Digital Terrain Model (DTM) for the Lower Mekong Basin | |
Data format: SDE Raster Dataset Coordinate system: Indian_1954_UTM_Zone_48N Location: Server=mekserv3; Service=5153; Database=mrc; User=sde; Version=sde.DEFAULT |
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Abstract:
Digital Terrain Model (DTM) for the Lower Mekong Basin. It is an updated version that derived from updating B-DTM50 with more detailed DEMs (MUN_DEM20, and DEM100) over the area of Mun River Basin and Mekong Delta (area from Phnom Penh to Center of MK delta). |
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No.184, Unit 18, Fa Ngoum Rd., Ban Sithane Neua
No.184, Unit 18, Fa Ngoum Rd., Ban Sithane Neua
No.184, Unit 18, Fa Ngoum Rd., Ban Sithane Neua
No.184, Unit 18, Fa Ngoum Rd., Ban Sithane Neua
Digital Terrain Model (DTM) for the Lower Mekong Basin. It is an updated version that derived from updating B-DTM50 with more detailed DEMs (MUN_DEM20, and DEM100) over the area of Mun River Basin and Mekong Delta (area from Phnom Penh to Center of MK delta).
No.184, Unit 18, Fa Ngoum Rd., Ban Sithane Neua
AREA : IN THE LOWER MEKONG BASIN INCLUDING: Cambodia (whole country, incl non-LMB part), Laos (whole country, incl non-LMB part), Thailand (LMB part), Vietnam (LMB part); SOURCE MAP : 1) Original DTM50 (B-DTM50) - American topo maps 1:50'000 and partiallly on Russian topo maps 1:100'000 2) Mun River Basin (MUN_DEM20) - 1:10,000 Topographic Map, 1982 3) Mekong floodplain from Phnom Penh to Center of Vietnamese Mekong Delta (DEM100) - unknown 4) DEM of Tonle Sap Region - unknown; SOURCE DATA SET : 1) B-DTM50: Watershed Classification Projects, WSCP 2) MUN_DEM20: mun_ct.shp (1m contours of Toong Kura Rong Hai, Surin Province ,Thailand) and mun_sh.shp (spot height of Toong Kura Rong Hai, Surin Province, Thailand) 3) DEM100: CT_BON - elevation contours with varying vertical intervals above source data sets derived from: hypsometric contour map scale: 1:100,000 date: 1960s compiling agency: SOGREAH - Societe Grenobloise d'Etudes et d'Applications Hydrauliques (for MRCS Predecessor) above source data sets generated by: MRCS Technical Support Division 4) DEM50: CONTOUR - elevation contours with 1 meter vertical intervals STREAM - streams [hydrographic features composed of single lines] all above source data sets derived from: topographic map scale: 1:100,000 (re-compiled from original scale of 1:40,000) date: 1964 compiling agency: Certeza Surveying Co. Inc. (for MRCS Predecessor) above source data sets generated by: MRCS Technical Support Division; SOURCE AGENCY : 1) Centre for Development and Environment, University of Bern and MRCS 2) Royal Irrigation Department, Topographic Survey Unit, Thailand 3) CT_BON dataset was generated by MRC Technical Support Division (TSD) 4) DEM50 - data generated by MRCS Technical Support Division; GENERATION : 1) B-DTM50: Dataset was created by Watershed Classification Projects, WSCP. For details see WSCP Tecnical Reports (available from the MRCS TSD) 2) MUN_DEM20: Generated using the TOPOGRID program in ArcINFO 7.2.1 Program parameters; topogrid mun_dtm3 20 datatype contour enforce ON outputs sinks3 drains3 report_mun_dtm3.txt boundary hull3 contour mun_ctall3 elev point mun_shall2 elev lake mun_lake tolerances 0.5 1 0 end 3) DEM100: Data generated from above source data with Arc/Info TOPOGRID setting as follows: contour CT_BON elev datatype contour enforce off iterations 50 tolerances 0.1 0.5 0 xyzlimits 550000 179000 450000 0 350 resoluting grid data projected as follows: from system: Projection: Bonne Indochina (Paris Meridian) Initial Point: east: 103.5 deg, north: 17.1 deg, X: 700000, Y: 1000000 Horizontal Datum: Hanoi Belvedere (dx: -471 dy: -321 dz: 165, meridian shift: -2.33722916666667 deg) Spheroid: Clarke 1880 IGN (sem maj axis: 6378249.2 inv flat: 293.4660213) to system: see below under UNITS 4) DEM50: data generated from above source data with ARC/INFO TOPOGRID settings as follows: contour CONTOUR elev datatype contour enforce on iterations 50 stream STREAM tolerances 0.5 0.5 0 xyzlimits 262025 1348025 497975 1516975 0 20 5) above four datasets were merged into update basin DTM with cell resolution 50m using the following parameters: a) merging DEMS: DEM-MRG1 = MERGE (resample(Mun_20, 50, bilinear), resample(Dem100, 50, bilinear), Dem50) b) merging DEMs: B-DTM50UPD = MERGE (INT(DEM-MRG1 + 0.5), B-DTM50) Note: the original DEMs, except B-DTM50, are floating format. They were converted to inter format to merge with B-DTM50. With adding 0.5 to all cells, the dicimal values were rounded instead of truncated; STATUS : Last updated: Compiled by Penroong B. (14 May 2003) Completion status: 100 %; COMMENTS : 1) Negative Values in the DTM do not only occure along the seaside in Cambodia, but in some areas not the whole map sheet had to be procesed (as some areas were not of LMB). And there minus values may occure. --> consult coverage b-dtmmin 2) DEM50 (Tonle Sap Region): calculated horizontal accuracy of source data: 65 meters estimated vertical accuracy of source data: 1 meter the elvation range modeled is constricted to 1 to 20 meters asl all areas below or above this level have been set to NODATA the lowest elevation of the Tonle Sap Lake has been assumed to be 1 meter asl; RASTER : Resolution: 50 meter cell size; VALUE ATTRIBUTE TABLE (vat) for grids : Value = Elevation in meters above sea level (integer format).
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