Meltwater Exposure Tracker

In development. This tracker has no published figures. The method is published first, ahead of any data, so that it can be examined and contested before a single value is released.

What it is

A basin-resolved public register of Himalayan cryosphere condition, set against the economic mass sitting downstream of it and the institutional capacity to absorb a loss.

What it is not

It is not a forecast. It is not a hazard warning system. It is not an early warning service, and it is not a substitute for statutory monitoring by the Central Water Commission, the National Disaster Management Authority or state agencies.

The tracker reports condition and exposure. It does not predict events. Any language in this product implying event prediction is an error, and readers should report it as one.

Why basins

Cryosphere condition is published regionally. Economic exposure is recorded by state. Neither resolution is useful for the question that matters, which is what condition a particular catchment is in and what sits underneath it.

The 2026 cycle demonstrated the cost of aggregation directly: in the year regional snow persistence recorded its deepest deficit on the series, one major basin recorded a positive anomaly. A regional headline erased that. So would a single composite score.

The tracker therefore reports at basin and sub-basin level, and reports three sub-indices separately. It does not publish a single number for the Himalaya, and it never will.

Coverage

Version 1 — the Indian Himalayan Region, organised by basin rather than by state.

Indus — Sutlej, Beas, Ravi, Chenab, the Jhelum headwaters and the Ladakh reach. Ganga — Yamuna, Bhagirathi, Alaknanda, and the Ghaghara, Gandak and Kosi headwaters. Brahmaputra — Teesta, the Siang/Dihang reach, Subansiri and Manas.

Two non-Indian mountain basins are carried as comparative references, selected for long instrumented records and material downstream exposure, so that the method can be shown to be portable rather than bespoke. The tracker does not extend to jurisdictions upstream of the Indian Himalayan Region and does not model transboundary allocation. That boundary is a design decision, stated here so it is not mistaken for an omission.

Series start. Glacier area and change from 1990, matching the established change baseline. Snow persistence from 2003, the start of the regional monitoring series. Installed generation from 2000, capturing the post-liberalisation Himalayan build-out. The event log from 1990, which is long enough to establish a base rate.

The three sub-indices

Each basin receives three scores and a stated data-completeness figure. They are never summed.

Cryosphere Condition

Glacierised area and its change against the 1990 baseline; glacier count; the share of glacier area sitting in the 4,500–6,000 metre band, which is where the region's ice is concentrated and where warming acts on most of the stock at once; snow persistence anomaly for the current season and as a multi-year rolling mean; consecutive below-normal seasons; snowmelt share of annual runoff; and glacial lake count and area where published inventories permit.

Stock and flow are reported separately throughout. Glacier mass is a multi-decade variable that bears on asset life and dry-season firm capacity. Seasonal snow is a within-year variable that bears on next season's generation and working capital. They answer different questions for different balance sheets, and an index that blends them answers neither.

Economic Mass

Installed hydropower capacity by basin — operational, under construction, and allotted but not commenced; lean-season generation and lean-season plant load factor; basin-fed irrigated command area; and population and built asset value within modelled runout and floodplain zones.

Lean-season generation is the load-bearing series. Annual mean flow is not the financially relevant variable; firm capacity in the months when melt rather than monsoon dominates runoff is, and that is the period a snow deficit reaches first.

Two components here do not exist in public data and are being constructed. The first is a concordance mapping installed generation capacity to basin rather than to state — capacity is published by state, cryosphere condition by basin, and nobody has joined the two tables. The second is asset value within modelled exposure zones. Both will be published with their full method, or not published at all.

Institutional Absorption

State disaster fund allocation and the applicable centre–state cost-sharing ratio; the ownership class of exposed generation capacity, which determines where a loss actually lands; early warning coverage as officially published; the legal status of state water levies; and insurance penetration on generation assets.

Insurance penetration on Himalayan generation assets does not appear to be published anywhere in consolidated form. The tracker will seek it. If it cannot be obtained it will be recorded as sought and not disclosed, and will never be estimated.

The event log

A separate register, one row per recorded cryosphere-driven loss event since 1990: date, basin, event type, trigger mechanism, peak discharge, sediment volume, generation capacity affected and destroyed, asset owner and ownership class, human impact, infrastructure damage, and whether the event produced a subsequent change of asset ownership.

Every entry carries a field recording conflicts in the published figures. This is a feature of the log rather than a caveat on it. The October 2023 Sikkim event alone carries materially divergent casualty figures across authoritative sources. A register that silently adopts one number is less credible than one that shows the divergence and says so.

How the data is presented

Three states of absence are distinguished and never collapsed into a single blank: not yet collected, sought and not disclosed, and structurally not applicable. Each renders differently.

Every figure traces to a named source with a date and a licence status. Data completeness is shown per basin without interaction, so that a basin at forty per cent completeness cannot be mistaken for one at ninety.

Each basin has a permanent URL — the basin page is the citation unit, not the tracker. Annual snapshots are versioned, so a reader citing the tracker in a later year can retrieve what it actually said in the year cited. The full dataset downloads as CSV and JSON without restriction or registration; citation reach is the objective and friction defeats it.

Corrections are published and linked from every page. Every revision is versioned, and none is silent.

Publication calendar

Once live, the tracker follows the publication cycle of its underlying sources rather than a fixed editorial schedule.

April. Regional snow data publishes; the tracker ingests the seasonal condition series within ten working days.

May. Snow brief — short, fast, basin-resolved.

June to August. Generation and fiscal series refresh.

September. Full tracker refresh, published with a changelog.

October. Annual analytical paper against the refreshed data.

Continuous. The event log updates within seventy-two hours of a credible recorded event.

Independence

HEF publishes the consulting, commercial and advisory relationships held by the institution and by the authors of any file, on every publication. Where a live commercial relationship touches a file, the author recuses. An independence claim survives disclosure; it does not survive discovery.