Assessment of non-water-retaining structures

Iv has developed its own approach for efficiently assessing large numbers of non-water-retaining structures (NWOs) within flood defences. This method, applied for various clients such as the Schieland and Krimpenerwaard District Water Board (HHSK), provides an efficient and practical solution for flood defence managers.

Using qualitative failure path analyses, combinations of failure mechanisms and the locations of objects are quickly classified into risk categories without requiring extensive object data. High-risk objects can then be examined in more detail. Additionally, Iv employs a scanning vehicle that uses point clouds and specially developed algorithms to detect objects and record characteristics such as tree trunk diameter and height. Objects such as trees, buildings, and cables are accurately analysed for their impact on the flood defence, ensuring water safety in an effective and efficient manner.

Iv has already assessed NWOs for seven different clients on both primary and regional flood defences, with the applied method tailored to the management area and the specific needs of each client. For one water authority, a pragmatic approach was adopted, where a generic reasoning framework was developed based on interviews with an expert on trees and sensitivity analyses. For another water authority, each individual object (over 1,000,000 in total) was assessed using various automated GIS analyses and Python scripts. This method has successfully prevented the unnecessary felling of thousands of trees.