Understanding Catchment Ecohydrological Processes and Their Interactions Across Multiple Spatiotemporal Scales: A Darwinian Approach

dc.contributor.advisorLi, Hong-Yi
dc.contributor.committeeMemberWang, Keh-Han
dc.contributor.committeeMemberMomen, Mostafa
dc.contributor.committeeMemberLee, Hyongki
dc.contributor.committeeMemberSivapalan, Murugesu
dc.creatorAbeshu, Guta Wakbulcho
dc.date.createdMay 2022
dc.description.abstractThe ecohydrological system is a complex adaptive system. Climatic signals propagation through this system takes nonunique pathways, creating nonlinear interactions between climate, soil, water, and vegetation. The synthesis of the links between these components can be approached by a detailed physics-based process understanding or based on emerging patterns and common functionalities across space and time. This dissertation develops a mechanistic understanding of hydrological and ecological processes interactions at the catchment scale based on the latter approach. It has five main objectives: (1) to develop a simple diagnostic framework for exploring links between water balance and vegetation dynamics, (2) to establish a scale-independent function for carbon-water coupling, (3) to explore hydrological processes underpinning vegetation carbon uptake seasonality, (4) to develop and implement a simple dynamic vegetation model global scale, and (5) to enhance global hydrologic model (Xanthos) by adding some aspects of water management. The dissertation begins with the development and validation of two functions. The first function is an analytical framework for the Horton index, derived based on the generalized proportionality hypothesis. The function helped depict the critical role vegetation plays in hydrologic partitioning. It also explained the space-time similarity of the catchment hydrologic state. The second function is a two-parameter linear relationship between carbon uptake and water balance. It simulated seasonal vegetation carbon uptake at catchment and patch levels reasonably. It is also valuable for understanding the catchment transpiration to vaporization ratio. Exploratory data analysis is performed for objective (3). Hysteresis between water supply and productivity and atmospheric demand and productivity was explained by the efficiency of catchment water, energy, and carbon use. It also reveals that vegetation in catchments oscillating between water- and energy-limited states are under hydrologic stress during the peak growing period. Functions from objectives (1) and (2) were coupled with Xanthos. Simulation with this model captured the seasonality and magnitudes of carbon uptake reasonably. Xanthos is further enhanced by adding a water management module that treats irrigation, hydropower, and flood-control reservoirs differently. It is the first attempt to represent hydropower reservoirs in a global model. The model performance is improved significantly in reproducing observed streamflow.
dc.description.departmentCivil and Environmental Engineering, Department of
dc.format.digitalOriginborn digital
dc.identifier.citationPortions of this document appear in: Abeshu, G.W., Li, H.Y., 2021. Horton Index: Conceptual Framework for Exploring Multi-Scale Links Between Catchment Water Balance and Vegetation Dynamics. Water Resour. Res. 57, 1–24. https://doi.org/10.1029/2020WR029343; and in: Abeshu, G.W., Li, H.Y., Zhu, Z., Tan, Z., Leung, L.R., Li, H.Y., 2022. Median bed-material sediment particle size across rivers in the contiguous US. Earth Syst. Sci. Data 14, 929–942. https://doi.org/10.5194/essd-14-929-2022
dc.rightsThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. UH Libraries has secured permission to reproduce any and all previously published materials contained in the work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).
dc.subjectHydrologic System
dc.subjectEcological System
dc.subjectHuman System
dc.subjectCatchment Ecohydrology
dc.subjectGlobal Hydrologic Model
dc.titleUnderstanding Catchment Ecohydrological Processes and Their Interactions Across Multiple Spatiotemporal Scales: A Darwinian Approach
dcterms.accessRightsThe full text of this item is not available at this time because the student has placed this item under an embargo for a period of time. The Libraries are not authorized to provide a copy of this work during the embargo period.
thesis.degree.collegeCullen College of Engineering
thesis.degree.departmentCivil and Environmental Engineering, Department of
thesis.degree.disciplineCivil Engineering
thesis.degree.grantorUniversity of Houston
thesis.degree.nameDoctor of Philosophy


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