The Corridors Held Through the Hottest Week. The Margin Did Not Widen.

They are the arteries a thirsty century built for itself, and this week, under the worst heat in memory, they held. The Sahel desalination corridor and the Makran corridor that feeds eastern Karachi both delivered continuous pressure through the eleven-day dome — no cutoffs beyond the scheduled rotations, no emergency tankering, the intake pumps and the fusion feed and the long pressurized runs all doing exactly what they were engineered to do. It is a genuine achievement, and the engineers who nursed them through the peak are entitled to a night's sleep. And yet the number that matters did not move. "We held the line," said hydrologist Farida Qadeer, walking the Makran intake at dawn. "We did not push it forward one meter." The corridors delivered at capacity, which is another way of saying they delivered with nothing to spare; a single failed monsoon, a single stalled unit, and the same taps run dry. The margin between coping and crisis is exactly as thin today as it was in spring — a dry season wide, no wider. The system passed its hardest test this summer by using everything it had. "Ask me again after one bad rain," Qadeer said. "That is the only test that counts."