In keeping with their ideal of "keeping many lakes to reflect the bright moon, so that one need not worry that there is nowhere to cast the golden hook," when the Chinese of the Tang dynasty (618-907) planned their cities, they kept many open spaces within them for lakes and ponds, in order to provide a water supply and to absorb flood waters.
所謂「留得五湖明月在，不愁無處拋金鉤」，唐朝中國人規劃城市，會在城中預留許多空地，作為湖泊、池塘，目的也是作為水源地、洩洪區。