Because freshwater covers such a small fraction of the Earth’s surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and carbon transport for a variety of aquatic systems, we have constructed a budget for the role of inland water ecosystems in the global carbon cycle. Our analysis conservatively estimates that inland waters annually receive, from a combination of background and anthropogenically altered sources, on the order of 1.9 Pg C y−1 from the terrestrial landscape, of which about 0.2 is buried in aquatic sediments, at least 0.8 (possibly much more) is returned to the atmosphere as gas exchange while the remaining 0.9 Pg y−1 is delivered to the oceans, roughly equally as inorganic and organic carbon. Thus, roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea. Over prolonged time net carbon fluxes in aquatic systems tend to be greater per unit area than in much of the surrounding land. Although their area is small, these freshwater aquatic systems can affect regional C balances. Further, the inclusion of inland, freshwater ecosystems provides useful insight about the storage, oxidation and transport of terrestrial C, and may warrant a revision of how the modern net C sink on land is described.

/pdf/plumbing-the-global-carbon-cycle-integrating-inland-waters-1enndt5kqx.pdf

Plumbing the Global Carbon Cycle: Integrating Inland Waters into the Terrestrial Carbon Budget

Landslide hazard evaluation: a review of current techniques and their application in a multi-scale study, Central Italy

Statistics and Data Analysis in Geology

Three criteria for evaluating the possible performance of water resource systems are discussed. These measures describe how likely a system is to fail (reliability), how quickly it recovers from failure (resiliency), and how severe the consequences of failure may be (vulnerability). These criteria can be used to assist in the evaluation and selection of alternative design and operating policies for a wide variety of water resource projects. The performance of a water supply reservoir with a variety of operating policies illustrates their use.

/pdf/reliability-resiliency-and-vulnerability-criteria-for-water-r6hc6h6q56.pdf

Reliability, resiliency, and vulnerability criteria for water resource system performance evaluation

A model for the topographic influence on shallow landslide initiation is developed by coupling digital terrain data with near-surface through flow and slope stability models. The hydrologic model TOPOG (O'Loughlin, 1986) predicts the degree of soil saturation in response to a steady state rainfall for topographic elements defined by the intersection of contours and flow tube boundaries. The slope stability component uses this relative soil saturation to analyze the stability of each topographic element for the case of cohesionless soils of spatially constant thickness and saturated conductivity. The steady state rainfall predicted to cause instability in each topographic element provides a measure of the relative potential for shallow landsliding. The spatial distribution of critical rainfall values is compared with landslide locations mapped from aerial photographs and in the field for three study basins where high-resolution digital elevation data are available: Tennessee Valley in Marin County, California; Mettman Ridge in the Oregon Coast Range; and Split Creek on the Olympic Peninsula, Washington. Model predictions in each of these areas are consistent with spatial patterns of observed landslide scars, although hydrologic complexities not accounted for in the model (e.g., spatial variability of soil properties and bedrock flow) control specific sites and timing of debris flow initiation within areas of similar topographic control.

/pdf/a-physically-based-model-for-the-topographic-control-on-3babhrnl49.pdf

A physically based model for the topographic control on shallow landsliding

A real-time system for issuing warnings of landslides during major storms is being developed for the San Francisco Bay region, California. The system is based on empirical and theoretical relations between rainfall and landslide initiation, geologic determination of areas susceptible to landslides, real-time monitoring of a regional network of telemetering rain gages, and National Weather Service precipitation forecasts. This system was used to issue warnings during the storms of 12 to 21 February 1986, which produced 800 millimeters of rainfall in the region. Although analysis after the storms suggests that modifications and additional development are needed, the system successfully predicted the times of major landslide events. It could be used as a prototype for systems in other landslide-prone regions.

https://science.sciencemag.org/content/sci/238/4829/921.full.pdf

Real-Time Landslide Warning During Heavy Rainfall

Deglaciation of the Laurentide Ice Sheet in North America was accompanied by sequestration of organic carbon in newly exposed soils. The greatest rate of land exposure occurred around 12,000 to 8,000 years ago, and the greatest increase in the rate of carbon sequestration by soils occurred from 8,000 to 4,000 years ago. Sequestration of carbon in deglaciated peat lands continues today, and a steady state has not been reached. The natural rate of carbon sequestration in soils, however, is small relative to the rate of anthropogenic carbon dioxide production.

https://science.sciencemag.org/content/sci/258/5090/1921.full.pdf

Dynamics of soil carbon during deglaciation of the laurentide ice sheet.

Rates of soil development from four soil chronosequences in the southern Great Basin

Correlation or linear regression estimates of earthquake magnitude from data on historical magnitude and length of surface rupture should be based upon the correct regression. For example, the regression of magnitude on the logarithm of the length of surface rupture L can be used to estimate magnitude, but the regression of log L on magnitude cannot. Regression estimates are most probable values, and estimates of maximum values require consideration of one-sided confidence limits.

Application of linear statistical models of earthquake magnitude versus fault length in estimating maximum expectable earthquakes

Historic fluctuations and late Quaternary deposits of Tulare Lake, in the southern San Joaquin Valley, indicate that maximum lake size has depended chiefly on the height of a frequently overtopped spillway. This dependence gives Tulare Lake a double record of paleoclimate. Climate in the Tulare Lake region has influenced the degree to which the lake fills its basin during dry seasons and dry years: during the past 100,000–130,000 yr, incidence of desiccation of Tulare Lake (inferred from stiffness, mud cracks, and other hand-specimen properties) has been broadly consistent with the lake9s salinity and depth (inferred from diatoms and ostracodes) and with regional vegetation (inferred from pollen). Climate, however, also appears to control basin capacity itself: Tulare Lake becomes large as a consequence of glacial-outwash aggradation of its alluvial-fan dam. Late Wisconsin enlargement of Tulare Lake probably resulted from the last major glaciation of the Sierra Nevada. The lake9s spillway coincides with the axis of the glacial-outwash fan of a major Sierra Nevada stream; moreover, sediment deposited in the transgressive lake resembles glacial rock flour from the Sierra Nevada. Differential tectonic subsidence and deposition by a Coast Range creek facilitated the building of Tulare Lake9s fan dam during the late Wisconsin but were less important than deposition of Sierra Nevada outwash. Four stratigraphically consistent 14 C dates on peat and wood give an age of 26,000 yr B.P. for the start of Tulare Lake9s late Wisconsin transgression. The last major Sierra Nevada glaciation (Tioga glaciation) thus may have begun about 26,000 yr B.P., provided that vigorous glacial-outwash deposition began early in the glaciation. Onset of the Tioga glaciation about 26,000 yr B.P. is consistent with new stratigraphic and radiocarbon data from the northeastern San Joaquin Valley. These data suggest that the principal episode of glacial-outwash deposition of Wisconsin age began in the San Joaquin Valley after 32,000 yr B.P., rather than at least 40,000 yr B.P., as previously believed. An earlier enlargement of Tulare Lake probably resulted from a fan dam produced by the penultimate major (Tahoe) glaciation of the Sierra Nevada. Average sedimentation rates inferred from depths to a 600,000-yr-old clay and from radiocarbon dates indicate that this earlier lake originated no later than 100,000 yr B.P. The Tahoe glaciation therefore is probably pre-Wisconsin.

Robert K. Mark

Papers

Real-Time Landslide Warning During Heavy Rainfall

Dynamics of soil carbon during deglaciation of the laurentide ice sheet.

Rates of soil development from four soil chronosequences in the southern Great Basin

Application of linear statistical models of earthquake magnitude versus fault length in estimating maximum expectable earthquakes

A fan dam for Tulare Lake, California, and implications for the Wisconsin glacial history of the Sierra Nevada