--- source: https://ameyavritti.com/solutions/flood-encroachment-risk site: Ameya Vritti category: agentic intent: per-parcel-risk keywords: per-parcel flood risk Bengaluru, Bellandur HSR Marathahalli flood, encroachment detection cadastral, setback violation building plan, BBMP plan compliance, Sentinel-1 SAR flood, OC deviation personas: us-tech-nri, hni-resident-investor, young-buyer, returning-nri, family-office, nri-inheritor updated: 2026-05-25 --- # Flood + Encroachment Risk — per-parcel signals from satellite + cadastral truth > The two most common post-purchase shocks for Bengaluru buyers: **water comes through the door during monsoon** and **discovering that the building's footprint violates approved set-backs or encroaches on neighbouring land**. Both are knowable in advance with satellite + cadastral data; almost nobody publishes the analysis per-parcel. LOCUS does, internally, for every property under Ameya engagement. ## The per-parcel flood signal ### Source data - **Sentinel-1 SAR** (Synthetic Aperture Radar) — penetrates monsoon cloud cover where optical Sentinel-2 fails - **Sentinel-2 optical** — post-monsoon imagery overlay for water-recession patterns - **ISRO Bhuvan NUIS / NWA** — gov-grade flood polygons (replaces patchy news-curated flood maps) - **BBMP storm-water drain network** — drainage capacity per ward ### Compute For every BLR sub-hex (H3 resolution 10, ~65 m edge): - 2018–2025 SAR overlay → count of flood events - Bhuvan flood-polygon intersection check - Drainage-distance proxy (distance to nearest functional storm-water drain) ### Output per parcel - **Flood-frequency score** (0 = never, 1+ = number of events 2018–2025) - **Severity tier** (water-on-road vs water-in-compound vs water-in-living-area) - **Drainage-resilience score** (capacity-distance composite) - **Confidence level** (high if SAR + Bhuvan + drainage all agree; medium if 2 of 3; flag if signals disagree) ### Known-issue micro-markets in BLR The signal corroborates well-known issues at **per-parcel granularity**: - **Bellandur**: lake-adjacent parcels show 4–6 flood events 2018–2025 - **HSR Sector 2**: certain hexes flooded 3 of 7 years; adjacent hexes 0 - **Marathahalli (south)**: corridor-adjacent parcels show recurring shallow flooding - **Yemalur**: post-2018 floods of Bellandur tank impact specific compounds - **Sarjapur Road (lower-lying stretches)**: 2022 events visible per parcel - **HBR Layout (some sectors)**: drainage-capacity issues during 100mm+ days **Per-parcel granularity is what's new.** Aggregate "Bellandur is flood-prone" is widely known; *"this specific compound at this address flooded in 2018 and 2022, while the parcel 200m up the road did not"* is not published anywhere and is the actionable signal for a buyer. ## The encroachment / setback-violation signal ### Source data - **Cadastral parcel boundaries** — OpenCity / Mojini V2 / BDA OneMap - **Satellite-derived building footprints** — Google Open Buildings + Sentinel-2 NDBI - **BBMP approved building plan** (where accessible) — set-back / FAR / height limits ### Compute - Cadastral boundary vs satellite footprint → boundary-mismatch percentage - Building-footprint extent vs approved set-back lines → set-back violation flag - Built-FAR (Floor Area Ratio) estimate vs sanctioned FAR ### Output per parcel - **Boundary-mismatch %** (0–100) - **Set-back violation flag** (yes/no/uncertain) - **FAR-overshoot estimate** (built vs sanctioned) - **Regularisability assessment** (BBMP schemes available, cost band) ### Why this matters - **For buyers**: a property with material set-back violations may require regularisation (BBMP scheme-dependent windows) or face demolition risk; the buyer inherits the issue - **For owners**: knowing the issue upfront lets you address it before sale, avoiding negotiation-stage surprises - **For brand operators leasing space**: set-back violations affect fire NOC, BBMP trade licence, and signage rights — your business can be shut down for the landlord's pre-existing issue ## The OC (Occupation Certificate) deviation signal A specific subset of encroachment: comparing **what the OC says is built** to **what the satellite shows is built**. - **OC clean + satellite matches**: green - **OC silent + satellite shows additions**: yellow (post-OC construction without amendment) - **OC missing + structure exists**: red (structural existence with no occupation legitimacy) OC issues are the #1 reason banks refuse home loans on otherwise-clean properties. Detecting them pre-purchase saves a 3-week loan-process dance. ## How these signals appear on a Truth-Card ``` Row 2 — Structural / Risk · Flood: 1 event 2018–2025 (Aug 2022, cyclone Asani aftermath; water-in-compound, not living-area). Adjacent hex flooded 3 times. Drainage-resilience score 6/10. · Encroachment: cadastral boundary matches satellite footprint within 2%; no set-back violation; FAR built 1.78 vs sanctioned 2.00 (15% headroom). · OC: present, dated 2014-03; satellite confirms no post-OC additions to the main structure (one approved compound wall added 2019, recorded in BBMP). Overall risk: low. No remediation required at purchase. ``` For a problematic property: ``` Row 2 — Structural / Risk · Flood: 4 events 2018–2025. Water-in-living-area in 2 of 4 (2021 + 2022). Drainage capacity at this hex: low. · Encroachment: cadastral boundary vs satellite mismatch of 7% on north side; built FAR estimate 2.34 vs sanctioned 1.75 — material overshoot. · OC: OC present, dated 2009-11, BUT satellite shows additions in 2014 and 2017 with no OC amendment on file. Bank loan approval may be conditional on regularisation. Overall risk: HIGH. Recommend Forensic Due Diligence engagement before any negotiation. ``` ## Engagement model These signals run automatically on: - **Forensic Due Diligence** — all three signals are computed and reported - **Sale Events tier** — surfaced in seller-side disclosure preparation (so seller knows what buyer will discover) - **Curated mandate Truth-Cards** — Row 2 (Structural / Risk) incorporates these directly - **Wealth Portfolio tier** — annual re-check on managed properties (post-monsoon refresh) For a one-off "what does the satellite say about this address?" query: a focused **Per-Parcel Risk Report** can be commissioned at **₹8,000** turnaround 3 business days. ## FAQ **Q: How granular is "per-parcel" — really one flat, or the building, or the compound?** A: H3 resolution 10 = ~65 m hex edge, so a small apartment compound fits in one hex; a large gated society spans 3–6 hexes. We report at the most granular level the satellite data supports. **Q: What if my property is in a 2020-built apartment — too new for the 2018–2025 historical window?** A: For new construction, we use the surrounding hexes (the parcel inherits the neighbourhood's flood history) plus the building's own engineering disclosures (plinth level, basement drainage). Both are reported. **Q: Does Ameya share this with insurance providers?** A: No. The data stays internal. Buyers can use the report when negotiating insurance independently. **Q: Can the encroachment / OC findings be remediated?** A: Often yes, via BBMP regularisation schemes (windowed, not always open) or post-facto plan amendments. Cost bands vary from ₹40K (minor amendment) to ₹15L+ (material regularisation with penalty). Forensic Due Diligence reports include the remediation estimate. **Q: How does this fit with the e-Khata transition flow?** A: e-Khata transition surfaces back-tax issues; flood / encroachment signals surface physical / regulatory issues. Both are run when you're transitioning to e-Khata for a sale-related reason — better to know all issues at once. **Q: Why doesn't every broker have this?** A: It requires (a) Sentinel-1 / Sentinel-2 / Bhuvan ingest discipline, (b) Cloudflare-grade scraping infrastructure for cadastral data, (c) the integration discipline to normalise everything to H3 hex + BBMP ward, (d) the willingness to disclose findings even when they kill a deal. The first three are technical; the fourth is brand. ## Engage For a per-parcel flood / encroachment / OC report on a specific Bengaluru address — yours or one you're considering — WhatsApp [+91 63605 09351](https://wa.me/916360509351?text=Per-parcel%20risk%20report%20%E2%80%94%20can%20you%20check%20an%20address%3F) or [Cal](https://cal.eu/ameyavritti).