Skip to content
GaliGali SoftLabsGaliGaliSoftLabs
Bhandara Water Watch
Tank desilting / strengthening · tank-6 Satellite-observed water body medium confidence · medium

Tank renovation near Umari

tank-6 · 21.0424, 80.0289 · Sakoli taluka · PIN 441802

Contributing catchment 0.04 km² · soil HSG-C (clay 37%).

In plain words

A tank at Umari (Sakoli) that both sensors track closely — it fills each monsoon and draws down hard by summer. One caution: the land-change screen shows the surrounding area is building up; Umari’s edge is urbanising.

What to build

Renovate — desilt and strengthen — but survey the encroachment first.

Why here

The water evidence is strong, but rising construction nearby both silts the tank faster (runoff off bare and built land) and can creep onto its bed.

How

Ground-truth the built-up encroachment against the tank boundary, then desilt and strengthen, and protect the foreshore from further encroachment.

The delta — now vs after

Renovated and protected, it holds its monsoon fill deeper into the year for Umari. Left alone, siltation and encroachment will keep shrinking it.

What it delivers · indicative

Impoundment
2,101 TCM
Irrigation
420 ha
Drinking (person-yrs)
38,201
Recharge
252 TCM

Live capacity from the observed satellite extent (140 ha) x 1.5 m mean depth. Desilting restores the depth lost to siltation — the tank empties to near-nothing by summer today, so recovered depth means water held later and more recharge. Irrigation ~5 TCM/ha; drinking 150 lpcd. Actual yield varies with monsoon reliability, seepage and siltation.

Incremental over today · the net-new gain, from the 4-year record

1,259 thousand m³ of net-new water · 252 ha irrigable · 22,891 drinking person-years.

recovered draw-down (84 ha of 90 ha peak) x 1.5 m — the water it loses to summer today. The site already carries ≈94 thousand m³ into summer today — that is not counted; only the recovered draw-down is new.

Why this site

Water-body area
7 ha
Catchment
0.04 km²
Soil (HSG)
HSG-C
Clay %
37%
Runoff CN
79
Peak water
140 ha

An existing water body — desilting and strengthening recovers lost storage at a fraction of new-build cost.

Seasonal water extent · dual-sensor

2022-06
2022-06-072 ha · MNDWI
161 ha— S2 optical — S1 radar2022-062026-05

Radar (S1, 48 passes) fills the monsoon gap that cloud hides from optical (S2, 23 scenes). Radar peak vs summer low: 90.26.3 ha, a 83.9 ha annual draw-down — the storage renovation recovers.

Cross-witness & confidence — independent corroboration

Two sensors track together

Optical (S2) and radar (S1) rise and fall together with correlation r = 0.83 across 23 paired months. Absolute extents match 63% — a close magnitude match strengthens the read on an open water body.

Independent inventory (HydroLAKES)

No HydroLAKES polygon within 800 m (nearest 957 m) — likely seasonal water not in the global inventory; treat as unconfirmed.

Land acquisition (submergence)

Submergence not computed for this structure type.

Displacement witness — real building footprints

No structures in footprint

In the submergence footprint

0

a renovation floods no new land — desilting restores depth within the existing waterspread, so nothing is displaced.

Nearest structure

187 m

to the closest mapped building.

Within 500 m

42

buildings in the influence ring.

Restoring lost depth within the existing waterspread raises no new water level and acquires no new land, so no one is displaced. Verify bed encroachment on the historical spread on the ground before restoring the full level.

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

Umari

966 m away · Sakoli taluka · PIN 441802

Nearest landmark

Aasha Kiran Palace

Schools within 2 km

3

nearest 1,123 m

Health within 2 km

1

nearest 901 m

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)

Built-up rise (encroachment)

Vegetation (NDVI) change

-0.029

300 ha lost · 69 ha gained over 1,749 ha land

Built-up (NDBI) change

301.2 ha

new built-up / bare (construction proxy)

Window

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

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

Construction / encroachment is rising in the site vicinity — this changes runoff and raises future land-acquisition cost. Prioritise an early ground check.

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.