Sustaining the Pearl River: Problems, Chanllenges, and Opportunities

The Pearl River is a large water system, which is the second largest river (in terms of mean annual water discharge) in China. The Pearl River Basin consists of three major rivers, the Xijiang River, the Beijiang Riverand the Dongjiang River. It nourishes nearly 200 million people, and the Pearl River Delta is the one of earliest regions benefited from China's “open door and reform” policy and the “Belt and Road Initiative”. Nine cities in the Pearl River Delta contribute to approximately 10% of China's GDP in 2021. Over the past decades, many studies have been performed on the Pearl River Basin. In this study, regarding the integrated study results in the Pearl River Basin on climate change, land use change, river channel change and human activities, we investigated the changes, challenges and impact factors of the eco-environment in the Pearl River Basin. The results indicated that the annual average temperature of the Pearl River basin has increased, especially in the Pearl River Delta region in light of the rapid urban expansion. The precipitation has decreased in summer and autumn, corresponding to an increasing trend in winter and spring, and thus drought is mainly observed in summer; The land cover of the basin has also changed dramatically, the cultivated land and forest land have decreased, while there was a significant increasing in the built-up land. In the middle and upper reaches, vegetation have been recovered benefiting from some regulation measures, including grain for green, reforestation and the control of expansion of rocky desertification. On the other hand, in the lower reaches (Pearl River Delta), many forest land has been occupied by human activities, such as urbanization and industrialization. The construction of dams and reservoirs on the main streams of the basin has led to a reduce in suspended sediment load to the estuary. However, the riverbed of the main stream has become lower because of the sand mining, leading to reduced coastal resources have and the salinity in the estuary. Based on the current situation of the Pearl River basin, we propose some suggestions for policy overhaul for basin management and response to future changes. The government should determine the proprieties for the ecological environment recovery based on the current status and major issues in the ecological environment in the Pearl River Basin, on the basis of the characteristics of the river basin and local real conditions. At the same time, the government should also enhance the collaboration among different local governments, and establish cross-basin, cross-regional, and cross-industry ecological and environmental protection policies; differences in precipitation and temperature in different regions have intensified, and the extreme drought in the west and southwest and the flood disasters in the Pearl River Delta are particularly typical. Technical measures should be combined to establish a drought monitoring and evaluation system and an early warning strategy for flood control to cope with future environmental changes and sustainable development.