Climatic controls on drainage basin hydrology and topographic evolution

  • Andrew Chen

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Climate is assumed to influence drainage basin evolution through interactions between rainfall, runoff, and erosion processes. Although former studies have extensively explored climatic controls on land surface processes and landforms, they were mainly targeted humid regions, owing to the lack of data in drylands and limited global databases. In addition, climatic controls tend to covary with other factors, such as vegetation and topography, complicating the detection of climatic signals on landforms. To explore the influences of climate on drainage basin topography across climate zones, this thesis meta-analysed hydrological regimes in the USA, and river longitudinal profile concavity and short- and long-term drainage basin erosion rates around the globe. The data were compiled from published literature and databases and classified by climate classifications. There is a spectrum of downstream changes in water discharge across basin aridity, reflecting different characteristics of rainfall–runoff links between climate zones. These various hydrological regimes control the shapes of river longitudinal profile, which are generally concave-up in all climate zones but systematically straighter with higher aridity. On the other hand, drainage basin erosion rates are influenced by various environmental controls between timescales. Long-term erosion rates are non-linearly related to climate, reflecting the balance between precipitation and vegetation cover. Long-term rates are also enhanced by past glaciation in mid- and high-latitude regions, and positively related to the topography of drainage basin. Short-term rates are dominated by anthropogenic activities and are more detectable in small basins with lower sediment buffering capacity. These results link climate with hydrology and land surface processes, improving our understanding on the influences of climate and climate change on drainage basin evolution.
Date of Award24 Jun 2021
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorDavid A Richards (Supervisor) & Katerina Michaelides (Supervisor)

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