The advice that I gave yesterday, about considering alternatives to adverbs, doesn't apply to IELTS writing task 1. For example, look at these verb-adverb phrases:
- increase dramatically
- rise steadily
- decrease significantly
- fall gradually
These phrases are fine, and I use them all the time.
If you avoid adverbs in task 1, you'll end up using words like this: soar, rocket, shoot up, creep up, dive, plummet. These words are not appropriate for an academic-style report, so I recommend that you avoid them.
Remember that you can also use adjective-noun phrases:
- a dramatic increase
- a steady rise
- a significant decrease
- a gradual fall