Percolation near Opara
pt-10 · 20.7716, 79.8028 · Lakhandur taluka · PIN 441803
Contributing catchment 1.54 km² · at a 3 m bund it impounds 94 thousand m³ over 12 ha · design monsoon yield 419 thousand m³ · soil HSG-C (clay 39%).
In plain words
A small new tank site on a headwater near Opara (Lakhandur), with a 1.5 km² catchment on lighter HSG-C soil. Both sensors track the fill (correlation 0.77), though the sharp monsoon pulse is caught mainly by radar. The catchment fills the modest 3 m design several times over.
What to build
Build a small percolation tank; the footprint clears settlement, with three structures about 175 m off to verify on the ground.
Why here
The lighter HSG-C soil favours recharge (around a third of storage percolates), so a small pond here turns headwater runoff into groundwater on a well-watered catchment — recharge, not just surface storage.
How
Construct a modest tank and weir to the area-capacity, verify the pour point, and check the three nearby structures before committing funds.
The delta — now vs after
From a headwater trickle lost downstream to a small recharge pond that lifts the water table around Opara through the dry months.
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
≈ 94 thousand m³ of net-new water · 19 ha irrigable · 1,709 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, 39 scenes). Radar peak vs summer low: 16.8 → 0 ha, a 16.8 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 = 0.77 across 39 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 12,278 m away.
Land acquisition (submergence)
A 3 m bund would submerge 12 ha — the land to be acquired. Cost & consent scale with this.
Displacement witness — real building footprints
Few structures — verifyIn the submergence footprint
3
buildings within the 198 m design-submergence radius (12 ha pond at 3 m).
Nearest structure
174 m
to the closest mapped building.
Within 500 m
50
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
Opara
1,050 m away · Lakhandur taluka · PIN 441803
Nearest landmark
Dokesarandi
Schools within 2 km
6
nearest 694 m
Health within 2 km
5
nearest 1,172 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
+0.052
69 ha lost · 354 ha gained over 1,864 ha land
Built-up (NDBI) change
41.3 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.