In particular, conflicts can emerge when communities in upstream locations want to change land use practices in a manner that affects water quality or quantity for downstream users (e.g., by converting forests into agricultural areas). One approach for resolving such conflicts is through the use of the Payments for Ecosystem Services (PES) model, where the user of an environmental service, such as water purification, pays the landowners who provide that service by maintaining the forest cover in the upper watershed. The basic logic is simple: those providing ecosystem services by foregoing alternative uses of the land should be compensated by the beneficiaries of the service. For PES to function, there must be a clearly defined user and supplier, as well as a number of other necessary conditions, such as land tenure security, systems for monitoring, enforcement and compliance, and an enabling legal framework. Remote sensing tools offer an effective way to equalize access to a common information base without needing to rely on direct information-sharing between the parties.