River basins are generally successive water resources where an international river flows from one sovereign state to another. Therefore there is often less incentive for upstream (often polluting/over-abstracting) countries to actively engage in the TDA process and less incentive to participate and endorse the SAP.
There will often be issues around data comparability and compatibility between upstream and downstream countries. Often countries will have different sampling, monitoring, analysing and reporting approaches. This often links to economic status.
River basins are not discrete systems – they generally (although not always, the Okavango being a case in point) flow into marine and lake ecosystems via an estuary or delta and this will need to be captured in the TDA. However, it may not result in interventions or action in the SAP - this will depend on the scope of the project and the SAP.
Many countries are adopting Integrated Water Resource Management (IWRM) or EU Water Framework (WF) planning processes into national policy. Consequently, appropriate linkages will need to be developed between the SAP and existing/developing IWRM or WF plans.