Forest land cover optimization for water management in the Ichawaynochaway creek basin

Climate change, population growth, and agricultural demands are increasing pressure on global water resources. In the Southeastern United States, researchers and policymakers are turning to alternative forest management strategies to complement agricultural initiatives aimed at reducing withdrawals or improving irrigation efficiency. We assess the watershed-scale viability of low-density, fire-maintained open pine systems as a nature-based solution to water scarcity concerns. We integrated upland vegetation modeling with Soil and Water Assessment Tool (SWAT) hydrologic simulations in the Ichawaynochaway Creek basin of Southwest Georgia. Flow contributions and financial returns at the subbasin level were optimized using an Integer/Binary Linear Programming Model to maximize watershed-scale financial returns while meeting various flow increase objectives above a 2.6% low flow ecological threshold. Converting all upland forests to restored longleaf pine forests increases water yield by a maximum of 167.09 L s^-1, but moderate increases in low flows up to 85 L s^-1 could also be achieved through the conversion of 10% of the convertible forested area of the watershed to loblolly pine savannas at a greater cost efficiency (<$1 million year-1) than longleaf pine restoration. These findings guide the implementation of forest-to-water markets in watersheds where low stream flows are primary ecological and economic concerns.