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.

This thesis attempted a cross-species replication of Bland, et. al., 2018. Human participants went through a computerized, automated shaping procedure that trained them to click on and discriminate between a blue square (SD) and red square (S-delta) on a VR 12 schedule of reinforcement. Three conditions were then presented to the participants consisting of a baseline, punishment, and control condition. In the punishment and control conditions, the SD was replaced by the S-delta or a novel stimulus respectively for 1-second on a VR 5 schedule. With each click, the reaction time and specific object clicked on were recorded. While the present study partially replicated the effect seen in earlier research, our results suggest that, depending on the lens of analysis used, either a punishment or an extinction effect may be causing the results seen.

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.

No / The prime concern by the Nigerian state in the management of the oil conflicts in the Niger Delta has been to maximise oil revenues. What is probably most confounding about this strategy is the evolving tendency to twist and treat every conflict in the Niger Delta, including some episodic 'epi-oil' conflicts abetted or orchestrated by the state itself, as oil conflicts. In other words, there is a tendency on the part of the state to wittingly 'oilify' some apparently extra-oil conflicts. Compared to other regimes before it, the present civilian administration has probably contributed most to the fast-tracking of this evolving phenomenon. This article unravels and analyses the evolving politics of oilification of extra-oil conflicts in the Niger Delta, its underlying rationale and consequences. Oilification, as the study demonstrates, is yet another in the series of dangerous contradictions engendered by the Nigerian state. How this and other dangerous contradictions could possibly be solved is a research conundrum for the relevant cognoscenti of state-society relations and conflicts in Nigeria. But would the Nigerian state take on board any useful and promising solutions materialising from such studies? This is most unlikely in the present conjuncture given the prevailing configuration of interests in the state.

Understanding the dynamics of agricultural basins has been difficult for decision-makers when developing cost-effective plans. An uncertainty analysis evaluates the impact of information gaps on hydrologic model’s output and performance. The Agricultural Policy/Environmental Extender (APEX v1501) was used to predict runoff, crop yield, sediment load, total phosphorus, and total nitrogen from agricultural fields in the Mississippi Delta to investigate the impact of using different input variables (climate, soils, and management practices) on mechanistic models. Results indicated that the use of surrogate information such as weather data from close weather stations, a predominant soil series, and simulated irrigation schedules, could be considered when available in situ information is restricted. Overall results provided information on model setup and output interpretation that may be useful to Mississippi Delta decision-makers.

This thesis examines the historical and contemporary roots of food apartheid in the Yazoo-Mississippi Delta, while employing a Black Food Geographies approach to highlight and interpret the lived experiences of people in the Delta. This work draws on interviews and participant observation in Clarksdale, Mississippi, to decenter popular narratives around food insecurity and region and instead center the ideas and opinions of people directly impacted. The thesis highlights Black Deltans’ experiences and understandings of food and foodways to provide a nuanced picture of how residents interpret, negotiate, and challenge the region’s unequal food geographies in light of a longer history of food apartheid

Integrating water-saving technologies with optimized nutrient management strategies provides opportunities for sustainable agriculture in the Mississippi Delta. Three studies were conducted to determine the effects of irrigation systems, row patterns, and nutrient management strategies on corn and soybeans. The first study determined the effects of irrigation, row pattern, and nitrogen (N) placement methods on corn (Zea mays L.) productivity and N use efficiency. The effects of N placement methods were only evident in 2021 when the rainfall events were more pronounced than in 2020. Regardless of the row pattern, placing N with one knife increased corn grain yield and the agronomic N use efficiency by 14.1% and 16.8%, respectively, when compared to the surface dribble method. The second study investigated the effects of irrigation systems and row patterns on grain yield, grain quality parameters, and irrigation water use efficiency (IWUE) on soybeans (Glycine max L.) grown on Sharkey clay. When irrigation was triggered at -80 kPa, furrow-irrigated soybeans produced 3.9% more grain yield compared to sprinkler-irrigated soybeans. The total amount of water applied by the sprinkler irrigation system represented 19-52% of the total amount applied by the furrow system. Narrow-row patterns achieved greater IWUE than single-row patterns. In the third study, we evaluated the effects of N and irrigation levels on grain quantity, quality, and plant growth on corn grown across different soil electrical conductivity (EC) levels and its implications for variable rate technology. Corn grain yields increased with the increase of N and irrigation levels but decreased as soil EC decreased. Overall, maintaining a sprinkler irrigation threshold between -40 and -70 kPa optimized corn yield. In addition, these results did not provide enough evidence to use variable rate irrigation or variable rate N application in the Mississippi Delta.

Thesis (MSc) -- Stellenbosch University, 1973. / The Marble Delta is an area of approximately 40 sq. km in Natal (30°22' Long., 30°40' Lat.), occupied by Precambrian marble and associated granites. The deeply dissected country was geologically mapped on a scale of I : 6 000. A new lithostratigraphic classification of the metasediments is proposed. The base of the lowermost Le Joncguet Formation (composed of dolomitic marble and siliceous beds) is not exposed. This is followed by the predominantly ca.lcitic Oribi Formation with interbedded dolomite and graphitic layers. The marble is unconformably overlain by the Cherrywillingham Formation which comprises mainly amphibolite and granulite. The .three formations together constitute the Marble Delta Group. The main petrological units are calc-silicate marble, metaquartzite, dolomite marble, cluster serpen~ine marble and ce,lcite marble. Graphite layers are considered to have originated in situ from organic remains; there is occasional evidence of ionic transfer of carbon from this graphite by magmatic fluids. The common mineral assemblages are diopside + calcite + dolomite, tremolite + calcite + diopside + quartz, calcite + quartz + dolomite, forsterite + calcite + dolomite, plagioclase + cordierite + garnet + quartz, amphibole + clinopyroxene + plagioclase, hornblende + clinopyroxene + calcite, wollastor~te + calcite + diopside. Other minerals are graphite, antigorite, chrysotile, sphene, spinel, clinohumite, chondrodite, zoisite, clinozoisite, hedenbergite, phlogopite, ilmenite, hercynite, dravite, cummingtonite, talc, apatite, microcline, saponite. The mineral assemblages resulted from regional metamorphism and polyphase contact metamorphism.

published_or_final_version / abstract / toc / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning

published_or_final_version / abstract / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy