One possible version:

Dear Bob,

It’s very kind of you to write to me and let me know about your beautiful city. Now I’d like to tell you something about my hometown Jiangcheng.

The city stands on the bank of the Changjiang River. It is a beautiful place for people to live in. Its economy has been developing rapidly in the past ten years. New factories, houses and roads have been built. More schools and hospitals are available for its people. However, there are some problems, such as water and air pollution and heavy traffic in rush hours. In my opinion, Jiangcheng should develop its economy scientifically. I would also think that the growth population should be bought under control so that we’ll have a better hometown in future.

Yours,

Li Hua

注意审题，组织好全文，推敲句子表达法。