What effect can be used to explain the promotion of tourism development to the economy?

It can be explained by multiplier effect.

Multiplier effect is an economic phenomenon, which refers to the chain reaction of variables caused by the change of one variable, and finally leads to the change of economic aggregate. In the field of tourism, the multiplier effect is that the increase of tourism consumption will drive the development of related industries, thus promoting the growth of the whole economy. The increase of tourism consumption will directly drive the development of tourism, and the income of hotels, restaurants, transportation, tourist attractions and other related industries will increase.