Percolation near Pimpalgaon
pt-15 · 21.3376, 79.6319 · Mohadi taluka · PIN 441909
Contributing catchment 9.99 km² · at a 3 m bund it impounds 248 thousand m³ over 27 ha · design monsoon yield 5,811 thousand m³ · soil HSG-D (clay 40%).
In plain words
A new percolation-tank site on a nala near Pimpalgaon (Mohadi) where the two satellites track the seasonal fill in near-lockstep — a correlation of 0.95, the tightest agreement of any new-build site. Its ~10 km² catchment delivers far more monsoon runoff than a 3 m tank can hold (over twenty times the storage), so it would fill reliably even in a deficit year.
What to build
Build a new percolation tank with a proper waste weir on the reach. The footprint clears settlement — a single structure sits about 185 m off, though Pimpalgaon is close, so verify the edge on the ground.
Why here
The soil here is heavy HSG-D clay, so this works as dependable surface storage rather than deep recharge (recharge is limited to roughly a tenth of what it holds). The strength of the site is inflow certainty: the catchment never runs short of water to harvest.
How
Construct the tank and weir sized to the terrain’s area-capacity, verify the pour point and foundations, and confirm the one adjacent structure before sanction.
The delta — now vs after
From runoff that drains off the clay and is lost, to a monsoon pond that holds a season’s water for Pimpalgaon — new surface storage and protective irrigation where there is none today.
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 (12% of storage). Actual yield varies with monsoon reliability, seepage and siltation.
Incremental over today · the net-new gain, from the 4-year record
≈ 248 thousand m³ of net-new water · 50 ha irrigable · 4,509 drinking person-years.
full design storage — no structure holds water here today.
Why this site
Sited where soil is lighter (HSG-D) 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, 38 scenes). Radar peak vs summer low: 5.6 → 0 ha, a 5.6 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 = 0.95 across 38 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 2,462 m away.
Land acquisition (submergence)
A 3 m bund would submerge 27 ha — the land to be acquired. Cost & consent scale with this.
⚠ catchment likely includes a through-flowing nala — verify pour point
Displacement witness — real building footprints
Few structures — verifyIn the submergence footprint
1
buildings within the 295 m design-submergence radius (27 ha pond at 3 m).
Nearest structure
185 m
to the closest mapped building.
Within 500 m
244
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
Pimpalgaon
482 m away · Mohadi taluka · PIN 441909
Nearest landmark
Kanhadgaon Post Office
Schools within 2 km
2
nearest 1,496 m
Health within 2 km
1
nearest 1,789 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
+0.033
85 ha lost · 220 ha gained over 1,851 ha land
Built-up (NDBI) change
32.5 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.