地理漫步·世界地理英语30篇（3）

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乍得湖流域：气候过渡带中的水文脆弱性

Lake Chad, straddling Chad, Cameroon, Niger, and Nigeria, occupies a Sahelian transition zone between savanna and desert.
Its surface area has shrunk by over 90% since the 1960s due to reduced rainfall and increased irrigation withdrawals.
Unlike tectonic or volcanic lakes, Chad is a shallow, endorheic basin fed mainly by the Chari River’s seasonal floods.
Evaporation exceeds inflow during prolonged droughts, exposing vast mudflats that alter regional albedo and dust emission.
Transboundary water management remains weak despite shared dependence on this shrinking hydrological node.
Aquifer recharge depends critically on floodplain infiltration during high-flow years—a process increasingly disrupted.
Vegetation belts migrate southward as groundwater tables drop, intensifying pastoralist-farmer land-use conflicts.
Satellite data show seasonal lake expansion now occurs later and contracts earlier each year on average.
Sediment cores from basin margins record centuries of wet-dry oscillations linked to Atlantic sea-surface temperature shifts.
Restoration efforts focus on re-establishing natural flood pulses rather than static water-level targets.