SEA is not meant to reduce or replace the need for project-level EIA; it is a way of incorporating environmental concerns (including biodiversity) into the decision-making process, often enhancing the project-level EIA process.
The CBD (CBD 2003 [find and link this]) lists particular situations where SEA is recommended:
- Where comprehensive monitoring of biodiversity has not been instituted. In such a case, SEA can provide baselines and indicators
- Where SEA enables assessment of the risk of cumulative impact on biodiversity
- Where ecosystem behavior is poorly understood and long lead-times are required to collect reliable baseline information
- Where ecosystems are unstable or fluctuating, more baseline data are required for predictions and these can reliably be obtained in the framework of an SEA
- Where important biodiversity resources are limited and fragmented SEA is more effective than project EIA and resources can be assessed throughout their range
- Where mitigation options are limited e.g. few suitable alternative sites are available
- Where replacement options are all long-term e.g. restored habitats will take a long time to establish
- Where biodiversity resources are threatened from many directions or by activities in a number of sectors
- Where there are many stakeholders requiring local uses of biodiversity to be sustained