The LTIS is an economic assessment showing what future flood and coastal erosion risk management (FCERM) could look like over the next 50 years in England. LTIS sets out the total national level of investment if the UK were to invest in all locations where the benefits are greater than the costs. This is called the optimum level of investment for FCERM. LTIS also determines how this would influence the chance and impacts of flooding and erosion over time. It does all this for a range of scenarios, for climate change and development, but also for government priorities.

Justin Butler, CEO of Ambiental

The LTIS is a national scale flood model plus a user interface that translates intervention options into costs and into model changes. LTIS provides compelling evidence to government and others and is needed to inform policy, investment choices and funding decisions. It provides a 'helicopter view' of all national investment to manage flood and coastal risk.

Key LTIS focus topics will likely include: the evolving role of insurance in transferring associated risks; and, how new technology and datasets can be used to better map, model and communicate flood risk from rivers, the sea and heavy rainfall now and in the future so that optimum levels of investment can be better specified over time and space. To a lesser extent, it may also include the role of catastrophe (CAT) modelling for specific topics, such as large geographical scale flood events.

Other subjects being considered at a project-level include:

• How to reflect the wider concept of resilience; not just flood defence investment
• How to best use local information to support the national scale model
• How the national picture of coastal erosion impacts on society

In an LTIS context, the challenge is to communicate complex results effectively, given different levels of uncertainty, and making the LTIS evidence engaging and accessible for policy advisers who are not flood risk experts. The main customers of LTIS evidence are within government - Defra, HM Treasury, and the Ministry of Housing, Communities and Local Government. Justin and colleagues on LTIS will also engage and collaborate with the National Infrastructure Commission, the Committee on Climate Change, infrastructure owners and operators, Natural England, the Forestry Commission, Flood Re and the ABI. One key objective of the engagement is to seek to learn from, influence and inform multiple stakeholders with an interest in FCERM.