Hi! I've developed a similar project for my city (as a personal project) at http://previniendo.me. It's a crime reporting webapp.
For your app I'm planning to use Ionic framework, this way it can be exported for Android and iOS. For a dashboard I think we can use the Facebook Parse Server Dashboard, that way there will be no need to add costs for the development of a dashboard or admin portal.
I need to know more about the GUI that you're planning to make sure I'm giving you the most accurate bid.
I'm looking forward to hearing from you.