The development of shrimp aquaculture in the Mekong Delta of Viet Nam is implicated in several patterns of local and regional change. These change trajectories are the emergent properties of complex processes embedded in particular social and spatial contexts. While places have become more interconnected through the global shrimp trade, those interconnections have been highly uneven, distributing risks and rewards disproportionately and producing new forms of conflict and cooperation among participants in the production network.Land use and farming systems in the coastal delta have changed profoundly in recent years. While some areas have become effectively `locked in' to shrimp farming due to environmental changes initiated by salt-water aquaculture, others have remained more flexible, able to rotate rice and shrimp seasonally. Hydrologic conditions, water infrastructures, and farmer experience all contribute to the path-dependence of these change trajectories, but commodity prices exhibit the strongest influence on their direction. Price stabilization may contribute to making prices a sustaining, `slow' variable in system change, not a disruptive `fast' one, heightening overall resilience.The production network of Mekong Delta shrimp is articulated through a variety of socially embedded relationships. Most producers are linked with international markets through informal ties with input suppliers based on trust and shrimp buyers, a relationship marked by opportunism. Processors operate through long-term informal relations with importers based on quality and consistency. This variegated network of relationships means farmers bear the brunt of price shocks, but processors lack quality assurance and traceability. Efforts to link chain participants into closer affiliation must pay attention to these relationships' effects on commodity chain governance.The globalization of the shrimp industry brought about conflicts between producers in the Mekong and Mississippi Deltas. Feminist geographers have posited several responses to globalization, from `counter-topographies' to `diverse economies/resubjectivization.' Living in Viet Nam and working with shrimp producers, I attempted to use these approaches to articulate an internationalist and trans-regional politics. Interactions with people there primarily resubjectivized me and reinforced national-scaled spatial imaginaries, however. Nevertheless, being `Uncle America' offered an insightful perspective into how some Vietnamese understood themselves and Viet Nam's tortured relationship with the U.S.

Thesis (Ph. D. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 288-298).

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23171号 / 工博第4815号 / 新制||工||1752(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 田中 茂信, 准教授 田中 賢治, 准教授 佐山 敬洋 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Rice production plays an important role in the economy of the Mekong River Delta (MRD), but rice production is endangered by sea-level rise and the associated increased incidence of salinity intrusion. This study examines the diffusion of salt-tolerant rice varieties (STRVs) in the MRD that were promoted through Consortium for Unfavorable Rice Environment (CURE) activities. Evidence is found of widespread adoption in salinity-prone areas, with CURE related varieties covering 47% of rice area in at least one of two growing seasons surveyed, but that adopting areas are highly clustered. Multivariate analysis reveals that location characteristics associated with high risk of salinity inundation, rather than individual characteristics associated with household risk preferences, explain the observed pattern of adoption in the MRD. In particular, CURE-related varieties are disproportionately likely to be adopted in non-irrigated areas and in irrigated areas that are not protected by salinity barrier gates. The results imply that CURE has effectively targeted unfavorable rice growing environments and that efforts to further diffuse STRVs need to both increase the area of suitability through further varietal adaptation and promote adoption in existing suitable areas by taking advantage of strong neighborhood externalities in household adoption decisions. In terms of varietal performance, inconclusive evidence is found of higher yields of CURE-related varieties in a low-salinity year. Further, any yield gains are more than off-set by lower market prices for CURE-related varieties. / Rice is a staple crop in the Vietnamese diet and one of Vietnam's leading exports. The Mekong River Delta (MRD) accounts for more than 90 percent of rice exports. However, rice production in the MRD is endangered by saltwater intrusion due to rising sea-levels. Farmers have adopted rice varieties that are tolerant to rice to reduce their production risk that were promoted through Consortium for Unfavorable Rice Environment (CURE) activities. This study examines the rates of adoption of these CURE-related varieties, the reasons farmers choose CURE-related varieties, and variety performance on farmers' fields. Results from a household-level survey show at 47% of fields in salinity-prone areas of the MRD grow a CURE-related variety in at least one of the areas two main rice-growing seasons. Farmers are particularly likely to adopt CURE-related varieties on fields that are not protected against salinity intrusion by gates. Adoption decisions are also highly correlated with neighbors’ decisions within villages. Finally, CURE- and non-CURE-related varieties yields are similar in a year with low levels of salinity intrusion. But revenues from CURE-related varieties are slightly lower due to their lower market price, suggesting CURE-related varieties are a relatively low-cost insurance policy for MRD rice farmers in salinity-prone areas against future salinity intrusion.

The Mekong River Basin (MRB) is famous for its rice farming and export and produces more than 20 million tons of rice per year. Rice production depends on climate, irrigation, soil fertility. However, this region is adversely impacted by several environmental concerns like nutrient deficiency from sediment and saltwater intrusion. The decrease in sediment deposition in the Mekong basin is caused by a number of factors. In China, Lao PDR, and Vietnam, the hydropower generation from dams has improved people's overall living standards, leading in more dams being built or planned in the future. However, dam construction work is adversely impacting the overall salinity condition in this region by reducing upstream flow. Upstream lower flows during the dry season contributes to the increased salinity in the lower Mekong Delta. In addition to these, multiple dams in the upper and middle region of the Mekong basin are trapping sediments and decreasing it in the lower zones. This study found that the reservoirs, built by China between 2008-2015, has reduced the sediment load at all five stations considered in the study. When a reservoir is removed from the model, the sediment load is increased which showed the substantial impact of reservoir construction on sediment load in this area. The landuse pattern is another factor for variability of the sediment yield in the study area. Forest area contributes to higher sediment production whereas agricultural area results in lower sediment yield. The GFDL RCP (4.5) and GFDL RCP (8.5) future climate change projection scenarios used in this study also demonstrated substantial variability in the precipitation pattern for the study region. GFDL RCP (4.5) scenario resulted in a lower sediment yield during the dry season. On contrary to that, GFDL RCP (8.5) showed higher sediment yield due to higher precipitation during the wet season. The severe salinity impact was observed in the Cai Nuoc, Nam Can, and Thanh Phu districts. In Ca Mau province, the observed salinity is highest among the provinces of the study area during dry season (February to May), about 12-14 PPT (parts per thousand) whereas the lowest level of salinity (less than 1 PPT) was observed in the Dong Thap and Vinh Long provinces. This salinity intrusion is adversely impacting the rice production in the study area. In the year 2000, rice production in the Ca Mau province was about 100-150 thousand tons. But salinity intrusion is drastically reducing the rice production in this area, about 10-30thousand tons per year during 2015-2017. Rice production is increasing in the upper deltaic part of the Mekong Delta region where preventive measures were taken. / Master of Science / The Mekong River Basin (MRB) is famous for its rice farming and export and produces more than 20 million tons of rice per year. The rice production is governed by rainfall, temperature, irrigation, soil fertility etc. However, this region is adversely impacted by multiple environmental concerns like nutrient deficiency, sediment concentration, and salinity. The decrease in sediment deposition in the Mekong basin is caused by several factors. In China, Lao PDR, and Vietnam, the hydropower sector has improved people's overall living standards. As a result, more reservoirs are being constructed or planned to be constructed in the future. But this dam construction work is adversely impacting the overall salinity condition in this region. Upstream flows rate during the dry season (February to May) contributes to the increased salinity condition in lower Mekong Delta. In addition to these, multiple dams in the upper portion of the Mekong basin are trapping sediments and decreasing it in the lower region. From the analysis performed in this study it was found that the reservoirs, built by China between 2008-2015, has reduced the sediment load at all five stations. When the reservoir is removed from the model, the sediment load is increased implying the substantial impact of reservoir construction on sediment load in this area. The landuse pattern is another dominating factor for variability of the sediment yield in the study area. Forest area contributes to higher sediment production whereas agricultural area results in lower sediment yield. Two future climate projection scenarios considered for this study are the GFDL RCP (4.5) and GFDL RCP (8.5). These two scenarios also demonstrated substantial variability in the precipitation pattern for the study region. The severe salinity impact was observed in the Cai Nuoc, Nam Can, and Thanh Phu districts. In Ca Mau province, the observed salinity is highest among the provinces of the study area during dry season (February to May), about 12-14 PPT ((parts per thousand) whereas the lowest level of salinity (less than 1 PPT) was observed in the Dong Thap and Vinh Long provinces. This salinity intrusion is adversely impacting the rice yield in the study area. In the year 2000, rice production in the Ca Mau province was about 100-150 thousand tons. But salinity intrusion is drastically reducing the rice production in this area, about 10-30thousand tons per year during 2015-2017. Rice production is increasing in the upper deltaic part of the Mekong Delta region where preventive measures were taken.

The temporal variation of nematode communities in eight mouth stations of the Mekong River system was investigated in order to compare the change between the dry and the wet season. The nematode data was analysed by multivariate techniques such as SIMPROF, MDS, ANOSIM and SIMPER in the software PRIMER v.6 – PERMANOVA. Our results showed that average dissimi-larity between seasons of the nematode communities in each station was high. Seasonal factor did not affect strongly their distribution pattern. Dominant genera Desmodora and Oncholaimellus usually occurred in the sand stations and Parodontophora and Halalaimus were characteristic for the silty group in both seasons. The spatial variations in this estuarine area have an influence that is larger than seasonal factors. / Sự phân bố theo thời gian của quần xã tuyến trùng sống tự do vùng cửa sông Mekong được nghiên cứu nhằm đánh giá sự khác biệt của chúng trong mùa mưa và mùa khô. Dữ liệu của tuyến trùng được xử lý và phân tích đa biến như SIMPROF, MDS, ANOSIM và SIMPER bằng phần mềm PRIMER v.6 – PERMANOVA. Kết quả nghiên cứu cho thấy sự khác biệt theo mùa trong quần xã tuyến trùng tại mỗi điểm là khá lớn nhưng yếu tố mùa không ảnh hưởng gì tới mô hình phân bố của chúng. Một số giống ưu thế trong nền đáy cát như Desmodora and Oncholaimellus trong khi đó Parodontophora và Halalaimus thích nghi nền bùn sét phù sa vẫn hiễn diện trong cả 2 mùa. Kết quả nghiên cứu cũng cho thấy sự biến động trong không gian ở đây lớn hơn sự biến động về mùa vụ.

River basins provide essential services for both humans and ecosystems. Understanding the connections between ecosystems and society and their function has been at the heart of resilience studies and has become an increasing important endeavor in research and practice. In this dissertation, I define basin resilience as a river basin system's capacity to absorb, manage, and adapt to biophysical, social-economic, and political changes (or stressors) while still maintaining its essential structure, feedbacks, and functional integrity. I address the question of resilience, scale, and development in the Mekong and Columbia River Basins. This dissertation answers the following questions: 1) is systems theory an appropriate model to evaluate basin resilience, 2) is the Mekong Basin resilient, 3) are the Mekong and Columbia River Basins resilient across multiple scales, 4) can conflict management and collaborative learning enhance resilience, 5) can a resilience framework be used for basin comparisons, and 6) what lessons can the Mekong basin take from rapid development in the Columbia basin? In Chapter 2, I create and apply a social-ecological systems (SES) model of the Mekong River Basin to assess resilience at sub-basin (provincial), watershed (national), and basin (regional) scales. Feedbacks, thresholds, vulnerability, and adaptive capacity are determined and used as inputs into an overall basin resilience assessment. Drawing upon field work done in the Mekong Basin, Chapter 3 uses Conflict Management and Collaborative Learning processes to address resilience weaknesses across multiple scales in the Mekong Basin. Chapter 4 uses the basin resilience framework to compare the Mekong and Columbia Basins against physical characteristics, development rate, conflict and cooperation, and institutional responses to development projects. In this dissertation I find the Mekong has medium-low basin resilience and that scale is a critical determinant in basin resilience assessments. I find that in this study, vulnerability is inversely proportional to resilience, and low resilience at one scale, for example fisheries in the Tonle Sap Lake in Cambodia, decreases resilience for the entire basin. I find that Cambodia and Lao PDR are the least resilience and Thailand the most resilient countries in the Mekong Basin ��� Thailand more resilient in some sectors than the Mekong River Commission (MRC). I find that the MRC's conflict management strategy is hampered by a restrictive mandate and weakness in capacity building at tributary and national scales but that Collaborative Learning processes are effective in enhancing resilience at the sub-basin scale. Finally, I demonstrate through the basin comparison that the Mekong has a highly resilient biophysical system and traditionally a resilient institutional system however, the proposed rate of development is unsustainable with trends indicating a significant erosion of resilience. I find the Columbia Basin lacking resilience in fishing, hydropower, and water quality ��� sectors mitigating the effects of development in the Columbia Basin, manifesting as overall negative trends in cooperation. However, the Columbia shows signs of increasing cooperation due recent inclusion of Tribal Nations in water management. Flexible and inclusive institutional responses to water resource development challenges, in the Mekong to rapid development on the mainstream and in the Columbia to negotiations over renewal of the Columbia River Treaty, are key determinants to whether or not each basin can halt the current negative trends and strengthen basin resilience to face the challenges now and those coming in the future. / Graduation date: 2013

In recent years, the Mekong delta has been strongly developed both for agriculture and aquaculture. However, there is scope for a negative impact of agriculture on aquaculture in term of production and quality of seafood products. Specifically, the large amount of pesticides imported and used in the Mekong delta not only help agriculture purposes but can also easily enter aquatic systems and affect aquaculture. Pesticides can be transported in the environment by chemo-dynamic procedures and hydrological processes. As a result, pesticides used in agriculture become dispersed and their residues in sediment, water and biota have been detected in the Mekong delta. This study investigated the overall pesticide process including pesticide use, modelling pesticide accumulation and evaluating the potential impact on aquaculture sites for some target aquatic species. The risk of pesticides use in the Mekong delta was addressed in three stages: (1) investigating current pesticide use status in the Mekong delta; (2) modelling pesticide loss and accumulation; (3) classifying pesticide risk areas for aquaculture of target cultured species. A survey of 334 farms covering a total area of ~20,000km2 in the Mekong delta took place between 2008 and 2009. Information on pesticide types and quantities was recorded using questionnaires, and it was found that 96 pesticides in 23 groups were popularly used for agricultural purposes. Dicarboximide, Carbamate and Conazole had the highest use at ~3000, ~2000 and ~2000 g/ha/year respectively. The survey revealed an increase in pesticide use per hectare since previous surveys in the Mekong delta in 1994, 2000, and 2004. However, the highly persistent compounds (WHO classification classes II, III and IV) appeared to have reduced in use. Insecticides previously represented >50% of the total pesticides used, however, the resent survey has shown their use has decreased to ~38%.There was a parallel increase in use of fungicides from previous levels of <30% of total pesticides to more recently ~41%. The combination of pesticide information and geo-location data enabled display and analysis of this data spatially using a Geographic Information System (GIS). A pesticide loss and accumulation model was established through combination of several sub-models including sediment loss and accumulation, direct loss, and water runoff, all of which were implemented and integrated within the GIS environment. MUSLE (Modified Universal Soil Loss Equation) was used to estimate sediment loss and accumulation in the Mekong delta and the Curve Number method (CN Method) was applied to predict water runoff and discharges and flow accumulation. Modelling commenced from the first pesticide application in April, based on 4 day time-steps. All mathematical calculations run within each time step automatically reiterated in the following time step with the new input datasets. The results from fuzzy classification of the pesticide model outcomes were considered in terms of the 96hr lethal concentration (LC50) in order to classify the risk and non-risk areas for catfish and tiger shrimp culture. The sediment loss and accumulation model shows that the highest loss of sediment was in the rainy season, especially in May to October. Vegetables and short term crop areas were found be most strongly eroded. The MUSLE model showed that the highest sediment accumulation was in the hilly areas (~1066.42 tonne/ha/year); lower in riverside areas (~230.39 tonne/ha/year) and lowest in flooded paddy areas (~150.15tonne/ha/year). Abamectin was used as an example throughout this study to estimate pesticide loss and its effects on aquaculture. The results showed that pesticide loss by runoff and sediment loss is less than the loss by half-life degradation (for Abamectin specifically). Accumulation of Abamectin occurred at highest rate in May and October and decreased with time. The spatial models showed that pesticide residues concentrated in the river and riverside areas. In order to evaluate the acute toxicity impacts, three levels of water depth in ponds were modelled as culture depths for catfish and tiger shrimp. The results show that the highest risk areas for catfish occurred in May and October with ~333,000 and ~420,000 ha at a pond depth of 0.5 m; ~136,000 and ~183,000 ha at a pond depth of 1.0 m; and ~10,840 and ~19,000 ha at a pond depth of 1.5 m. Risk areas for catfish mainly concentrated at the riverside and in part of the coastal areas. For tiger shrimp, the risk periods during the year were similar to those found for catfish. The highest risk areas for shrimp were ~648,000 and ~771,000 ha at 0.5 m pond depth; ~346,000 and ~446,700 ha at 1.0 m pond depth; and ~185,000 and ~250,000 ha at 1.5 m pond depth. Overall, deeper ponds reduced the risk. This study has developed a method to evaluate the negative impact of input pesticides to the environment from agricultural use related to fluctuation of aquaculture risk areas. The research indicates the potential relationship between pesticide input and the risk areas for aquaculture. The model has several significant uses: 1) it can provide information to policy makers for a more harmonized development of both aquaculture and agriculture in the Mekong delta in the future, 2) it provides data for aquaculture investment analysis to decrease the hazards caused by pesticide impacts, and 3) it provides a model capable of application to wide field scenarios and suitable for any pesticide type.