MECHANISM OF LOCALLY-INDUCED CONVECTION DEVELOPMENT AND ITS EFFECTS ON VAPOR TRANSPORTATION OVER TONLE SAP LAKE AREA

The changing environment is expected to intensify the challenges that people in developing countries are facing, particularly among the groups whose livelihoods depend on natural resources. The adaptive capacity of livelihoods largely defines the extent to which people can cope with future environmental changes, whether caused by climate change or other factors such as land use changes and water resources development. This article analyses the resilience and adaptive capacity of rural livelihoods around Cambodia's Tonle Sap Lake, an exceptional lake-floodplain system dominated by flood pulse. The research findings demonstrate that despite the people's tradition of adapting to the remarkable seasonal variation of water and related resources, their capacity to adapt to unusual environmental changes is weak, with the poorest being clearly the most vulnerable group. Reasons for the weak resilience include villages' relatively homogenous livelihood structures, unjust governance practices, increasing inequality and the lack of opportunities for livelihood diversification. It is concluded that while climate change is likely to pose a remarkable challenge to people's livelihoods in the longer term, climate change adaptation activities should also take into account other environmental changes. Equally critical is the understanding of the broader socio-political context and its dynamics in increasing—and decreasing—livelihood resilience.

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Drastic decline of floodpulse in the Cambodian floodplains (the Mekong River and the Tonle Sap system)

10.5194/hess-2021-378 ◽

2021 ◽

Author(s):

Samuel De Xun Chua ◽

Xi Xi Lu ◽

Chantha Oeurng ◽

Ty Sok ◽

Carl Grundy-Warr

Keyword(s):

Reverse Flow ◽

Mekong Delta ◽

Water Levels ◽

Water Withdrawal ◽

Lake Area ◽

Wet Season ◽

Tonle Sap Lake ◽

Tonle Sap ◽

Maximum Water ◽

Flooding Season

Abstract. The Cambodian floodplains experience a yearly floodpulse that is essential to sustain fisheries and the agricultural calendar. Sixty years of data from 1960–2019 are used to track the changes to the floodpulse there. We find that minimum water levels in 2010–2019 have increased by up to 1.55 m at Kratie and maximum water levels have decreased by up to 0.79 m at Prek Kdam when compared to 1960–1991 levels, causing a reduction of the annual flood extent. Concurrently, the duration of the flooding season has decreased by about 26 days (Kompong Cham) – 40 days (Chaktomuk), with the season starting later and ending much earlier. Along the Tonle Sap River, the average annual reverse flow from the Mekong to the Tonle Sap Lake has decreased by 56.5 %, from 48.7 km3 in 1962–1972 to 31.7 km3 in 2010–2018. As a result, wet-season water levels at Tonle Sap Lake has dropped by 1.05 m in 2010–2019 since 1996–2009, corresponding to a 20.6 % shrinkage of the Lake area. In addition to known upstream contributors such as hydropower dams, two anthropogenic causes of the drastic alterations to the floodpulse are identified: irrigation and channel incision. We estimate that water withdrawal in the Cambodian floodplains is occurring at a rate of (2.1 ± 0.3) km3/yr and incision-induced water levels reduction is in the order of (0.43–1.02) m. As the floodpulse is essential for the ecological habitats, fisheries and livelihoods of the region, its reduction will pose major implications throughout the basin, from the Tonle Sap system to the Vietnamese Mekong Delta downstream.

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