# Sustainable Urban Water Management in China: A Case Study from Guangzhou and Kunming
## 3 Case Study Cities in China
### Concerns Regarding the Water Quality  
Guangzhou has a significant number of dispersed pollution producing factories and industries, a high energy consumption rate, a high level of pollution, and widespread manufacturing units. Although the 147 rivers had been largely cleaned, the water quality remained unstable, with a potential of reverting to dark and odorous conditions [40]. The river's poor water quality puts a strain on Guangzhou's water management. Although each river has its own 'River Management System,' the implementation of proper supervision and a methodical strategy for treating the contaminated rivers are rather ignored. The treatment of black and odorous rivers is independent, and the upstream and downstream rivers still lack coordination within the River Management Systems [41]. Guangzhou's treatment plan also lacks technical procedures for ecological rehabilitation. The majority of river courses have hardened bottoms and shorelines, and the river's ecological potential for self-purification is insufficient.  
Additionally, the wetlands in Guangzhou are polluted by human-related activities. Some wetlands have been transformed into eco-natural parks in recent years for the sake of amusement and tourism. Haizhu Wetland is one of the largest hybrid wetland systems in the world, consisting of rivers, lake wetland, and orchard. Numerous negative actions on the part of some people (e.g., the tourists) have resulted in significant damage to the wetland's environment, including flowers and the grassland. Apart from the wetland, there are several residential areas in the urban region; thus, the wetland is under pressure to discharge polluted wastes; additionally, the fruit bearing trees are grown using fertilizers and insecticides in this wetland area [42].  
Neonicotinoids (Neonics) have been the world's most extensively utilized insecticides in recent years. Neonics are emerging pollutants in drinking water due to their hydrophilic nature. The total amount of neonicotinoids in surface water ranged from 92.6 to 321 ng/L, with a geometric mean (GM) of 174 ng/L, according to an assessment of the residual level of neonicotinoids in the Guangzhou part of the Pearl River [43]. The drinking water treatment plants are capable of only removing roughly 50% of neonics from surface water. The western and frontier river routes of the Guangzhou section of the Pearl River that acted as a water resource were more contaminated with neonicotinoids than the rear river routes, as a result of receiving more effluents from WWTPs and being subjected to extensive commercial and human activity. Hence, the metropolitan area of Guangzhou may suffer from moderate pollution and pose major ecological problems [44].  
Water quality has also been a problem in Kunming, following the deterioration of Dian Lake's water quality. The reasons for the reduction in water quality are industrial and domestic discharges, as well as the agricultural land occupying a wide area due to Kunming's other significant economic activity--landscaping-plants import and export [45]. Anew, the residents' poor public participation increases the community's resistance to  
Figure 1: Map showing: (**a**) the elevation, and (**b**) the rainfall distribution in Kunming (adapted from Ref. [39]).  
solving urban water problems. A classic example is that the tourists toss debris into rivers, clogging the channels and impairing the drainage system's performance.  
Kunming and Guangzhou continue to face social and environmental concerns, and the issues are not isolated but are part of a larger social and environmental catastrophe. In the future, a metropolis with a blue-and-green environment that is hospitable to both humans and animals is expected.