ISRO, in its studies, has revealed that there is a 178% increase in the size of the Ghepang Ghat Glacial Lake. In which of the following States/UTs is this lake located?
- (a)Jammu & Kashmir
- (b)Ladakh
- (c)Himachal Pradesh
- (d)Uttarakhand
Correct — C, Himachal Pradesh. Ghepan Ghat, printed here as Ghepang Ghat, is a glacial lake in the Lahaul valley of Lahaul and Spiti district in Himachal Pradesh, lying above the village of Sissu at roughly 4,000 metres and fed by the retreating snout of the Ghepan glacier. Satellite monitoring by the National Remote Sensing Centre, taken up with the Himachal Pradesh State Disaster Management Authority, tracked its surface from about 36.5 hectares in 1989 to about 101.3 hectares in 2022 — an increase of roughly 178 per cent, or close to two hectares a year. That growth is why it is on the list of high-risk lakes: a moraine-dammed lake that keeps filling as its parent glacier melts is the classic setting for a glacial lake outburst flood, and the settlements of the Chandra valley lie downstream. An early warning system has since been installed at the lake, the first such installation in the State.
- (a)Jammu & Kashmir — Not where this lake lies. Glacial lakes in the Union Territory are monitored on the same satellite programme, but Ghepan Ghat is in the Lahaul valley.
- (b)Ladakh — Ladakh's best known high-altitude lakes, Pangong Tso and Tso Moriri, are not glacier-fed lakes of this kind, and Ghepan Ghat is not there.
- (d)Uttarakhand — The tempting answer, because Uttarakhand is where the February 2021 Chamoli disaster occurred and where much glacial-lake reporting is centred. Ghepan Ghat, however, is in Himachal Pradesh.
A glacial lake forms where meltwater collects behind a moraine ridge or in a hollow left by a retreating glacier. As warming accelerates retreat, such lakes grow, and the loose debris dam that holds them can fail — from overtopping, from a landslide or ice avalanche into the lake, or from the melting of ice buried inside the moraine. The resulting glacial lake outburst flood travels down narrow valleys with great force. India's Himalayan states are monitored for these lakes through satellite inventories maintained by the Central Water Commission and the National Remote Sensing Centre.
The item is a place-fixing question wrapped around a statistic. The route in is the name: Ghepan is a Lahauli name, and Lahaul is in Himachal Pradesh. Failing that, remember which agency did the study — a state disaster management authority is named in reporting on the lake, and it is Himachal Pradesh's. As of the 2024 exam this was current news; since then Himachal has installed an early warning system at the lake and glacial lake monitoring has widened across the Himalaya, so the specific numbers move but the location does not. Worth flagging: UPSC has not released a key for this paper, and some answer keys in circulation mark (d), Uttarakhand. The lake and the study that measured it are both in Himachal Pradesh, so this card takes (c).
- Ghepan Ghat lake lies in the Lahaul valley of Lahaul and Spiti district, Himachal Pradesh, above Sissu.
- Satellite monitoring recorded growth from about 36.5 hectares in 1989 to about 101.3 hectares in 2022, roughly a 178 per cent increase.
- The National Remote Sensing Centre is ISRO's centre for satellite-based earth observation and disaster support.
- A glacial lake outburst flood occurs when the natural moraine or ice dam holding such a lake gives way; the Chamoli disaster of February 2021 in Uttarakhand is the best known recent Himalayan flood event of this family.
- Defaulting to Uttarakhand for any Himalayan glacial-lake question.
- Confusing glacial lakes with tectonic or oxbow lakes.
- Assuming a lake that is growing is safer than one that is shrinking — growth against a weak moraine dam is precisely the risk.
As a locate-the-lake item, or as a statements question on glacial lake outburst floods and the agencies that monitor them.
In which one of the following States/UT, is the Lake Tsomgo located?
- (a) Ladakh
- (b) Himachal Pradesh
- (c) Sikkim
- (d) Uttarakhand
Answer(c) Sikkim
The same kind of item — a named Himalayan glacial lake to be placed in the right State. Both reward building a short mental list of high-altitude lakes with their States attached rather than guessing from the sound of the name.
- practice — not a real PYQ
A glacial lake outburst flood is most directly caused by
- (a)the failure of the moraine or ice dam holding a glacial lake
- (b)a cloudburst over a plateau
- (c)the silting of a reservoir
- (d)the diversion of a river for irrigation
Answer(a) the failure of the moraine or ice dam holding a glacial lake — releasing the impounded water down the valley in a sudden flood.
- practice — not a real PYQ
The South Lhonak lake, whose outburst caused severe flooding along the Teesta in October 2023, lies in which State?
- (a)Arunachal Pradesh
- (b)Sikkim
- (c)Uttarakhand
- (d)Himachal Pradesh
Answer(b) Sikkim — the outburst sent a flood down the Teesta valley and damaged the Chungthang dam.