In recent years, river runoff and total water resources in the southern region have increased, increasing by nearly 5%, while the amount of water resources in the northern region has decreased significantly. The Yellow River, Huaihe, Haihe and Liaohe regions are the most significant, and the total resources have decreased by 12%. According to the current normal needs, if the groundwater is not over-exploited, the country will lack nearly 40 billion cubic meters of water in normal years. What does this passage mean? ['In recent years, the national water shortage situation is still very serious.', 'The total amount of water resources in northern China is significantly lower than in the south.', "China's water resources are unevenly distributed in the south and north.", 'The total amount of water resources across the country is on the decline.']