Definition – Credibility refers to the quality of being trusted or believed. A person or organisation that does not keep its word will soon lose its credibility.
Relevance to SUMP – Maintaining the credibility of organisations leading the preparation of a SUMP is important to ensure citizen support for the plan. For example, where a measure is proposed within a SUMP, the credibility of the organisation proposing the measure will be enhanced where there is a detailed and realistic implementation plan confirming that finance and resources are available to deliver the measure in a reasonable time scale.
Source: Oxford Dictionaries (online)