Michael Bliss Singer

Michael Bliss Singer
University of California, Santa Barbara | UCSB · Earth Research Institute

PhD

About

92
Publications
18,414
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1,686
Citations
Introduction
Additional affiliations
July 2017 - present
Cardiff University
Position
  • Academic
June 2003 - present
University of California, Santa Barbara
Position
  • Researcher

Publications

Publications (92)
Article
Full-text available
Dryland riparian woodlands are considered to be locally buffered from droughts by shallow and stable groundwater levels. However, climate change is causing more frequent and severe drought events, accompanied by warmer temperatures, collectively threatening the persistence of these groundwater dependent ecosystems through a combination of increasin...
Article
Full-text available
Climate and weather services support important decision making in many sectors across the Greater Horn of Africa. Though constantly improving, there is a mismatch between the provision of these services and the needs of target stakeholders. To better understand this, we interviewed 23 practitioners who work with climate, weather, and hydrological i...
Preprint
Potential evapotranspiration (PET) represents the evaporative demand in the atmosphere for the removal of water from the land and is an essential variable for understanding and modelling land-atmosphere interactions. Weather generators are often used to generate stochastic rainfall time series; however, no such model exists for stochastically gener...
Article
Full-text available
Dryland regions are characterised by water scarcity and are facing major challenges under climate change. One difficulty is anticipating how rainfall will be partitioned into evaporative losses, groundwater, soil moisture, and runoff (the water balance) in the future, which has important implications for water resources and dryland ecosystems. Howe...
Article
Full-text available
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 e...
Article
Full-text available
As global climate change continues to impact regional water cycles, we may expect further shifts in water availability to forests that create challenges for certain species and biomes. Lowland deciduous riparian forests are particularly vulnerable because tree species cannot migrate out of the stream corridor, and they rely on root zone water avail...
Article
Full-text available
As droughts become more frequent and more severe under anthropogenic climate change, water stress due to diminished subsurface supplies may threaten the health and function of semi-arid riparian woodlands, which are assumed to be largely groundwater dependent. To better support the management of riparian woodlands under changing climatic conditions...
Article
Significance Riparian ecosystems are biodiversity hotspots under intense pressure from multiple stressors. In most water-limited regions, high human water use from agricultural and urban development eclipses environmental water needs and intensifies ecosystem water stress. In particular, adequate consideration of riparian water needs in water resou...
Article
Full-text available
Vegetation distribution, composition and health in arid regions are largely dependent on water availability controlled by climate, local topography and geology. Despite a general understanding of climatic and geologic drivers in plant communities, trends in plant responses to water distribution and storage across areas under different local control...
Preprint
Full-text available
Dryland regions are characterized by water scarcity and are facing major challenges under climate change. One difficulty is anticipating how rainfall will be partitioned into evaporative losses, groundwater, soil moisture and runoff (the water balance) in the future, which has important implications for water resources and dryland ecosystems. Howev...
Preprint
Full-text available
Measuring erosion rates, analysing their temporal variations, and exploring environmental controls are crucial in the field of geomorphology because erosion through sediment transport in drainage basins shapes landforms and landscapes. Thus, important insights into landscape controls can be gleaned from analyses of erosion rates measured over diffe...
Preprint
Full-text available
In drylands, characterised by water scarcity and frequent meteorological droughts, knowledge of soil moisture dynamics and its drivers (evapotranspiration, soil physical properties and the timing and sequencing of precipitation events) is fundamental to understanding changes in water availability to plants and human society, especially under a nons...
Article
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Despite clear signals of regional impacts of the recent severe drought in California, e.g., within Califor-nian Central Valley groundwater storage and Sierra Nevada forests, our understanding of how this drought affected soil moisture and vegetation responses in lowland grasslands is limited. In order to better understand the resulting vulnerabilit...
Article
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Climate variability and change along with anthropogenic water use have affected the (re)distribution of water storage and fluxes across the Contiguous United States (CONUS). Available hydrological models, however, do not represent recent changes in the water cycle. Therefore, in this study, a novel Bayesian Markov Chain Monte Carlo-based Data Assim...
Article
Semi‐arid riparian woodlands face threats from increasing extractive water demand and climate change in dryland landscapes worldwide. Improved landscape‐scale understanding of riparian woodland water use (evapotranspiration, ET) and its sensitivity to climate variables is needed to strategically manage water resources, as well as to create successf...
Preprint
Full-text available
Despite clear signals of regional impacts of the recent severe drought in California within Central Valley groundwater storage and Sierra Nevada forests, our understanding of how this drought affected soil moisture and vegetation responses in lowland grasslands is limited. In order to better understand the resulting vulnerability of these landscape...
Article
Full-text available
Transmission losses from the beds of ephemeral streams are thought to be a widespread mechanism of groundwater recharge in arid and semi‐arid regions and support a range of dryland hydro‐ecology. Dryland areas cover ~40% of the Earth's land surface and groundwater resources are often the main source of freshwater. It is commonly assumed that where...
Preprint
Submitted manuscript currently under review at Geophysical Research Letters (American Geophysical Union publication).
Article
Historically, hydrological models have been developed to represent land-atmosphere interactions by simulating water storage and water fluxes. These models, however, have their own unique characteristics (strength and weakness) in capturing different aspects of the water cycle, and their results are typically compared to or calibrated against in-sit...
Article
Full-text available
Hydrological regimes are being perturbed under climate change due to the regional expression of the water cycle across the globe, leading to alterations in the spatial and temporal distribution of water near the Earth's surface. Water is a critical resource for plant ecosystems, and hydrological limitations on vegetative health are particularly com...
Article
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It has long been suggested that climate shapes land surface topography through interactions between rainfall, runoff and erosion in drainage basins1–4. 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...
Article
Cache Creek (Coast Range, California) and the Yuba River (Sierra Nevada Foothills, California) are two river systems affected by extensive mercury (Hg) contamination due to legacy sources of Hg related to mining. Stable Hg isotope techniques have proven useful for elucidating the complex cycling of Hg within aquatic ecosystems, and we applied these...
Article
Full-text available
Since the onset of hydraulic gold mining in California’s Sierra Nevada foothills in 1852, the environmental damage caused by displacement and storage of hydraulic mining sediment (HMS) has been a significant ecological problem downstream. Large volumes of mercury-laden HMS from the Yuba River watershed were deposited within the river corridor, crea...
Article
Full-text available
Assessments of water balance changes, watershed response, and landscape evolution to climate change require representation of spatially and temporally varying rainfall fields over a drainage basin, as well as the flexibility to simply modify key driving climate variables (evaporative demand , overall wetness, storminess). An empirical-stochastic ap...
Article
Full-text available
Bed load sediment transport is an inherently challenging process to measure within a river, which is further complicated by the typically transient nature of the hydrograph. Here we use laboratory experiments to explore how sediment flux under transient—unsteady and intermittent—flow differ from those under steady flow. For a narrow unimodal sedime...
Article
Full-text available
Assessments of water balance, watershed response, and landscape evolution to climate change require representation of spatially and temporally varying rainfall fields over a drainage basin, as well as the flexibility to simply modify key driving climate variables (evaporative demand, overall wetness, storminess). An empirical-stochastic approach to...
Article
Full-text available
Soil moisture patterns in floodplains are highly dynamic, owing to the complex relationships between soil properties, climatic conditions at the surface, and the position of the water table. Given this complexity, along with climate change scenarios in many regions, there is a need for a model to investigate the implications of different conditions...
Article
Full-text available
The long-term evolution of channel longitudinal profiles within drainage basins is partly determined by the relative balance of hillslope sediment supply to channels and the evacuation of channel sediment. However, the lack of theoretical understanding of the physical processes of hillslope-channel coupling makes it challenging to determine whether...
Chapter
The geomorphology and sediment regimes of intermittent rivers and ephemeral streams (IRES) are extremely diverse, owing in large part to the substantial spatiotemporal variability of the associated hydrological regimes. We describe the geomorphological character and sediment transport processes along IRES within the context of four geomorphological...
Article
Full-text available
In drylands, convective rainstorms typically control runoff, streamflow, water supply and flood risk to human populations, and ecological water availability at multiple spatial scales. Since drainage basin water balance is sensitive to climate, it is important to improve characterization of convective rainstorms in a manner that enables statistical...
Poster
Full-text available
Poster on the impacts of transient hydrographs on sediment mixtures. The key take away is that the total sediment flux depends on the integral of the forcing above the yield stress of the bed mixture, but not to the specific details of the flood.
Article
Monomethyl mercury (MMHg) and total mercury (THg) concentrations and Hg stable isotope ratios (δ202Hg and Δ199Hg) were measured in sediment and aquatic organisms from Cache Creek (California Coast Range) and Yolo Bypass (Sacramento Valley). Cache Creek sediment had a large range in THg (87 to 3870 ng/g) and δ202Hg (− 1.69 to − 0.20‰) reflecting the...
Article
The biogeochemical cycling of metals and other contaminants in river-floodplain corridors is controlled by microbial activity responding to dynamic redox conditions. Riverine flooding thus has the potential to affect speciation of redox-sensitive metals such as mercury (Hg). Therefore, inundation history over a period of decades potentially holds i...
Article
Full-text available
The seasonal availability of water within a tree's rooting zone may be an important determinant for individual tree growth and overall forest health, particularly in riparian corridors of Mediterranean climate zones that are vulnerable to water stress. Here, we present a new method that combines dendro-isotopes and isotope modelling for determining...
Article
Full-text available
We measured total mercury (THg) and monomethyl mercury (MMHg) concentrations and mercury (Hg) isotopic compositions in sediment and aquatic organisms from the Yuba River (California, USA) to identify Hg sources and biogeochemical transformations downstream of a historical gold mining region. Sediment THg concentrations and δ202Hg decreased from the...
Article
Full-text available
Sediment supply from banks and terraces has important implications for grain-size distributions in alluvial rivers (and by extension for aquatic habitat), as well as for the delivery of floodplain-stored nutrients and contaminants to the aquatic environment. The interactions between streamflow hydrographs and lateral channel boundary failure contro...
Article
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Most large rivers in industrialized nations are managed carefully to maximize their benefits (e.g., water supply, hydroelectricity), while limiting their hazards (e.g., floods). Management strategies employed in lowland river systems such as large dams, levees, and bypasses affect flow regimes, sediment supply to channels, and the net flux of sedim...
Article
Full-text available
Flooding is a major hazard to lives and infrastructure, but trends in flood hazard are poorly understood. The capacity of river channels to convey flood flows is typically assumed to be stationary, so changes in flood frequency are thought to be driven primarily by trends in streamflow. We have developed new methods for separately quantifying how t...
Poster
Full-text available
Link to paper: http://onlinelibrary.wiley.com/doi/10.1002/2014GL062482/abstract
Article
Full-text available
The lack of topographic complexity in ephemeral dryland channels, despite large variations in hydraulic controls and sediment texture, presents an unexplained paradox that limits understanding of their long-term evolution. In dryland basins, spatially and temporally discontinuous channel flow transports and sorts sediment along the bed intermittent...
Article
Full-text available
Sediment supply from hillslopes to channels is an important control on basin functioning and evolution. However, current theoretical frameworks do not adequately consider processes of runoff-driven hillslope sediment supply, which affect river channels spatially and temporally. Mountainous dryland basins exhibit an important manifestation of these...
Article
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Key points: Water shifts due to climatic fluctuations between floodplain storage reservoirsAnthropogenic changes to hydrology directly impact water available to treesEcohydrologic approaches to integration of hydrology afford new possibilities.
Article
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The interrelationships between hydrologically driven evolution of legacy landscapes downstream of major mining districts and the contamination of lowland ecosystems are poorly understood over centennial time scales. Here, we demonstrate within piedmont valleys of California's Sierra Nevada, through new and historical data supported by modeling, tha...
Article
Growth responses of riparian trees to changes in water availability are poorly understood, thereby limiting understanding of regional drought implications in river corridors. We used dendrochronological methods to develop growth series and analysed oxygen isotopic ratios (d 18 O) in a-cellulose from individual tree rings for two co-occurring ripari...
Article
We analyzed eight sediment cores from wetland and subtidal locations around San Francisco (SF) Bay, terrace sediment from the Yuba River, CA and precipitation from the SF Bay region. We defined the Hg isotopic composition of uncontaminated SF Bay sediment, two contributing endmember sediments contaminated by distinct Hg sources, and regional precip...
Article
Full-text available
Alluvial riverbed elevation responds to the balance between sediment supply and transport capacity, which is largely dependent on climate and its translation into fluvial discharge. We examine these relations using U.S. Geological Survey streamflow and channel measurements in conjunction with basin characteristics for 915 reference (“least disturbe...
Article
Full-text available
Direct measurements of suspended sediment concentration (SSC) in rivers are surprisingly sparse. We present an approach for measuring these concentrations from space, tailored to fit rivers with limited records of flood-level SSC. Our approach requires knowledge of a typical particle-size distribution of sediment suspended during floods, the domina...
Conference Paper
Riparian trees have growth responses to varying water sources that are more subtle than those of their upland counterparts, but differences in water use between co-occurring riparian species are not easily discerned by conventional dendrochronology. While tree ring isotopes have been developed as a useful tool for understanding past climate (temper...
Article
Full-text available
Landscape erosion rates are a function of several independent and interacting variables including drainage area, topographic relief, lithology, climate, and anthropogenic influences. Although there exist measurements of basin-wide erosion rates over 10^4-10^7 timescales within the conterminous USA and site-based topographic measurements of erosion/...
Article
The fate and transport of mercury are of critical concern in lowland floodplains and wetlands worldwide, especially those with a history of upstream mining that increases the mobility of both dissolved and sediment-bound Hg in watersheds. A mass budget of total mercury (THg) quantifies sources and storage for particular areas - knowledge that is re...
Article
Full-text available
Julien P. Y. 2010. Erosion and Sedimentation, 2nd ed. xviii + 371 pp. Cambridge University Press. Price £80.00, US$ 140.00 (HB); £35.00, US$ 60.00 (PB). ISBN 978 0 521 83038 (HB); 978 0 521 53737 7 (PB). - Volume 148 Issue 4 - Michael B. Singer
Article
Theories for the development of longitudinal and grain size profiles in perennial fluvial systems are well developed, allowing for generalization of sediment flux and sorting in these fluvial systems over decadal to millennial time scales under different forcings (e.g., sediment supply, climate changes, etc). However, such theoretical frameworks ar...
Article
Full-text available
Hydraulic gold mining in the Sierra Nevada, California (1853–1884) displaced ~1.1 billion m3 of sediment from upland placer gravels that were deposited along piedmont rivers below dams where floods can remobilize them. This study uses topographic and planimetric data from detailed 1906 topographic maps, 1999 photogrammetric data, and pre- and post-...
Article
The lower Ebro experiences long-term hydrological and sedimentary alterations due to upstream reservoirs. One of the most important consequences is the disruption of sediment transfer, a fact that reduces the sediment load and affects river morphology. Among other factors, the low rates of sediment transport in the fluvial system favour the develop...
Article
Full-text available
Flow Country blanket bogs in northern Scotland are the most expansive in Europe covering an area of ~4000 km2, and they significantly impact the global carbon cycle because of their high rates of carbon production and storage, as well as their role in the transfer of carbon to oceans through rivers or greenhouse gas exchange (Moore et al., 1998). T...
Article
Full-text available
Hillslope-channel coupling has been shown to be an important control on sediment supply. It can affect the calibre and amount of sediment reaching the channel, and therefore, the texture of the bed material. In coupled reaches colluvial input greatly alters the bed material grain size and may suppress any pattern of downstream fining. In decoupled...