Knowledge
The theory behind every number on this site: how a reservoir stores and releases water, what a rainfall forecast can and cannot tell you, how inflow and outflow are measured, and exactly how JalaNet turns those readings into a colour-coded risk level.
Articles
Reservoirs 101
How a reservoir works
Storage levels, FRL, MWL, dead storage and why a dam at 100% is not automatically dangerous.
Reservoirs · 6 min read
Rainfall
Reading rainfall forecasts
What 24 h and 72 h catchment totals mean, why forecast rain matters more than fallen rain, and forecast uncertainty.
Rainfall · 5 min read
Flow
Inflow, outflow and spilling
Cumecs explained, how shutter openings are reported, and how to read a rising or falling reservoir.
Flow · 5 min read
Risk
How flood and landslide risk is computed
The exact factors behind JalaNet's colour codes, what the engine deliberately does not claim, and how to challenge a score.
Risk · 7 min read
Method
Where the data comes from
The full chain of custody from a KSDMA PDF to a number on screen, and what JalaNet refuses to publish.
Reservoirs · 5 min read
Guided explainers
Guided: how to read a reservoir card
1. Percentage
The big number is storage against live capacity. Compare it with the change since the last report, shown to the right.
2. Colour bar
The bar takes the colour of the computed alert level, so a glance across the grid shows where pressure is building.
3. Water level vs FRL
Two metre readings: current level and FRL. The gap between them is freeboard, the strongest single predictor of gate opening.
4. Rain next 24 h
Forecast catchment rainfall. Read it together with freeboard — low freeboard plus heavy rain is the escalation case.
5. Provenance
Expand it to see which PDF the row came from, when it was ingested, and whether a unit correction was applied.
Guided: what to do when your dam turns orange
Check the remark
The Official alerts strip carries the operator's verbatim notice, including how many shutters are open and by how much.
Look downstream
Open the dam page and read the River system panel: releases from an upstream dam add to whatever the next structure is already passing.
Watch the trend, not the instant
The storage history chart shows whether the level is still climbing after releases began.
Follow official channels
District administration and KSDMA notices are authoritative. JalaNet is a monitoring aid, not a warning authority.
Glossary (22)
- FRL
- Full Reservoir Level — the maximum level at which water is normally stored, in metres above mean sea level.
- MWL
- Maximum Water Level — the highest level the dam is designed to withstand during an extreme flood, above FRL.
- Freeboard
- The vertical distance between the current water level and FRL. Low freeboard means gate operations are imminent.
- Cumec
- Cubic metre per second, the unit for inflow and outflow. 1 cumec sustained for a day moves about 0.0864 MCM.
- MCM
- Million cubic metres — the unit used for reservoir storage volume.
- Live storage
- The usable volume between the lowest outlet and FRL. Storage percentage is expressed against this, not gross capacity.
- Dead storage
- Water below the lowest outlet level, which cannot be released by gravity.
- Catchment
- The area of land whose rainfall drains into a reservoir. Rain here — not rain at the dam wall — drives inflow.
- Spillway
- The structure through which surplus water is released, usually via mechanical shutters or gates.
- Rule level
- A pre-declared elevation (blue, orange, red) at which specific operational and public-warning actions are triggered.
- Blue alert
- Issued when the water level reaches the first rule curve; operators prepare, downstream residents are informed.
- Orange alert
- Issued when the level approaches FRL; gate opening is likely and downstream areas are put on notice.
- Red alert
- Issued when spilling is imminent or under way at scale; evacuation of low-lying areas may follow.
- Inflow
- The rate at which water enters the reservoir from its catchment, in cumecs.
- Outflow
- Total release rate through turbines, canals and spillway gates, in cumecs.
- Antecedent rainfall
- Rain that has already fallen in preceding days. Saturated soil converts new rain into runoff far faster.
- Runoff coefficient
- The share of rainfall that reaches a watercourse rather than infiltrating or evaporating.
- Orographic rainfall
- Rain produced when moist monsoon air is forced up the Western Ghats — the mechanism behind Kerala's extreme catchment totals.
- Landslide susceptibility
- The likelihood of slope failure given terrain, soil saturation and rainfall intensity — highest on steep, deforested midland slopes.
- Barrage
- A low, gate-controlled structure that regulates flow rather than storing large volumes. Pazhassi is the best-known Kerala example.
- Installed capacity
- The maximum electrical output a power station is rated for, in megawatts. It is not a measure of how much is being generated now.
- MU
- Million units — one million kilowatt-hours, the unit Kerala uses for daily electricity generation and consumption.