PPS 15 Planning and Flood Risk (Revised)·Page 18·4.6
Cross-boundary flood risk implications
Development plans must consider potential flood risk impacts beyond their area boundaries, including where development outside the plan area could affect flood risk within it, or where plan proposals could increase flood risk elsewhere.
In addition, development plans may also need to consider the potential implications of flood risks beyond the Plan area. This may be necessary where: a) development in locations beyond the Plan area has the potential to impact upon flood risk within the Plan area; or b) Plan proposals could cause or increase the potential for flood risk in locations beyond the Plan area.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/PPS 15 - Planning and Flood Risk (Revised).pdf