Hydrological consequences of natural rubber plantations in Southeast Asia

Since the turn of the century, rubber plantations have been expanding their footprint across Southeast Asia in response to an increasing global demand for rubber products. Between 2000 and 2014, the area cultivated with rubber more than doubled. It is not clear how this major change in the agricultural landscape of Southeast Asia, the main area of rubber production in the world, is affecting land-use patterns and water resources in the region. Here we use maps of rubber plantations and other croplands in conjunction with a hydrological model and remote sensing analyses to assess landuse patterns and water resources affected by natural rubber plantations. Results show water requirements of rubber trees are comparable to those of forests but by far exceed those of the other predominant crops and shrubland vegetation with the effect of potentially increasing water scarcity when rubber plantations replace these crops. The expansion of rubber plantations accounts for a 38 km3/yr increase in green water consumption, thereby exacerbating the monthly water scarcity, with an additional 2.4 million people and more than 0.6 Mha facing water scarcity in the driest months as a result of the increase in rubber production. Monthly runoff substantially decreases (by up to 25%) in 14% of the basins where rubber was planted. These results highlight the existence of major land use and hydrological impacts of agricultural development in Southeast Asia that affect the local environment and rural communities, calling for a more sustainable management of the limited land and water resources.