Adjustment and extension of the Hansen and Rattray estuarine classification diagram

Abstract

AbstractThe classification diagram developed by Hansen and Rattray (1966, Limnol. Oceanogr.) is one of the classic papers on classification of estuarine salinity dynamics. However, we found several inconsistencies in both their stratification-circulation and estuarine classification diagrams. These findings considerably change the interpretation of their work. Furthermore, while their classification includes salt wedge estuaries, the model used to derive this is only applicable to well-mixed and partially mixed estuaries. Here, we identify and solve these inconsistencies, and we propose new adjusted and extended stratification-circulation and classification diagrams. To this end, we summarise the model of Hansen and Rattray and extend their work to find analytical model solutions and an adjusted stratification-circulation diagram. Using this new diagram, it is shown that Hansen and Rattray incorrectly discussed the behaviour of dispersion dominated estuaries and that several parts of the diagram correspond to physically unrealistic model solutions. This is then used to demonstrate that several estuarine classes identified by Hansen and Rattray correspond to physically unrealistic model solutions and can therefore not be interpreted. A new and extended classification is proposed by using a recently developed model that extends the work of Hansen and Rattray to salt wedge estuaries. This results in an extended estuarine classification including examples of the location of 12 estuaries in this new diagram.