Two geographers in Singapore have analyzed the increase in sand mining activities at the Mekong in Phnom Penh—and their results suggest a link between sand mining and the shrinking of the Tonle Sap.
The Tonle Sap lake significantly decreased in size from 1980 to 2018. It has been suggested that upstream dams and the impacts of climate change, including periods of severe drought, are to blame.
However, geographers Ng and Park show that sand mining at Phnom Penh is also an important factor. Using hydrological data from 1960-2020 and views from Google Earth between 2014-2020, they suggest that extensive sand mining at the Mekong, where it flows past Phnom Penh, has affected water levels more than climatic drivers or changes in hydrology relating to the operation of dams on the Upper Mekong.
This diagram depicts their hypothesis that riverbed incision for sand mining relates to reduced inflow of water into the Tonle Sap.
From 2007 to 2015, Cambodia exported more than 7.2 million tons of sand to Singapore. River sand is also in high demand for domestic building projects within Cambodia. Ng and Park's research used historic data from Google Earth to count the number of sand barges on the Mekong where it flows past the capital of Phnom Penh.
This issue is common to other developing countries in the region, with Indonesia, Myanmar, Thailand and Viet Nam experiencing similar problems. Since the early 2000s, some countries have banned or limited sand exports, to prevent harmful environmental impacts. Cambodia has yet to do so.
This research provides a basis for considering what policies can best protect Southeast Asia’s largest freshwater lake, an important fishery and food source for many.
The research approach also shows how freely available data can be used to better understand the impacts of human activities on the environment, despite current limitations on fieldwork and overseas travel.
Read more about this and similar projects here: https://www.nie.edu.sg/niews/december2020/enjoying-overseas-field-trips-via-remote-sensing.html
Source: Wen Xin Ng and Edward Park. Shrinking Tonlé Sap and the recent intensification of sand mining in the Cambodian Mekong River. Science of The Total Environment, Vol. 777, 2021, 146180, ISSN 0048-9697 https://doi.org/10.1016/j.scitotenv.2021.146180
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