Jing-Hang Great Canal is the earliest canal in the world, it has an important role in the transportation
between south and north China during almost 2,000 years. But with the development new technologies,
the Great Canal has lost its role from 19th century. Especially in Nanwang part of canal, it has
disappeared as a dry drain now. In order to find the reason of Nanwang canal disappeared from 1700
gradually, we put forward a new method to find the change of it. In this paper ,we first use an old map
which draw in 300 years ago to obtain the old time environment status and correct it into nowadays
remote sensing data to reveal the old sub-rivers which has run into canal in the old time. We also use
some history materials to get the social information such as population data, county and village data.
Second we using present remote sensing data to extract river, farmland data, we also collect the
population data now in this area. In the end we compared this two period data to find the different
hydrographic net in 300 years. The result will give us the answer for the canal change and give us a
hint for reconstruction the Great Canal in the future.