Check dam near Kolari
cd-11 · 20.7035, 79.5519 · Chimur taluka · PIN 441910
Contributing catchment 34.33 km² · at a 2 m bund it impounds 143 thousand m³ over 23 ha · design monsoon yield 19,968 thousand m³ · soil HSG-D (clay 43%).
In plain words
A check-dam site near Kolari (Chimur) with a 34 km² catchment. Both sensors catch a monsoon pulse, but the flowing water is thin and they disagree on how much (optical ~6 ha, radar ~3 ha) — the case is the catchment’s runoff, not a standing pool. A full 3 m bund would flood houses, so it is sized to 2 m; even then, eight buildings fall within the footprint (nearest ~78 m).
What to build
Survey the eight structures and verify the pour point; build a 2 m check dam / nala bund if the land clears.
Why here
The 34 km² catchment delivers real monsoon runoff (the 2 m pond fills 30× over), but the thin, noisy water signal and the eight nearby structures both need ground confirmation.
How
Cadastral + ground survey of the eight structures; confirm the pour point and that the monsoon flow is as the catchment implies.
The delta — now vs after
A 2 m bund clear of the houses gives Kolari ~140 thousand m³ of new storage; if the land or flow will not confirm, drop it.
What it delivers · indicative
Indicative benefit at a 2 m bund (DEM area-capacity at 2 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
≈ 142 thousand m³ of net-new water · 28 ha irrigable · 2,582 drinking person-years.
full design storage — no structure holds water here today.
Why this site
Sited on an order-3 nala with a 34.3 km² contributing catchment and gentle grade — a nala/check dam impounds monsoon runoff on the clay lowlands where infiltration is low.
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: 0.9 → 0 ha, a 0.8 ha annual draw-down — the storage renovation recovers.
Area-capacity (DEM, 30 m) · gross storage by bund height
Design point stepped down to 2 m: a full 3 m bund here would flood settlement, so the site is sized to the largest height that clears it while the catchment still fills the pond.
Cross-witness & confidence — independent corroboration
Two sensors track together
Optical (S2) and radar (S1) rise and fall together with correlation r = -0.08 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 6,811 m away.
Land acquisition (submergence)
A 3 m bund would submerge 59 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
Several structures — survey neededIn the submergence footprint
8
buildings within the 271 m design-submergence radius (23 ha pond at 2 m).
Nearest structure
78 m
to the closest mapped building.
Within 500 m
60
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
Kolari
1,298 m away · Chimur taluka · PIN 441910
Nearest landmark
Cian Agro Industries & Infrastructure Limited (Amrutdhara Cooking Oil Unit)
Schools within 2 km
2
nearest 1,080 m
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)
Greening (more vegetation)Vegetation (NDVI) change
+0.061
69 ha lost · 360 ha gained over 1,861 ha land
Built-up (NDBI) change
57.6 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.