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Bhandara Water Watch
Gully plug / gabion · gp-9 Terrain-modelled (sub-pixel) low confidence · nala / local

Gully plug near Pangadi

gp-9 · 21.2456, 79.9594

Contributing catchment 0.27 km² · soil HSG-D (clay 44%).

What it delivers · indicative

Primary benefit

Erosion & silt control

Catchment

0.27 km²

Recharge

Minor / local

A headwater gully plug has no modelled reservoir — its value is slowing erosive runoff and trapping silt in the ravine, which protects downstream tanks and check dams from siltation and seeds minor localized recharge. Not a water-storage structure.

Why this site

Priority
78
Strahler
1
Slope
4%
Catchment
0.27 km²
Runoff CN
79
Lineament
7 km/km²

A first-order channel with steeper grade — a gully plug / gabion slows erosive flow and traps silt in the upper catchment.

Seasonal water extent · dual-sensor

2022-06
2022-06-070 ha · MNDWI
1 ha— S2 optical — S1 radar2022-062026-05

Radar (S1, 48 passes) fills the monsoon gap that cloud hides from optical (S2, 36 scenes). Radar peak vs summer low: 00 ha, a 0 ha annual draw-down — the storage renovation recovers.

⚠ A gully plug’s pond is well under 0.5 ha — below the 10 m Sentinel pixel. This series reflects wetness in the surrounding ravine, not the structure itself; the real evidence here is terrain (flow accumulation, catchment, slope), not water extent.

Cross-witness & confidence — independent corroboration

Two sensors track together

Optical (S2) and radar (S1) rise and fall together with correlation r = across 36 paired months. Absolute extents match 0% — they differ by sensor physics on a flowing nala, so the shared rhythm is the witness, not the magnitude.

Nala flow (new-build site)

No existing lake here — expected for a new structure. Sensors show only a weak flow signal in the nala; nearest mapped lake is 3,214 m away.

Land acquisition (submergence)

Submergence not computed for this structure type.

Low confidence — sensors disagree and no independent lake confirms this site. It must be ground-truthed before any commitment of funds.

Displacement witness — real building footprints

No structures in footprint

In the submergence footprint

0

buildings within the 120 m nominal radius.

Nearest structure

2,656 m

to the closest mapped building.

Within 500 m

0

buildings in the influence ring.

Overture Maps buildings 2026-05-20.0 (union of OSM / Google Open Buildings / Microsoft / Esri), Bhandara admin_code=506. A desktop displacement screen — precedes, not replaces, cadastral (7/12) verification.

Reconnaissance context & access — Ola + Google Places

Nearest habitation

Pangadi

2,194 m away

Nearest landmark

Schools within 2 km

0

Health within 2 km

0

Google Places (New) searchNearby + Ola Maps Places nearbysearch · reconnaissance-grade. Independent witness to the buildings displacement layer — dense amenities near a site corroborate high displacement. Does not replace cadastral 7/12 records, geotechnical bores or a level survey.

Human pressure — land-cover change (2022 → 2026)

Stable land cover

Vegetation (NDVI) change

+0.048

0 ha lost · 0 ha gained over 1,856 ha land

Built-up (NDBI) change

0 ha

new built-up / bare (construction proxy)

Window

2022-11..2023-02 (8 scenes)

2025-11..2026-02 (8 scenes)

Sentinel-2 L2A dry-season MEDIAN composites (2022-23 vs 2025-26), water-masked; NDVI+NDBI change screen — not cadastral or DEM cut/fill

DPR-grade desktop hydrology from Copernicus GLO-30 (30 m) + ISRIC SoilGrids + ESA WorldCover; water extent from Sentinel-2 L2A MNDWI (optical) and Sentinel-1 GRD VV radiometrically calibrated to σ⁰ (DN²/sigmaNought² from the product calibration LUT, GCP thin-plate-spline geocoded, open water at σ⁰ < −17 dB; thermal-noise floor not subtracted). A desktop assessment that precedes — not replaces — the statutory ground & geotechnical survey.