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We used the Water Table Model (WTM) to simulate steady-state water tables at the Last Glacial Maximum (LGM, 21,000 calendar years before present), and in the present day. This dataset includes two GeoTIFF files (one for each time simulated). These files represent steady-state water table depth, including both groundwater table and lake surfaces. Water table depth is reported in metres relative to the land surface: negative numbers represent groundwater, and positive numbers represent lakes. The WTM does not include ice hydrology, such that lakes atop ice sheets may not be well represented. 

Abstract Historical accounts suggest that Euro-American agricultural practices (post–1850 CE) accelerated soil erosion in the Paleozoic Plateau of the Upper Mississippi River Valley (USA). However, the magnitude of this change compared to longer-term Late Pleistocene rates is poorly constrained. Such context is necessary to assess how erosion rates under natural, high-magnitude climate and eco-geomorphic change compare against Euro-American agricultural erosion rates. We pair cosmogenic 10Be analyses and optically stimulated luminescence (OSL) ages from samples of alluvium to build a paleoerosion-rate chronology for Trout Creek in southeastern Minnesota (USA). Erosion rates and their associated integration periods are 0.069–0.073 mm yr−1 (32–20 ka), 0.049 mm yr−1 (28–14 ka), and 0.053 mm yr−1 (14–0 ka). Based on previous studies, we relate these rates to (1) the transition from forest to permafrost at the onset of the Last Glacial Maximum, (2) the decline of permafrost coupled with limited vegetation, and (3) climate warming and vegetation re-establishment. These pre-settlement erosion rates are 8× to 12× lower than Euro-American agricultural erosion rates previously quantified in the region. Despite a limited sample size, our observed rapid increase in erosion rates mirrors other sharply rising anthropogenic environmental impacts within the past several centuries. Our results demonstrate that agricultural erosion rates far exceed climate-induced erosion-rate magnitude and variability during the shift from the last glaciation into the Holocene. 

Abstract. Ice-free land comprises 26 % of the Earth's surface and holds liquid water that delineates ecosystems, affects global geochemical cycling, and modulates sea levels. However, we currently lack the capacity to simulate and predict these terrestrial water changes across the full range of relevant spatial (watershed to global) and temporal (monthly to millennial) scales. To address this knowledge gap, we present the Water Table Model (WTM), which integrates coupled components to compute dynamic lake and groundwater levels. The groundwater component solves the 2D horizontal groundwater flow equation using non-linear equation solvers from the C++ PETSc (Portable, Extensible Toolkit for Scientific Computation) library. The dynamic lake component makes use of the Fill–Spill–Merge (FSM) algorithm to move surface water into lakes, where it may evaporate or affect groundwater flow. In a proof-of-concept application, we demonstrate the continental-scale capabilities of the WTM by simulating the steady-state climate-driven water table for the present day and the Last Glacial Maximum (LGM; 21 000 calendar years before present) across the North American continent. During the LGM, North America stored an additional 14.98 cm of sea-level equivalent (SLE) in lakes and groundwater compared to the climate-driven present-day scenario. We compare the present-day result to other simulations and real-world data. Open-source code for the WTM is available on GitHub and Zenodo. 

Minor updates to the Water Table Model: some deprecated code, set nodata values, update readme. What's Changed Update README.md by @KCallaghan in https://github.com/KCallaghan/WTM/pull/66 Full Changelog: https://github.com/KCallaghan/WTM/compare/v2.0.0...v2.0.1 If you use this software, please cite it as below. 

Earth's drainage networks encode clues that can be used to decipher geologic and geomorphic history. Dendritic drainage patterns, the most common, typically form on approximately homogeneous bedrock. Variations in rock properties or lithologic structure can disrupt dendritic patterns and form, e.g., trellis or rectangular networks. Although textbooks include such lithological–drainage links, the mechanisms driving drainage reorganization via lithologic variability remain poorly understood. To cast light on this mystery, we study drainage patterns in post-glacial landscapes of the Upper Mississippi River Valley (UMRV). Pleistocene glaciers deposited till across parts of this region, burying a landscape of fluvially dissected sedimentary rock whose buried valley network differs from modern-day drainage patterns. As the current river network erodes and exhumes the bedrock, it comes to a geomorphic "decision point": Does it reorganize to recreate the paleodrainage network, or does it maintain its new drainage pattern? To understand this decision-making, we conducted idealized landscape evolution modeling experiments. Modeled landscapes that reintegrated more of the paleodrainage network exhibited higher tortuosity, measured by dividing the real flowpath length by shortest path-length to the outlet, and obtuse tributary-junction angles. We apply this metric to two adjacent landscape types in the UMRV: (1) never glaciated (Driftless Area, DA) and (2) formerly till-mantled (Driftless-style Area, DSA), and measure the basin-averaged tortuosity for sub-basins draining streams of order 1 through 7. Across the UMRV, tortuosity increases as the maximum stream order of the sub-basin increases. For each order, tortuosity is statistically higher in areas that had been previously buried and re-exhumed (DSA) than the DA, indicating that the rivers in the DSA have reintegrated the paleodrainage network since deglaciation. For the 1st and 2nd order sub-basins, the mean basin-averaged tortuosity in the DSA is ~1-2% higher than the DA (p-value < 0.01) and ~10-14% higher (p-value < 0.01) in the 6th and 7th order sub-basins. Our analysis suggests that a drainage-based metric, tortuosity, can identify landscapes where lithological heterogeneity or structure plays a dominant role in drainage organization. 

Abstract The Northern and Southern Patagonian Icefields are rapidly losing volume, with current volume loss rates greater than 20 km³a⁻¹. However, details of the spatial and temporal distribution of their volume loss remain uncertain. We evaluate the rate of 21st-century glacier volume loss using the hydrological balance of four glacierised Patagonian river basins. We isolate the streamflow contribution from changes in ice volume and evaluate whether the rate of volume loss has decreased, increased, or remained constant. Out of 11 glacierised sub-basins, seven exhibit significant increases in the rate of ice volume loss, with a 2006–2019 time integrated anomaly in the rate of glacier volume loss of 135 ± 50 km³. This anomaly in the rate of glacier-volume-loss is spatially heterogeneous, varying from a 7.06 ± 1.69 m a⁻¹increase in ice loss to a 3.18 ± 1.48 m a⁻¹decrease in ice loss. Greatest increases in the rate of ice loss are found in the early spring and late summer, suggesting a prolonging of the melt season. Our results highlight increasing, and in some cases accelerating, rates of volume loss of Patagonia's lake-terminating glaciers, with a 2006–2019 anomaly in the rate of glacier volume loss contributing an additional 0.027 ± 0.01 mm a⁻¹of global mean sea-level rise. 

For landscapes to achieve a topographic steady state, they require steady tectonic uplift and climate, and a bedrock that is uniformly erodible in the vertical direction. Basic landscape evolution models predict that incising drainage networks will eventually reach a static geometric equilibrium – that is, the map-view channel pattern will remain constant. In contrast, natural rivers typically incise through heterogeneous bedrock, which can force reorganization of the drainage structure. To investigate how lithological variability can force landscape reorganization, we draw inspiration from formerly glaciated portions of the upper Mississippi Valley. In this region, depth-to-bedrock maps reveal buried dendritic river networks dissecting paleozoic sedimentary rock. During the Pleistocene, ice advance buried the bedrock topography with glacial till, resurfacing the landscape and resetting the landscape evolution clock. As newly formed drainage networks develop and incise into the till-covered surface, they exhume the buried bedrock topography. This then leads to a geomorphic "decision point": Will the rivers follow the course of the bedrock paleodrainage network? Or will they maintain their new pattern? Using a numerical landscape evolution model, we find that two parameters determine this decision: (1) the contrast between the rock erodibility of the glacial till (more erodible) and of the buried sedimentary rock (less erodible) and (2) the orientation of the surface drainage network with respect to the buried network. We find that as the erodibility contrast increases, the drainage pattern is more likely to reorganize to follow the buried bedrock valleys. Additionally, as the alignment of the two networks increases, the surface drainage network also tends to restructure itself to follow the paleodrainage network. However, when there is less contrast and/or alignment, the surface drainage pattern becomes superimposed on the bedrock topography, with streams cutting across buried bedrock ridges. Our results agree with field studies demonstrating that variability in erodibility exerts a first-order control on landscape evolution and morphology. Our findings can provide insight into how lithologic variation affects surface processes, drives drainage reorganization, and creates geopatterns. 

Abstract. Determining the timing and extent of Quaternary glaciations around the globe is critical to understanding the drivers behind climate change and glacier fluctuations. Evidence from the southern mid-latitudes indicates that local glacial maxima preceded the global Last Glacial Maximum (LGM), implying that feedbacks in the climate system or ice dynamics played a role beyond the underlying orbital forcings. To shed light on these processes, we investigated the glacial landforms shaped and deposited by the Lago Argentino glacier (50° S), an outlet lobe of the former Patagonian Ice Sheet, in southern Argentina. We mapped geomorphological features on the landscape and dated moraine boulders and outwash sediments using 10Be cosmogenic nuclides and feldspar infrared stimulated luminescence (IRSL) to constrain the chronology of glacial advance and retreat. We report that the Lago Argentino glacier lobe reached more extensive limits prior to the global LGM, advancing during the middle to late Pleistocene between 243–132 ka and during Marine Isotope Stage 3 (MIS 3), culminating at 44.5 ± 8.0 and at 36.6 ± 1.0 ka. Our results indicate that the most extensive advance of the last glacial cycle occurred during MIS 3, and we hypothesize that this was a result of longer and colder winters, as well as increased precipitation delivered by a latitudinal migration of the Southern Westerly Winds belt, highlighting the role of local and regional climate feedbacks in modulating ice mass changes in the southern mid-latitudes. 

Atmospheric and oceanic warming over the past century have driven rapid glacier thinning and retreat, destabilizing hillslopes and increasing the frequency of landslides. The impact of these landslides on glacier dynamics and resultant secondary landslide hazards are not fully understood. We investigated how a 262 ± 77 × 106 m3 landslide affected the flow of Amalia Glacier, Chilean Patagonia. Despite being one of the largest recorded landslides in a glaciated region, it emplaced little debris onto the glacier surface. Instead, it left a series of landslide-perpendicular ridges, landslide-parallel fractures, and an apron of ice debris—with blocks as much as 25 m across. Our observations suggest that a deep-seated failure of the mountainside impacted the glacier flank, propagating brittle deformation through the ice and emplacing the bulk of the rock mass below the glacier. The landslide triggered a brief downglacier acceleration of Amalia Glacier followed by a slowdown of as much as 60% of the pre-landslide speed and increased suspended-sediment concentrations in the fjord. These results highlight that landslides may induce widespread and long-lasting disruptions to glacier dynamics.