▁the ▁River ▁Og lio ▁provides ▁the ▁border ▁with ▁the ▁Province ▁of ▁Mant ua . ▁Other ▁rivers ▁in ▁the ▁north ▁of ▁the ▁province ▁include ▁the ▁River ▁Ser io ▁and ▁the ▁River ▁T orm o , ▁and ▁the ▁River ▁M ella ▁makes ▁up ▁a ▁short ▁stretch ▁of ▁the ▁border ▁with ▁the ▁Province ▁of ▁Bres cia . ▁These ▁rivers ▁are ▁linked ▁by ▁a ▁network ▁of ▁can als ▁which ▁have ▁been ▁in ▁place ▁since ▁at ▁least ▁the ▁six teenth ▁century ▁and ▁are ▁largely ▁used ▁for ▁ir rig ation . ▁The ▁M uz za ▁Canal ▁takes ▁its ▁water ▁from ▁the ▁River ▁Add a ▁and ▁ir rig ates ▁the ▁land ▁between ▁that ▁river ▁and ▁the ▁River ▁T ic ino , ▁converting ▁the ▁plain ▁into ▁a ▁fert ile ▁area ▁with ▁rich ▁me adows ▁and ▁product ive ▁agricult ural ▁land . ▁ ▁The ▁total ▁area ▁of ▁the ▁province ▁is ▁. ▁Although ▁the ▁province ▁is ▁essentially ▁flat , ▁there ▁are ▁some ▁und ulations ▁in ▁the ▁surface ▁formed ▁by ▁the ▁varying ▁courses ▁of ▁the ▁rivers ▁over ▁the ▁mill enn ia . ▁For ▁historical ▁reasons , ▁the ▁province ▁is ▁sub div ided ▁into ▁four ▁rural ▁districts , ▁cent red ▁on ▁Cre ma , ▁S ores ina , ▁C rem ona ▁and ▁Cas al mag giore . ▁In ▁the ▁north , ▁some ▁water c ourses ▁emer ge ▁from ▁the ▁ground ▁in ▁the ▁" line ▁of ▁spr ings ", ▁a ▁phenomen on ▁of ▁the ▁northern ▁Lomb ard y ▁P lain , ▁where ▁m elt - water ▁from ▁the ▁Al ps ▁flows ▁under ground ▁through ▁por ous