Public water reading
Upper Seletar Reservoir
Singapore, Singapore · 1.4037, 103.7913 · ninety-three hectares of water
Good water, pressed at the margin.
Upper Seletar Reservoir is sound water with clear regenerative upside at its edge, scoring 63 out of 100. The surface reads as bloom-prone: algal pigment is high. Something discharges to, or works beside, this water. 11 of 12 sources answered; the silent ones lowered confidence, not the score.
Five readings
11 of 12 sources answered · 100% of pillar weight read · silent: the population grid
The water
What this body is, how it reads from orbit, whether it stays, and the basin it sits in.
The body
3 mapped inflows · River Quest
Beside: False Gavial
Clarity · from orbit
One Sentinel-2 pass, 2026-09-03, 22% cloud in the scene. Indices, not concentrations: a bottle to a lab decides; this says where to dip it.
Permanence · 1984–2021
The basin
The edge
What the shore is made of, what lives here, what presses on the water, and what the climate does to it.
The shore · 300 m ring
- Tree cover 97%
- Built-up 3%
Life
Most recorded: Pycnonotus plumosus · Spilopelia chinensis · Acridotheres javanicus · Copsychus saularis
Pressure
industrial land on the shore
Climate · to 2050
Expect is the honest verb: the middle of a range of futures, one scenario, not a certainty. Warmer air means warmer, more stratified water and more evaporation.
Hazard screen
- River flood low
- Urban flood high
- Coastal flood no data
- Earthquake low
- Landslide low
- Tsunami low
- Volcano no data
- Cyclone no data
- Water scarcity no data
- Extreme heat medium
- Wildfire medium
ThinkHazard, at the scale of Central Singapore, Singapore — a planning prompt, not a site assessment.
The reading
What the figures mean together, what to do first, how to check it, and what only the water itself can answer.
Findings
- Risk
The surface reads as bloom-prone: algal pigment is high.
High chlorophyll from orbit is the signature of nutrient loading — a shore or an inflow feeding the water more than it can carry.
Chlorophyll index 0.1 (red-edge against red) on the same pass. An index, not a concentration: a bottle to a lab confirms it. · medium confidence
- Risk
Something discharges to, or works beside, this water.
A mapped outfall or industrial edge is a point source to ask about before any other question; the map shows presence, never what leaves the pipe.
1 mapped outfall or treatment plant and industrial land use on the shore within about 3 km, from the public map. · medium confidence
- Risk
The division screens high for urban flood.
A screening class at administrative scale — a prompt to read the shoreline and the record, not a site assessment.
ThinkHazard (GFDRR) for Central Singapore, Singapore. · low confidence
- Permanence
The archive shows how much of this boundary holds water, and how often.
Permanence is the first property of a water asset: what stays can be planned around; what comes and goes must be designed for.
20% permanent, 8% seasonal; where water was seen it was present 71% of the time (JRC Global Surface Water, Landsat 1984–2021). · high confidence
- Clarity
48% of the boundary read as open water on the latest clear pass.
The share of the drawn boundary the scene classifies as water says whether the reading is about the water or about its edge.
Sentinel-2 scene classification, 2026-09-03; turbidity clear, chlorophyll high. · medium confidence
- Climate
The surface of the water read 34.6 °C on the latest clear thermal pass.
Warm water holds less oxygen and feeds algae; above thirty degrees the fish and the bloom both notice.
Landsat Collection 2 surface temperature, 2026-09-03; a skin reading from orbit, warmer than the water a metre down. · medium confidence
- The shore
The shore is mostly natural cover.
The edge decides what reaches the water: a wooded or wetland shore filters runoff; a built or cropped shore delivers it.
300 m ring: Tree cover 97% · Built-up 3% (ESA WorldCover 2021, land pixels only). · high confidence
- Life
This water is well recorded by naturalists.
Occurrence counts measure where people have looked as much as what lives here; a thin record is an unknown, not an absence.
5,785 GBIF occurrence records inside the boundary; most recorded: Pycnonotus plumosus, Spilopelia chinensis, Acridotheres javanicus. · medium confidence
- Climate
Expect the seasons here about 1.3 °C warmer by 2050, with 25% less rain.
Warmer air means warmer, more stratified water and more evaporation; less rain means less inflow. Expect is the honest verb: this is the middle of a range.
CMIP6 (MPI-ESM1-2-XR, SSP5-8.5) 2045–2049 against the 2004–2024 record; longest dry spell expected 13 days. · medium confidence
- Pressure
This water is regulated by works in its channel.
Roads, towns, harbours and works are the pressure the water lives under; each is also a party to any plan for it.
A main road 1 km away; 5 dams or weirs on the water; 11 harbour, marina or pier features (OpenStreetMap). · medium confidence
- The body
Upper Seletar Reservoir reads as fresh reservoir.
Kind and salinity set the whole frame: a reservoir has an operator, an estuary has a tide, a lake has a catchment that is its fate.
30% open water, 3 mapped inflows (River Quest) (OpenStreetMap; ESA WorldCover 2021). · medium confidence
- The basin
The water surface sits at about 38 m above sea level.
A lake's altitude sets its temperature regime and tells you how far its water has to fall to the next basin.
AWS Terrarium z12 (ETOPO1 below sea level), 43 samples, 24 m of relief across them. Bathymetry is ETOPO1-grade (~1.8 km): a screen, never a chart. · medium confidence
What it means together
About 2,855 mm of rain falls on this water in a year, and the water stays: most of the boundary has held water through four decades of passes.
The shore is 97% natural cover, so what reaches the water is filtered first — and the water reads clear, which says the edge is doing its job.
This is regulated, used water. Any plan for it runs through the operator of the works in the channel, whoever holds the discharge permit, the harbour or marina: they set conditions the reading cannot see.
Upper Seletar Reservoir is sound water with clear regenerative upside at its edge; the weakest reading is pressure from the edge, and that is where the leverage is.
What to do first
- 1
Walk the inflows after the next rain and find where the load comes from.
From orbit the water reads clear in turbidity and high in algal pigment; the source is upstream, on land, and usually visible on foot.
On the water · Turbidity tube or Secchi disk at three points (inflow, middle, outlet); one chlorophyll-a and one nutrient (N, P) bottle to a lab from the middle. · first wet-season month
- 2
Ask for the discharge permit and the last monitoring report for every outfall on the map.
A mapped outfall is the one point source you can name; its permit says what is allowed to leave it, and the report says what did.
On the water · Sample E. coli and nutrients 100 m upstream and 100 m downstream of the outfall on the same morning. · before any offer
- 3
Read the operating regime of the works in the channel before reading anything else.
A dam or weir decides the level, the flow and the flush; the water's behaviour is a management decision, not a season.
On the water · Ask the operator for the rule curve or release schedule; find the nearest gauge and read a year of it. · first month
- 4
Take a baseline in four bottles before anything changes.
Every figure here is read from orbit or the public record; a baseline on the water is what makes the next reading a trend.
On the water · Temperature, dissolved oxygen, pH and conductivity at the surface and one metre down; Secchi depth; one bottle for E. coli. Same three points every time. · first visit
Open questions
- —Who holds rights to this water — to take from it, to discharge to it, to fish it — and who enforces them?
- —Who operates the works in the channel, under what rule, and what happens to the level in a dry year?
- —What is in the sediment on the bottom — the memory of everything the catchment has sent down?
- —What is the land above doing this year that the satellite has not caught up with yet?
Sources & method
Upper Seletar Reservoir was read from public satellite and open-data records; the sources are named below with their licence and grain. The weights that turn them into the Water Score are not published — the data is public, the lens is the product.
- Place — OpenStreetMap / Nominatim · Nominatim reverse geocodesettlement · live · ODbL 1.0
- Climate — Open-Meteo · Archive 2004–2024 + MPI-ESM1-2-XR to 2050~9 km · 2004–2024 / 2045–2049 · CC-BY 4.0 (data); non-commercial API tier
- Surface water — JRC Global Surface Water · Global Surface Water v1.4 — occurrence & seasonality30 m · 1984–2021 · Copernicus / open (attribution)
- Biodiversity — GBIF · Occurrence records (count + top species)point · live · Mixed CC0 / CC-BY / CC-BY-NC (per dataset)
- Water bodies, works & shore uses — OpenStreetMap · Overpass (natural=water, waterways, coastline, dams/weirs, harbours, industry, aquaculture, outfalls, roads, places, protected areas)vector · live · ODbL 1.0
- Body & shore cover — ESA WorldCover · WorldCover 2021 v200 inside the boundary and in a 300 m shore ring10 m · 2021 · CC-BY 4.0 (commercial promotion: notify due@esa.int)
- Basin — AWS Terrarium (Mapzen) with ETOPO1 bathymetry · Terrarium elevation tiles sampled inside the boundary~10–30 m on land; ~1.8 km below sea level · 2017 (ETOPO1: 2009) · Open (attribution)
- Water optics — Copernicus Sentinel-2 · Scene classification water mask; MNDWI, NDTI (turbidity proxy), NDCI (chlorophyll proxy) over the water pixels of one clear pass10–20 m · live (latest clear scene, ≤ 120 days) · Copernicus Sentinel data — free, full and open
- Surface temperature — Landsat Collection 2 Level-2 · Landsat C2 L2 surface temperature (ST_B10) over the boundary, latest clear scene100 m (resampled to 30 m) · live (≤ 365 days) · US public domain
- Watershed — Global Watersheds (MERIT-Hydro) · Upstream basin + downstream flowpath (screening hydrography)~90 m · MERIT-Hydro 2019 · Open service, no warranty; engine open source (delineator)
- Hazard screening — ThinkHazard! · Multi-hazard classes at admin-division scale (screening-grade; hazard sets ~2015–2020)admin division · division report (mixed vintages) · GFDRR open (attribution)
Read 2026-09-18 02:18 UTC in 10.0 s · lens v1