Bayugan flood explorer
Explore rainfall, runoff and flood-prone areas.
Learning demo · not a flood forecast
Based on MCS-T1. We chose the external data, methods, study area, assumptions and defaults for this demo. Values from the paper are labeled separately. Results depend on these choices and have not been checked against local measurements or flood records. Do not use for flood warnings, land-use decisions or emergency planning.
Bayugan City study map
Runoff · mm · tap a cell
Cell 41,41 · 77.6 mm runoff.
Numbered points · risk reported in the paper
Poblacion, at the sample
Land height and waterways near the paper’s sample point.
8.7154 N, 125.7542 E
- Land height
- 34m
- Approx. slope
- 0.9°
- Mapped river
- ~100m away
SRTMShuttle Radar Topography Mission: a space-shuttle radar survey from February 2000 used to map land height. Here, 30 m is the approximate map pixel size, not the height accuracy. Buildings and trees can affect the readings. v3 · about 30 m pixels · measured February 2000. Distance is to the river’s mapped centre line in OpenStreetMap.
The sample is near a mapped river. The nearby land has a gentle slope. These features can help us explore why a place may be prone to flooding.
The 25 height samples range from 34 to 40 m. The paper’s sample is near the lower end of this small area. This alone does not show poor drainage or predict flooding.
Soil groups come from a broad map. We have not checked local soil, drain capacity or current river conditions. This demo does not assign a new flood-risk category.
How does it compare?
Other sources give different values at the same sample point.
| At this point | Paper | External reference |
|---|---|---|
| Flood category | High | Moderatevia MGB lookup |
| Land height | 23 m | 34 mvia SRTMShuttle Radar Topography Mission: a space-shuttle radar survey from February 2000 used to map land height. Here, 30 m is the approximate map pixel size, not the height accuracy. Buildings and trees can affect the readings. · 30 m pixels |
MGB checks 100 m east and south return High.
SRTM with 90 m pixels gives 36 m. Both SRTM maps use the same survey.
Checked 22 Oct 2026; data version unknown. This does not explain the differences or describe the whole barangay.
The MGB map is live; these point values were saved on the date above. Neither is a prediction made by this demo.
What drives this result?
64.0 ha around the sample. Land cover from ESA WorldCover 2021; reclassified HYSOGs250m supplies soil groups C and D.
| Cover | Share | CNCurve number: a value from a published table, chosen using land cover, soil group and surface assumptions. A higher CN usually gives more runoff for the same rain. | mm |
|---|---|---|---|
| Cropland | <0.1% | 89 | 70.2 |
| Tree cover | 29.9% | 73, 79 | 46.5 |
| Grassland | 2.7% | 84 | 58.8 |
| Built-up | 66.9% | 90, 92 | 77.0 |
| Bare / sparse | 0.5% | 94 | 82.9 |
Satellites identify built-up land, but not its exact share of hard surfaces. The surface choice is an assumption. Tree, grass and crop cover use matching table entries. Map resolutionThe ground size represented by a map pixel. Land cover is about 10 m; soil data is about 250 m. Drawing smaller cells does not add finer soil information.: 10 m land cover, 250 m soil data.
Method, inputs and limits
SCS/NRCS method, assuming average starting wetness. P is rainfall; CN comes from the selected table entry. S = 25400/CN − 254. The initial loss is 0.2S. Runoff is zero below this amount, otherwise (P − 0.2S)²/(P + 0.8S). All water amounts are in mm.
We calculate runoff for each cell, then add up the water amounts. Total rain: 64,000 m³; runoff: 43,117 m³; held back: 20,883 m³. Water held back is not all water that soaked into soil.
HYSOGs is a broad soil map, not a local soil test. Stanford’s version assigns soils that may need drainage to group D, assuming no added drainage. It does not measure local soil wetness or how quickly water soaks in.
These table values have not been adjusted using local measurements. We do not track water moving downhill, river inflow, drains or flood depth and spread. Land-height dots and the MGB map do not enter the equation. The paper names HEC-HMS/SWAT but does not specify this exact method.
Sources, calculations and snapshot downloads
Elevation and approximate gradient
NASA / USGS SRTM v3 via Open Topo Data. Acquired February 2000; elevations in metres relative to EGM96. The 30 m and 90 m figures describe approximate raster resolution.
Twenty-five bilinearly interpolated samples are spaced 100 m apart in a 400 m window. Gradient uses the east–west and north–south elevation differences over 200 m, combined as atan(√(dx² + dy²)). This is an approximate sampled surface gradient.
The data do not establish current drain capacity, a closed depression, height above the river, or flood depth. Both SRTM resolutions share an acquisition lineage.
Waterways and distance
© OpenStreetMap contributors, ODbL 1.0, via bounded Overpass queries. The map uses waterways around all seven study points, with a 0.03-degree margin around their extent. The Poblacion distance calculation keeps its original three-way, 1 km search snapshot. Neither includes unmapped drains or claims a complete drainage inventory.
Distance is the shortest point-to-segment distance in a local projection. It measures proximity to a mapped centreline, not a river bank, flow path, or flood boundary. The nearest mapped river is unnamed in the snapshot.
Paper and reference comparison
The MGB overlay streams the provider’s public cached flood-susceptibility map. Native classes and colors are preserved, with adjustable opacity. Cache levels 6–14 are advertised; zooming closer enlarges those tiles and does not add geographic detail. Service checked 22 Oct 2026; the source does not identify a hazard edition.
MCS-T1 Table 1, PDF page 37 / printed 29 supplies the anchor, 23 m and High classification. The dated MGB comparison comes from five small attribute lookups; it is not a live assessment. The paper’s MGB-attributed map may share source lineage.
Barangay-boundary containment, soil permeability, imperviousness and drainage conditions remain unverified. No model coefficients, susceptibility weights or rainfall-to-flood rule have been introduced.
Pinned snapshots · 2026-10-22
These locally bundled snapshots work without a terrain or waterway API at page load. Download the source-specific GeoJSON and the manifest containing request details, retrieval times and SHA-256 hashes.