Beyond the boom-bust cycle: An interdisciplinary framework for analysing crop booms

The expansion of commercial agriculture is one of the primary drivers of livelihood and land-use changes in the world. Globalisation and other factors have intensified this expansion to the point where booms in single cash crops overtake entire regions before going bust, a pattern that is particularly pervasive in resource frontiers. Using case studies across the Mekong Region, a place which serves as a harbinger for crop booms globally, we propose a new analytical framework for understanding and governing crop booms. We combine multiple theoretical approaches to study crop booms and draw on insights from case study work conducted across temporal and spatial scales. The framework consists of three components: 1) the nested nature of crop boom-bust trajectories, 2) the cyclical spatial and temporal patterns of crop booms, and 3) the variegated pathways and impacts of agrarian change. The framework presents new insights into the processes of agricultural intensification in frontier spaces. As such, it facilitates a better understanding of the drivers, characteristics and impacts of crop booms for researchers and decision-makers alike with the intention of supporting efforts to develop more sustainable pathways in the region and beyond.     

Sediment-related impacts due to upstream reservoir trapping, the Lower Mekong River

A sharp decrease in total suspended solids (TSS) concentration has occurred in the Mekong River after the closure of the Manwan Dam in China in 1993, the first of a planned cascade of eight dams. This paper describes the upstream developments on the Mekong River, concentrating on the effects of hydropower dams and reservoirs. The reservoir-related changes in total suspended solids, suspended sediment concentration (SSC), and hydrology have been analyzed, and the impacts of such possible changes on the Lower Mekong Basin discussed. The theoretical trapping efficiency of the proposed dams has been computed and the amount of sediment to be trapped in the reservoirs estimated. The reservoir trapping of sediments and the changing of natural flow patterns will impact the countries downstream in this international river basin. Both positive and negative possible effects of such impacts have been reviewed, based on the available data from the Mekong and studies on other basins.     

澜湄次区域旅游合作的特点及西双版纳对策

澜湄次区域的旅游合作是由政府高层问的经济合作促成的，通过对澜湄次区域旅游发展现状的分析，发现其旅游产品出现边境游成熟、纵深游起步、水上游以分段游为主的特征，并且区域内国家之间的旅游贸易出现不对等的现象，各个旅游中心城市竞争激烈，在各个因素中，政治环境是影响区域竞争与合作的根本性因素。区域旅游合作既给西双版纳旅游发展带来第二次飞跃的机会，但同时也面临被边缘化、过境化的威胁，针对目前西双版纳旅游发展的现状，提出西双版纳在区域旅游合作中的发展思路和对策。     

EFFECTIVENESS OF REGIONAL TOURISM INTEGRATION——Case of Quadrangle Economic Cooperation Zone in Great Mekong Region

1INTRODUCTION Quadrangle Economic Cooperation Zone (called the Golden Quadrangle) among China, Laos, Myanmar and Thailand is one of the most isolated and troublesome re- gionsinthe world. It hasa longhistoryasone ofthe most politicallysensitive spotsin the world. Wars, refugee mi- grations, drug, closed national borders and lack ofinfras- tructurehavelongbeenconstantbarrierstothisarea. Quadrangle Economic Cooperation Zone is now the focus of Asia. Thailand, Myanmar, Laos and China …     

Hydrogeological investigation in the Mekong Delta around Ho-Chi-Minh City (South Vietnam) by electric tomographyInvestigation hydrogéologique dans le delta du Mékong,autour de la ville de Ho-Chi-Minh (Sud-Vietnam), par tomographie électrique

In the Mekong Delta (South Vietnam), the agglomeration of Ho-Chi-Minh (HCM) City, with more than 5 million inhabitants, is confronted with a dramatic shortage of fresh water supply because of the pollution of several aquifers at different depths. The electric tomography, obtained by concurrent inversion of two complementary geoelectrical methods, the Vertical Electrical Sounding (VES) and the Magneto-Telluric Sounding (MTS), turned out to be very efficient to provide a complete electrical image of the underground from the surface until about 800 m depth. This methodology constitutes a very cheap guide for the evaluation of the quality of the groundwater resources in the vast alluvial plain of the Mekong Delta. To cite this article: V.N. Pham et al., C. R. Geoscience 334 (2002) 733–740.     

大湄公河次地区主要结合带的对比与连接

大湄公河次地区有多条结合带。根据它们及相关构造单元的时空演化和配置关系,对其南北延伸和连接提出了一些新的意见:(1)印缅山脉结合带向北延与葡萄-密支那结合带汇合后,西接雅鲁藏布江结合带;(2)葡萄-密支那结合带西接雅鲁藏布江结合带,向南西被实皆右行断裂错断,其错断部分为西缅中央火山弧带北段的夏杜苏-隆东带,其南段可能潜没在古近纪沉积层之下;(3)班公湖-怒江结合带南延接潞西-抹谷结合带,再南可能潜伏在墨吉群和抹谷群推覆体之下;(4)昌宁-孟连结合带南延接清迈结合带,并在南奔一带与澜沧江结合带相交汇,原先的昌宁-孟连-清迈洋可能与西藏地区的马利-同卡裂谷盆地和双湖-冈玛错小洋盆构成一个类似现今日本海、东海海槽和南海那样呈串珠状分布的盆地带;(5)澜沧江结合带主体为一隐伏在东达山-临沧-景栋花岗岩带推覆体之下的隐伏结合带,向南接清莱-湄他一带的隐伏结合带和马来半岛的文冬-劳勿结合带,向北在西金乌兰湖一带与可可西里-金沙江结合带相交汇,可可西里-澜沧江-文冬-劳勿结合带构成晚古生代冈瓦纲大陆和劳亚大陆的分界;(6)难河-程逸结合带向北延至思茅西边小黑江一带,可能终止在小黑江以北地区,向南接沙缴和贡布-何仙结合带;(7)哀牢山-斯雷博河结合带是新厘定的结合带,从哀牢山向南经南乌河带、老挝奠边府的镁铁质和超镁铁质岩线接黎府结合带和斯雷博河结合带;(8)马江结合带同哀牢山带一样,是一个早、晚古生代两个结合带相叠合的带,早古生代的结合带西接金沙江-哀牢山带,向东经红河左行断裂完全复位后可接越北的斋江结合带(华南洋俯冲形成),与之相应的,它们北面的右江裂谷盆地可与黑河裂谷盆地(或小洋盆)和甘孜-理塘小洋盆相对应,构成一个围绕峨眉地幔柱,并受其影响而形成的晚古生代末-早中生代的盆地带。     

Constructing Risk: multi-scale change,livelihoods and vulnerability in the Mekong Delta,Vietnam

ABSTRACT

Change has been at the heart of the livelihoods concept since its inception, allowing for a clear focus on how people perceive, respond to and experience risk. The ardent focus on ‘the local’ within livelihoods work, both in research and programmatic terms, has to some extent overshadowed attention on the role of wider-scale political economic and environmental processes in generating change and determining responses to change. Livelihoods in the Mekong Delta have never been ‘local’, having long been historically embedded in international, regional and national economic, political and environmental transformations. Drivers of change at these wider scales have intensified, complicating local responses to change, whether through economic, social or political means. A more nuanced appreciation of how scaled relations can be supported is required to better anticipate and respond to the political ecology of risk.     

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

While 1992 marked the first major dam – Manwan – on 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 mega-dam period has increased by up to 98% during the dry season and decreased up as much as −35% 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 −1.55 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 drought – the most severe one in the recent history in the Lower Mekong Basin – was 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.     

Soil salinity and sodicity in a shrimp farming coastal area of the Mekong Delta,Vietnam

Soil salinity and sodicity are environmental problems in the shrimp farming areas of the Cai Nuoc district, Ca Mau province, Vietnam. In 2000, farmers in the district switched en masse from rice cropping to shrimp culture. Due to recent failure in shrimp farming, many farmers wish to revert to a rotational system with rice in the wet season and shrimps in the dry season. So far, all their attempts to grow rice have failed. To assess soil salinity and sodicity, 25 boreholes in shrimp ponds were analysed in four consecutive seasons from 2002 to 2004. The results showed that soil salinity was quite serious (mean EC_e 29.25 dS m⁻¹), particularly in the dry season (mean EC_e 33.44 dS m⁻¹). In the wet season, significant amounts of salts still remained in the soil (mean EC_e 24.65 dS m⁻¹) and the highest soil salinity levels were found near the sea. Soil sodicity is also a problem in the district (exchangeable sodium percentage range 9.63–72.07%). Sodicity is mainly a phenomenon of topsoils and of soils near the sea. Both soil salinity and sodicity are regulated by seasonal rainfall patterns. They could together result in disastrous soil degradation in the Cai Nuoc district.