Glossary J - M


A product that is approved or accredited for a particular use e.g. flood gate barrier.

Source: FLOWS, County of Lincolnshire, 2006

Knowledge uncertainty

Uncertainty due to lack of knowledge of all the causes and effects in a physical or social system. For example, a numerical model of wave transformation may not include an accurate mathematical description of all the relevant physical processes. Wave breaking aspects may be parameterised to compensate for the lack of knowledge regarding the physics. The model is thus subject to a form of knowledge uncertainty.

Various forms of knowledge uncertainty exist, including:

  • Process model uncertainty:

 All models are an abstraction of reality and can never be considered true. They are thus subject to process model uncertainty. Measured data versus modelled data comparisons give an insight into the extent of model uncertainty but do not produce a complete picture.

  • Statistical inference uncertainty:

Formal quantification of the uncertainty of estimating the population from a sample. The uncertainty is related to the extent of data and variability of the data that make up the sample. 

  • Statistical model uncertainty:

Uncertainty associated with the fitting of a statistical model. The statistical model is usually assumed to be correct. However, if two different models fit a set of data equally well but have different extrapolations/ interpolations then this assumption is not valid and there is statistical model uncertainty.

Source: FLOODsite

Lamb Drove

Site of residential show case development. Lamb Drove is thought to be the first residential development in the UK with comprehensive natural sustainable drainage. The project has been entered into the Royal Town Planning Institutes Planning Awards 2006. The awards give recognition for outstanding achievement in town planning and look beyond purely physical outcomes to recognise innovative processes, techniques and public service improvements. The awards look at the problems a project has tackled, the solutions devised and the results achieved.

Source: FLOWS, Cambridgeshire County Council, 2006

Landuse planning

The development of land use strategies to best meet people’s current and future needs, according to the land’s capabilities. Urban, city, or town planning, deals with design of the built environment from the municipal and metropolitan perspective. Regional planning deals with a still larger environment, at a less detailed level.

Source: TUHH

Legal uncertainty

the possibility of future liability for actions or inaction. The absence of undisputed legal norms strongly affects the relevant actors’ decisions.

Source: FLOODsite

Limit state

The boundary between safety and failure.

Source: FLOODsite


Refers to environmental factors such as high river flows, water levels and wave heights, to which the flooding and erosion system is subjected.

Source: FLOODsite

Low lying areas

Low lying areas are defined here as “areas with artificially maintained levels in watercourses, where peak water (river or tide) levels are higher than the surrounding land levels”.

Source: FLOWS (2005), Environment Agency Offices in Peterborough, UK.


A map is a simplified depiction of a space which highlights relations between objects within that space. Most usually a map is a two-dimensional, geometrically accurate representation of a three-dimensional space. Maps are a common instrument to illustrate flood related information. Depending on the information that is to be shown different notations are in use.

Source: FLOWS


is a small self-contained website, which is separated and independent from the properly website.

Source: FLOWS


  • Post-Flood Mitigation:

Measures and instruments after flood events to remedy flood damages and to avoid further damages.

  • Pre-Flood Mitigation:

Measures and instruments in advance to a flood event to provide prevention (reducing flood hazards and flood risks by e.g. planning) and preparedness (enhancing organizational coping capacities).

Source: FLOODsite


An abstract construct to represent a system for the purposes of reproducing, simplifying, analysing, or understanding it. The definition of a model can be broadly divided into perceptual, conceptual and procedural models.

Source: FLOODsite

Model, perceptual

Summary of our (personal) perceptions on how a system responds. Perceptual models are frameworks representing how a given theorist views the phenomena of concern to a discipline. People receive information, process this information, and respond accordingly many times each day. This sort of processing of information is essentially a perceptual model of how things in our surrounding environment work. The perceptual understanding of systems is far greater than most material model implementations.

Source: FLOODsite

Model, conceptual

The mathematical description of a perceptual model is a conceptual model. It is a construct of mathematical and logical statements that describe a complex system in quantitative terms; a carefully constructed, but sharply limited simulation of nature. It includes hypotheses and assumptions to simplify the processes.

Source: FLOODsite

Model, procedual

Converts a conceptual model essentially to a computer code for example the replacement of differentials of the original equation by finite-difference or finite-volume equivalents.

Source: FLOODsite


Modelling is the process of imitating a real phenomenon or process with a set of mathematical formulas. In principle, any phenomena that can be reduced to mathematical data and equations can be simulated on a computer. But, as natural phenomena are subject to an almost infinite number of influences the most tricky task developing useful simulations is to determine the most important factors.

Source: FLOWS

Municipal master plan

A spatial plan at a municipal level.

Source: FLOWS

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