Arabian Sea cyclones briefly refill desert aquifers
A few intense tropical cyclones now supply most of interior Oman’s rain and can add cubic kilometres of groundwater, interrupting chronic depletion.
Source
Intensifying tropical cyclones in the Arabian Sea replenish depleting aquifers
What they did
The authors tracked 1990–2020 Arabian Peninsula landfalling cyclones, then estimated Najd (200,000 km2) recharge from Keila (2011), Mekunu (2018), and Cyclone 2020 using GRACE TWS, well levels, and a calibrated RiverFlow2D model.
What they found
Najd received >60% of precipitation from TCs (Mekunu 20.1 km3 rain). GRACE TWS rose 3.2 ± 1.4 km3 after Mekunu, matching modelled recharge of 3.5 km3; Keila and 2020 barely moved GRACE. Unconfined water tables rose 1.7 m after Mekunu/2020, with up to 55 m rise in confined Hanfit wells. Background GRACE depletion was −0.4 then −0.9 km3 yr−1.
The limits
What it doesn't show
Three storms cannot prove every future cyclone will recharge. GRACE cannot isolate 2020 from lingering Mekunu. Agricultural pumping (cultivated area 5 to 95 km2) still dominates the long-term budget. RiverFlow2D ran only 17–18 days per storm.
Key terms
- TC precipitation (TCP)
- Rain delivered by a tropical cyclone, here a large share of annual totals in hyper-arid Najd.
- GRACE TWS
- Satellite-measured terrestrial water storage, used as a basin-scale recharge proxy.
- Umm Er Radhuma aquifers
- Confined carbonate aquifers of the Najd whose outcrop in the Dhofar mountains receives cyclone rain.
Flashcards
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Mekunu’s Najd rainfall volume was about:
Common questions
Why did Mekunu recharge when Keila’s rain did not show in GRACE?
Mekunu’s 20.1 km3 dwarfed Keila’s 9.7 km3; only the larger storm produced a clear TWS jump (3.2 km3).
Are cyclones becoming more important?
Landfalling TCs on the AP rose from 3 (1990s) to 7 (2010s); intense storms doubled in the last decade.
Does recharge last?
It interrupts depletion but GRACE resumed falling afterward as irrigation expanded.
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