Non-glacial Catchments Research Articles

Lithological and glacial controls on sulfide weathering and the associated CO2 budgets in the Tibetan Plateau: New constraints from small catchments

The Tibetan Plateau, a region that hosts low to middle-latitude glaciers and a high density of metasedimentary rocks, is a hotspot of continental weathering and carbon cycling. However, quantitative estimations of sulfide oxidation and how it affects CO2 budgets from the plateau weathering are lacking. Here we use chemical and isotopic datasets from the studied small catchments in the Tibetan Plateau to estimate that 69.1% to 77.0% of stream SO42– originates from sulfide oxidation. Thus, more than 80% of the CO2 consumed by silicate weathering is counterbalanced by transient CO2 release from H2SO4-driven carbonate dissolution in the study area. In addition, the sulfide oxidation rate for glacial catchments is 5 times that of nonglacial catchments. The CO2 release rate from acid generated by sulfide oxidation in metasedimentary catchments is approximately 3 times that of granitic catchments. We propose that sulfide oxidation has greatly modified the CO2 budget of chemical weathering of the Tibetan Plateau. This study reveals new constraints on the CO2 budget in the Tibetan Plateau weathering, and will provide important insights into the carbon cycle during the plateau uplifting in Cenozoic.

Changes in hydrological regime in High Arctic non-glaciated catchment in 1979–2020 using a multimodel approach

Assessing hydrological consequences of climate change at the catchment scale is recently among key problems in hydrology. This study focuses on the estimation of changes in the hydrological regime in the Fuglebekken catchment in SW Spitsbergen (Svalbard). For this purpose, 50 rainfall-runoff models were calibrated using available hydrometeorological observations. The models were validated based on archival flow and SWE observations, and proxy data from time-lapse cameras. Six models (FLEX-IS, GSM-SOCONT, PRMS, HBV, Nordic HBV, and GR4J) with the best performance were applied to reconstruct the past hydrological conditions and analyse the trends in flow regime in the period 1979–2020. Statistically significant changes at 0.05 level in the flow regime indicators were detected, including the number of days with the active flow during the calendar year (10.8 d per decade), during the mid-May‒November period (9.8 d per decade), the date of the first day with the flow (−4.7 d per decade), and the last day with the flow during mid-May‒November (8.4 d per decade). A statistically significant increase in runoff was estimated for two periods from mid-May to the end of June and the second part of August till mid-November. The changes in the first period result from increases in air temperature and earlier snowmelt-driven floods. An estimated runoff increase in the second period corresponds to large increases in rainfall. The increase in air temperature, earlier disappearance of snow, and decrease in precipitation in July and the first part of August result in runoff reduction. The presented results show that the Fuglebekken ‘catchment's hydrological regime has already changed. The magnitude of the changes is larger compared to catchments located in lower latitudes.

Erosive Response of Non-Glaciated Pyrenean Headwater Catchments to the Last Major Climate Transition and Establishing Interglacial Conditions

Non-glaciated mountain headwater catchments feature high-resolution geomorphic archives, which provide important insight into erosive processes and sediment dynamics in mountain ranges. As such the Valle de la Fueva catchments in the southern Pyrenees present high-lying talus remnants, extensive denudation surfaces (pediments), deeply incised tributary ravines, and low-lying fluvial-cut terraces. Based on geomorphic analyses and absolute dating using terrestrial cosmogenic nuclides and optically stimulated luminescence, a (late stage) catchment erosion model for the Valle de la Fueva was elaborated and indicates successive development stages of (i) lasting pedimentation under cold-climate conditions during Marine Isotope Stages 4–2, (ii) rapid fluvial dissection, sediment remobilization and downcutting of ravines in response to the last major climate transition and establishing interglacial conditions, and (iii) late stage fluvial incision after 3–4 ka due to regionally increased flood magnitudes, and/or intensification of agriculture and forest management. Valle de la Fueva headwater catchment analysis indicated that the styles and magnitudes of basin surface processes were directly correlated with the amplitude and nature of paleoclimatic changes, modified by the interplay of environmental parameters. In contrast to large-scale fluvial systems, mountain headwater catchments seemed to be less afflicted with temporal and spatial averaging biases. They are thus useful targets for investigating direct climate change effects, surface process coupling, and non-linear response mechanisms in Quaternary fluvial systems.

Evaluation of SWAT Model performance on glaciated and non-glaciated subbasins of Nam Co Lake, Southern Tibetan Plateau, China

This paper presents an assessment of the Soil and Water Assessment Tool (SWAT) on a glaciated (Qugaqie) and a non-glaciated (Niyaqu) subbasin of the Nam Co Lake. The Nam Co Lake is located in the southern Tibetan Plateau, two subbasins having catchment areas of 59 km2 and 388 km2, respectively. The scores of examined evaluation indices (i.e., R2, NSE, and PBIAS) established that the performance of the SWAT model was better on the monthly scale compared to the daily scale. The respective monthly values of R2, NSE, and PBIAS were 0.94, 0.97, and 0.50 for the calibration period while 0.92, 0.88, and −8.80 for the validation period. Glacier melt contribution in the study domain was simulated by using the SWAT model in conjunction with the Degree Day Melt (DDM) approach. The conjunction of DDM with the SWAT Model ensued improved results during both calibration (R2=0.96, NSE=0.95, and PBIAS=−13.49) and validation (R2=0.97, NSE=0.96, and PBIAS=−2.87) periods on the monthly time scale. Average contribution (in percentage) of water balance components to the total streamflow of Niyaqu and Qugaqie subbasins was evaluated. We found that the major portion (99.45%) of the streamflow in the Niyaqu subbasin was generated by snowmelt or rainfall surface runoff (SURF_Q), followed by groundwater (GW_Q, 0.47%), and lateral (LAT_Q, 0.06%) flows. Conversely, in the Qugaqie subbasin, major contributor to the streamflow (79.63%) was glacier melt (GLC_Q), followed by SURF_Q (20.14%), GW_Q (0.13%), and LAT_Q (0.089%). The contribution of GLC_Q was the highest (86.79%) in July and lowest (69.95%) in September. This study concludes that the performance of the SWAT model in glaciated catchment is weak without considering glacier component in modeling; however, it performs reasonably well in non-glaciated catchment. Furthermore, the temperature index approach with elevation bands is viable in those catchments where streamflows are driven by snowmelt. Therefore, it is recommended to use the SWAT Model in conjunction with DDM or energy base model to simulate the glacier melt contribution to the total streamflow. This study might be helpful in quantification and better management of water resources in data scarce glaciated regions.

Comparison of hydrochemistry and organic compound transport in two non-glaciated high Arctic catchments with a permafrost regime (Bellsund Fjord, Spitsbergen)

An increase in air temperature related to climate change results in the retreat of glaciers, the degradation of permafrost, and the expansion of glacier-free areas in the polar regions. All these processes lead to changes in the Arctic landscape. They influence the hydrochemistry of streams and rivers fed by glaciers and thawing permafrost. In this study, we examine eighty two water samples from two non-glaciated catchments with snow-permafrost regime: the Tyvjobekken Creek and the Reindeer Creek (NW Wedel-Jarlsberg Land, Spitsbergen). We cover hydrometeorological measurements, fluctuations of physicochemical parameters (pH, specific electrolytic conductivity (SEC)), and the presence of selected organic compounds (dissolved organic carbon (DOC), formaldehyde (HCHO), ∑phenols). The obtained levels of DOC (0.061–0.569mgCL−1) and HCHO (<LOD-0.140mgL−1) in water samples of these two high Arctic creeks confirm the role of the melting permafrost as a rich source of terrestrial organic carbon and organic pollutants, as well as the impact of rainfall on surface water chemistry. It was found that fluctuations of physicochemical indices (pH, SEC, DOC) were related to changes in mean daily discharge of Reindeer Creek (0.012–0.034m3s−1) and Tyvjobekken Creek (0.011–0.015m3s−1) (r>0.40). The Tyvjobekken Creek catchment, in contrast to Reindeer Creek catchment, turned out to be resistant to rapid changes in meteorological conditions (r<0.10) and surface runoff. The processes of permafrost thawing, calcium carbonate dissolution, and biogeochemical “breathing” of soils proved to be crucial for the development of water chemistry. In conclusion, the surface water chemistry of the Reindeer Creek was found to result from the mutual influence of hydrometeorological indices and the biogeochemical environment of the catchment.

Impact of a newly-formed periglacial environment and other factors on fresh water chemistry at the western shore of Admiralty Bay in the summer of 2016 (King George Island, Maritime Antarctica)

This study provides a comprehensive analysis of the inorganic chemistry of flowing water at the western shore of Admiralty Bay. In the water samples, ions, and major and trace metals (and B) were detected and quantified. Additionally, the parameters of pH, specific electrolytic conductivity (SEC25) and total organic carbon (TOC) were determined. Moreover, multivariate data set was created and Principal Component Analysis (PCA) was performed. Generally, the water has low total content of the measured mineral constituents <100mgL−1. PCA analysis we distinguished two groups of chemical variables shaping water chemistry in the investigated creeks: I – components of marine aerosol origin (presence of Na+, Cl− and B) and II – those associated with chemical weathering processes (presence of Al and Fe). Furthermore, the results showed that the flowing water in the newly-formed periglacial areas (formed over the last 30years) are rich in easily soluble Al and Fe and have lower total measured contents of mineral constituents during the summer period than creeks in non-glacial catchments. Permafrost influence on water chemistry is difficult to identify. The rather insignificant difference between TOC concentrations in waters during summer indicates that permafrost is not a store of organic matter in the studied area. Moreover, local biological factors (lichens and mosses) and those limited to the sea-shore vicinity (seabirds and mammals activity) are significant sources of PO43−, NO3−, and NH4+. Despite the described geological and biological features influencing water chemistry, the impact of anthropogenic activity still needs to be verified, especially in terms of heavy metal concentrations.

Geomorphic evolution of a non-glaciated river catchment in Lesser Himalaya: Response to tectonics

The study discusses detail valley formation and sedimentation processes in the monsoon dominated non-glaciated catchment of the Ramganga river in the Lesser Himalaya. The geomorphic and sedimentological studies in this basin indicates phases of massive aggradation that was controlled mainly by channel bound processes and debris flows/landslides. The luminescence chronology of the fill sequences suggests that the valley filling occurred mainly in response to the enhanced monsoon after the Last Glacial Maxima (LGM), during Medieval Warm Period (MWP) and Little Ice Age (LIA). This phase is common in both glaciated and the non-glaciated catchments of Himalaya.The Ramganga River that flows through various tectonic structures of the Lesser Himalaya shows development of wide valleys with thick fill deposits in the fault zones. Chaukhutiya Fault (CF) and Binau-Bhikiyasain-Naurar Fault (BBNF) are the two main transverse faults where the evolved geomorphology pertains to their tectonic activity. The computed morphometric variables such as Ratio of valley floor width to valley height (Vf) and Stream Gradient Index (SL) show higher values in the transverse fault zones. Basin asymmetry vectors along the South Almora Thrust and BBNF are characterized by preferred stream migration in NE and SW direction suggesting BBNF with dip slip movement. Thick clay deposits at different sites along the Ramganga River resulting from blocking of the river, particularly along the BBNF, also point towards tectonically induced landslide and channel blockage. Later phase of tectonic activity, bracketed between 27 and 24 ka, is evident from deformed fluvial deposits in the form of folds and faults. Evidences of tectonic activity in the form of soft sediment deformation structures (SSDS) generic to seismic activity in layers comprising alternation of clay and sand are observed in the Himalayan Frontal Thrust (HFT) zone. The diagnostic features such as dykes, faults and folds suggests that the shaking event took place between 38 ka and 30 ka.

Continental weathering and terrestrial (oxyhydr)oxide export: Comparing glacial and non-glacial catchments in Iceland

Glaciers enhance terrestrial erosion and sediment export to the ocean. Glaciers can also impact mineral specific weathering rates relative to analogous non-glacial terrains. In tandem these processes affect continent sediment export to the oceans over glacial-interglacial cycles. This study summarizes field data from glacial and non-glacial Icelandic river catchments to quantify the impact of weathering regime on iron and aluminium (oxyhydr)oxide mineral formation and flux rates. Aluminium and iron (oxyhydr)oxides are strong indicators of organic carbon preservation in soils and marine sediments. Tracing changes in (oxyhydr)oxide formation and deposition therefore provides a means of evaluating potential changes in organic carbon sequestration rates over glacial-interglacial cycles. Overall, there are several measurable chemical differences between the studied glacial and non-glacial catchments which reflect the key role of soil formation on terrestrial weathering. One of the noted chemical differences is that weathering in non-glacial catchments is characterized by higher apparent rates of iron and aluminium (oxyhydr)oxide formation relative to glacial catchments. However, the offset in (oxyhydr)oxide formation does not appear to be transferred into river sediment compositions, and physical weathering appears to be the dominant control of river sediment composition and export. Glacial rivers export far more total sediment to nearshore marine environments than analogous non-glacial rivers suggesting glacial weathering enhances carbon burial by increasing nearshore marine (oxyhydr)oxide accumulation.

Geomorphology of the Burnt River, eastern Oregon, USA: Topographic adjustments to tectonic and dynamic deformation

Eastern Oregon contains the deepest gorge in North America, where the Snake River cuts vertically down 2300m. This deep gorge is known as Hells Canyon. A landscape containing such a topographic feature is likely undergoing relatively recent deformation. Study of the Burnt River, a tributary to the Snake River at the upstream end of Hells Canyon, yields data on active river incision in eastern Oregon, indicating that Quaternary faults are a first order control on regional landscape development. Through 1:24,000-scale geologic mapping, a 500,000-year record of fluvial incision along the Burnt River was constructed and is chronologically anchored by optically stimulated luminescence dating and tephrochronology analyses. A conceptual model of fluvial terrace formation was developed using these ages and likely applies to other non-glaciated catchments in eastern Oregon. Mapped terraces, inferred to have formed during glacial-interglacial cycles, provide constraints on rates of incision of the Burnt River. Incision through these terraces indicates that the Burnt River is down-cutting at 0.15 to 0.57mkyr−1. This incision appears to reflect a combination of local base-level adjustments tied to movement along the newly mapped Durkee fault and regional base-level control imposed by the downcutting of the Snake River. Deformation of terraces as young as 38.7±5.1ka indicates Quaternary activity along the Durkee fault, and when combined with topographic metrics (slope, relief, hypsometry, and stream-steepness), reveals a landscape in disequilibrium. Longer wavelength lithospheric dynamics (delamination and crustal foundering) that initiated in the Miocene may also be responsible for continued regional deformation of the Earth's surface.

Texture and geochemistry of surface horizons of Arctic soils from a non-glaciated catchment, SW Spitsbergen

AbstractPhysical and chemical properties of Arctic soils and especially the properties of surface horizons of the soils are very important because they are responsible for the rate and character of plant colonization, development of vegetation cover, and influence the rate and depth of thawing of soils and development of active layer of permafrost during summer. The main aim of the present study is to determine and explain the spatial diversity of selected physical and chemical properties of surface horizons of Arctic soils from the non-glaciated Fuglebekken catchment located in the Hornsund area (SW Spitsbergen) by means of geostatistical approach. Results indicate that soil surface horizons in the Fuglebekken catchment are characterized by highly variable physical and chemical properties due to a heterogeneous parent material (marine sediments, moraine, rock debris), tundra vegetation types, and non-uniform influence of seabirds. Soils experiencing the strongest influence of seabird guano have a lower pH than other soils. Soils developed on the lateral moraine of the Hansbreen glacier have the highest pH due to the presence of carbonates in the parent material and a lack or presence of a poorly developed and discontinuous A horizon. The soil surface horizons along the coast of the Hornsund exhibit the highest content of the sand fraction and SiO2. The surface of soils occurring at the foot of the slope of Ariekammen Ridge is characterized by the highest content of silt and clay fractions as well as Al2O3, Fe2O3, and K2O. Soils in the central part of the Fuglebekken catchment are depleted in CaO, MgO, and Na2O in comparison with soils in the other sampling sites, which indicates the highest rate of leaching in this part of the catchment.

Organic carbon and nutrients (N, P) in surface soil horizons in a non-glaciated catchment, SW Spitsbergen

AbstractOrganic carbon, nitrogen, and phosphorus in the soils of the High Arctic play an important role in the context of global warming, biodiversity, and richness of tundra vegetation. The main aim of the present study was to determine the content and spatial distribution of soil organic carbon (SOC), total nitrogen (Ntot), and total phosphorus (Ptot) in the surface horizons of Arctic soils obtained from the lower part of the Fuglebekken catchment in Spitsbergen as an example of a small non-glaciated catchment representing uplifted marine terraces of the Svalbard Archipelago. The obtained results indicate that surface soil horizons in the Fuglebekken catchment show considerable differences in content of SOC, Ntot, and Ptot. This mosaic is related to high variability of soil type, local hydrology, vegetation (type and quantity), and especially location of seabird nesting colony. The highest content of SOC, Ntot, and Ptotoccurs in soil surface horizons obtained from sites fertilized by seabird guano and located along streams flowing from the direction of the seabird colony. The content of SOC, Ntot, and Ptotis strongly negatively correlated with distance from seabird colony indicating a strong influence of the birds on the fertility of the studied soils and indirectly on the accumulation of soil organic matter. The lowest content of SOC, Ntot, and Ptotoccurs in soil surface horizons obtained from the lateral moraine of the Hansbreen glacier and from sites in the close vicinity of the lateral moraine. The content of Ntot, Ptot, and SOC in soil surface horizons are strongly and positively correlated with one another,i.e.the higher the content of nutrients, the higher the content of SOC. The spatial distribution of SOC, Ntot, and Ptotin soils of the Hornsund area in SW Spitsbergen reflects the combined effects of severe climate conditions and periglacial processes. Seabirds play a crucial role in nutrient enrichment in these weakly developed soils.

The Greenland Ice Sheet as a hot spot of phosphorus weathering and export in the Arctic

AbstractThe contribution of ice sheets to the global biogeochemical cycle of phosphorus is largely unknown, due to the lack of field data. Here we present the first comprehensive study of phosphorus export from two Greenland Ice Sheet glaciers. Our results indicate that the ice sheet is a hot spot of phosphorus export in the Arctic. Soluble reactive phosphorus (SRP) concentrations, up to 0.35 µM, are similar to those observed in Arctic rivers. Yields of SRP are among the highest in the literature, with denudation rates of 17–27 kg P km−2 yr−1. Particulate phases, as with nonglaciated catchments, dominate phosphorus export (&gt;97% of total phosphorus flux). The labile particulate fraction differs between the two glaciers studied, with significantly higher yields found at the larger glacier (57.3 versus 8.3 kg P km−2 yr−1). Total phosphorus yields are an order of magnitude higher than riverine values reported in the literature. We estimate that the ice sheet contributes ~15% of total bioavailable phosphorus input to the Arctic oceans (~11 Gg yr−1) and dominates total phosphorus input (408 Gg yr−1), which is more than 3 times that estimated from Arctic rivers (126 Gg yr−1). We predict that these fluxes will rise with increasing ice sheet freshwater discharge in the future.

Soil moisture and temperature variation under different types of tundra vegetation during the growing season: A case study from the Fuglebekken catchment, SW Spitsbergen

The main objective of this paper is to discuss the range of temperature and moisture differences and variability in tundra vegetation and Arctic soils in the context of weather changes during the growing season. Research was carried out in Wedel Jarlsberg Land (SW Spitsbergen) in a small non-glaciated catchment in the vicinity of the Polish Polar Station in Hornsund. Measurements of air and soil temperature and changes in volumetric soil water content were carried out between June 24 and September 9 of 2008. The studied sites represented: (1) Turbic Cryosol, poorly covered by vegetation and exhibiting evidences of strong cryogenic processes; (2) Hyperskeletic Cryosol covered by a community of wet moss tundra vegetation with variable moisture which evolves under the influence of water flowing from the adjacent mountain slopes occupied by Little Auk colonies; and (3) Haplic Cryosol covered by lichen–herb–heath tundra vegetation, located on a raised marine terrace. Hyperskeletic Cryosol is the wettest of all the soil profiles studied. This profile shows the largest fluctuations in water content, related to the rate of snow melting on mountain slopes and the outflow of ablation water. The volumetric soil water content in Hyperskeletic Cryosol varies from 29% to 71%, with an average value of 49%. The mean volumetric soil water content in the driest Haplic Cryosol is 6% and ranges from 3% to 10% throughout the growing season. This is related to its sandy texture and a large number of stones, which leads to fast infiltration of snowmelt water and rainfall. Turbic Cryosol shows an intermediate volumetric water content ranging from 21% to 38%, with a mean value of 30%. The thermal regimes of the soils studied are also variable. The warmest soil was the driest Haplic Cryosol, as no influence of cold thawing water was observed. During the measurement period, the mean soil temperature at a depth of 10cm in Haplic Cryosol was 6.3°C. Turbic Cryosol was ca. 1.2°C–1.5°C colder than Haplic Cryosol. Hyperskeletic Cryosol was the coldest in comparison with the other soils studied because of the moss cover having insulating capacity. The temperatures recorded in this profile at a depth of 10cm reached a mean value of 3.2°C. The results indicate that cold water inflow from melting snow cover greatly affects soil temperature in the first part of summer (ablation season). This is related to an increase in solar radiation and air temperature leading to more intensive snow melting. This relationship is particularly evident in the first ten days of July. The highest soil surface temperatures (>20°C) were recorded in the beginning of July under intense solar radiation (25–27MJ/m2d−1). In the second part of August, thermal gradients were weaker and soil temperatures in all the pedons studied were almost the same, ranging between +3°C and +6°C. This was due to limited solar energy inflow and heat migration into the soil transported with rainfall.

Multi-scale curvature for automated identification of glaciated mountain landscapes

Erosion by glacial and fluvial processes shapes mountain landscapes in a long-recognized and characteristic way. Upland valleys incised by fluvial processes typically have a V-shaped cross-section with uniform and moderately steep slopes, whereas glacial valleys tend to have a U-shaped profile with a changing slope gradient. We present a novel regional approach to automatically differentiate between fluvial and glacial mountain landscapes based on the relation of multi-scale curvature and drainage area. Sample catchments are delineated and multiple moving window sizes are used to calculate per-cell curvature over a variety of scales ranging from the vicinity of the flow path at the valley bottom to catchment sections fully including valley sides. Single-scale curvature can take similar values for glaciated and non-glaciated catchments but a comparison of multi-scale curvature leads to different results according to the typical cross-sectional shapes. To adapt these differences for automated classification of mountain landscapes into areas with V- and U-shaped valleys, curvature values are correlated with drainage area and a new and simple morphometric parameter, the Difference of Minimum Curvature (DMC), is developed. At three study sites in the western United States the DMC thresholds determined from catchment analysis are used to automatically identify 5×5km quadrats of glaciated and non-glaciated landscapes and the distinctions are validated by field-based geological and geomorphological maps. Our results demonstrate that DMC is a good predictor of glacial imprint, allowing automated delineation of glacially and fluvially incised mountain landscapes.

The stable calcium isotopic composition of rivers draining basaltic catchments in Iceland

Calcium isotopic compositions (δ44/42Ca) were measured in Icelandic rivers draining a range of catchment types. The δ44/42Cavalues of the rivers ranged from 0.45‰ to 0.67‰, which in all cases was higher than the δ44/42Ca value of basaltic rock standards (0.42±0.03‰). A single explanation was unable to satisfactorily explain the δ44/42Ca values of all rivers, rather it was found that the rivers formed three distinct groups based on the extent of glacial coverage in each catchment. The Ca isotopic composition of rivers draining catchments with less than 10% glacial cover could be explained by the mixing of water sources: basalt-derived solutes, meltwater (taken to represent meteorological precipitation inputs) and hydrothermal water. However, fractionation of δ44/42Ca in these catchments cannot unequivocally be ruled out. In catchments with greater than 22% glacial cover, Ca isotopic compositions could not be explained by a mixture of water sources and instead reflected a fractionation process, most likely the precipitation of Ca-bearing secondary minerals or the adsorption/ion-exchange of Ca onto mineral surfaces. The fractionation factor (α) for this process was calculated to be 0.9999. The third group of rivers, with partially glaciated (10–21%) catchments, grouped with glaciated catchments with respect to their Sr geochemistry and with non-glaciated catchments with respect to their Ca geochemistry. The difference in the controls of Ca isotope fractionation between glaciated and unglaciated catchments was attributed to different weathering regimes.

Cosmogenic 10Be measurements of Quaternary and Pliocene sedimentation rates from non-glaciated catchments

Cosmogenic 10Be measurements of Quaternary and Pliocene sedimentation rates from non-glaciated catchments

Variations in suspended and dissolved matter fluxes from glacial and non-glacial catchments during a melt season at Urumqi River, eastern Tianshan, central Asia

The effects of climatic conditions on the delivery patterns of suspended solid and dissolved matter are evaluated by examining their correlation with air temperature, precipitation and runoff from glacial and non-glacial catchments at the headwaters of Urumqi River in eastern Tianshan, central Asia. The results show that the physical and chemical weathering fluxes (168 and 23 t km − 2 yr − 1 , respectively) associated with the glacial catchment are higher than those of the non-glacial catchment (34 and 12 t km − 2 yr − 1 , respectively). Significant linear correlations are found between river fluxes and air temperature in both catchments. For each degree of temperature increase, the runoff, physical weathering flux and chemical weathering flux from the glacial catchment increase by 12%, 16% and 5%, respectively. On the other hand, in the non-glacial catchment, these values are 9%, 13% and 15%, respectively, if the temperature is below 4 °C; the variations in runoff, physical and chemical weathering fluxes are irregular when the temperature exceeds 4 °C. Such a pattern for the non-glacial catchment during the melt season may be due to the influence of multiple water sources. In contrast, the relation to precipitation is relatively weak in both catchments. Furthermore, although the glacial catchment has a higher increasing rate of physical weathering flux in response to temperature increase than the non-glacial catchment, this is not the case for the chemical weathering flux, suggesting that glaciers play an important role in the effect of air temperature change on physical weathering flux. ► The effects of climatic conditions on river materials are evaluated. ► River materials in the catchments have different variations for temperature increase. ► Precipitation has a relatively weak impact on the river materials. ► Glacial catchment has a higher increasing rate of physical weathering flux.

Hydrological modeling in alpine catchments: sensing the critical parameters towards an efficient model calibration

For the Tyrolean part of the river Inn, a hybrid model for flood forecast has been set up and is currently in its test phase. The system is a hybrid system which comprises of a hydraulic 1D model for the river Inn, and the hydrological models HQsim (Rainfall-runoff-discharge model) and the snow and ice melt model SES for modeling the rainfall runoff form non-glaciated and glaciated tributary catchment respectively. Within this paper the focus is put on the hydrological modeling of the totally 49 connected non-glaciated catchments realized with the software HQsim. In the course of model calibration, the identification of the most sensitive parameters is important aiming at an efficient calibration procedure. The indicators used for explaining the parameter sensitivities were chosen specifically for the purpose of flood forecasting. Finally five model parameters could be identified as being sensitive for model calibration when aiming for a well calibrated model for flood conditions. In addition two parameters were identified which are sensitive in situations where the snow line plays an important role.

POP bioaccumulation in macroinvertebrates of alpine freshwater systems

This study serves to investigate the uptake of POPs in the different trophic levels (scrapers, collectors, predators, shredders) of macroinvertebrate communities sampled from a glacial and a non-glacial stream in the Italian Alps. The presented results show that the contaminant concentrations in glacial communities are generally higher compared to those from non-glacial catchments, highlighting the importance of glaciers as temporary sinks of atmospherically transported pollutants. Moreover, the data also suggests that in mountain systems snow plays an important role in influencing macroinvertebrate contamination. The main chemical uptake process to the macroinvertebrates is considered to be bioconcentration from water, as similar contaminant profiles were observed between the different trophic levels. The role of biomagnification/bioaccumulation is thought to be absent or negligible. The enrichment of chemicals observed in the predators is likely to be related to their greater lipid content compared to that of other feeding groups.

Correlation of fluvial terraces within the Hikurangi Margin, New Zealand: implications for climate and baselevel controls

A correlation of fluvial terraces is presented for eight non-glacial catchments of the eastern North Island, New Zealand, within the actively uplifting Hikurangi Margin. Using a combination of loess and tephra coverbed stratigraphy, and radiocarbon and OSL dating of fluvial deposits and loess coverbeds, we demonstrate correlation of four fill terraces, T1–T4. The available age constraints suggest T1=15–30 ka, T2=31–50 ka, T3=50–70 ka, and T4=∼115 ka, but the association and temporal link with loess deposits suggest correlation with cold periods, and thus the refinement of T2=late MIS 3 (31–40 ka), T3=MIS 4 (55–70 ka), T4=MI Substage 5b (∼90 ka), 5d (∼110 ka), or MIS 6 (∼140–160 ka). The ability to correlate terraces between catchments, plus the lack of independent evidence for tectonic triggering events, indicates terraces have probably formed in response to either climate (terrestrial) or baselevel (sea level) control. Climate control is indicated by the temporal link of post-glacial incision with re-establishment of forest cover, and of LGM aggradation with limited grass and shrub cover and periglacial processes. Aggradation due to increased sediment supply under reduced vegetation is dramatically demonstrated by formation of the Taupo Pumice Alluvium terrace in response to inundation by volcanic deposits (unwelded ignimbrite) following the 1.8 ka Taupo eruption, and the response to post-settlement (<500 yr BP) deforestation. The upstream limit of post-glacial baselevel control is recorded by a post-glacial sediment wedge burying older terraces in six catchments. In one catchment, the inner (landward) edge of the wedge is a mid-Holocene fill terrace, interpreted to have formed in response to the post-glacial sea level highstand, and thus is a baselevel-controlled terrace. Evidence defining the downstream extent of climate control during the LGM (and thus the upstream limit of baselevel-controlled lowstand incision) is now buried beneath the continental shelf, but limited fluvial features on the inner shelf (<20 km offshore), and LGM aggradation despite a range of shelf gradients indicate climate-induced aggradation probably extended at least to the present day inner shelf.