《水经注·卷三十三》
城北有龙堤池，城东有千秋池，城西有柳池，西北有天井池，都有水渠相通，冬夏不涸。
城北又有龙堤池，城东有千秋池，西有柳池，西北有天井池。津流径通，冬夏不竭。
North of the city was Long堤Lake. East of the city was Qianqiu Lake. West of the city was Liu Lake. Northwest of the city was Tianjing Lake. They were all connected by canals. They did not dry up in winter or summer.