Dynamic optimization of water management in aquatic–agricultural systems for net-zero carbon

Abstract

In this work, we present a novel mathematical model within a dynamic optimization framework to address the management of a salt lake and its basin within a semiarid region, facing extreme weather events. The objective is to propose strategies to mitigate the effects of droughts on lake salinity and agricultural and livestock activities, focusing on achieving the net zero carbon goal at the end of the analyzed time horizon. The model is formulated as an optimal control problem subject to a Differential Algebraic Equations (DAE) system. We present a case study on Chasico Lake, a salt-lake in a semiarid endorheic basin, in Argentina. The study comprises a five-year drought period that requires freshwater derivation from a constructed reservoir to keep the salt-lake’s salinity within acceptable ranges for reproduction of a valuable fish species. At the same time, sustainable land use and livestock activities must be ensured. Freshwater is used for irrigation of crops, pasture and native species tree as well as for livestock drinking requirements. The control variable is freshwater diverted from the reservoir, and the decision variable is the land area allocated to crops so as to offset livestock emissions.Numerical results demonstrate that net-zero carbon emissions could be achieved while effectively managing drought periods and preserving ecological balance.