammetry measurements of Opak river segment of Sumberagung village in Yogyakarta to support tourist village planning

Opak river is one of the rivers that flow through Yogyakarta Province, especially Sleman and Bantul Districts. One of the villages crossed by this river in Bantul district is Sumberagung village. The village government plans to utilize the Opak river in their administrative area as a tourist location to grow the town as a tourist village. One of the initial efforts in planning is to collect as much data about the river and its surroundings, that is, river depth and the planimetric map around the area. Therefore, a bathymetric survey was done to obtain depth data of the Opak River, while photogrammetry technology was conducted to produce a digital image map of the river. The river depth data was acquired using Unmanned Surface Vehicle (USV) and geodetic GPS instrument as its positioning, while the photogrammetric measurement was conducted using UAV (Unmanned Aerial Vehicle). As a result, the bathymetric map shows the river depth range from 2 to 6 meters from the water level. The standard deviation value is ± 0.51 meters, and TVU (Total Vertical Uncertainty) falls into the 1a or 1b order depth accuracy category based on the IHO 5th Edition, Special Publication No.44 2008. The photogrammetric map shows the RMSEr value is 7.5 cm and the CE90 (Circular Error) is 0.113, which suits Class 1 for 1:1000 base map based on the Regulation of Geospatial Information Agency of Indonesia regarding base map accuracy. In addition, the LE90 (Linear Error) passes Class 3 for 1:5000 base map.