Table 4.

Models with No. of tourists.

Citation	Tourists related variables	Water-related variables	Pollution related variables
[121]	Tourists, Tourists satisfaction, Tourists' needs	Not mentioned	Not mentioned
[105]	Use value for tourists, Number of tourists, Spending per tourist	Mussels	Degree of sustainability in tourist facilities
[69]	Tourists, Tourism Business Owners, Tourism Services	Water Consumption, Water Quality	Not mentioned
[136]	Domestic tourists, Foreign tourists, Tourists in Galapagos	Boat-based domestic tourists, Tourists in Galapagos	Not mentioned
[70]	Tourists coming rate, Tourists Tourists Leaving rate	Not mentioned	Not mentioned
[102]	Number of tourists, Tourist amenities	Fish population, Coral reef coverage	Pollution, Water Quality, Waste, Waste treatment, waste discharge rate of tourists, fraction of waste polluting environment
[103]	Tourism Area, Tourist attraction, Tourists per year, Tourist Revenues, Tourists Investments	Canal Waste Treatment	Environmental State, Pollution, Waste Treat
[89]	The number of tourist subsystem, The number of domestic tourists, The number of foreign tourists	The CO2 emission from the ferry	The CO2 emission subsystem, Total CO2 emission from mini tour bus, Total CO2 emission from private car
[67]	Tourists Flow, Mass Tourism, Tourism Infrastructure	Not mentioned	Environment, Environmental degradation Factor