scholarly journals Moisture Sources for Precipitation and Hydrograph Components of the Sutri Dhaka Glacier Basin, Western Himalayas

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2242 ◽  
Author(s):  
Singh ◽  
Rahaman ◽  
Sharma ◽  
Laluraj ◽  
Patel ◽  
...  
Keyword(s):  
Fresh Water ◽  
Water Isotopes ◽  
Back Trajectory ◽  
Western Himalayas ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Study Region ◽  
Moisture Sources ◽  
Himalayan Glaciers ◽  
Recent Climate

Himalayan glaciers are the major source of fresh water supply to the Himalayan Rivers, which support the livelihoods of more than a billion people living in the downstream region. However, in the face of recent climate change, these glaciers might be vulnerable, and thereby become a serious threat to the future fresh water reserve. Therefore, special attention is required in terms of understanding moisture sources for precipitation over the Himalayan glaciers and the hydrograph components of streams and rivers flowing from the glacierized region. We have carried out a systematic study in one of the benchmark glaciers, “Sutri Dhaka” of the Chandra Basin, in the western Himalayas, to understand its hydrograph components, based on stable water isotopes (δ18O and δ2H) and field-based ablation measurements. Further, to decipher moisture sources for precipitation and its variability in the study region, we have studied stable water isotopes in precipitation samples (rain and snow), and performed a back-trajectory analysis of the air parcel that brings moisture to this region. Our results show that the moisture source for precipitation over the study region is mainly derived from the Mediterranean regions (>70%) by Western Disturbances (WDs) during winter (October–May) and a minor contribution (<20%) from the Indian Summer Monsoon (ISM) during summer season (June–September). A three-component hydrograph separation based on δ18O and d-excess provides estimates of ice (65 ± 14%), snowpack (15 ± 9%) and fresh snow (20 ± 5%) contributions, respectively. Our field-based specific ablation measurements show that ice and snow melt contributions are 80 ± 16% and 20 ± 4%, respectively. The differences in hydrograph component estimates are apparently due to an unaccounted snow contribution ‘missing component’ from the valley slopes in field-based ablation measurements, whereas the isotope-based hydrograph separation method accounts for all the components, and provides a basin integrated estimate. Therefore, we suggest that for similar types of basins where contributions of rainfall and groundwater are minimal, and glaciers are often inaccessible for frequent field measurements/observations, the stable isotope-based method could significantly add to our ability to decipher moisture sources and estimate hydrograph components.

scholarly journals New water fractions and transit time distributions at Plynlimon, Wales, estimated from stable water isotopes in precipitation and streamflow

2019 ◽  
Author(s):  
Julia L. A. Knapp ◽  
Colin Neal ◽  
Alessandro Schlumpf ◽  
Margaret Neal ◽  
James W. Kirchner
Keyword(s):  
Time Series ◽  
Stable Isotope ◽  
Transit Time ◽  
Transport Processes ◽  
Water Isotopes ◽  
Data Sets ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Isotope Data ◽  
Water Fractions

Abstract. Long-term, high-frequency time series of passive tracers in precipitation and streamflow are essential for quantifying catchment transport and storage processes, but few such data sets are publicly available. Here we describe, present, and make available to the public two extensive data sets of stable water isotopes in streamflow and precipitation at the Plynlimon experimental catchments in mid-Wales. Stable isotope data are available at 7-hourly intervals for 17 months, and at weekly intervals for 4.25 years. Precipitation isotope values were highly variable in both data sets, and the high temporal resolution of the 7-hourly streamwater samples revealed rich isotopic dynamics that were not captured by the weekly sampling. We used ensemble hydrograph separation to calculate new water fractions and transit time distributions from both data sets. Transit time distributions estimated by ensemble hydrograph separation were broadly consistent with those estimated by spectral fitting methods, suggesting that they can reliably quantify the contributions of recent precipitation to streamflow. We found that on average, roughly 3 % of streamwater was made up of precipitation that fell within the previous 7 hours, and 13–15 % of streamwater was made up of precipitation that fell within the previous week. The contributions of recent precipitation to streamflow were highest during large events, as illustrated by comparing new water fractions for different discharges and precipitation rates. This dependence of new water fractions on water fluxes was also reflected in their seasonal variations, with lower new water fractions and more damped catchment transit time distributions in spring and summer compared to fall and winter. We also compared new water fractions obtained from stable water isotopes against those obtained from concentrations of chloride, a solute frequently used as a passive tracer of catchment transport processes. After filtering the chloride data for dry deposition effects, we found broadly similar new water fractions using chloride and stable water isotopes, indicating that these different tracers may yield similar inferences about catchment storage and transport, if potentially confounding factors are eliminated. These stable isotope time series comprise some of the longest and most detailed publicly available catchment isotope data sets. They complement extensive solute data sets that are already publicly available for Plynlimon, enabling a wide range of future analyses of catchment behavior.

scholarly journals Stable water isotope tracing through hydrological models for disentangling runoff generation processes at the hillslope scale

2014 ◽  
Vol 18 (10) ◽  
pp. 4113-4127 ◽  
Author(s):  
D. Windhorst ◽  
P. Kraft ◽  
E. Timbe ◽  
H.-G. Frede ◽  
L. Breuer
Keyword(s):  
Water Isotopes ◽  
Richards Equation ◽  
Advective Transport ◽  
Stable Water Isotopes ◽  
Runoff Generation ◽  
Modeling Framework ◽  
Mixing Processes ◽  
Study Region ◽  
Modeling Experiment ◽  
Water Isotope

Abstract. Hillslopes are the dominant landscape components where incoming precipitation becomes groundwater, streamflow or atmospheric water vapor. However, directly observing flux partitioning in the soil is almost impossible. Hydrological hillslope models are therefore being used to investigate the processes involved. Here we report on a modeling experiment using the Catchment Modeling Framework (CMF) where measured stable water isotopes in vertical soil profiles along a tropical mountainous grassland hillslope transect are traced through the model to resolve potential mixing processes. CMF simulates advective transport of stable water isotopes 18O and 2H based on the Richards equation within a fully distributed 2-D representation of the hillslope. The model successfully replicates the observed temporal pattern of soil water isotope profiles (R2 0.84 and Nash–Sutcliffe efficiency (NSE) 0.42). Predicted flows are in good agreement with previous studies. We highlight the importance of groundwater recharge and shallow lateral subsurface flow, accounting for 50 and 16% of the total flow leaving the system, respectively. Surface runoff is negligible despite the steep slopes in the Ecuadorian study region.

Hydrograph separation and precipitation source identification using stable water isotopes and conductivity: River Ganga at Himalayan foothills

2010 ◽  
Vol 25 (10) ◽  
pp. 1521-1530 ◽  
Author(s):  
A. S. Maurya ◽  
Miral Shah ◽  
R. D. Deshpande ◽  
R. M. Bhardwaj ◽  
A. Prasad ◽  
...  
Keyword(s):  
Source Identification ◽  
Water Isotopes ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Himalayan Foothills ◽  
River Ganga

Identification of source-sink relationships in southern Africa by stable water isotopes analysis and Lagrangian moisture source diagnostics

2020 ◽  
Author(s):  
Marielle Geppert ◽  
Stephan Pfahl ◽  
Ulrich Struck ◽  
Ingo Kirchner ◽  
Elisha Shemang ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Southern Africa ◽  
Specific Humidity ◽  
Water Isotopes ◽  
Stable Water Isotopes ◽  
Moisture Source ◽  
Moisture Sources ◽  
Transport Patterns ◽  
Isotope Measurements ◽  
Water Isotope

&lt;p&gt;Many palaeoclimate reconstructions are based on the fact that stable water isotopes are conserved in different highly resolved paleo-archives such as ice cores or calcium carbonates. Stable water isotopes are tracers of moisture in the atmosphere because they record information about evaporation and condensation processes during the transport of air parcels. These processes cause isotopic fractionation that leads to isotopic enrichment or depletion. The isotopic composition of precipitation is strongly correlated with altitude above sea level, distance to the coast and local surface air temperature. Knowledge on the source and transport of moisture is thus crucial for the interpretation of stable isotopes in precipitation and in palaeo-archives.&lt;br&gt;Studies analysing the linkage between stable water isotope measurements and moisture sources in southern Africa are scarce. Yet, as changes in the transport pattern can influence precipitation patterns and amounts, in a semi-arid region like southern Africa that is threatened by droughts, this knowledge is of particular interest. Thus, the aims of this study are (1) to reveal the principal moisture source areas and transport routes of specific target areas in southern Africa, (2) to assess the influence of different transport patterns on the isotopic composition of precipitation and by this (3) to create a modern analogue for palaeoclimate studies in this region.&lt;br&gt;About 200 water samples, mainly from headwaters of rivers, but also from precipitation events, springs and lakes, were collected throughout southern Africa and the stable water isotope composition (&amp;#948;&lt;sup&gt;2&lt;/sup&gt;H and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O) was analysed. To detect moisture sources for this set of isotope measurements, backward air parcel trajectories were calculated from the sample location, using the LAGRANTO tool based on ERA5 reanalysis data. Variations in specific humidity along the trajectories were then used to detect moisture uptake.&lt;br&gt;The analysis reveals main transport patterns related to the Intertropical Convergence Zone and easterly winds as well as the effects of topographical forcing, which is, for example, very pronounced above Lesotho. The results provide detailed insights into the relationships between atmospheric circulation and &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H and &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O values of precipitation over southern Africa, which is a prerequisite for the interpretation of isotopic records that are used for palaeoclimatic reconstructions.&lt;/p&gt;

scholarly journals New water fractions and transit time distributions at Plynlimon, Wales, estimated from stable water isotopes in precipitation and streamflow

2019 ◽  
Vol 23 (10) ◽  
pp. 4367-4388 ◽  
Author(s):  
Julia L. A. Knapp ◽  
Colin Neal ◽  
Alessandro Schlumpf ◽  
Margaret Neal ◽  
James W. Kirchner
Keyword(s):  
Time Series ◽  
Stable Isotope ◽  
Transit Time ◽  
Transport Processes ◽  
Water Isotopes ◽  
Data Sets ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Isotope Data ◽  
Water Fractions

Abstract. Long-term, high-frequency time series of passive tracers in precipitation and streamflow are essential for quantifying catchment transport and storage processes, but few such data sets are publicly available. Here we describe, present, and make available to the public two extensive data sets of stable water isotopes in streamflow and precipitation at the Plynlimon experimental catchments in central Wales. Stable isotope data are available at 7-hourly intervals for 17 months, and at weekly intervals for 4.25 years. Precipitation isotope values were highly variable in both data sets, and the high temporal resolution of the 7-hourly streamwater samples revealed rich isotopic dynamics that were not captured by the weekly sampling. We used ensemble hydrograph separation to calculate new water fractions and transit time distributions from both data sets. Transit time distributions estimated by ensemble hydrograph separation were broadly consistent with those estimated by spectral fitting methods, suggesting that they can reliably quantify the contributions of recent precipitation to streamflow. We found that on average, roughly 3 % of streamwater was made up of precipitation that fell within the previous 7 h, and 13 %–15 % of streamwater was made up of precipitation that fell within the previous week. The contributions of recent precipitation to streamflow were highest during large events, as illustrated by comparing new water fractions for different discharges and precipitation rates. This dependence of new water fractions on water fluxes was also reflected in their seasonal variations, with lower new water fractions and more damped catchment transit time distributions in spring and summer compared to fall and winter. We also compared new water fractions obtained from stable water isotopes against those obtained from concentrations of chloride, a solute frequently used as a passive tracer of catchment transport processes. After filtering the chloride data for dry deposition effects, we found broadly similar new water fractions using chloride and stable water isotopes, indicating that these different tracers may yield similar inferences about catchment storage and transport, if potentially confounding factors are eliminated. These stable isotope time series comprise some of the longest and most detailed publicly available catchment isotope data sets. They complement extensive solute data sets that are already publicly available for Plynlimon, enabling a wide range of future analyses of catchment behavior.

scholarly journals Stable water isotope tracing through hydrological models for disentangling runoff generation processes at the hillslope scale

2014 ◽  
Vol 11 (5) ◽  
pp. 5179-5216 ◽  
Author(s):  
D. Windhorst ◽  
P. Kraft ◽  
E. Timbe ◽  
H.-G. Frede ◽  
L. Breuer
Keyword(s):  
Water Isotopes ◽  
Richards Equation ◽  
Advective Transport ◽  
Stable Water Isotopes ◽  
Runoff Generation ◽  
Modeling Framework ◽  
Mixing Processes ◽  
Study Region ◽  
Modeling Experiment ◽  
Water Isotope

Abstract. Hillslopes are the dominant landscape components where incoming precipitation is transferred to become groundwater, streamflow or atmospheric water vapor. However, directly observing flux partitioning in the soil is almost impossible. Hydrological hillslope models are therefore being used to investigate the involved processes. Here we report on a modeling experiment using the Catchment Modeling Framework (CMF) where measured stable water isotopes in vertical soil profiles along a tropical mountainous grassland hillslope transect are traced through the model to resolve potential mixing processes. CMF simulates advective transport of stable water isotopes 18O and 2H based on the Richards equation within a fully distributed 2-D representation of the hillslope. The model successfully replicates the observed temporal pattern of soil water isotope profiles (R2 0.84 and NSE 0.42). Predicted flows are in good agreement with previous studies. We highlight the importance of groundwater recharge and shallow lateral subsurface flow, accounting for 50% and 16% of the total flow leaving the system, respectively. Surface runoff is negligible despite the steep slopes in the Ecuadorian study region.

New water fractions, transit time distributions, and solute concentrations at Plynlimon, Wales.

2020 ◽  
Author(s):  
Julia Knapp ◽  
James Kirchner
Keyword(s):  
Transit Time ◽  
Water Isotopes ◽  
Water Fluxes ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Water Fractions ◽  
Lag Times ◽  
And Storage ◽  
Average Contribution ◽  
Insight Into

&lt;p&gt;Transit time distributions estimated from stable water isotopes (deuterium and oxygen-18) are frequently used to assess transport and storage of water in catchments. We analyzed 2.25 years of 7&amp;#8209;hourly and 4.5 years of weekly measurements of stable water isotopes in precipitation and streamwater at the Plynlimon catchments in Wales, UK using the ensemble hydrograph separation technique. We thereby quantified new water fractions &amp;#8211; the average contribution of recent precipitation to streamflow &amp;#8211; in the different subcatchments, and determined transit time distributions as the contribution of precipitation to streamflow over a range of lag times.&lt;/p&gt;&lt;p&gt;We found that on average only 3 % of streamwater was made up of precipitation that fell within the last 7 hours, and 13-15 % of streamwater was made up of precipitation that fell within the previous week. However, these new water fractions increased with discharge, indicating that more recent precipitation reached the stream when the catchment was wet, and the contributions of recent precipitation to streamflow were highest during large events. This dependence of new water fractions on water fluxes was also reflected in their seasonal variations, with lower new water fractions and more damped catchment transit time distributions in the drier spring and summer compared to fall and winter.&lt;/p&gt;&lt;p&gt;A comparison between changes in solute concentrations and new water fractions with discharge provides additional insight into the storage and release of water and solutes from the catchments. Our analysis demonstrates that changes in solute concentrations primarily reflect changes in flowpaths between dry and wet conditions, rather than changes in the fraction of recent precipitation in streamflow.&lt;/p&gt;

scholarly journals A Lagrangian perspective on stable water isotopes during the West African Monsoon

2021 ◽  
Author(s):  
Christopher Johannes Diekmann ◽  
Matthias Schneider ◽  
Peter Knippertz ◽  
Andries Jan de Vries ◽  
Stephan Pfahl ◽  
...  
Keyword(s):  
West African Monsoon ◽  
West African ◽  
Water Isotopes ◽  
Stable Water Isotopes ◽  
The West ◽  
African Monsoon

scholarly journals An Optimized Snowmelt Lysimeter System for Monitoring Melt Rates and Collecting Samples for Stable Water Isotope Analysis

2019 ◽  
Vol 67 (1) ◽  
pp. 20-31 ◽  
Author(s):  
Andrea Rücker ◽  
Massimiliano Zappa ◽  
Stefan Boss ◽  
Jana von Freyberg
Keyword(s):  
Isotopic Composition ◽  
Isotope Analysis ◽  
Ground Level ◽  
Isotopic Signature ◽  
Small Scale ◽  
Spatial And Temporal Variability ◽  
Environmental Tracers ◽  
Hydrograph Separation ◽  
Stable Water Isotopes ◽  
Restricted Volume

Abstract The contribution of snow meltwater to catchment streamflow can be quantified through hydrograph separation analyses for which stable water isotopes (18O, 2H) are used as environmental tracers. For this, the spatial and temporal variability of the isotopic composition of meltwater needs to be captured by the sampling method. This study compares an optimized snowmelt lysimeter system and an unheated precipitation collector with focus on their ability to capture snowmelt rates and the isotopic composition of snowmelt. The snowmelt lysimeter system consists of three individual unenclosed lysimeters at ground level with a surface of 0.14 m2 each. The unheated precipitation collector consists of a 30 cm-long, extended funnel with its orifice at 2.3 m above ground. Daily snowmelt samples were collected with both systems during two snowfall-snowmelt periods in 2016. The snowmelt lysimeter system provided more accurate measurements of natural melt rates and allowed for capturing the small-scale variability of snowmelt process at the plot scale, such as lateral meltwater flow from the surrounding snowpack. Because of the restricted volume of the extended funnel, daily melt rates from the unheated precipitation collector were up to 43% smaller compared to the snowmelt lysimeter system. Overall, both snowmelt collection methods captured the general temporal evolution of the isotopic signature in snowmelt.

Sign in / Sign up

Export Citation Format

Share Document