The unseen transboundary commons that matter for Cambodia's inland fisheries: Changing sediment flows in the Mekong hydrological flood pulse

Grundy‐Warr, Carl; Lin, Shaun

doi:10.1111/apv.12266

Cited by 16 publications

(16 citation statements)

References 32 publications

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“…Especially for the Mekong, the yearly flood season is closely tied to the planting calendar (Fukai & Ouk, 2012) and fish migratory pattern (Baran et al, 2001). Therefore, alterations to dry/wet season water amounts will have a direct social and ecosystem impacts (Grundy‐Warr & Lin, 2020). For example, a reduction in wet‐season flows will restrict the movement of fish species to their spawning areas (Barlow et al, 2008).…”

Section: Methodsmentioning

confidence: 99%

River Discharge and Water Level Changes in the Mekong River: Droughts in an Era of Mega‐Dams

Chua

2021

Hydrological Processes

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While 1992 marked the first major dam -Manwanon the main stem of the Mekong River, the post-2010 era has seen the construction and operationalisation of mega dams such as Xiaowan (started operations in 2010) and Nuozhadu (started operations in 2014) that were much larger than any dams built before. The scale of these projects implies that their operations will likely have significant ecological and hydrological impacts from the Upper Mekong Basin to the Vietnamese Delta and beyond. Historical water level and water discharge data from 1960 to 2020 were analysed to examine the changes to streamflow conditions across three time periods: 1960-1991 (pre-dam), 1992-2009 (growth) and 2010-2020 (mega-dam). At Chiang Saen, the nearest station to the China border, monthly water discharge in the megadam period has increased by up to 98% during the dry season and decreased up as much as À35% during the wet season when compared to pre-dam records. Similarly, monthly water levels also rose by up to +1.16 m during the dry season and dropped by up to À1.55 m during the wet season. This pattern of hydrological alterations is observed further downstream to at least Stung Treng (Cambodia) in our study, showing that Mekong streamflow characteristics have shifted substantially in the post-2010 era. In light of such changes, the 2019-2020 droughtthe most severe one in the recent history in the Lower Mekong Basinwas a consequent of constructed dams reducing the amount of water during the wet season. This reduction of water was exacerbated by the decreased monsoon precipitation in 2019. Concurrently, the untimely operationalisation of the newly opened Xayaburi dam in Laos coincided with the peak of the 2019-2020 drought and could have aggravated the dry conditions downstream. Thus, the mega-dam era (post-2010) may signal the start of a new normal of wet-season droughts.

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Section: Methodsmentioning

confidence: 99%

River Discharge and Water Level Changes in the Mekong River: Droughts in an Era of Mega‐Dams

Chua

2021

Hydrological Processes

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“…Institutional frameworks for governing transboundary water commons rarely consider ways of seeing and valuing water resources that are not readily tangible in terms of economic productivity. Grundy‐Warr and Lin (2020) develop the concept of ‘unseen transboundary commons’ to describe the biophysical geopolitics of governing overlooked or unvalued nutrients, sediment and other mobile resources that are transported via the annual flood pulse system of the Mekong Delta and Tonle Sap ecosystem to sustain inland fisheries in Cambodia. In addition to these precious resources being largely ignored in institutional arrangements, the capital‐driven relations and infrastructures that exploit, deplete and degrade them are equally unseen in the sense that they are treated as biophysically separate from their broader socioecological context, which in turn displaces intergenerational knowledge systems required to sustain them.…”

Section: Overview Of This Collectionmentioning

confidence: 99%

Governing transboundary commons in Southeast Asia

Miller

Rigg

Taylor

2020

Asia Pacific Viewpoint

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The recent uptake of the concept of transboundary commons has directed attention towards the complexities of cross-border environmental governance. Transboundary commons are broadly defined as the spatial arrangements for governing shared resources and coordinating responses to environmental threats and crises that traverse jurisdictions and property boundaries within, as well as between, nation-states (Giordano, 2003;Hirsch, 2020;. Etymologically and genealogically, transboundary commons inscribe a specific set of relationships that value resources 'in common' across borders. Scholarship on the global commons and transnational commons has focused on the international dimensions of dispersed and overlapping resource regimes (Holder and Flessas, 2008;Corson and MacDonald, 2012). While sharing many characteristics with these allied concepts, the notion of transboundary commons does not restrict the study of cross-border relations to national-level units of analysis but extends to encompass all scales of environmental governance. As such, the analytical lens of transboundary commons prompts critical reimagination of the myriad connections between place-based forms of resource organisation and distant decisionmaking processes, labour, technologies and markets that shape (re)distributional outcomes within and among countries.This special issue is concerned with increasing the understanding of the challenges and opportunities involved in governing environmental issues that are cross-jurisdictional and multi-scalar in nature. By definition, the transboundary commons problem cannot be addressed by individual groups of resource users, sectors or administrations. Common environmental goods, such as biodiversity, regional

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“…However, during the wet season, large tracts of the floodplains are inundated, and flow is reversed from the Mekong to the lake. This annual flood pattern is critical for both the productivity of fisheries (Halls and Hortle, 2021;Sabo et al, 2017;Ziv et al, 2012) and the agrarian communities that are reliant upon the annual floodwaters for replenishment of nutrients and water (Arias et al, 2012;Grundy-Warr and Lin, 2020).…”

Section: Introductionmentioning

confidence: 99%

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

Chua

Oeurng

et al. 2022

Hydrol. Earth Syst. Sci.

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Abstract. The Cambodian floodplains experience a yearly flood pulse 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 flood pulse there. We find that minimum water levels over 2010–2019 increased by up to 1.55 m at Kratie and maximum water levels 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 d (Kampong Cham) and 40 d (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 dropped by 1.05 m in 2010–2019 compared to 1996–2009, corresponding to a 20.6 % shrinkage of the lake area. We found that upstream contributors such as current hydropower dams cannot fully account for the observed decline in flood pulse. Instead, local anthropogenic causes such as irrigation and channel incision are important drivers. We estimate that water withdrawal in the Cambodian floodplains is occurring at a rate of (2.1 ± 0.3) km3 yr−1. Sediment decline and ongoing sand-mining operations have also caused channel erosion. As the flood pulse is essential for the ecological habitats, fisheries and livelihoods of the region, its reduction will have major implications throughout the basin, from the Tonle Sap system to the Vietnamese Mekong Delta downstream.

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The unseen transboundary commons that matter for Cambodia's inland fisheries: Changing sediment flows in the Mekong hydrological flood pulse

Cited by 16 publications

References 32 publications

River Discharge and Water Level Changes in the Mekong River: Droughts in an Era of Mega‐Dams

River Discharge and Water Level Changes in the Mekong River: Droughts in an Era of Mega‐Dams

Governing transboundary commons in Southeast Asia

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

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