Percolation near Mangli
pt-5 · 21.3614, 79.7385 · PIN 441912
Contributing catchment 5.78 km² · at a 3 m bund it impounds 598 thousand m³ over 54 ha · design monsoon yield 2,832 thousand m³ · soil HSG-C (clay 40%).
In plain words
A percolation-tank site near Mangli with the largest storage of the surveyable tanks (~600 thousand m³ at a 3 m bund) on HSG-C soil. But that 3 m design floods a wide 54 ha footprint, and eleven buildings fall inside it.
What to build
Survey the eleven structures and study a lower bund — the footprint is large enough that a smaller design may cut the displacement sharply while keeping real storage.
Why here
The recharge and storage potential is the highest in this tier, but the wide submergence and eleven structures make the land question the deciding factor, not the water.
How
Cadastral + ground survey of the 11 structures; an area-capacity study across bund heights to find the height that avoids the structures.
The delta — now vs after
A right-sized bund that avoids the structures would make Mangli a strong recharge site; at full 3 m height the displacement may be prohibitive.
What it delivers · indicative
Indicative benefit at a 3 m bund (DEM area-capacity at 3 m bund) under standard norms (irrigation ~5 TCM/ha; drinking 150 lpcd). Recharge is limited on HSG-D clay (35% of storage). Actual yield varies with monsoon reliability, seepage and siltation.
Incremental over today · the net-new gain, from the 4-year record
≈ 598 thousand m³ of net-new water · 120 ha irrigable · 10,873 drinking person-years.
full design storage — no structure holds water here today.
Why this site
Sited where soil is lighter (HSG-C) or fractures raise infiltration — a percolation tank turns runoff into recharge rather than surface storage.
Seasonal water extent · dual-sensor
Radar (S1, 48 passes) fills the monsoon gap that cloud hides from optical (S2, 36 scenes). Radar peak vs summer low: 3.2 → 0.4 ha, a 2.8 ha annual draw-down — the storage renovation recovers.
Area-capacity (DEM, 30 m) · gross storage by bund height
Cross-witness & confidence — independent corroboration
Two sensors track together
Optical (S2) and radar (S1) rise and fall together with correlation r = 0.52 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 confirm a monsoon flow pulse in the nala; nearest mapped lake is 3,730 m away.
Land acquisition (submergence)
A 3 m bund would submerge 54 ha — the land to be acquired. Cost & consent scale with this.
Displacement witness — real building footprints
Several structures — survey neededIn the submergence footprint
11
buildings within the 415 m design-submergence radius (54 ha pond at 3 m).
Nearest structure
124 m
to the closest mapped building.
Within 500 m
19
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
Mangli
748 m away · PIN 441912
Nearest landmark
Tumsar
Schools within 2 km
16
nearest 438 m
Health within 2 km
20
nearest 1,511 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)
Stable land coverVegetation (NDVI) change
+0.047
44 ha lost · 191 ha gained over 1,843 ha land
Built-up (NDBI) change
22.4 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.