Comparisons, trends and method
Analysis विश्लेषण
How the seven ghats compare, how readings changed across the 2023, 2024 and 2025 festival seasons, and exactly how the provisional index is built.
Historical MPPCB readings, 2023–2025 · not live monitoring
Basin compliance at a glance समग्र अनुपालन
All seven ghats combined, 2023–2025, against CPCB Class B. Counts exclude below-detection and not-sampled readings.
- —DO tests below 5.0 mg/l
- —BOD tests above 3.0 mg/l
- —pH tests outside 6.5–8.5
- —readings of zero dissolved oxygen
Ghat comparison घाटों की तुलना
Sub-scores are 0–100 before weighting. Measured columns come straight from the engine's parameter summaries.
| Rank | Ghat | CRI | Oxygen deficit ×0.40 | Organic load ×0.30 | Metal hazard ×0.20 | Lagged impact ×0.10 | DO tests < 5.0 | Mean BOD mg/l | Peak lead mg/l |
|---|
Year-by-year readings वर्षवार रीडिंग
Mean of the numeric MPPCB readings for each year, across Ganesh and Durga festivals and all phases (pre, during, after). Highlighted cells breach the CPCB Class B limit (DO below 5.0 mg/l or BOD above 3.0 mg/l). n is the number of readings. These are historical averages, not a forecast.
| Ghat | Mean dissolved oxygen (mg/l) | Mean BOD (mg/l) | ||||
|---|---|---|---|---|---|---|
| 2023 | 2024 | 2025 | 2023 | 2024 | 2025 | |
Post-immersion (lagged) impact विसर्जन के बाद का प्रभाव
Paired festival events where the "after" reading worsened compared with "during" (BOD rose or DO fell). Full per-event citations are in each ghat's evidence panel on the dashboard.
| Ghat | Comparable pairs (during & after sampled) | Worsened after immersion | Lagged sub-score (% worsened) | Examples (during → after) |
|---|
How the Composite Risk Index works CRI पद्धति
Statutory CPCB limits are kept separate from the provisional scoring choices made for this project.
1. Statutory Standards (Official Central Pollution Control Board)
Under CPCB Class B (Outdoor Bathing Organised) criteria from cpcb_water_quality_criteria.csv:
- Dissolved Oxygen (DO): Minimum ≥ 5.0 mg/l. Values < 5.0 mg/l cause aquatic hypoxia. 0.0 mg/l is total biological anoxia.
- Biochemical Oxygen Demand (BOD): Maximum ≤ 3.0 mg/l (5 days at 20°C). Measures organic waste load consuming oxygen.
- pH: Permissible range 6.5 to 8.5.
2. Provisional Operational Composite Risk Index (CRI)
Because the CPCB does not publish a composite multi-parameter index, this model was designed for BMC decision support:
CRI = (0.40 × S_DO) + (0.30 × S_BOD) + (0.20 × S_Metal) + (0.10 × S_Lagged)
- S_DO (40% Weight):
0.60 × (DO Violation Rate %) + 0.40 × (Zero DO Anoxia Rate %) - S_BOD (30% Weight):
0.60 × (BOD Violation Rate %) + 0.40 × min(100, max(0, (Mean_BOD - 3.0)/10.0 × 100)). Excess ceiling of 10.0 mg/l represents BOD = 13.0 mg/l. - S_Metal (20% Weight):
0.70 × (Detection Rate %) + 0.30 × (min(1.0, Peak_Lead / 1.5) × 100). Lead ceiling of 1.5 mg/l represents a 15x exceedance of CPCB Schedule VI discharge limits (0.1 mg/l) and 150x exceedance of IS 10500 drinking limits (0.01 mg/l). - S_Lagged (10% Weight): Percentage of paired festival events where post-immersion 'after' conditions deteriorated further.
3. Data Quality & Integrity Disclosures
- BDL (Below Detection Limit): Preserved as non-elevated trace detection. Never converted to zero or counted as missing.
- Missing Data: Excluded from compliance denominators and surfaced as explicit data gap alerts.
- Durga 2025 Missing Data: Bairagarh and Malikhedi lack Durga 2025 tables in the MPPCB report.
- Rani Kamlapati Site Ambiguity: Ganesh tables sampled an artificial kund; Durga tables sampled open lake water.
Data sources डेटा स्रोत
Monitoring evidence
- MPPCB idol-immersion monitoring reports, 2023, 2024 and 2025 (Ganesh & Durga Visarjan), parsed to
bhopal_ghats_2023_2025.csv. Each parameter row in a ghat's evidence panel cites the report year and PDF page. - CPCB Water Quality Criteria, Class B (Outdoor Bathing, Organised):
cpcb_water_quality_criteria.csv.
What this tool is not
- Not real-time monitoring. All readings are historical (2023–2025) and cannot establish current water safety.
- Not an official BMC, MPPCB or CPCB publication or endorsement. The CRI is a provisional planning method under review.
Limitations सीमाएँ
- Historical, not live. Readings are from 2023–2025 and cannot establish water safety today. Real-time pre-immersion testing is still required.
- Missing records. The 2025 MPPCB report has no Durga tables for Bairagarh or Malikhedi; missing data is never treated as clean.
- Limited parameters. No bacteriological parameters and only four heavy metals (Pb, Cr, Cu, Zn) were reported; nothing else is estimated.
- Site ambiguity. Rani Kamlapati / Kamla Park: Ganesh tables sampled an artificial kund, Durga tables sampled open lake water (medium confidence).
- Provisional index. CRI weights and ceilings are planning choices under review, not regulatory standards.
- Year means are descriptive. Each year mixes festivals and phases, and some years have fewer readings (see n).