Bomb experts in the German city of Koblenz are working out how to defuse a massive World War II-era bomb that surfaced in the Rhine River due to low water levels.

Almost half of all the residents in the western city -- about 45,000 residents -- will be evacuated from their homes while the bomb is made safe Sunday, Der Spiegel reported.

Two hospitals, seven retirement homes and a local jail will also be emptied.

The bomb measures 10 feet long and weighs 1.8 tons.

Unexploded bombs from World War II often turn up in German cities, forcing authorities to evacuate areas while the bombs are defused or destroyed. But they rarely involve such a large number of local people having to leave their homes.

German authorities said further bomb discoveries along the riverbed were likely due to the unexpectedly low water levels caused by an unseasonably dry November.