Water quality and assessment under scarcity: Prospects and challenges in Mediterranean watersheds

摘要

Water scarcity is result of a structural, persistent drought affecting aquatic ecosystems. How persistent a drought should be to be named as part of scarcity? Is this a matter of opinion? Scarcity could be defined as a structural drought, based on reliable records of drought situations in a given place, area, region or watershed. Repeated or frequent (related to local conditions) drought episodes can be indicative of structural effects, but still this might not be sufficient. Long-term records are therefore necessary to define scarcity as a structural situation. The long-term records may be obtained directly from long-term data sites where reliable records are available, but this is often not the case. Alternative records can be derived from tree ring chronology (Gray et al., 2003) as well as from events of daily life being recorded in documentary data (administrative, from local government institutions, both civil and ecclesiastical; Rodrigo and Barriendos, 2008).