scholarly journals Change in Frozen Soils and Its Effect on Regional Hydrology in the Upper Heihe Basin, on the Northeastern Qinghai-Tibetan Plateau

2017 ◽  
Author(s):  
Bing Gao ◽  
Dawen Yang ◽  
Yue Qin ◽  
Yuhan Wang ◽  
Hongyi Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Elevation ◽  
Annual Runoff ◽  
Base Flow ◽  
Permafrost Degradation ◽  
Frozen Ground ◽  
Frozen Soils ◽  
Physically Based ◽  
Hydrological Cycles

Abstract. Frozen ground has an important role in regional hydrological cycles and ecosystems, especially on the Qinghai-Tibetan Plateau, which is characterized by high elevation and a dry climate. This study modified a distributed physically based hydrological model and applied it to simulate the long-term (from 1971 to 2013) change of frozen ground and its effect on hydrology in the upper Heihe basin located in the northeastern Qinghai-Tibetan Plateau. The model was validated carefully against data obtained from multiple ground-based observations. Based on the model simulations, we analyzed the changes of frozen soils and their effects on the hydrology. The results showed that the permafrost area shrank by 9.5 % (approximately 600 km2), especially in areas with elevation between 3500 m and 3900 m. The maximum frozen depth of seasonally frozen ground decreased at a rate of approximately 5.2 cm/10 yr, and the active layer depth over the permafrost increased by about 3.5 cm/10 yr. Runoff increased significantly during cold seasons (November–March) due to the increase in liquid soil moisture caused by rising soil temperature. Areas where permafrost changed into seasonally frozen ground at high elevation showed especially large changes in runoff. Annual runoff increased due to increased precipitation, the base flow increased due to permafrost degradation, and the actual evapotranspiration increased significantly due to increased precipitation and soil warming. The groundwater storage showed an increasing trend, which indicated that the groundwater recharge was enhanced due to the degradation of permafrost in the study area.

scholarly journals Change in Frozen Soils and its Effect on Regional Hydrology in the Upper Heihe Basin, the Northeast Qinghai-Tibetan Plateau

2017 ◽  
Author(s):  
Bing Gao ◽  
Dawen Yang ◽  
Yue Qin ◽  
Yuhan Wang ◽  
Hongyi Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Hydrological Cycle ◽  
High Elevation ◽  
Annual Runoff ◽  
Base Flow ◽  
Permafrost Degradation ◽  
Frozen Ground ◽  
Increasing Trend ◽  
Physically Based

Abstract. Frozen ground has an important role in regional hydrological cycle and ecosystem, especially on the Qinghai-Tibetan Plateau, which is characterized by high elevation and a dry climate. This study modified a distributed physically-based hydrological model and applied it to simulate the long-term (from 1961 to 2013) change of frozen ground and its effect on hydrology in the upper Heihe basin located at Northeast Qinghai-Tibetan Plateau. The model was validated carefully against data obtained from multiple ground-based observations. The model results showed that the permafrost area shrank by 9.5 % (approximately 600 km2), especially in areas with elevation between 3500 m and 3900 m. The maximum frozen depth of seasonally frozen ground decreased at a rate of approximately 4.1 cm/10 yr, and the active layer depth over the permafrost increased by about 2.2 cm/10 yr. Runoff increased significantly during cold seasons (November–March) due to the increase in liquid soil moisture caused by rising soil temperature. Areas where permafrost changed into the seasonally frozen ground at high elevation showed especially large changes in runoff. Annual runoff increased due to increased precipitation, the base flow increased due to permafrost degradation, and the actual evapotranspiration increased significantly due to increased precipitation and soil warming. The groundwater storage showed an increasing trend, which indicated that the groundwater recharge was enhanced due to the degradation of permafrost in the study area.

scholarly journals Change in frozen soils and its effect on regional hydrology, upper Heihe basin, northeastern Qinghai–Tibetan Plateau

2018 ◽  
Vol 12 (2) ◽  
pp. 657-673 ◽  
Author(s):  
Bing Gao ◽  
Dawen Yang ◽  
Yue Qin ◽  
Yuhan Wang ◽  
Hongyi Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Cold Season ◽  
Annual Runoff ◽  
Base Flow ◽  
Active Layer Thickness ◽  
Frozen Ground ◽  
Frozen Soils ◽  
Soil Temperatures ◽  
Spatio Temporal ◽  
High Elevations

Abstract. Frozen ground has an important role in regional hydrological cycles and ecosystems, particularly on the Qinghai–Tibetan Plateau (QTP), which is characterized by high elevations and a dry climate. This study modified a distributed, physically based hydrological model and applied it to simulate long-term (1971–2013) changes in frozen ground its the effects on hydrology in the upper Heihe basin, northeastern QTP. The model was validated against data obtained from multiple ground-based observations. Based on model simulations, we analyzed spatio-temporal changes in frozen soils and their effects on hydrology. Our results show that the area with permafrost shrank by 8.8 % (approximately 500 km2), predominantly in areas with elevations between 3500 and 3900 m. The maximum depth of seasonally frozen ground decreased at a rate of approximately 0.032 m decade−1, and the active layer thickness over the permafrost increased by approximately 0.043 m decade−1. Runoff increased significantly during the cold season (November–March) due to an increase in liquid soil moisture caused by rising soil temperatures. Areas in which permafrost changed into seasonally frozen ground at high elevations showed especially large increases in runoff. Annual runoff increased due to increased precipitation, the base flow increased due to changes in frozen soils, and the actual evapotranspiration increased significantly due to increased precipitation and soil warming. The groundwater storage showed an increasing trend, indicating that a reduction in permafrost extent enhanced the groundwater recharge.

scholarly journals Growth of a high-elevation large inland lake, associated with climate change and permafrost degradation in Tibet

2010 ◽  
Vol 14 (3) ◽  
pp. 481-489 ◽  
Author(s):  
J. Liu ◽  
S. Kang ◽  
T. Gong ◽  
A. Lu
Keyword(s):  
High Elevation ◽  
Annual Runoff ◽  
Annual Precipitation ◽  
The Tibetan Plateau ◽  
Permafrost Degradation ◽  
Lake Area ◽  
Pan Evaporation ◽  
Precipitation Increase ◽  
Nam Co Lake

Abstract. This study analyzed satellite images and long term climate variables from a high-elevation meteorological station (4730 m) and streamflow records to examine hydrological response of Nam Co Lake (4718 m), the largest lake on the Tibetan Plateau, over the last 50 years. The results show the lake area extended by 51.8 km2 (2.7% of the total area) when compared with the area in 1976. This change is associated with an annual precipitation increase of 65 mm (18.6%), annual and winter mean temperature increases of 0.9 °C and 2.1 °C respectively, an annual runoff increase of 20% and an annual pan evaporation decrease of about 2%, during the past 20 years. The year of the change point in annual precipitation, air temperature, annual pan evaporation and runoff occurred in 1971, 1983, 1997 and 1997, respectively. The timing of the lake growth corresponds with the abrupt increase in annual precipitation and runoff since the mid-1990s.

scholarly journals Growth of a high-elevation large inland lake, associated with climate change and permafrost degradation in Tibet

2009 ◽  
Vol 6 (4) ◽  
pp. 5445-5469 ◽  
Author(s):  
J. Liu ◽  
S. Kang ◽  
T. Gong ◽  
A. Lu
Keyword(s):  
Tibetan Plateau ◽  
High Elevation ◽  
Annual Runoff ◽  
Annual Precipitation ◽  
The Tibetan Plateau ◽  
Permafrost Degradation ◽  
Lake Area ◽  
Pan Evaporation ◽  
Inland Lake ◽  
Precipitation Increase

Abstract. This study analyzed satellite images and long term climate variables from a high-elevation meteorological station (4730 m) and streamflow records to examine hydrological response of Nam Co Lake (4718 m), the largest lake on the Tibetan Plateau, over the last 50 years. The results show the lake area extended by 51.8 km2 (2.7% of the total area) when compared with the area in 1976. This change is associated with an annual precipitation increase of 65 mm (18.6%), annual and winter mean temperature increases of 0.9°C and 2.1°C respectively, an annual runoff increase of 20% and an annual pan evaporation decrease of about 2%, during the past 20 years. The year of the change point in annual precipitation, air temperature, annual pan evaporation and runoff occurred in 1971, 1983, 1997 and 1997, respectively. The timing of the lake growth corresponds with the abrupt increase in annual precipitation and runoff since the mid-1990s. This study suggests a strong positive water balance in the largest inland lake on the Tibetan Plateau.

scholarly journals Application of New Precipitation and Reconstructed Streamflow Products to Streamflow Trend Attribution in Northern Eurasia

2008 ◽  
Vol 21 (8) ◽  
pp. 1807-1828 ◽  
Author(s):  
Jennifer C. Adam ◽  
Dennis P. Lettenmaier
Keyword(s):  
River Discharge ◽  
Low Frequency ◽  
The Arctic ◽  
Northern Eurasia ◽  
Permafrost Degradation ◽  
Northeastern Siberia ◽  
Physically Based ◽  
Streamflow Trends ◽  
Precipitation Trends

Abstract River runoff to the Arctic Ocean has increased over the last century, primarily during the winter and spring and primarily from the major Eurasian rivers. Some recent studies have suggested that the additional runoff is due to increased northward transport of atmospheric moisture (and associated increased precipitation), but other studies show inconsistencies in long-term runoff and precipitation trends, perhaps partly due to biases in the observational datasets. Through trend analysis of precipitation, temperature, and streamflow data, the authors investigate the extent to which Eurasian Arctic river discharge changes are attributable to precipitation and temperature changes as well as to reservoir construction and operation between the years of 1936 and 2000. Two new datasets are applied: a gridded precipitation product, in which the low-frequency variability is constrained to match that of long-term bias-corrected precipitation station data, and a reconstructed streamflow product, in which the effects of reservoirs have been minimized using a physically based reservoir model. It is found that reservoir operations have primarily affected streamflow seasonality, increasing winter discharge and decreasing summer discharge. To understand the influences of climate on streamflow changes, the authors hypothesize three cases that would cause precipitation trends to be inconsistent with streamflow trends: first, for the coldest basins in northeastern Siberia, streamflow should be sensitive to warming primarily as a result of the melting of excess ground ice, and for these basins positive streamflow trends may exceed precipitation trends in magnitude; second, evapotranspiration (ET) in the warmer regions of western Siberia and European Russia is sensitive to warming and increased precipitation, therefore observed precipitation trends may exceed streamflow trends; and third, streamflow from the central Siberian basins should respond to both effects. It is found that, in general, these hypotheses hold true. In the coldest basins, streamflow trends diverged from precipitation trends starting in the 1950s to 1960s, and this divergence accelerated thereafter. In the warmest basins, precipitation trends consistently exceeded streamflow trends, suggesting that increased precipitation contributed to increases in both ET and streamflow. In the central basins, permafrost degradation and ET effects appear to be contributing to long-term streamflow trends in varying degrees for each basin. The results herein suggest that the extent and state of the permafrost underlying a basin is a complicating factor in understanding long-term changes in Eurasian Arctic river discharge.

scholarly journals The Role of Debris Cover in Catchment Runoff: A Case Study of the Hailuogou Catchment, South-Eastern Tibetan Plateau

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2601 ◽  
Author(s):  
Yong Zhang ◽  
Shiyin Liu ◽  
Qiao Liu ◽  
Xin Wang ◽  
Zongli Jiang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Elevation ◽  
The Tibetan Plateau ◽  
Eastern Tibetan Plateau ◽  
South Eastern ◽  
Lower Elevation ◽  
Debris Cover ◽  
Physically Based ◽  
Catchment Runoff

Runoff from high-elevation, debris-covered glaciers is a crucial water supply in the Tibetan Plateau (TP) and its surroundings, where insufficient debris thickness data make it difficult to analyze its influence. Here, we investigated the role of debris cover in runoff formation of the Hailuogou catchment in the south-eastern Tibetan Plateau for the 1988–2017 period, based on long-term observations combined with a physically based glacio-hydrological model. The catchment is characterized by extensive thin debris on the ablation zones of three debris-covered glaciers. An increasing trend in catchment runoff has been observed in the past three decades, more than 50% of which is attributed to glacier runoff in the last decade. With the exception of the influence of temperature rising and precipitation decreasing, our results underline the importance of debris cover and its spatial features in the glaciological and hydrological processes of the catchment, in which the acceleration effect of debris cover is dominant in the catchment. An experimental analysis indicated that the extraordinary excess meltwater in the catchment is generated from the debris-covered surface, especially the lower elevation region below 3600 m a.s.l.

scholarly journals Quantifying the evaporation amounts of 75 high-elevation large dimictic lakes on the Tibetan Plateau

2020 ◽  
Vol 6 (26) ◽  
pp. eaay8558 ◽  
Author(s):  
Binbin Wang ◽  
Yaoming Ma ◽  
Zhongbo Su ◽  
Yan Wang ◽  
Weiqiang Ma
Keyword(s):  
Spatial Distribution ◽  
Energy Balance ◽  
Tibetan Plateau ◽  
Satellite Data ◽  
High Elevation ◽  
The Tibetan Plateau ◽  
Large Variability ◽  
Plausible Hypothesis ◽  
Lake Evaporation ◽  
Hydrological Cycles

Lake evaporation can influence basin-wide hydrological cycles and is an important factor in loss of water resources in endorheic lakes of the Tibetan Plateau. Because of the scarcity of data, published lake evaporation values are inconsistent, and their spatial distribution has never been reported. Presenting a plausible hypothesis of energy balance during the ice-free seasons, we explored the multiyear (2003–2016) average ice phenology and evaporation amounts of 75 large dimictic lakes by using a combination of meteorological and satellite data. Evaporation amounts show large variability in spatial distribution, with a pattern of higher values in the south. Lakes with higher elevation, smaller area, and higher latitude are generally associated with a shorter ice-free season and lower evaporation. The total evaporated water amounts have values of approximately 29.4 ± 1.2 km3 year−1 for the 75 studied lakes and 51.7 ± 2.1 km3 year−1 for all plateau lakes included.

scholarly journals A long-term (2005–2016) dataset of integrated land–atmosphere interaction observations on the Tibetan Plateau

2020 ◽  
Author(s):  
Yaoming Ma ◽  
Zeyong Hu ◽  
Zhipeng Xie ◽  
Weiqiang Ma ◽  
Binbin Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tibetan Plateau ◽  
Soil Temperature ◽  
Water Content ◽  
Global Climate ◽  
High Elevation ◽  
Observation System ◽  
The Tibetan Plateau ◽  
Atmosphere Interaction

Abstract. The Tibetan Plateau (TP) plays a critical role in influencing regional and global climate, via both thermal and dynamical mechanisms. Meanwhile, as the largest high-elevation part of the cryosphere outside the polar regions, with vast areas of mountain glaciers, permafrost and seasonally frozen ground, the TP is characterized as an area sensitive to global climate change. However, meteorological stations are sparely and biased distributed over the TP, owing to the harsh environmental conditions, high elevations, complex topography, and heterogeneous surfaces. Moreover, due to the weak representative of the stations, atmospheric conditions and the local land-atmosphere coupled system over the TP as well as its effects on surrounding regions are poorly quantified. This paper presents a long-term (2005–2016) dataset of hourly land-atmosphere interaction observations from an integrated high-elevation, cold region observation network, which is composed of six field observation and research platforms on the TP. In-situ observations, at the hourly resolution, consisting of measurements of micrometeorology, surface radiation, eddy covariance (EC), and soil temperature and soil water content profiles. Meteorological data were monitored by automatic weather station (AWS) or a planetary boundary layer (PBL) observation system composed of multiple meteorological element instruments. Multilayer soil hydrothermal data were recorded to capture vertical variations in soil temperature and water content and to study the freeze-thaw processes. In addition, to capture the high-frequency vertical exchanges of energy, momentum, water vapor and carbon dioxide within the atmospheric boundary layer, an EC system consisting of an ultrasonic anemometer and an infrared gas analyzer was installed at each station. The release of these continuous and long-term datasets with hourly time resolution represents a leap forward in scientific data sharing over the TP, and it has been partially used in the past to assist in understanding key land surface processes. This dataset is described here comprehensively for facilitating a broader multidisciplinary community by enabling the evaluation and development of existing or new remote sensing algorithms as well as geophysical models for climate research and forecasting. The whole datasets are freely available at Science Data Bank (http://www.dx.doi.org/10.11922/sciencedb.00103, Ma et al., 2020) and, additionally at the National Tibetan Plateau Data Center (https://data.tpdc.ac.cn/en/data/b9ab35b2-81fb-4330-925f-4d9860ac47c3/).

scholarly journals Long-term deglacial permafrost carbon dynamics in MPI-ESM

2018 ◽  
Vol 14 (12) ◽  
pp. 2011-2036 ◽  
Author(s):  
Thomas Schneider von Deimling ◽  
Thomas Kleinen ◽  
Gustaf Hugelius ◽  
Christian Knoblauch ◽  
Christian Beer ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Soil Carbon ◽  
Carbon Accumulation ◽  
Surface Model ◽  
Model Parameters ◽  
Moderate Increase ◽  
Permafrost Degradation ◽  
Frozen Ground ◽  
Near Surface

Abstract. We have developed a new module to calculate soil organic carbon (SOC) accumulation in perennially frozen ground in the land surface model JSBACH. Running this offline version of MPI-ESM we have modelled long-term permafrost carbon accumulation and release from the Last Glacial Maximum (LGM) to the pre-industrial (PI) age. Our simulated near-surface PI permafrost extent of 16.9 × 106 km2 is close to observational estimates. Glacial boundary conditions, especially ice sheet coverage, result in profoundly different spatial patterns of glacial permafrost extent. Deglacial warming leads to large-scale changes in soil temperatures, manifested in permafrost disappearance in southerly regions, and permafrost aggregation in formerly glaciated grid cells. In contrast to the large spatial shift in simulated permafrost occurrence, we infer an only moderate increase in total LGM permafrost area (18.3 × 106 km2) – together with pronounced changes in the depth of seasonal thaw. Earlier empirical reconstructions suggest a larger spread of permafrost towards more southerly regions under glacial conditions, but with a highly uncertain extent of non-continuous permafrost. Compared to a control simulation without describing the transport of SOC into perennially frozen ground, the implementation of our newly developed module for simulating permafrost SOC accumulation leads to a doubling of simulated LGM permafrost SOC storage (amounting to a total of ∼ 150 PgC). Despite LGM temperatures favouring a larger permafrost extent, simulated cold glacial temperatures – together with low precipitation and low CO2 levels – limit vegetation productivity and therefore prevent a larger glacial SOC build-up in our model. Changes in physical and biogeochemical boundary conditions during deglacial warming lead to an increase in mineral SOC storage towards the Holocene (168 PgC at PI), which is below observational estimates (575 PgC in continuous and discontinuous permafrost). Additional model experiments clarified the sensitivity of simulated SOC storage to model parameters, affecting long-term soil carbon respiration rates and simulated ALDs. Rather than a steady increase in carbon release from the LGM to PI as a consequence of deglacial permafrost degradation, our results suggest alternating phases of soil carbon accumulation and loss as an effect of dynamic changes in permafrost extent, ALDs, soil litter input, and heterotrophic respiration.

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