By that I mean, for example, I was a researcher in solar cell materials, and currently, I want to research the study of evaporation in soil and water, i.e. in the processes of solving water shortage problems.
@Altyeb Ali Abaker Omer, Further the above researchers' comments, you should read books or many research papers from your research area. Use keywords to search i.e. in your case, the keywords would be "water evaporation in soil" and "water shortages". You can learn a new field fast. Best of luck