TEMPO.CO, Jakarta - China's massive afforestation efforts over the past few decades have altered the country's water distribution. This is reflected at least in the results of the latest study published in the Journal Earth's Future on October 4, 2025. The study indicates that tree planting and grassland restoration to combat land degradation and climate change have shifted water on a large and unexpected scale.
The research notes that between 2001 and 2020, changes in vegetation cover reduced the availability of freshwater for humans and ecosystems in the East Asian monsoon region and the arid northwest, which encompasses 74 percent of China's land area. At the same time, water availability increased in the Tibetan Plateau region.
"We find that land cover changes redistribute water," said study co-author and assistant professor of ecosystem resilience at Utrecht University, Netherlands, Arie Staal, as quoted from the Earth report on December 3, 2025.
Staal added that China has been actively engaging in extensive afforestation in recent decades. They have actively restored ecosystems to regain fertility, especially in the Loess Plateau. "This has also reactivated the water cycle," he said.
The researchers in the study explained that increased evaporation and transpiration (plant evaporation) are related to vegetation cover, water availability, and solar energy. "Both grassland and forests generally tend to increase evapotranspiration. This is especially strong in forests, as trees can have deep roots that access water in dry moments," Staal explained.
China is known to have been running a greening program through the Great Green Wall project, which began in 1978. The program aimed at halting desertification has succeeded in increasing forest cover from about 10 percent in 1949 to over 25 percent at present. The Chinese government has also implemented other programs, such as Grain for Green and the Natural Forest Protection Program, which promote the conversion of agricultural land into forests and grasslands and prohibit logging in primary forests.
This study used precipitation data, evapotranspiration data, and high-resolution land change imagery. The results show that evapotranspiration increased more than rainfall.
The evaporated water can be carried by the wind for thousands of kilometers, causing rain to fall in different areas from its evapotranspiration source. As a result, the East Asian monsoon region and the arid northwest experienced reduced water availability, while rainfall increased in the Tibetan Plateau. "Even though the water cycle is more active, at local scales more water is lost than before," said Staal.
These findings present new challenges for water management in China, particularly given the uneven distribution of water. Although the northern region contains only about 20 percent of the country's total water, it is home to 46 percent of the population and contains 60 percent of the agricultural land. The researchers believe that effective policies for managing the water crisis will be difficult to implement without considering the impact of massive afforestation-induced water redistribution.
Staal added that changes in land cover in other countries likely affect their water cycles as well. "From a water resources point of view, we need to see case-by-case whether certain land cover changes are beneficial or not," he said. "It depends among other things on how much and where the water that goes into the atmosphere comes down again as precipitation."
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