Why watering flowers when it is raining?

 Water is an important resource for every life on the earth, and the amount of it is limited. Therefore we need to be more concerned when we use them!

Lack of water

Watering plants 

Nowadays, there is a general phenomenon I found that pulsed sprinklers are usually working in the rain on campus which makes me feel so confused. I cannot figure out why plants need to be watered when it is raining.So I search the internet and try to find the answers. 





I read some introduces about smart irrigation system and I find that overall smart irrigation system consists of sensors, controllers and background monitoring system, valves and systems for water supply solenoid and other common components. And the operating principle is that firstly, the sensor will bring soil temperature and humidity monitoring and information to the driver on the control terminal of the sensor signal from the terminal (as conversion, filtering, amplification) after conversion . By detecting the value of the resulting humidity is less than the preset value, the solenoid valve opens as sprinklers, sprinklers sprinkle in different rotation angles. Similarly, detection of the humidity reaches the set value, the control terminal control solenoid valve is closed irrigation end.

smart irrigation system

This makes me get a better understanding of how the smart irrigation system works, however, it cannot explain why UNSW`s smart irrigation system always works even in the rain. I guess it may be due to some of the sensor probably doesn`t work well and cannot get the right reflect to the terminal. In my opinion I think it is a kind of waste if it keeps watering the plants when it is raining, because it not only wastes the electric energy, but also the water resource.




Pictures from:
http://imgm.photophoto.cn/010/017/014/0170140023.jpg
http://img.shushi100.com/images/b2ffa794-ee1e-4638-93a2-917e1560d455.jpg
http://shunfeng.fanyacdn.com/imglibs/files/shunfeng-water%20resources%20management.jpg