SOURCE MAPS AND COORDINATES
Reading the coastal boundaries
A legal designation, its coordinate schedule and a digitised map can describe different versions of the same place. These comparisons explain where the available sources agree and where they leave a boundary uncertain.
Read the completed fisheries-table comparison and newly recovered park geometry
What the comparisons cover
Original instruments support the historical designations of the 55 fisheries zones and four protected-area outlines in the atlas. None of those 59 outlines is presented as a fully amended, certified current boundary. The separate Koh Tang outline is a proposal.
This comparison transcribed 54 coordinate pairs from nine fisheries schedules and all 121 printed coordinate rows from the 2023 Botum Sakor and Peam Krasop annexes. Joining printed points in table order is a reproducible comparison; it does not resolve coastlines, omitted vertices or the legal meaning of a map legend.
Botum Sakor: a much closer 2023 outline
A newer ODC layer references Sub-decree 175 of 17 July 2023. Its area overlaps the literal 78-point annex polygon by 99.96% on an intersection-over-union comparison. Seventy-seven listed points lie within 1 m of the ODC line; point 37 lies about 176 m away. The two polygons measure approximately 144,307 and 144,243 ha, respectively, compared with the decree’s stated 143,895 ha.
This supplies a strong comparison layer. It does not establish that every subsequent amendment is included. The displayed atlas outline remains the older 2014 version.
Original 78-point schedule, page 5 · ODC protected areas: all_npa_after_reclass resource
Peam Krasop: two versions still differ
The newer ODC layer references Sub-decree 164 of 17 July 2023. Thirty of the 43 printed coordinate rows agree with its line within 1 m. Point 22 is almost 2 km from that line. The original schedule repeats point number 23; both rows were preserved in this comparison.
The ODC polygon measures about 17,052 ha, while straight lines through all printed rows enclose about 16,779 ha; the decree states 16,982 ha. Subsequent parcel changes also need to be included in a current consolidated map.
Original coordinate schedule, page 5 · Later 2023 land instrument · ODC comparison layer
Koh Rong: the internal island boundaries are recoverable
The clearer Ministry of Environment original contains 180 coordinate rows numbered up to 181, grouped under seven island headings; point number 177 is absent, alongside the map’s land categories. This is substantially more detail than the outer outline displayed in the atlas. The coordinates have now been reconstructed as ten included park-land parcels. A complete net park outline still needs the shoreline and development exclusions, together with later parcel changes including Sub-decree 48 of 2023.
Read the detailed original map and coordinates, page 4 · Ministry publication · 2023 land reclassification
Ream: the newer catalogue still carries an older outline
The alternative ODC file retains the older Ream geometry. It does not supply the enlarged 2022 marine outline or a consolidation of the later land instruments. A newer download date therefore does not establish a newer boundary.
Ream’s 2022 designation · Later instruments and displayed source version
Fisheries-zone comparisons
The Kep references have been corrected: the 45-ha conservation zone is row 2; the 49-ha zone is row 1 of Prakas 193. The original Khmer coordinate tables take precedence over English copies containing transcription errors.
Preaek Svay · 3-ha conservation zone
All four mapped corner coordinates match the original schedule. Those coordinates enclose about 2.21 ha, although the schedule states 3 ha. The disagreement is present in the source itself.
Koh Rong Sanloem · 37-ha conservation zone
The six scheduled coordinates form a self-intersecting ring when joined in table order. The displayed outline is ODC’s historical digitisation; the intended traversal of the scheduled points remains unclear.
Preaek Svay · 30-ha multiple-use zone
Joining the eight scheduled coordinates with straight lines gives about 27.30 ha; the source states 30 ha and the atlas outline measures about 39.56 ha. The schedule and the digitised shoreline have not been reconciled.
Preaek Svay · 2-ha multiple-use zone
The schedule supplies only two coordinates for this 2-ha zone. Both occur on the displayed outline, but two points cannot define its complete boundary.
Koh Touch · 7-ha recreation zone
The nine scheduled coordinates lie within 3 m of the displayed boundary, but connecting them in table order creates a self-intersection. The source states 7 ha; the atlas outline measures about 8.03 ha. Point ordering and shoreline treatment remain unresolved.
Preaek Svay · 8-ha recreation zone
The coordinate schedule places this 8-ha recreation zone about 4 km from its position on the original map. The atlas broadly follows the map. The conflict between the two parts of the source prevents a reliable replacement outline.
Kep · 45-ha conservation zone
The four scheduled corners define an outer rectangle of about 85.23 ha. The atlas excludes an island and measures about 78.12 ha, still above the 45 ha stated in the schedule. The island exclusion alone does not explain the difference.
Kep · 49-ha conservation zone
The six scheduled coordinates enclose about 56.50 ha when joined by straight lines. The atlas follows a detailed southern coastal inset and measures about 49.35 ha, close to the stated 49 ha. The original map depicts an inset, but the sparse coordinate schedule does not verify its detailed shape.
Preaek Svay community fishery · 7,011 ha
The seven scheduled points form a self-intersecting ring in table order. The source GIS polygon is also invalid and remains outside the map display. Reordering points without the intended boundary connections would create an unsupported interpretation.
Where a definitive answer should come from
- Fisheries Administration / MAFF: signed schedules and current zoning instruments for the Koh Rong and Kep fisheries areas, including corrections to coordinate tables.
- Ministry of Environment, Department of GIS and Marine and Coastal Zone Conservation Department: current protected-area geometry, internal land categories, parcel exclusions and amendments.
- Open Development Cambodia’s GIS team: the digitisation method, shoreline sources and processing history behind each published shape. This establishes mapping provenance; legal confirmation rests with the issuing authorities.
- Cambodia’s SCS SAP team: the dated GIS layers described as archived in the 2025 national transboundary diagnostic assessment annex.
A usable boundary package needs the spatial file, coordinate reference system, effective date, signed source map, amendment list and explanation of exclusions. A shapefile alone cannot settle conflicting instruments.
SCS SAP ministry roles · National assessment GIS archive description, PDF page 46 · ODC contact