A poster is a representation of an announcement, an advertisement, etc. A poster must be capable of catching the viewer's attention and must consist of necessary information that is to be communicated. We will not be able to design the poster for you. However, here are a few details which you might highlight in your poster:
- Poster divided into two equal halves; one depicting the wrong things happening and the other half depicting the ways to harvest water
- Right things:
* Building reservoirs to preserve rainwater
* Make canals, well, etc. in villages for proper channeling of water
* Construction of large dams
- Wrong things:
* Extra overflow of water from tanks, taps on streets, etc.
* Building of metros underground
* Over use of ground water resources
Hope these ideas help you. Make sure its very colourful, the font size is large enough to be visible to the entire class and the meaning is clearly conveyed. Best of luck!