About Madurai Water Intelligence

How “Days of Water Left” Works

We compute three scenarios based on current reservoir storage, daily consumption, and inflow patterns:

How Madurai's tap is fed today

Madurai's drinking water travels a long path before it reaches a tap: Mullaperiyar Dam (Kerala) → Periyar-Vaigai diversion tunnel → Vaigai Dam → Pannaipatty Water Treatment Plant → Madurai Municipal Corporation distribution mains → 23 overhead reservoirs across 81 zones → ~96,048 connections → tap.

Two things are worth knowing when reading the dashboard's headline:

• Vaigai is a multi-purpose dam, not a city reservoir. It's owned by the Tamil Nadu Public Works Department and shared across Madurai, Theni, Sivagangai and Ramanathapuram districts for both irrigation and drinking water. MMC's sanctioned drinking-water allocation is 1,500 mcft per year- a small slice of Vaigai's total storage. The most recent reported actual draw is ~900 mcft per year (≈70 MLD continuous).
• We haven't yet found a public daily feed.Pannaipatty WTP's daily raw-water intake and treated output, the 23 OHTs' live levels, and zone-by-zone supply are tracked inside MMC's ICCC and SCADA systems for internal monitoring; we don't have a route to a daily public surface for them today. So a single "days of water left" number for the city would be guesswork; we don't generate one.

What the dashboard doesshow: Vaigai's live dam level (sourced daily from the Tamil Nadu Agriculture Department's reservoir page), MMC's public allocation and recent-draw constants, and the structural infrastructure of Pannaipatty WTP and the distribution network. That's the honest version of what's currently knowable from outside MMC.

What's missing today

A few daily-operations layers aren't currently part of Madurai's public dataset. Most of these data points are tracked inside MMC's ICCC and SCADA systems for internal monitoring; they just aren't routed to a public surface yet. Listed here so users know where this dashboard's daily view ends.

If any of these become available, the dashboard can move from structural numbers (annual allocation, plant capacity) to a real measured daily runway.

Default consumption assumptions (Madurai)

Madurai-specific defaults used to compute days-of-water-left. These are conservative starting points; the dashboard exposes sliders so users can substitute their own.

Users can adjust consumption and desalination values via sliders on the dashboard.

Home / dashboard

The home page anchors Madurai's reservoir picture. Vaigai dam (the drinking-water source) is the headline; Mullaperiyar (Periyar reservoir in Idukki, Kerala) is the upstream feeder via the 1886 lease tunnel and contributes ~80% of Vaigai's annual yield.

9-year history chart

Daily storage and percent-FRL trends going back to 2018, sourced from TN Agriculture's public reservoir archive. Toggle between 90 days, 1 year, 3 years, and the full archive; toggle Vaigai vs Mullaperiyar independently.

14-day forecast

Each reservoir gets its own AutoARIMA fit. Seasonal differencing kicks in once we have at least two years of history; the forecast is shown as a dashed continuation line plus a shaded 80% confidence band. Refits daily as new readings land.

• Each reservoir is forecast independently - no cross-source pooling.
• The model retrains on every refresh; we don't freeze parameters.
• 14-day horizon is aggressive but useful; the 80% band widens as you go out.
• Predictions clamp at 0 and the registered FRL capacity per source.

Groundwater

Madurai's groundwater page combines two authoritative views: CGWB block exploitation (the official annual classification across the district) and a 3-factor ward-level risk composite (composite_score · gw_depth · wb_density · wb_health). The map also shows the CGWB Year Book point network as click-through markers for direct depth readings at known wells.

Block exploitation (GWR)

11 CGWB-classified blocks across Madurai district (Madurai East/North/South/West, Melur, Peraiyur, Thirupparankundram, Tirumangalam, Usilampatti, Vadipatti, Kallikudi) coloured by the latest annual draft-percentage from CGWB's Dynamic Ground Water Resources assessment. Status classes: Safe / Semi Critical / Critical / Over Exploited.

CGWB Year Book point overlay

21 monitoring stations from CGWB's Ground Water Year Book of Tamil Nadu & Puducherry (2023-24 and 2024-25 editions) - peer-reviewed, manually-measured dug wells in the phreatic / unconfined aquifer. Each station carries quarterly depth-to-water-level readings (May / Aug / Nov / Jan) spanning May 2023 - January 2025. Click any marker for the well's hydrograph and full reading history. Stations are tagged with their CGWB block (Alanganallur, Chellampatti, Kallikudi, Kottampatti, Madurai East, Madurai West, Melur, Sedapatti, T.Kallupatty, Thirumangalam, Thirupparankundram, Usilampatti, Vadipatti).

Ward risk composite

A 3-factor weighted percentile score per ward, A-F graded. Chennai uses 5 factors (drainage 25%, sewerage 25%, flood 25%, WB-health 15%, WB-density 10%); Madurai's drainage / sewerage / flood-hazard GeoJSON layers don't exist publicly yet, so v1 ships a reduced composite with what we have:

Each factor is converted to a city-wide percentile (0=best, 100=highest risk), weighted, and summed. Composite ≤20 = A, ≤40 = B, ≤60 = C, ≤80 = D, >80 = F.

Water bodies

715 water-body polygons across Madurai district, sourced from OpenStreetMap. Click any polygon for its tags; the 19 hand-curated flagship tanks carry extra metadata (status, area, builder/era, court-order anchors).

Vaigai mainstem polygons are explicitly labelled - a post-process matches each unnamed river polygon to the nearest section of the Vaigai polyline within 500 m, so long stretches of the river are no longer left blank on the map.

The lake-restoration narrative (lost tanks, flagships, programmes, court orders) lives on its own page rather than the map view; jump in via Lake restoration.

Rivers

Vaigai-system scope: 304 km Vaigai mainstem, 121 km Periyar (Kerala feeder), 72 km Suruliyaru, 27 km Manjalar, 117 km Varaha tributaries. Per-river sidebar shows length, status, upstream/downstream termini, and feed.

CPCB monitoring stations

Vaigai is on CPCB's Priority III polluted-stretch list. Two stations on the National Water Monitoring Programme cover the Madurai stretch - one upstream of the city, one downstream - with annual readings for dissolved oxygen, BOD, pH, conductivity, fecal coliform, and nitrate. We extract those readings from CPCB's annual River Water Quality reports (2021-2024 covered today) and show them as a per-station table when you select Vaigai in the sidebar.

Markers are colour-coded by the latest BOD reading: red above 6 mg/L, amber above 3, green at or below 3, grey when no readings exist. The four other Vaigai stations a journalist might expect (Vaigai dam, Andipatti, Manamadurai, Ramanathapuram) stay grey because CPCB doesn't monitor them today.

Court orders & key events

A hand-curated event log filtered to the selected river. Today it covers the Madras HC's December 2024 suo motu cognisance of Vaigai pollution (177 sewage / industrial discharge points across 5 districts, 36 samples below CPCB Class D), the Supreme Court's 2014 Mullaperiyar verdict (142 ft storage cap, still-active Supervisory Committee), and the operational threshold around Vaigai dam release that triggers Madurai-city flood warnings (about 6,000 cusecs).

Industrial pollution sources

Six hand-curated Vaigai-basin polluters mapped as type-coloured markers: the SIDCO industrial estates at Kappalur and K. Pudur, the Sellur sewage discharge zone, the Dindigul tannery cluster, the Theni textile dyeing units, and the multi-district outfall inventory cited in the December 2024 Madras HC order. Compiled from TNSIDCO records, the DHAN Foundation CURE study, the Columbia GSAPP Madurai studio, NGT orders, and news reporting. The Tamil Nadu Pollution Control Board's online effluent monitoring portal (OCMMS) is referenced as the live cross-check.

Flood risk

Narrative-only stub. Hazard-zone polygons (5/10/25/50/100/200-year return periods), historical flood-hotspot layers, drainage GeoJSON, and sewerage overlays don't exist publicly for Madurai (in contrast with Chennai's OpenCity-published layers). The page surfaces the Vaigai dam-release threshold (~6,000 cusecs as Madurai-city flood warning; 12,000+ during the 2018 floods) and a documented locality risk note pending RTI to Madurai Corporation.

Lake restoration

Madurai-only narrative-rich page (Chennai redirects /lake-restoration to /water-bodies). Sections: 14 lost urban tanks, 12 severely-reduced tanks, 19 hand-curated flagships, restoration programmes (Kudimaramathu / AMRUT / Smart City / IAMWARM), Madras HC court-order anchors, DHAN partnership target.

Restoration priority badge

Each flagship carries a colour-coded priority badge built from four signals:

• Status severity 0-80 - drying / lost > severely reduced > encroached / polluted > restored.
• Cultural bonus 0-35 - Biodiversity Heritage Site (+25), Ramsar candidate (+20), HC PIL anchor (+15), pre-1700 heritage (+10), dynasty-era (+8).
• Size 4-25 - acres bucketed (very large / large / medium / small / tiny).
• Source confidence ×0.7-1.0 - V (verified), N (newsroom), C (claim only) downweights.

Sum is bucketed: ≤40 low, ≤60 moderate, ≤80 high, >80 critical. First run produced 5 critical, 2 high, 7 moderate, 5 low. Top 5: Vandiyur 100, Thenkal Kanmoi 100, Madakulam 88, Avaniyapuram 85, Samanatham 80.

My Ward / Report Card

Ward-boundary map for Madurai Corporation's 100 wards (5 zones, 2022 delimitation). Click a ward to see zone, area, centroid, and a link into the per-ward report card.

Per-ward report card

Each report card shows a large A-F grade badge, the composite score out of 100, the ward's rank within the city, and a per-factor breakdown (raw value, percentile, weight). Without a specific ward selected, the page renders an index grouping ward chips by grade so you can jump straight to the worst-graded wards.

Madurai's report card is intentionally slimmer than Chennai's. Chennai's is built on a 5-factor composite plus an uplift-planner cost matrix; that costing layer is out of scope for the Madurai launch because the underlying drainage and sewerage layers aren't published.

Water facts

Journalist-ready quotable stats grouped by freshness tier - live (this season), derived (last 12 months), historical (documented), and heritage (pre-modern). Today Madurai ships 14 hand-curated heritage and governance facts plus 9 auto-derived stats that compute from the data layers we ship: over-exploited blocks, critical and semi-critical blocks, restoration priority counts, F-grade ward count and worst ward, citywide interpolated groundwater depth, Vaigai BOD pollution gradient, Vaigai dissolved oxygen downstream, urban tank area lost.

How we classify river health

CPCB publishes two parallelriver-water-quality classification systems, and they don't always agree. Knowing which one we use - and why - matters for reading our river status badges honestly.

Our status badges ("dead", "severely degraded", "degraded", "stressed", "healthy") are computed from current readings via the Designated Best-Use thresholds- not from the PRS Priority list. We take the worst classification across a river's monitored stations and surface that as the river-level status.

Practical consequence: a river on CPCB's PRS Priority list (e.g. the Madurai-Manamadurai stretch of the Vaigai is Priority III) won't automatically render as "severely degraded" here. If the underlying NWMP readings show only Class C/D conditions, the badge reflects that. The PRS designation belongs in the river description as historical context, not as the live status.

Methodology lives in src/lib/utils/river-classification.ts; readings are from CPCB NWMP annual River Water Quality reports.

Open data gaps in Madurai

Some layers we'd like to surface aren't publicly released yet for Madurai. We've listed each one with the workaround currently in place; tracked as RTI follow-ups where applicable.

Known Limitations

• Estimates are approximations. Actual water availability depends on factors not modeled (groundwater extraction, Krishna water transfer, distribution losses, industrial use).
• CMWSSB data may occasionally be stale (weekends, holidays). The dashboard shows a freshness indicator.
• Groundwater data from OpenCity may lag by months. The map always shows the most recent available period.
• Forecasts use ARIMAX (AutoARIMA with inflow/outflow as exogenous regressors) and work best with 2+ years of daily data.
• Risk scores are relative indicators for comparison between wards, not absolute measures of water safety.
• Satellite spread is a summary of surface water extent, not a direct measure of storage volume, water quality, or inflow source. A lake can look broad and still hold less usable water than expected.
• Reservoir catchment polygons are reviewed operational geometries for rainfall context, not official legal boundaries. This matters especially in Chennai's managed canal and transfer system.
• Current satellite context relies on optical Sentinel-2 observations. During persistently cloudy periods, some water bodies may temporarily lose this insight until a radar fallback is added.

Documented lost urban tanks (Vencatesan + DHAN)

Disclaimer

Open Source

Neer Vazhvu is fully open source. The code, data pipeline, and methodology are transparent and available on GitHub. Contributions, bug reports, and data corrections are welcome.

Support this project

Neer Vazhvu is free and open source. If you find it useful, consider supporting us on Patreon to help cover satellite data, hosting, and API costs.