| Summary: | Beside supplies natural resources potential, Merapi Mount also produces natural
disasters. One of them is eruption which produces primary and secondary risks.
Secondary risk or following risk as a mud flow happened after eruption when rain
fell on mount peak. Rain water in current river bring so much materials from
mount peak until sediment made. These sediment need to be measured to get the
mud flow volume information. The aims of this research were: (1) to take the
topographic information as Digital Elevation Model (DEM) especially Digital
Surface Model (DSM) from small format aerial photograph (SFAP) by using
photographic remote sensing application and GIS, (2) to take accuration rate
from DEM (DSM) SFAP, (3) to estimate mud flow sediment volume in a part of
Kali Gendol with before and after DEM by also using application small format
remote sensing and GIS.
Creating DEM through small format aerial photograph (SFAP) pass some digital
photogrammetric processes. Basically, digital photogrammetric process are
similar with conventional photogrammetric process except by considering also
lens distortion. Digital photogrammetric processes to make DEM and its
accuracy are flying lines reconstruction, GCP identification (it means don�t need
SFAP registration), camera calibration, inner orientation, tie points (same points
in some photos) identification, absolute orientation, creating DEM, and DEM
accuracy test. Sediment volume was made by processing LiDAR DEM first until
profiles compared to calculate volume through pre (from SFAP) and post
eruption.SFAP DEM has 5 m in resolution while it has 12,9 m in horizontal accuracy and
17,51 m in vertical accuracy. Through FUFK-DEM and LiDAR-DEM, we get 23
polygons calculated by cut and fill process to get sediment material volume. Total
adding sediment volume is 4.96 million m³, total removal sediment volume is 4,96
million m³, while final total volume after calculated is 0,31 million m³ along the
river.
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