Land use changes can cause more intense flooding

While the climate and biodiversity impacts of land use changes have been widely documented, not much is known about how changes in land use may affect local water cycles. In a new study from the University of Göttingen, researchers have found that the expansion of palm oil plantations and other monocultures is causing more intense flooding across Indonesia. 

The findings suggest that flooding associated with rapid land use change is triggered by the interaction of complex factors – including soil degradation and the construction of flood protection dams. 

For the investigation, the researchers did not rely on science alone. They conducted almost 100 interviews with Indonesian land managers, residents of local villages, and decision-makers in the Jambi province of Sumatra. 

The study was also focused on measurements of precipitation, river and groundwater levels, soil properties, and land use maps. 

“Many studies on the relationship between land use changes and flooding are only based on analyses by individual disciplines and thus provide only fragmentary insights into the underlying processes,” said lead author Jennifer Merten. 

“It was therefore important for us to use the widest possible range of data from different disciplines and also to include observations from the local population.”

The study highlights the impact of expanding oil palm and rubber plantations on local water cycles. 

“The large-scale land-use change leads to a compaction of the soil, so that less rain is absorbed by the soil and the water quickly runs off at the surface,” explained study co-author Christian Stiegler. “In particular, the advancing destruction of floodplains plays an important role in this process.” 

From the perspective of village residents, the construction of flood dams and drainage channels contributes to a change in local patterns of flooding. Such infrastructure is often built by larger plantation owners when their operations are expanded into wetlands such as river floodplains or peatlands.

“However, such dams often lead to increased flooding on neighboring smallholder plantations,” said Merten, drawing from her observations in the area. This increase in flooding also leads to new social tensions and conflicts.

Soil protection and improved land use planning can play an important role in reducing the impact of land use change on the water cycle, especially in floodplains and wetlands.

“Yet, it is just as important to regulate and control landscape interventions for flood protection and drainage more closely,” says Merten. “Otherwise it might happen that the effects of increasing flooding will affect above all the poorest in society, because larger companies simply pass on the water.”

The study is published in the journal Ecology and Society.

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By Chrissy Sexton, Earth.com Staff Writer