IN a reversal of their normal role of encouraging people to visit Hong Kong and spend money, members of the tourism industry today will be doing the visiting and spending the money. The visit will be to Stanley Fort, where they will dig deep into their pockets for charity. Those earning the money will be taking part in this year's ''Tourism Walks for Charity'', a pleasant 90-minute stroll around one of the few areas in Hong Kong not generally open to the public. The organisers hope to raise $1.5 million to be divided between the Suen Mei Speech and Hearing Centre for the Deaf, and the Ebenezer School for the Blind. Last year, which was the first time the event was held, more than 1,000 walkers raised $1.1 million for the Community Chest. Everyone who completes the walk will get a souvenir, and teams and individuals who raise large money through sponsorship will receive special awards. The choice of Stanley Fort was opportune. Next year, after the Black Watch leaves Hong Kong, the fort will probably be closed. Events have been designed to complement the charity walk. The Hong Kong Sports Institute Scholarship football team has challenged a team of movie stars. There will be hot-air balloon rides, and an inflatable bouncing castle for children to exhaust themselves. Adults will be able to take part in karaoke and beer drinking contests. ''Photoland'' will offer everyone a chance of having a photo taken with soldiers of the Black Watch. There will be games and stalls for young and old alike, and the Friends of the Earth will be manning some interesting environmental exhibits as well as demonstrating how to recycle paper and aluminium cans. Food and drink will be available throughout the day, courtesy of some of Hong Kong's leading hotels and restaurants.