Water this land to cool it! To do that, you need to restore the great Lake Chad to its former glory. To do that, you need to clear the Typha weed from the whole basin, and dredge the soil it has built up. There is an enormous amount to be cleared. Fortunately, Typha can be made into fuel of several different sorts. Charcoal, ethanol, biomass briquettes, and fuel gas can all be made from Typha. The soil harvested can be used to rehabilitate other soil, or to fight coastal erosion. If you get the lake working again, it will recharge the aquifers, and reestablish "lake effect" rains. You can speed up the recovery with diverted water from healthier streams, but the price is guaranteed to include salination somewhere. If the weeds aren't cleared, the water will just be wasted, anyway.

Liberate your continent from aquatic weeds! Do so at a profit in fuel!