Geomorphic and Sedimentary Effects of Modern Climate Change: Current and Anticipated Future Conditions in the Western United States

The availability of planetary-scale geospatial datasets that can support the study of water-related disasters in the Anthropocene is rapidly growing. We review 124 global and free datasets allowing ...

https://onlinelibrary.wiley.com/doi/pdf/10.1002/wat2.1424

A review of freely accessible global datasets for the study of floods, droughts and their interactions with human societies

An improved understanding of changes in flood hazard and the underlying driving mechanisms is critical for predicting future changes for better adaptation strategies. While recent increases in flooding across the world have been partly attributed to a range of atmospheric or landscape drivers, one often-forgotten driver of changes in flood properties is the variability of river conveyance capacity. This paper proposes a new framework for connecting flood changes to longitudinal variability in river conveyance, precipitation climatology, flows and sediment connectivity. We present a first step, based on a regional analysis, towards a longer-term research effort that is required to decipher the circular causality between floods and rivers. The results show how this system of interacting units in the atmospheric, hydrologic and geomorphological realm function as a nonlinear filter that fundamentally alters the frequency of flood events. To revise and refine our estimation of future flood risk, this work highlights that multidriver attribution studies are needed, that include boundary conditions such as underlying climate, water and sediment connectivity, and explicit estimations of river conveyance properties.

/pdf/floods-and-rivers-a-circular-causality-perspective-38drq499gk.pdf

Floods and rivers: a circular causality perspective

Challenges exist for assessing the impacts of climate and climate change on the hydrological cycle on local and regional scales, and in turn on water resources, food, energy, and natural hazards. Potential evapotranspiration (PET) represents atmospheric demand for water, which is required at high spatial and temporal resolutions to compute actual evapotranspiration and thus close the water balance near the land surface for many such applications, but there are currently no available high-resolution datasets of PET. Here we develop an hourly PET dataset (hPET) for the global land surface at 0.1° spatial resolution, based on output from the recently developed ERA5-Land reanalysis dataset, over the period 1981 to present. We show how hPET compares to other available global PET datasets, over common spatiotemporal resolutions and time frames, with respect to spatial patterns of climatology and seasonal variations for selected humid and arid locations across the globe. We provide the data for users to employ for multiple applications to explore diurnal and seasonal variations in evaporative demand for water.

https://biblio.ugent.be/publication/8720026/file/8720027.pdf

Hourly potential evapotranspiration at 0.1° resolution for the global land surface from 1981-present

Constraining Remote River Discharge Estimation Using Reach-Scale Geomorphology

It has long been suggested that climate shapes land surface topography through interactions between rainfall, runoff and erosion in drainage basins1,2,3,4. The longitudinal profile of a river (elevation versus distance downstream) is a key morphological attribute that reflects the history of drainage basin evolution, so its form should be diagnostic of the regional expression of climate and its interaction with the land surface5,6,7,8,9. However, both detecting climatic signatures in longitudinal profiles and deciphering the climatic mechanisms of their development have been challenging, owing to the lack of relevant global data and to the variable effects of tectonics, lithology, land surface properties and human activities10,11. Here we present a global dataset of 333,502 river longitudinal profiles, and use it to explore differences in overall profile shape (concavity) across climate zones. We show that river profiles are systematically straighter with increasing aridity. Through simple numerical modelling, we demonstrate that these global patterns in longitudinal profile shape can be explained by hydrological controls that reflect rainfall–runoff regimes in different climate zones. The most important of these is the downstream rate of change in streamflow, independent of the area of the drainage basin. Our results illustrate that river topography expresses a signature of aridity, suggesting that climate is a first-order control on the evolution of the drainage basin.

/pdf/aridity-is-expressed-in-river-topography-globally-14yl8b54ub.pdf

Aridity is expressed in river topography globally.

/pdf/author-correction-aridity-is-expressed-in-river-topography-vnuoodyz.pdf

Author Correction: Aridity is expressed in river topography globally

Abstract. Erosion is directly tied to landscape evolution through
the relationship between sediment flux and vertical lowering of the land
surface. Therefore, the analysis of erosion rates across the planet measured
over different temporal domains may provide perspectives on the drivers and
processes of land surface change over various timescales. Different
metrics are commonly used to quantify erosion (or denudation) over
timescales of <101 years (suspended sediment flux) and
103–106 years (cosmogenic radionuclides), meaning that reconciling potentially
contrasting rates at these timescales at any location is challenging.
Studies over the last several decades into erosion rates and their controls
have yielded valuable insights into geomorphic processes and landforms over
time and space, but many are focused at local or regional scales. Gaps remain
in understanding large-scale patterns and exogenous drivers (climatic,
anthropogenic, tectonic) of erosion across the globe. Here we leverage the
expanding availability and coverage of cosmogenic-derived erosion data and
historical archives of suspended sediment yield to explore these controls
more broadly and place them in the context of classical geomorphic theory.
We make the following findings in this paper: (1) there are relationships between both long- and short-term erosion rates and mean annual precipitation, as well as aridity, similar to that proposed in classic
geomorphic literature on erosion; (2) agricultural activities have apparently
increased short-term erosion rates, outpacing natural drivers; (3) short-term
erosion rates exceed long-term rates in all climatic regions except in mid- and high latitudes, where long-terms rates are higher due to the influence
of repeated glacial cycles; and (4) tectonically active margins have generally
higher long-term erosion rates and apparently lower rainfall thresholds for
erosion which potentially arise due to steeper slopes and associated
landslides, overcoming vegetative root reinforcement. These results
highlight the complex interplay of external controls on land surface
processes and reinforce the view that timescale of observation may reveal
different erosion rates and principal controls.


/pdf/exploring-exogenous-controls-on-short-versus-long-term-1d4imp1o.pdf

Exploring exogenous controls on short- versus long-term erosion rates globally

/pdf/author-correction-aridity-is-expressed-in-river-topography-16h9gg3q.pdf

Shiuan-An Chen

Papers

Aridity is expressed in river topography globally.

Author Correction: Aridity is expressed in river topography globally

Exploring exogenous controls on short- versus long-term erosion rates globally

Author Correction: Aridity is expressed in river topography globally

Reply to: Climate versus tectonics as controls on river profiles