Browsing by Author "Tran, Hoa Thi"

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    Drought and Human Impacts on Land Use and Land Cover Change in a Vietnamese Coastal Area
    Tran, Hoa Thi; Campbell, James B. Jr.; Wynne, Randolph H.; Shao, Yang; Phan, Son Viet (MDPI, 2019-02-08)
    Drought is a dry-weather event characterized by a deficit of water resources in a period of year due to less rainfall than normal or overexploitation. This insidious hazard tends to occur frequently and more intensively in sub-humid regions resulting in changes in the landscape, transitions in agricultural practices and other environmental-social issues. The study area is in the sub-humid region of the northern coastal zone of Binh Thuan province, Vietnam—Tuy Phong district. This area is indicated as a subject of prolonged droughts during 6-month dry seasons, which have occurred more frequently in recent years. Associated with economic transitions in agricultural practicing, urbanization, and industrialization, prolonged droughts have resulted in rapid changes in land use and land cover (LULC) in Tuy Phong, especially in three coastal communes: Binh Thanh, Lien Huong, and Phuoc The. A bi-temporal analysis using high-resolution data, the 2011 WorldView2 and the 2016 GeoEye1, was examined to assess LULC changes from observed severe droughts in those three communes. Results showed a dramatic reduction in the extent of hydrological systems (about 20%), and significant increases of tree canopies in urban areas and near the coastal areas (approximately 76.8%). Paddy fields declined by 51% in 2016; such areas transitioned to inactive status or were alternated for growing drought-tolerant plants. Shrimp farming experienced a recognizable decrease by approximately 44%. The 2014 map and field observations during summer 2016 provide references for object-based classification and validation. Overall agreement of results is about 85%.
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    Integration of Geospatial Technologies in Monitoring Drought Events in a Coastal Area of Vietnam (Case study: Binh Thuan Province)
    Tran, Hoa Thi (Virginia Tech, 2019-11-08)
    Drought is a climatic event regarding prolonged "drier than normal" conditions. Precipitation deficits, crop-moisture stress, soil-water unbalance, sudden stream flow cut-offs and low carrying capacity of ecosystems are responses to drought. Drought can occur in humid to arid climates, however, drought is more severe in arid and semi-arid areas due to the fact that in those distinctive areas, water resources are extremely limited and restricted. Additionally, local ecologies and ecosystems in arid regions are very fragile. Once a water competition occurs, critical services of ecosystems such as pure water, recreation, and land productivity will be threatened. This research focuses on prolonged drought events that have been occurring more frequently in a coastal province of South Central Vietnam – named Binh Thuan. The study area is distinctive because its climate is characterized as one of the driest provinces in Vietnam. Annual rainfall in the North and near the coast of the province is less than 800 mm per year. During 6 months of dry season, there is almost no rain, or less than 50 mm. Due to precipitation deficits and high surface temperatures in recent years, meteorological droughts have occurred more frequently, and lasted longer, thereby stressing water resources for vegetation, wildlife, households, and industry. The occurrence of prolonged droughts has constrained economic activities in the coastal areas, especially agriculture and aquaculture. Furthermore, a long duration of dry conditions coupled with unsustainable land management (such as overgrazing), "drought-sensitive" soils in areas with sand and barren lands may introduce and accelerate risks of desertification processes (land productivity deterioration and unable to recover). This research uses geospatial technologies to monitor drought severity and drought impacts on land use and land cover. Chapter 1 is a brief introduction and literature review of the drought context in Binh Thuan Province to place the research questions and objectives in content. Chapter 2 discusses the occurrence of meteorological droughts in Binh Thuan Province, then proposes climatic indices able to monitor this type of drought. Chapter 3 focuses on explaining and assessing uneven dry conditions that stressed vegetation health in the study area. This chapter investigates spatiotemporal distributions and frequencies of prolonged agricultural droughts using remotely sensed data and anomalies of precipitation distribution. Results indicate that coastal areas in the North of Binh Thuan are subject to severe droughts. Chapter 4 assesses human impacts on land management and practices in the study area during drought periods. Results show that in recent years (2010 to present), local governments and residents have implemented strategies to prevent sand dominance and to adapt to water shortages during dry seasons, such as vegetative cover, crop rotation with drought-tolerant plants and wind breaks. Accuracy was assessed using field data collected in the summer of 2016, in conjunction with Google Earth imagery. In summary, this dissertation enhances understanding of drought events and impacts in Binh Thuan Province by considering different types of drought - meteorological and agricultural drought, and interactions of drought and human impacts upon land management and land practices during dry periods. Furthermore, findings and results of this research have demonstrated the effectiveness of remotely sensed datasets, and other geospatial technologies, such as geographic information systems, in modeling drought severity and in examining efforts and drought-adaptive practices of local residents. This work is a valuable foundation on which further studies can build to support policy development to protect and reserve soil-land productivity in Binh Thuan and other coastal regions of Vietnam affected by prolonged droughts.
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