River constructions in North Rhine - Westphalia Guide for the field survey of constructions in rivers
Arbeitsblatt 38, englische Version, LANUV 2021
For centuries people have built constructions in and on watercourses for example to drive mill wheels or to irrigate the land. Usually, constructions have been built perpendicular or diagonal to the flow direction of the river. They have an influence on water flow, migration of organisms and bed-load transport. Thus, the continuity of rivers is limited or is non-existent.
The European Water Framework Directive (WFD) sees river continuity as mandatory to achieve the good ecological status. The directive “Infrastructure for Spacial Information in Europe” (INSPIRE) regards river constructions as an inventory of water management activities and obliges member states to publish the corresponding spatial data.
The present document of North Rhine-Westphalia State Agency for Nature, Environment and Consumer Protection enables a standardised and digital survey of constructions in and on rivers for the first time in German-speaking regions. The term “construction” describes here selected technical installations which can directly affect river morphology, discharge dynamics, water flow, sediment transport and organisms’ migration as well as indirectly influence water quality, for instance oxygen content and temperature balance.
The described procedure is based on experiences and knowledge gained since the statewide survey of river morphology in the years 2011 to 2013. Detailed knowledge of the assignment of constructions to the various categories, groups of types and construction types is not required. Rather, a dichotomous decision tree based on measurable parameters, clearly visible in the field, leads the surveyor to the respective construction type. Each type is described in the annex and the variety of forms is documented with numerous photos.
A survey of river constructions performed according to the present method can be carried out simultaneously with a river morphology survey or separately. Using the software BEACH, the recorded data can be stored and used together in a database, for example for
- localisation of technical installations in and on rivers
- an overview of constructions to evaluate river continuity
- the derivation of the extension of living space by eliminating constructions
- the success monitoring and efficiency certificate of realised construction removals and
- the historicisation of single constructions
My thanks goes to all participants, which have participated in the development of the procedure for a standardised and digital survey and mapping of constructions in and on rivers
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