The researchers developed a method to estimate pollution loads in Dongguan by using a water quality model. They first built a relationship between pollution sources and water quality, then calculated pollution loads based on optimization equations. By analyzing water consumption and pollution data, they estimated that in 2005, the domestic and industrial CODCr load in Dongguan was 25.2×104 tons, with domestic pollution accounting for 60.4% and industrial pollution for 39.6%. This estimation accurately reflected the water quality changes in Dongguan at that time.