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  1. Article: Snow cover persistence reverses the altitudinal patterns of warming above and below 5000 m on the Tibetan Plateau

    Zhang, Hongbo / Immerzeel, W.W. / Zhang, Fan / de Kok, Remco J. / Chen, Deliang / Yan, Wei

    Science of the total environment. 2022 Jan. 10, v. 803

    2022  

    Abstract: The Tibetan Plateau (TP) is a global warming hotspot, however, the warming status at high elevation (>5000 m) is poorly understood due to very sparse observations. Here we analyze spatial patterns in TP warming rates based on a novel near-surface air ... ...

    Abstract The Tibetan Plateau (TP) is a global warming hotspot, however, the warming status at high elevation (>5000 m) is poorly understood due to very sparse observations. Here we analyze spatial patterns in TP warming rates based on a novel near-surface air temperature dataset of 1980–2014 recently developed by ingesting high-elevation observations and downscaled reanalysis datasets. We show that the high snow cover persistence at high elevation reduces strengthening of positive feedbacks responsible for elevation dependent warming at low-middle elevations, leading to reversed altitudinal patterns of TP warming above and below 5000 m. An important negative feedback is induced by the presence of snow and glaciers at elevations above 5000 m, due to their “buffering” effects by consuming or reflecting energy that would be used for warming in the absence of snow or ice. A further decrease in snow cover and glacier extent at high elevations may thus amplify the warming on the TP.
    Keywords air temperature ; altitude ; data collection ; energy ; glaciers ; ice ; snow ; snowpack ; China
    Language English
    Dates of publication 2022-0110
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2021.149889
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Snow cover persistence reverses the altitudinal patterns of warming above and below 5000 m on the Tibetan Plateau.

    Zhang, Hongbo / Immerzeel, W W / Zhang, Fan / de Kok, Remco J / Chen, Deliang / Yan, Wei

    The Science of the total environment

    2021  Volume 803, Page(s) 149889

    Abstract: The Tibetan Plateau (TP) is a global warming hotspot, however, the warming status at high elevation (>5000 m) is poorly understood due to very sparse observations. Here we analyze spatial patterns in TP warming rates based on a novel near-surface air ... ...

    Abstract The Tibetan Plateau (TP) is a global warming hotspot, however, the warming status at high elevation (>5000 m) is poorly understood due to very sparse observations. Here we analyze spatial patterns in TP warming rates based on a novel near-surface air temperature dataset of 1980-2014 recently developed by ingesting high-elevation observations and downscaled reanalysis datasets. We show that the high snow cover persistence at high elevation reduces strengthening of positive feedbacks responsible for elevation dependent warming at low-middle elevations, leading to reversed altitudinal patterns of TP warming above and below 5000 m. An important negative feedback is induced by the presence of snow and glaciers at elevations above 5000 m, due to their "buffering" effects by consuming or reflecting energy that would be used for warming in the absence of snow or ice. A further decrease in snow cover and glacier extent at high elevations may thus amplify the warming on the TP.
    MeSH term(s) Environmental Monitoring ; Ice Cover ; Snow ; Temperature ; Tibet
    Language English
    Publishing date 2021-08-30
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2021.149889
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Variable 21st Century Climate Change Response for Rivers in High Mountain Asia at Seasonal to Decadal Time Scales

    Khanal, S. / Lutz, A.F. / Kraaijenbrink, P. D. A. / van den Hurk, B. / Yao, T. / Immerzeel, W. W.

    Water resources research. 2021 May, v. 57, no. 5

    2021  

    Abstract: The hydrological response to climate change in mountainous basins manifests itself at varying spatial and temporal scales, ranging from catchment to large river basin scale and from sub‐daily to decade and century scale. To robustly assess the 21st ... ...

    Abstract The hydrological response to climate change in mountainous basins manifests itself at varying spatial and temporal scales, ranging from catchment to large river basin scale and from sub‐daily to decade and century scale. To robustly assess the 21st century climate change impact for hydrology in entire High Mountain Asia (HMA) at a wide range of scales, we use a high resolution cryospheric‐hydrological model covering 15 upstream HMA basins to quantify the compound effects of future changes in precipitation and temperature based on the range of climate change projections in the Coupled Model Intercomparison Project Phase 6 climate model ensemble. Our analysis reveals contrasting responses for HMA's rivers, dictated by their hydrological regimes. At the seasonal scale, the earlier onset of melting causes a shift in the magnitude and peak of water availability, to earlier in the year. At the decade to century scale, after an initial increase, the glacier melt declines by the mid or end of the century except for the Tarim river basin, where it continues to increase. Despite a large variability in hydrological regimes across HMA's rivers, our results indicate relatively consistent climate change responses across HMA in terms of total water availability at decadal time scales. Although total water availability increases for the headwaters, changes in seasonality and magnitude may diverge widely between basins and need to be addressed while adapting to future changes in a region where food security, energy security as well as biodiversity, and the livelihoods of many depend on water from HMA.
    Keywords biodiversity ; climate change ; climate models ; energy ; food security ; glaciers ; mountains ; research ; temperature ; water ; watersheds ; Asia
    Language English
    Dates of publication 2021-05
    Publishing place John Wiley & Sons, Ltd
    Document type Article
    Note JOURNAL ARTICLE
    ZDB-ID 5564-5
    ISSN 1944-7973 ; 0043-1397
    ISSN (online) 1944-7973
    ISSN 0043-1397
    DOI 10.1029/2020WR029266
    Database NAL-Catalogue (AGRICOLA)

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  4. Article: Creating 1-km long-term (1980–2014) daily average air temperatures over the Tibetan Plateau by integrating eight types of reanalysis and land data assimilation products downscaled with MODIS-estimated temperature lapse rates based on machine learning

    Zhang, Hongbo / Immerzeel, W.W. / Zhang, Fan / de Kok, Remco J. / Gorrie, Sally J. / Ye, Ming

    International journal of applied earth observation and geoinformation. 2021 May, v. 97

    2021  

    Abstract: Air temperature (Tair) is critical to modeling environmental processes (e.g. snow/glacier melting) in high-elevation areas of the Tibetan Plateau (TP). To resolve the issue that Tair observations are scarce in the TP western part and at high elevation, ... ...

    Abstract Air temperature (Tair) is critical to modeling environmental processes (e.g. snow/glacier melting) in high-elevation areas of the Tibetan Plateau (TP). To resolve the issue that Tair observations are scarce in the TP western part and at high elevation, many studies have estimated daily air temperatures by using MODIS land surface temperature (LST) and various reanalysis datasets. These estimates are however inadequate for supporting high-resolution long-term hydrological simulations or climate analysis due to the high cloud cover, short time span or low spatial resolution. To improve the Tair estimation, this study develops a novel machine-learning based method that uses the Gradient Boosting model to efficiently integrate observations from high-elevation stations with eight widely used air temperature reanalysis and assimilation datasets (i.e., NNRP-2, 20CRV2c, JRA-55, ERA-Interim, MERRA-2, CFSR, ERA5 and GLDAS2) downscaled with remote sensing-based temperature lapse rates (TLR). This method is used to generate a new dataset of daily air temperature with the 1-km resolution for the period of 1980–2014. To overcome the problem that TLR derived from limited stations may be unreliable, a new TLR estimation method is developed to first estimate spatially continuous monthly TLRs from MODIS LST and then downscale daily mean Tair from eight reanalysis and assimilation datasets to obtain Tair at the 1-km resolution using the MODIS-estimated TLRs. The Gradient Boosting (GB) model is selected for integrating the eight downscaled Tair and five other auxiliary variables. The models are trained and validated using observations from 100 common stations (i.e. China Meteorology Administration stations) and 13 independent high-elevation stations (4 on glaciers). The results show that the proposed TLR estimation method can efficiently reduce exceptional TLRs in the meantime keeping acceptable downscaling accuracy. The downscaled Tair from JRA-55 is the best among the eight downscaled datasets followed by ERA-Interim, MERRA-2, CFSR and others. Finally, the GB-integrated Tair further outperforms the downscaled JRA-55 Tair with the mean root-mean-squared-deviation (RMSD) of 1.7 °C versus 2.0 °C, especially in high-elevation stations with mean RMSD of 1.9 °C versus 2.7 °C. Both the MODIS-estimated TLR and the high-elevation training observations are demonstrated to significantly improve the air temperature estimation accuracy of the GB model in high-elevation stations. This study also provides a framework for integrating multiple reanalysis and assimilation temperature data with elevation correction in mountainous regions that is not restricted to the TP.
    Keywords air ; air temperature ; altitude ; artificial intelligence ; climate ; cloud cover ; data collection ; glaciers ; hydrology ; meteorology ; models ; mountains ; snow ; spatial data ; surface temperature ; China
    Language English
    Dates of publication 2021-05
    Publishing place Elsevier B.V.
    Document type Article
    ISSN 1569-8432
    DOI 10.1016/j.jag.2021.102295
    Database NAL-Catalogue (AGRICOLA)

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  5. Article: A novel method to quantify consumed fractions and non-consumptive use of irrigation water: Application to the Indus Basin Irrigation System of Pakistan

    Simons, G.W.H / Bastiaanssen, W.G.M / Cheema, M.J.M / Ahmad, B / Immerzeel, W.W

    Agricultural water management. 2020 June 30, v. 236

    2020  

    Abstract: Increasing irrigation efficiencies remains the focus of numerous efforts to mitigate water scarcity. In reality, higher local efficiencies do often not reduce water scarcity, but instead cause a redistribution of water flows when the entire irrigation ... ...

    Abstract Increasing irrigation efficiencies remains the focus of numerous efforts to mitigate water scarcity. In reality, higher local efficiencies do often not reduce water scarcity, but instead cause a redistribution of water flows when the entire irrigation scheme or river basin is considered. Insufficient understanding of consumed fractions and non-consumptive use (i.e. return flows) have led to ineffective, or even harmful, water conservation measures. In this paper, we demonstrate a novel method for spatial quantification of the Consumed Fraction (CF) of withdrawn irrigation water based on satellite remote sensing and the Budyko Hypothesis. This method was applied to evaluate consumption of irrigation water (ETblue), total water supply, and non-consumptive use across the Indus Basin Irrigation System (IBIS) of Pakistan. An average ETblue of 707 mm/yr from irrigated cropland was found for 2004–2012, with values per Canal Command Area (CCA) varying from 421 mm/yr to 1011 mm/yr. Although canal supply (662 mm/yr on average) in most CCAs was largely sufficient to sustain ETblue, a similar volume of additional pumping (690 mm/yr) was required to comply with hydro-climatological principles prescribed by Budyko theory. CF values between 0.38 and 0.66 were computed at CCA level, with an average value of 0.52. Co-occurrence of relatively low CF values, high additional water supply, and long-term canal diversions similar to ETblue, implies that the IBIS is characterized by extensive reuse of non-consumed flows within CCAs. In addition, the notably higher CF of 0.71−0.93 of the full IBIS indicates that return flow reuse between CCAs cannot be neglected. These conclusions imply that the IBIS network of irrigators is adapted to extensively recover and reuse drainage flows on different spatial scales. Water saving and efficiency enhancement measures should therefore be implemented with great caution. By relying on globally available satellite products and limited additional data, this novel method to determine Consumed Fractions and non-consumed flows can support policy makers worldwide to make irrigation systems more efficient without detriment to downstream users.
    Keywords basin irrigation ; drainage ; drainage water ; irrigated farming ; irrigation management ; irrigation water ; issues and policy ; remote sensing ; satellites ; water conservation ; water shortages ; watersheds ; Pakistan
    Language English
    Dates of publication 2020-0630
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 751144-9
    ISSN 1873-2283 ; 0378-3774
    ISSN (online) 1873-2283
    ISSN 0378-3774
    DOI 10.1016/j.agwat.2020.106174
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: South Asian agriculture increasingly dependent on meltwater and groundwater

    Lutz, A. F. / Immerzeel, W. W. / Siderius, C. / Wijngaard, R. R. / Nepal, Santosh / Shrestha, A. B. / Wester, P. / Biemans, H.

    Nature Climate Change

    2022  

    Abstract: Irrigated agriculture in South Asia depends on meltwater, monsoon rains and groundwater. Climate change alters the hydrology and causes shifts in the timing, composition and magnitude of these sources of water supply. Simultaneously, socio-economic ... ...

    Abstract Irrigated agriculture in South Asia depends on meltwater, monsoon rains and groundwater. Climate change alters the hydrology and causes shifts in the timing, composition and magnitude of these sources of water supply. Simultaneously, socio-economic growth increases water demand. Here we use a high-resolution cryosphere–hydrology–crop model forced with an ensemble of climate and socio-economic projections to assess how the sources of irrigation water supply may shift during the twenty-first century. We find increases in the importance of meltwater and groundwater for irrigated agriculture. An earlier melt peak increases meltwater withdrawal at the onset of the cropping season in May and June in the Indus, whereas increasing peak irrigation water demand during July and August aggravates non-renewable groundwater pumping in the Indus and Ganges despite runoff increases. Increasing inter-annual variability in rainfall runoff increases the need for meltwater and groundwater to complement rainfall runoff during future dry years.
    Keywords meltwater ; groundwater ; agriculture ; irrigated farming ; climate change ; forecasting ; hydrological modelling ; socioeconomic aspects ; water availability ; water supply ; water demand ; irrigation water ; water extraction ; rain ; runoff ; glaciers ; river basins ; monsoon climate ; crops
    Language English
    Publishing date 2022-07-18T14:47:47Z
    Publisher Springer
    Publishing country fr
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: South Asian agriculture increasingly dependent on meltwater and groundwater

    Lutz, A.F. / Immerzeel, W.W. / Siderius, C. / Wijngaard, R.R. / Nepal, S. / Shrestha, A.B. / Wester, P. / Biemans, H.

    Nature Climate Change

    2022  Volume 12, Issue 6

    Abstract: Irrigated agriculture in South Asia depends on meltwater, monsoon rains and groundwater. Climate change alters the hydrology and causes shifts in the timing, composition and magnitude of these sources of water supply. Simultaneously, socio-economic ... ...

    Abstract Irrigated agriculture in South Asia depends on meltwater, monsoon rains and groundwater. Climate change alters the hydrology and causes shifts in the timing, composition and magnitude of these sources of water supply. Simultaneously, socio-economic growth increases water demand. Here we use a high-resolution cryosphere–hydrology–crop model forced with an ensemble of climate and socio-economic projections to assess how the sources of irrigation water supply may shift during the twenty-first century. We find increases in the importance of meltwater and groundwater for irrigated agriculture. An earlier melt peak increases meltwater withdrawal at the onset of the cropping season in May and June in the Indus, whereas increasing peak irrigation water demand during July and August aggravates non-renewable groundwater pumping in the Indus and Ganges despite runoff increases. Increasing inter-annual variability in rainfall runoff increases the need for meltwater and groundwater to complement rainfall runoff during future dry years.
    Keywords Life Science
    Subject code 550
    Language English
    Publishing country nl
    Document type Article ; Online
    ZDB-ID 2614383-5
    ISSN 1758-6798 ; 1758-678X
    ISSN (online) 1758-6798
    ISSN 1758-678X
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article ; Online: Impact of a global temperature rise of 1.5 degrees Celsius on Asia's glaciers.

    Kraaijenbrink, P D A / Bierkens, M F P / Lutz, A F / Immerzeel, W W

    Nature

    2017  Volume 549, Issue 7671, Page(s) 257–260

    Abstract: Glaciers in the high mountains of Asia (HMA) make a substantial contribution to the water supply of millions of people, and they are retreating and losing mass as a result of anthropogenic climate change at similar rates to those seen elsewhere. In the ... ...

    Abstract Glaciers in the high mountains of Asia (HMA) make a substantial contribution to the water supply of millions of people, and they are retreating and losing mass as a result of anthropogenic climate change at similar rates to those seen elsewhere. In the Paris Agreement of 2015, 195 nations agreed on the aspiration to limit the level of global temperature rise to 1.5 degrees Celsius ( °C) above pre-industrial levels. However, it is not known what an increase of 1.5 °C would mean for the glaciers in HMA. Here we show that a global temperature rise of 1.5 °C will lead to a warming of 2.1 ± 0.1 °C in HMA, and that 64 ± 7 per cent of the present-day ice mass stored in the HMA glaciers will remain by the end of the century. The 1.5 °C goal is extremely ambitious and is projected by only a small number of climate models of the conservative IPCC's Representative Concentration Pathway (RCP)2.6 ensemble. Projections for RCP4.5, RCP6.0 and RCP8.5 reveal that much of the glacier ice is likely to disappear, with projected mass losses of 49 ± 7 per cent, 51 ± 6 per cent and 64 ± 5 per cent, respectively, by the end of the century; these projections have potentially serious consequences for regional water management and mountain communities.
    Language English
    Publishing date 2017-09-13
    Publishing country England
    Document type Journal Article
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/nature23878
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Spatial quantification of groundwater abstraction in the irrigated Indus basin.

    Cheema, M J M / Immerzeel, W W / Bastiaanssen, W G M

    Ground water

    2014  Volume 52, Issue 1, Page(s) 25–36

    Abstract: Groundwater abstraction and depletion were assessed at a 1-km resolution in the irrigated areas of the Indus Basin using remotely sensed evapotranspiration (ET) and precipitation; a process-based hydrological model and spatial information on canal water ... ...

    Abstract Groundwater abstraction and depletion were assessed at a 1-km resolution in the irrigated areas of the Indus Basin using remotely sensed evapotranspiration (ET) and precipitation; a process-based hydrological model and spatial information on canal water supplies. A calibrated Soil and Water Assessment Tool (SWAT) model was used to derive total annual irrigation applied in the irrigated areas of the basin during the year 2007. The SWAT model was parameterized by station corrected precipitation data (R) from the Tropical Rainfall Monitoring Mission, land use, soil type, and outlet locations. The model was calibrated using a new approach based on spatially distributed ET fields derived from different satellite sensors. The calibration results were satisfactory and strong improvements were obtained in the Nash-Sutcliffe criterion (0.52 to 0.93), bias (-17.3% to -0.4%), and the Pearson correlation coefficient (0.78 to 0.93). Satellite information on R and ET was then combined with model results of surface runoff, drainage, and percolation to derive groundwater abstraction and depletion at a nominal resolution of 1 km. It was estimated that in 2007, 68 km³ (262 mm) of groundwater was abstracted in the Indus Basin while 31 km³ (121 mm) was depleted. The mean error was 41 mm/year and 62 mm/year at 50% and 70% probability of exceedance, respectively. Pakistani and Indian Punjab and Haryana were the most vulnerable areas to groundwater depletion and strong measures are required to maintain aquifer sustainability.
    MeSH term(s) Agricultural Irrigation ; Calibration ; China ; Groundwater/analysis ; Hydrology/methods ; India ; Models, Theoretical ; Pakistan ; Plant Transpiration ; Rain ; Water Supply
    Language English
    Publishing date 2014-01
    Publishing country United States
    Document type Journal Article
    ZDB-ID 246212-6
    ISSN 1745-6584 ; 0017-467X
    ISSN (online) 1745-6584
    ISSN 0017-467X
    DOI 10.1111/gwat.12027
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  10. Article ; Online: Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes.

    Lutz, A F / Immerzeel, W W / Kraaijenbrink, P D A / Shrestha, A B / Bierkens, M F P

    PloS one

    2016  Volume 11, Issue 11, Page(s) e0165630

    Abstract: The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are ... ...

    Abstract The Indus basin heavily depends on its upstream mountainous part for the downstream supply of water while downstream demands are high. Since downstream demands will likely continue to increase, accurate hydrological projections for the future supply are important. We use an ensemble of statistically downscaled CMIP5 General Circulation Model outputs for RCP4.5 and RCP8.5 to force a cryospheric-hydrological model and generate transient hydrological projections for the entire 21st century for the upper Indus basin. Three methodological advances are introduced: (i) A new precipitation dataset that corrects for the underestimation of high-altitude precipitation is used. (ii) The model is calibrated using data on river runoff, snow cover and geodetic glacier mass balance. (iii) An advanced statistical downscaling technique is used that accounts for changes in precipitation extremes. The analysis of the results focuses on changes in sources of runoff, seasonality and hydrological extremes. We conclude that the future of the upper Indus basin's water availability is highly uncertain in the long run, mainly due to the large spread in the future precipitation projections. Despite large uncertainties in the future climate and long-term water availability, basin-wide patterns and trends of seasonal shifts in water availability are consistent across climate change scenarios. Most prominent is the attenuation of the annual hydrograph and shift from summer peak flow towards the other seasons for most ensemble members. In addition there are distinct spatial patterns in the response that relate to monsoon influence and the importance of meltwater. Analysis of future hydrological extremes reveals that increases in intensity and frequency of extreme discharges are very likely for most of the upper Indus basin and most ensemble members.
    MeSH term(s) Afghanistan ; China ; Climate ; Climate Change/statistics & numerical data ; Hydrology/methods ; Hydrology/statistics & numerical data ; Ice Cover ; India ; Models, Statistical ; Pakistan ; Rivers ; Seasons ; Snow ; Temperature ; Water Movements ; Water Supply/statistics & numerical data
    Language English
    Publishing date 2016
    Publishing country United States
    Document type Journal Article
    ISSN 1932-6203
    ISSN (online) 1932-6203
    DOI 10.1371/journal.pone.0165630
    Database MEDical Literature Analysis and Retrieval System OnLINE

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