They are in the middle stage of the 2011-2015 plan.
>>The plan is representative of China’s efforts to rebalance its economy, shifting emphasis from investment towards consumption and development from urban and coastal areas toward rural and inland areas - initially by developing small cities and greenfield districts to absorb coastal migration.<<
Central planners stockpile, meet quotas then sit on the couch. If they are planning for a migration back to the interior, they need to feed the masses.
Maybe, but that doesn't fully explain the stockpiling of precious metals, iron ore, and other commodities. As the article says, one possibility is the exchange of fiat currencies for things of real value while the prices are low.