The hydro-dam can help increase adaptation to climate change and meet water, energy, and food needs as a widely adopted water infrastructure. However, it alters and fragments ecosystems, especially at places where hydro-dam constructions are gaining popularity for the sake of more socio-economic benefits. This dissertation examines and characterizes the process and outcomes of ecosystem changes owing to hydro-dams, using the Mekong River Basin as an example. The overarching research question is answered from four angles, including 1) finding new essential properties of dams, 2) determining dams' impact scope on land change, 3) estimating cascade consequences of dams on significant water bodies, and 4) analyzing dams' ripple effect on the atmosphere. The main body (Chapters 2-4) of this dissertation consists of three articles. In Chapter 2, I achieve the first two research goals by performing time-serial trajectory analyses on 67 working Mekong hydro-dams and the lands surrounding them using long-term geospatial imageries and statistical methods. In Chapter 3, I calculated and analyzed the open water surface area of the Tonle Sap Lake and the changes at a 16-day interval from 2001 to 2015 to assess how upstream hydro-dam proliferation has influenced the largest inland lake in the lower basin. In Chapter 4, the spatial variations of inundation areas in the Tonle Sap Lake floodplain and temporal changes of the greenhouse gas (such as carbon dioxide and nitrous oxide) emissions from the changing lands were modeled and quantified using geospatial datasets and a biogeochemical model to provide a solution to the fourth research question. In summary, this dissertation has successfully established a new remote sensing approach that enables hydro-dam characterization and set up a combined framework combining geospatial modeling and biogeochemical modeling. The three studies come to the conclusions that 1) hydro-dams' impact scale on land change is spatially anisotropic at the local level, 2) hydro-dams' cascade consequence on a large water body at a remote place is significant, and 3) hydro-dams' ripple effect on floodplain via water and lands can cause more greenhouse gas emissions into the atmosphere. This dissertation can enrich the current literature regarding human-nature interactions, focusing on hydro-dam's role in the ecosystem. It also broadens the knowledge of hydro-dams' impacts and attracts more relevant studies and environmental protection efforts. More importantly, this dissertation can assist future policy-making, especially for sustainable hydro-dam planning and transboundary water resource management.
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