Cooperative water-sharing agreements between highlands and drylands: The Tambo-Santiago-Ica river basin in Peru

Inefficient water allocations in river basins limit economic benefits and feed conflicts. We study how institutional change triggered by investments and new technologies can improve water-use efficiency and mitigate conflicts. We develop a bargaining framework to analyse the Peruvian Tambo–Santiago–Ica river basin, which has important economic and social inequalities. We model agents’ welfare changes when joint investments are implemented that are instrumental in overcoming conflict. While upstream communities are poor and rely on rainfed agriculture and cattle-raising, downstream agricultural producers are well-off and produce high-value crops. We find that joint investments can increase both regions’ payoffs and gains from cooperation can be strengthened by side-payments.