canals are waterways or passages constructed artificially for the passage of ships and boats and it is also used for irrigation.the two types of canals is waterways and aqueducts.
they were quite useful in the development of civilization in the past.they are now days being used as a passage of transportation.many cities are also built on the bridges just on top of these canals.
there are many canals in this world.they may have been very old so they needs to be reconstructed.if they are not reconstructed then it may cause harm to many people especially hose living on top of it.
pond is small water body.it can be formed naturally or formed artificially.pond contains many aquatic animals.the two types of ponds is wetland ponds and vernal ponds.wetland ponds remains wet through out the year and the vernal ponds dry up for once in a year.
ponds are used for fish breeding.many aquatic animals lives in this water as it is suitable for their survival.they are also an important source of recreation.they are also used for religious baths.
these ponds becomes dirty because of its excess usage and they needs to be cleaned and also reconstructed if any damage is caused to save the aquatic animals and to avoid the shortage of water for human beings.