Low-altitude periglacial activity in southeastern Australia during the late Pleistocene

Only a small area of the Australian mainland was glaciated during the Pleistocene, whereas periglacial deposits are far more common, indicating that cold environments were extensive and a major influence on landscape evolution. Here we identify representative low-elevation examples of scree slopes and frost action, together with fans and valley fills, indicating pronounced erosion cycles during the Pleistocene. To date the deposits, we explore approaches using radiocarbon, optically stimulated luminescence, and profile dating using the cosmogenic nuclide 10Be. The radiocarbon and optical ages show that screes, alluvial valley fill, and fans were deposited between 66–13 ka during the coldest part of the last glacial cycle, and within the previous glacial cycle. Exposure dating indicates further landscape erosion cycles back to the mid Pleistocene. Together, the deposits indicate the frost cracking limit was ~1300 m lower at 680 ± 10 m and mean winter temperature was 8.2 ± 0.5°C colder than present. Periglacial conditions probably affected much of southeastern Australia. The treeless and dry conditions resulted in widespread erosion and increased run off. Combined with increased snow storage within catchments, rivers were paradoxically larger, with high seasonal discharge and sediment loads.

Spatiotemporal distribution of seasonal snow water equivalent in High Mountain Asia from an 18-year Landsat–MODIS era snow reanalysis dataset

Seasonal snowpack is an essential component in the hydrological cycle and plays a significant role in supplying water resources to downstream users. Yet the snow water equivalent (SWE) in seasonal snowpacks, and its space–time variation, remains highly uncertain, especially over mountainous areas with complex terrain and sparse observations, such as in High Mountain Asia (HMA). In this work, we assessed the spatiotemporal distribution of seasonal SWE, obtained from a new 18-year HMA Snow Reanalysis (HMASR) dataset, as part of the recent NASA High Mountain Asia Team (HiMAT) effort. A Bayesian snow reanalysis scheme previously developed to assimilate satellite-derived fractional snow-covered area (fSCA) products from Landsat and MODIS platforms has been applied to develop the HMASR dataset (at a spatial resolution of 16 arcsec (∼500 m) and daily temporal resolution) over the joint Landsat–MODIS period covering water years (WYs) 2000–2017. Based on the results, the HMA-wide total SWE volume is found to be around 163 km3 on average and ranges from 114 km3 (WY2001) to 227 km3 (WY2005) when assessed over 18 WYs. The most abundant snowpacks are found in the northwestern basins (e.g., Indus, Syr Darya and Amu Darya) that are mainly affected by the westerlies, accounting for around 66 % of total seasonal SWE volume. Seasonal snowpack in HMA is depicted by snow accumulating through October to March and April, typically peaking around April and depleting in July–October, with variations across basins and WYs. When examining the elevational distribution over the HMA domain, seasonal SWE volume peaks at mid-elevations (around 3500 m), with over 50 % of the volume stored above 3500 m. Above-average amounts of precipitation causes significant overall increase in SWE volumes across all elevations, while an increase in air temperature (∼1.5 K) from cooler to normal conditions leads to an redistribution in snow storage from lower elevations to mid-elevations. This work brings new insight into understanding the climatology and variability of seasonal snowpack over HMA, with the regional snow reanalysis constrained by remote-sensing data, providing a new reference dataset for future studies of seasonal snow and how it contributes to the water cycle and climate over the HMA region.

Assessment of a snow storage gradient across a maritime mountain environment: a ground penetrating radar investigation

<p>The Southern Alps of New Zealand experience some of the highest precipitation rates globally, and dramatic west to east climatic gradients. Our current knowledge of this precipitation distribution is based on weather station data and river discharge measurements, but there is a clear data gap in the high elevation, central Southern Alps. Here, estimates of precipitation strongly diverge. This problem exists because of the difficulties of quantifying the depth and distribution of snow in a remote, high-altitude mountainous region. In order to improve our knowledge of snow distribution within this data-poor region, snow depths of (< 10m) were assessed parallel to the prevailing westerly wind direction at five locations across the mountain range, between the névé of Franz Josef Glacier, Waiho catchment, to the west and Jollie Valley, Pukaki catchment, in the east. The geophysical method of Ground Penetrating Radar (GPR) was used because of its ability to image the deep snow packs experienced in the study region. Comparison of measurement techniques over the (< 3km) surveyed transects showed that ground-based GPR gave the best sample size (41000 samples) and accuracy due to the high spatial resolution. Airborne GPR (8571 samples) overestimated snow depth by 8 % in low-gradient homogenous terrain, and 24% in steep heterogeneous terrain. The difference is ascribed to the larger view area of the GPR in the airborne survey. Direct probing of snow depth also performed poorly in comparison to ground-based GPR when generalising snow distribution over an area. Across-mountain precipitation peaked ~5 km west of the main divide, between 1700 and 2000 m a.s.l, providing the first empirical support to existing estimates of the location of peak precipitation. Results show decreasing precipitation from 12 ma-1 at Franz Josef Glacier, in the Waiho catchment, to 1.8 ma-1 at Jollie River valley, in the Lake Pukaki catchment, 25 km to the south-east. Internal reflection horizons in snow-pack radargrams allowed snowfall events to be tracked, and a relationship lowland and mountain precipitation to be established. Snowfall accumulation 'factors' were derived for different atmospheric circulation indices, and these will enable improved accuracy in modelling of snow accumulation processes. Further research is required to refine the relationship between synoptic-classed accumulation rates and inter-annual variations in climatic circulation. These refinements of measurement techniques and quantification of and snow distribution and depth allow for better estimation of river discharge and timing estimates for, hydroelectric power generation, and glacier mass balance.</p>

Living Snow Fences: International Practices

In winter, in the countries with snow covered regions, one of the main tasks of road maintenance is to combat snow deposits, snowpacks and snowdrifts on the roadway. Living snow fences consisting of tree and shrub plantings are among known world practices to protect roads against effects of snow deposits. They are environmentally friendly, durable and have great snow retention capacity. However, there are several constraints regarding application of those practices.The analysis of the design, spacing and planting schemes refers to Russian and foreign living snow fences used to protect highways, considers the features, advantages, and disadvantages of living fences in different countries. Japanese and American designs are reviewed as international experience. The influence of the state of trees on the efficiency of their snow-retaining function has been determined. As a result, the need for monitoring and proper maintenance of existing living snow fences throughout their life cycle was confirmed using the examples of surveys of forest plantations in Kazakhstan and in Volgograd region of the Russian Federation.The author presents promising directions for improving the structures and planting schemes of snow storage living fences, namely, an integrated approach to their design as of a protection not only against snowdrifts, but also against pollutants. Such solutions include the design of protective living fences using only tall shrubs, providing the best blowing of roadside areas and dispersion of contaminants. Another solution is to complement the species planted within living fences with willow and corn. Besides, referring to global climate changes, an important task for modern science has been identified, that is to update the current standards for the design of living fences under the current meteorological conditions.Recommendations on the use of mathematical modelling with the help of computer software are suggested regarding development of new configurations of living fences, assessment of their effectiveness, as well as on the adoption of modern technologies such as video cameras and drones during field tests.

Assessment of a snow storage gradient across a maritime mountain environment: a ground penetrating radar investigation

<p>The Southern Alps of New Zealand experience some of the highest precipitation rates globally, and dramatic west to east climatic gradients. Our current knowledge of this precipitation distribution is based on weather station data and river discharge measurements, but there is a clear data gap in the high elevation, central Southern Alps. Here, estimates of precipitation strongly diverge. This problem exists because of the difficulties of quantifying the depth and distribution of snow in a remote, high-altitude mountainous region. In order to improve our knowledge of snow distribution within this data-poor region, snow depths of (< 10m) were assessed parallel to the prevailing westerly wind direction at five locations across the mountain range, between the névé of Franz Josef Glacier, Waiho catchment, to the west and Jollie Valley, Pukaki catchment, in the east. The geophysical method of Ground Penetrating Radar (GPR) was used because of its ability to image the deep snow packs experienced in the study region. Comparison of measurement techniques over the (< 3km) surveyed transects showed that ground-based GPR gave the best sample size (41000 samples) and accuracy due to the high spatial resolution. Airborne GPR (8571 samples) overestimated snow depth by 8 % in low-gradient homogenous terrain, and 24% in steep heterogeneous terrain. The difference is ascribed to the larger view area of the GPR in the airborne survey. Direct probing of snow depth also performed poorly in comparison to ground-based GPR when generalising snow distribution over an area. Across-mountain precipitation peaked ~5 km west of the main divide, between 1700 and 2000 m a.s.l, providing the first empirical support to existing estimates of the location of peak precipitation. Results show decreasing precipitation from 12 ma-1 at Franz Josef Glacier, in the Waiho catchment, to 1.8 ma-1 at Jollie River valley, in the Lake Pukaki catchment, 25 km to the south-east. Internal reflection horizons in snow-pack radargrams allowed snowfall events to be tracked, and a relationship lowland and mountain precipitation to be established. Snowfall accumulation 'factors' were derived for different atmospheric circulation indices, and these will enable improved accuracy in modelling of snow accumulation processes. Further research is required to refine the relationship between synoptic-classed accumulation rates and inter-annual variations in climatic circulation. These refinements of measurement techniques and quantification of and snow distribution and depth allow for better estimation of river discharge and timing estimates for, hydroelectric power generation, and glacier mass balance.</p>

Assessment of Snowmelt Quality Discharging from a Cold-Climate Urban Landscape During Spring Melt

Stormwater results from precipitation events and melting snow running off urban landscapes and typically being released into receiving water bodies with little to no treatment. Despite evidence of its deleterious impacts, snowmelt (SM) management and treatment are limited, partly due to a lack of quality and loading data. This study examines snowmelt quality during the spring for a cold-climate, semi-arid Canadian city (Saskatoon, Saskatchewan). Four snow storage facilities receiving urban snow plowed from roads in mixed-land-use urban catchments (228 km2) were sampled including snow piles (five events) and SM (twelve events) runoff in 2019 and 2020. Samples were analyzed for pH, EC, TDS, TSS, COD, DOC, metals, chloride, PAHs, and Raphidocelis subcapitata and Vibrio fischeri toxicity. Notable event-specific TSS spikes occurred on April 13th, 2019 (3,513 mg/L) and April 24th, 2019 (3,838 mg/L), and TDS, chloride, and manganese on March 26th, 2020 (15,000 mg/L, 5,800 mg/L, 574 mg/L), April 17th, 2020 (5,200 mg/L, 2,600 mg/L, 882 mg/L), and April 23rd, 2020 (5,110 mg/L, 2,900 mg/L, 919 mg/L), though chloride remained elevated through May 1st, 2020 samples (1,000 mg/L). Additionally, at two sites sampled April 13th, 2019 pulses of aluminum (401 mg/L) and PAHs (pyrene, phenanthrene, anthracene; 71 µg/L, 317 µg/L, 182 µg/L) were detected. The EC50 for R. subcapitata and V. fischeri was observed, if at all, above expected toxicity thresholds.

A Decrease in the Regulatory Effect of Snow-Related Phenomena in Spanish Mountain Areas Due to Climate Change

Climate change undoubtedly will affect snow events as temperature and precipitation are expected to change in the future. Spanish mountains are especially affected by that situation, since snow storage is there focussed on very specific periods of the hydrological year and plays a very important role in the management of water resources. In this study, an analysis of the behaviour of the complex snow-related phenomena in the four main mountain regions of Spain in the next 50 years is conducted. The ASTER hydrological model is applied using temperature and precipitation data as basic input, estimated under a climate change scenario. Results show different changes in the maximum and average expected flows, depending on the very different magnitude and sign of changes in precipitation. An increase of flooding episodes may occur as a result of a complex relation between changes in precipitation and an increase in maximum snowmelt intensities that range from 2.1% in the Pyrenees to 7.4% in the Cantabrian Mountains. However, common patterns are shown in a shorter duration of the snow bulk reserves, expected to occur 45 days earlier for the Cantabrian Mountains, and about 30 days for the rest of the studied mountain regions. Changes observed also lead to a concerning decrease in the regulatory effect of the snow-related phenomena in the Spanish rivers, with a decrease in the average snow accumulation that ranges from about 28% for the Pyrenees and Sierra Nevada to 42% for the Central System and the Cantabrian Mountains. A decrease in average flow is expected, fluctuating from 2.4% in the Pyrenees to 7.3% in Cantabrian Mountains, only increasing in the Central System by 4.0%, making all necessary to develop new adaptation measures to climate change.