Table 1 Search strings per database

EBSCO Business Source Elite

Title, abstract, keywords

((TI “inland waterway transport” OR SU “inland waterway transport” OR AB “inland waterway transport”) OR (TI IWT OR SU IWT OR AB IWT) OR (TI “inland navigation” OR SU “inland navigation” OR AB “inland navigation”)) AND ((TI bottleneck* OR SU bottleneck* OR AB bottleneck*) OR (TI “low water” OR SU “low water” OR AB “low water”) OR (TI “shallow water” OR SU “shallow water” OR AB “shallow water”))

Emerald Collections

Title, abstract

((title:IWT OR title:“inland navigation” OR title:“inland waterway transport”) OR (abstract:IWT OR abstract:“inland navigation” OR abstract:“inland waterway transport”)) AND ((title:bottleneck* OR title:“low water” OR (title:“shallow water”) OR (abstract:bottleneck* OR abstract:“low water” OR abstract:“shallow water”))

Google Scholar

title, keywords

(((intitle:IWT OR keyword:IWT) OR (intitle:“inland navigation” OR keyword:“inland navigation”) OR (intitle:“inland waterway transport” OR keyword:“inland waterway transport”)) AND ((intitle:bottleneck* OR keyword:bottleneck*) OR (intitle:“low water” OR keyword:“low water”) OR (intitle:“shallow water” OR keyword:“shallow water”)))

IEEE

Title, abstract, keywords

(“All Metadata”: “inland navigation” OR IWT OR “inland waterway transport”) AND (“All Metadata”: bottleneck* OR “low water” OR “shallow water”)

Scopus

Title, abstract, keywords

TITLE-ABS-KEY (“inland navigation” OR IWT OR “inland waterway transport”) AND (bottleneck* OR “shallow water” OR “low water”)