Firstly you need to use minimum 150 words and your essay has only 139 words.
Please rephrase some of your sentences to make them grammatically correct.
turns into vapour in a process labelled as
turns into vapour and this process is labelled as
When the concentration of water vapour increases the density of the clouds it becomes heavy which results in rain
water vapour increases, the cloud's density also increases making them heavy, causing it to burst in rain
able to hold back huge amounts of water by constructing strong barriers called dams
hold back huge amounts of water because of construction of strong barriers called dams.. reprashae the above sentence also.
Also try to give a overall conclusion for the above topic. Dont end it abruptly like above just give it a smooth ending like, thus from the above diagrmas we can see that ...
something like that