scholarly journals Characterization of Interannual and Seasonal Variability of Hydro-Climatic Trends in the Upper Indus Basin

2021 ◽  
Author(s):  
Muhammad Usman Liaqat ◽  
Giovanna Grossi ◽  
Shabeh ul Hasson ◽  
Roberto Ranzi
Keyword(s):  
Trend Analysis ◽  
Hydrological Cycle ◽  
Winter Season ◽  
Rain Gauge ◽  
Indus Basin ◽  
Annual Precipitation ◽  
Monthly Precipitation ◽  
Catchment Scale ◽  
Upper Indus Basin ◽  
Annual Scale

Abstract A high resolution seasonal and annual precipitation climatology of the Upper Indus Basin was developed, based on 1995-2017 precipitation normals obtained from four different gridded datasets (Aphrodite, CHIRPS, PERSIANN-CDR and ERA5) and quality-controlled high and mid elevation ground observations. Monthly precipitation values were estimated through the anomaly method at the catchment scale and compared with runoff data (1975-2017) for verification and detection of changes in the hydrological cycle. The gridded dataset is then analysed using running trends and spectral analysis and the Mann–Kendall test was employed to detect significant trends. The nonparametric Pettitt test was also used to identify the change point in precipitation and runoff time series. The results indicated that bias corrected CHIRPS precipitation dataset, followed by ERA5, performed better in terms of RMSE, MAE, MAPE and BIAS in simulating rain gauge-observed precipitation. The running trend analysis of annual precipitation exhibited a very slight increase whereas a more significant increase was found in the winter season (DJF). A runoff coefficient value greater than one, especially in glacierized catchments (Shigar, Shyok and Gilgit) indicate that precipitation was likely underestimated and glacial melt in a warming climate provides excess runoff volumes. As far as the streamflow is concerned, variabilities are more pronounced at the seasonal rather than at the annual scale. At the annual scale, trend analysis of discharge shows slightly significant increasing trend for the Indus River at the downstream Kachura, Shyok and Gilgit stations. Seasonal flow analysis reveals more complex regimes and its comparison with the variability of precipitation favours a deeper understanding of precipitation, snow- and ice-melt runoff dynamics, addressing the hydroclimatic behaviour of the Karakoram region.

scholarly journals Characterization of Interannual and Seasonal Variability of Hydro-Climatic Trends in the Upper Indus Basin

2020 ◽  
Author(s):  
Muhammad Usman Liaqat ◽  
Roberto Ranzi ◽  
Giovanna Grossi ◽  
Talha Mahmood
Keyword(s):  
Trend Analysis ◽  
Change Point ◽  
Winter Season ◽  
Kendall Test ◽  
Indus Basin ◽  
Percentage Error ◽  
Monsoon Period ◽  
Upper Indus Basin ◽  
Climatic Trends ◽  
Basin Scale

<p>A major part of Pakistan’s economy is dependent upon agriculture which is irrigated from the water resources of the Upper Indus Basin (UIB). Therefore the human impact of hydroclimatic variability in this area is of paramount importance. The Upper Indus Basin is characterized by uncertain hydro-climatic behaviour with changing patterns in different sub-basins. Many studies have worked on hydro-climatic trends at basin scale but only few studies focused on the hydroclimate, precipitation dynamics and their magnitude at sub-basin level. Based upon this scenario, high resolution seasonal and annual climatology of UIB was developed. It is based on precipitation normals 1995-2017 obtained from four different gridded satellite datasets (Aphrodite, Chirps, PERSIANN-CDR and GPCC) as well as quality- controlled high and mid elevation ground observations (1250–4500 m a.s.l.). The quality-control of the gridded dataset is computed by the anomaly method. In order to, evaluate the data quality of the gridded rainfall, four statistics i.e., BIAS, Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE) and Root Mean Square Error (RMSE) are used in this study. Using running trends and spectral analysis with multi-gauge based anomaly, the study analyses the precipitation and runoff   seasonal and annual temporal variability at sub-basin scale. For this, Mann–Kendall test was employed to detect the presence of any trend while their slope is calculated by Theil Sen’s slope method. The nonparametric Pettitt Test was also used in this study to eventually identify the change point in hydro-climatic time series. The results indicated that bias corrected CHIRPS precipitation datasets performed better in simulating precipitation with RMSE, MAE, MAPE [%] and BIAS followed by APHRODITE. The annual and seasonal precipitation climatology exhibited higher precipitation in the lower side of the basin. The comparison between short and long duration climatologies is being investigated as well. The annual running trend analysis of precipitation exhibited a very slight change whereas a more significant increase was found in the winter season (DJF) and most of sub-basins feature a significant decreasing rate in precipitation and constant change point within the monsoon period (JJA). Similarly, trend analysis for runoff in main rivers of Upper Indus Basin at Gilgat, Indus (Besham Qila, Bunji) exhibit nonsignificant increase except Hunza and Indus at Kharmong which are showed decrease annual trends and will be further investigated for seasonal patterns. Overall, these findings would assist to better understand precipitation, snow- and ice-melt runoff dynamics, addressing the hydroclimatic behaviour of the Karakoram region.</p>

Snowpack energy balance and changes in the frequency and extremity of rain-on-snow events in the warming climate

2021 ◽  
Author(s):  
Ondrej Hotovy ◽  
Michal Jenicek
Keyword(s):  
Energy Balance ◽  
Air Temperature ◽  
Snow Water Equivalent ◽  
Hydrological Cycle ◽  
Winter Season ◽  
Catchment Scale ◽  
The Future ◽  
Snow Water ◽  
The Impact ◽  
Catchment Runoff

<p>Seasonal snowpack significantly influences the catchment runoff and thus represents an important input for the hydrological cycle. Changes in the precipitation distribution and intensity, as well as a shift from snowfall to rain is expected in the future due to climate changes. As a result, rain-on-snow events, which are considered to be one of the main causes of floods in winter and spring, may occur more frequently. Heat from liquid precipitation constitutes one of the snowpack energy balance components. Consequently, snowmelt and runoff may be strongly affected by these temperature and precipitation changes.</p><p>The objective of this study is 1) to evaluate the frequency, inter-annual variability and extremity of rain-on-snow events in the past based on existing measurements together with an analysis of changes in the snowpack energy balance, and 2) to simulate the effect of predicted increase in air temperature on the occurrence of rain-on-snow events in the future. We selected 40 near-natural mountain catchments in Czechia with significant snow influence on runoff and with available long-time series (>35 years) of daily hydrological and meteorological variables. A semi-distributed conceptual model, HBV-light, was used to simulate the individual components of the water cycle at a catchment scale. The model was calibrated for each of study catchments by using 100 calibration trials which resulted in respective number of optimized parameter sets. The model performance was evaluated against observed runoff and snow water equivalent. Rain-on-snow events definition by threshold values for air temperature, snow depth, rain intensity and snow water equivalent decrease allowed us to analyze inter-annual variations and trends in rain-on-snow events during the study period 1965-2019 and to explain the role of different catchment attributes.</p><p>The preliminary results show that a significant change of rain-on-snow events related to increasing air temperature is not clearly evident. Since both air temperature and elevation seem to be an important rain-on-snow drivers, there is an increasing rain-on-snow events occurrence during winter season due to a decrease in snowfall fraction. In contrast, a decrease in total number of events was observed due to the shortening of the period with existing snow cover on the ground. Modelling approach also opened further questions related to model structure and parameterization, specifically how individual model procedures and parameters represent the real natural processes. To understand potential model artefacts might be important when using HBV or similar bucket-type models for impact studies, such as modelling the impact of climate change on catchment runoff.</p>

Changes in snow storages and their impact on occurrence and extremity of runoff caused by rain-on-snow events

2020 ◽  
Author(s):  
Ondrej Hotovy ◽  
Michal Jenicek
Keyword(s):  
Air Temperature ◽  
Snow Water Equivalent ◽  
Hydrological Cycle ◽  
Winter Season ◽  
Model Performance ◽  
Catchment Scale ◽  
The Future ◽  
Snow Water ◽  
The Impact ◽  
Catchment Runoff

<p>Seasonal snowpack significantly influences the catchment runoff and thus represents an important input for the hydrological cycle. Changes in the precipitation distribution and intensity, as well as a shift from snowfall to rain is expected in the future due to climate changes. As a result, rain-on-snow events, which are considered to be one of the main causes of floods in winter and spring, may occur more frequently.</p><p>The objective of this study is 1) to evaluate the frequency, inter-annual variability and extremity of rain-on-snow events in the past based on existing measurements and 2) to simulate the effect of predicted increase in air temperature on the occurrence of rain-on-snow events in the future. We selected 59 near-natural mountain catchments in Czechia with significant snow influence on runoff and with available long-time series (>35 years) of daily hydrological and meteorological variables. A semi-distributed conceptual model, HBV-light, was used to simulate the individual components of the water cycle at a catchment scale. The model was calibrated for each of study catchments by using 100 calibration trials which resulted in respective number of optimized parameter sets. The model performance was evaluated against observed runoff and snow water equivalent. Rain-on-snow events definition by threshold values for air temperature, snow depth, rain intensity and snow water equivalent decrease allowed us to analyze inter-annual variations and trends in rain-on-snow events during the study period 1980-2014 and to explain the role of different catchment attributes.</p><p>The preliminary results show that a significant change of rain-on-snow events related to increasing air temperature is not clearly evident. Since both air temperature and elevation seem to be an important rain-on-snow drivers, there is an increasing rain-on-snow events occurrence during winter season due to a decrease in snowfall fraction. In contrast, a decrease in total number of events was observed due to the shortening of the period with existing snow cover on the ground. Modelling approach also opened further questions related to model structure and parameterization, specifically how individual model procedures and parameters represent the real natural processes. To understand potential model artefacts might be important when using HBV or similar bucket-type models for impact studies, such as modelling the impact of climate change on catchment runoff.</p>

scholarly journals Prevailing climatic trends and runoff response from Hindukush–Karakoram–Himalaya, upper Indus basin

2015 ◽  
Vol 6 (1) ◽  
pp. 579-653 ◽  
Author(s):  
S. Hasson ◽  
J. Böhner ◽  
V. Lucarini
Keyword(s):  
High Altitude ◽  
Water Availability ◽  
Winter Season ◽  
Indus Basin ◽  
Climatic Trend ◽  
Upper Indus Basin ◽  
Climatic Trends ◽  
Mixed Response ◽  
Long Term Trends

Abstract. Largely depending on meltwater from the Hindukush–Karakoram–Himalaya, withdrawals from the upper Indus basin (UIB) contribute to half of the surface water availability in Pakistan, indispensable for agricultural production systems, industrial and domestic use and hydropower generation. Despite such importance, a comprehensive assessment of prevailing state of relevant climatic variables determining the water availability is largely missing. Against this background, we present a comprehensive hydro-climatic trend analysis over the UIB, including for the first time observations from high-altitude automated weather stations. We analyze trends in maximum, minimum and mean temperatures (Tx, Tn, and Tavg, respectively), diurnal temperature range (DTR) and precipitation from 18 stations (1250–4500 m a.s.l.) for their overlapping period of record (1995–2012), and separately, from six stations of their long term record (1961–2012). We apply Mann–Kendall test on serially independent time series to assess existence of a trend while true slope is estimated using Sen's slope method. Further, we statistically assess the spatial scale (field) significance of local climatic trends within ten identified sub-regions of UIB and analyze whether the spatially significant (field significant) climatic trends qualitatively agree with a trend in discharge out of corresponding sub-region. Over the recent period (1995–2012), we find a well agreed and mostly field significant cooling (warming) during monsoon season i.e. July–October (March–May and November), which is higher in magnitude relative to long term trends (1961–2012). We also find general cooling in Tx and a mixed response in Tavg during the winter season and a year round decrease in DTR, which are in direct contrast to their long term trends. The observed decrease in DTR is stronger and more significant at high altitude stations (above 2200 m a.s.l.), and mostly due to higher cooling in Tx than in Tn. Moreover, we find a field significant decrease (increase) in late-monsoonal precipitation for lower (higher) latitudinal regions of Himalayas (Karakoram and Hindukush), whereas an increase in winter precipitation for Hindukush, western- and whole Karakoram, UIB-Central, UIB-West, UIB-West-upper and whole UIB regions. We find a spring warming (field significant in March) and drying (except for Karakoram and its sub-regions), and subsequent rise in early-melt season flows. Such early melt response together with effective cooling during monsoon period subsequently resulted in a substantial drop (weaker increase) in discharge out of higher (lower) latitudinal regions (Himalaya and UIB-West-lower) during late-melt season, particularly during July. These discharge tendencies qualitatively differ to their long term trends for all regions, except for UIB-West-upper, western-Karakorum and Astore. The observed hydroclimatic trends, being driven by certain changes in the monsoonal system and westerly disturbances, indicate dominance (suppression) of nival (glacial) runoff regime, altering substantially the overall hydrology of UIB in future. These findings largely contribute to address the hydroclimatic explanation of the "Karakoram Anomaly".

scholarly journals Future Hydrological Regimes in the Upper Indus Basin: A Case Study from a High-Altitude Glacierized Catchment

2015 ◽  
Vol 16 (1) ◽  
pp. 306-326 ◽  
Author(s):  
Andrea Soncini ◽  
Daniele Bocchiola ◽  
Gabriele Confortola ◽  
Alberto Bianchi ◽  
Renzo Rosso ◽  
...  
Keyword(s):  
High Altitude ◽  
Climate Models ◽  
Hydrological Cycle ◽  
Global Climate ◽  
Ice Cover ◽  
Global Climate Models ◽  
Indus Basin ◽  
Rapid Decline ◽  
Climate Projections ◽  
Upper Indus Basin

Abstract The mountain regions of the Hindu Kush, Karakoram, and Himalayas (HKH) are considered Earth’s “third pole,” and water from there plays an essential role for downstream populations. The dynamics of glaciers in Karakoram are complex, and in recent decades the area has experienced unchanged ice cover, despite rapid decline elsewhere in the world (the Karakoram anomaly). Assessment of future water resources and hydrological variability under climate change in this area is greatly needed, but the hydrology of these high-altitude catchments is still poorly studied and little understood. This study focuses on a particular watershed, the Shigar River with the control section at Shigar (about 7000 km2), nested within the upper Indus basin and fed by seasonal melt from two major glaciers (Baltoro and Biafo). Hydrological, meteorological, and glaciological data gathered during 3 years of field campaigns (2011–13) are used to set up a hydrological model, providing a depiction of instream flows, snowmelt, and ice cover thickness. The model is used to assess changes of the hydrological cycle until 2100, via climate projections provided by three state-of-the-art global climate models used in the recent IPCC Fifth Assessment Report under the representative concentration pathway (RCP) emission scenarios RCP2.6, RCP4.5, and RCP8.5. Under all RCPs, future flows are predicted to increase until midcentury and then to decrease, but remaining mostly higher than control run values. Snowmelt is projected to occur earlier, while the ice melt component is expected to increase, with ice thinning considerably and even disappearing below 4000 m MSL until 2100.

scholarly journals Reconciling high altitude precipitation in the upper Indus Basin with glacier mass balances and runoff

2015 ◽  
Vol 12 (5) ◽  
pp. 4755-4784 ◽  
Author(s):  
W. W. Immerzeel ◽  
N. Wanders ◽  
A. F. Lutz ◽  
J. M. Shea ◽  
M. F. P. Bierkens
Keyword(s):  
High Altitude ◽  
River Flow ◽  
Hydrological Cycle ◽  
Indus Basin ◽  
Mass Balances ◽  
Mountain Ranges ◽  
Upper Indus Basin ◽  
Water Demands ◽  
Planning And Design ◽  
Hydropower Plants

Abstract. Mountain ranges in Asia are important water suppliers, especially if downstream climates are arid, water demands are high and glaciers are abundant. In such basins, the hydrological cycle depends heavily on high altitude precipitation. Yet direct observations of high altitude precipitation are lacking and satellite derived products are of insufficient resolution and quality to capture spatial variation and magnitude of mountain precipitation. Here we use glacier mass balances to inversely infer the high altitude precipitation in the upper Indus Basin and show that the amount of precipitation required to sustain the observed mass balances of the large glacier systems is far beyond what is observed at valley stations or estimated by gridded precipitation products. An independent validation with observed river flow confirms that the water balance can indeed only be closed when the high altitude precipitation is up to a factor ten higher than previously thought. We conclude that these findings alter the present understanding of high altitude hydrology and will have an important bearing on climate change impact studies, planning and design of hydropower plants and irrigation reservoirs and the regional geopolitical situation in general.

scholarly journals Spatiotemporal Variations of Precipitation over Iran Using the High-Resolution and Nearly Four Decades Satellite-Based PERSIANN-CDR Dataset

2020 ◽  
Vol 12 (10) ◽  
pp. 1584 ◽  
Author(s):  
Hamidreza Mosaffa ◽  
Mojtaba Sadeghi ◽  
Negin Hayatbini ◽  
Vesta Afzali Gorooh ◽  
Ata Akbari Asanjan ◽  
...  
Keyword(s):  
Kendall Test ◽  
Rain Gauge ◽  
Annual Precipitation ◽  
Management Decision ◽  
Monthly Precipitation ◽  
Precipitation Trend ◽  
Climate Data ◽  
Suitable Alternative ◽  
Precipitation Estimation ◽  
Precipitation Trends

Spatiotemporal precipitation trend analysis provides valuable information for water management decision-making. Satellite-based precipitation products with high spatial and temporal resolution and long records, as opposed to temporally and spatially sparse rain gauge networks, are a suitable alternative to analyze precipitation trends over Iran. This study analyzes the trends in annual, seasonal, and monthly precipitation along with the contribution of each season and month in the annual precipitation over Iran for the 1983–2018 period. For the analyses, the Mann–Kendall test is applied to the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Climate Data Record (PERSIANN-CDR) estimates. The results of annual, seasonal, and monthly precipitation trends indicate that the significant decreases in the monthly precipitation trends in February over the western (March over the western and central-eastern) regions of Iran cause significant effects on winter (spring) and total annual precipitation. Moreover, the increases in the amounts of precipitation during November in the south and south-east regions lead to a remarkable increase in the amount of precipitation during the fall season. The analysis of the contribution of each season and month to annual precipitation in wet and dry years shows that dry years have critical impacts on decreasing monthly precipitation over a particular region. For instance, a remarkable decrease in precipitation amounts is detectable during dry years over the eastern, northeastern, and southwestern regions of Iran during March, April, and December, respectively. The results of this study show that PERSIANN-CDR is a valuable source of information in low-density gauge network areas, capturing spatiotemporal variation of precipitation.

scholarly journals Trends in timing and magnitude of flow in the Upper Indus Basin

2013 ◽  
Vol 17 (4) ◽  
pp. 1503-1516 ◽  
Author(s):  
M. Sharif ◽  
D. R. Archer ◽  
H. J. Fowler ◽  
N. Forsythe
Keyword(s):  
Mass Balance ◽  
Trend Analysis ◽  
River Flow ◽  
Annual Runoff ◽  
Indus Basin ◽  
Onset Date ◽  
Trend Test ◽  
Glacier Mass Balance ◽  
Climate Trends ◽  
Upper Indus Basin

Abstract. River flow is a reflection of the input of moisture and its transformation in storage and transmission over the catchment. In the Upper Indus Basin (UIB), since high-altitude climate measurement and observations of glacier mass balance are weak or absent, analysis of trends in magnitude and timing in river flow provides a window on trends and fluctuations in climate and glacier outflow. Trend analysis is carried out using a Mann–Kendall nonparametric trend test on records extending from 1960 to 1998. High-level glacial catchments show a falling trend in runoff magnitude and a declining proportion of glacial contribution to the main stem of the Indus. Elsewhere annual flow has predominantly increased with several stations exhibiting statistically significant positive trends. Analysis of timing using spring onset date (SOT) and centre of volume date (CoV) indicated no clear trends – in direct contrast to what has been observed in western North America. There is, however, a consistent relationship between CoV and annual runoff volume. A consistently positive correlation was also found between SOT and CoV for all the stations, implying that initial snowpack conditions before the onset of runoff influence timing throughout the season. The results of the analysis presented here indicate that the magnitude and timing of streamflow hydrograph is influenced both by the initial snowpack and by seasonally varied trends in temperature. The study contributes to the understanding of the links between climate trends and variability and river runoff and glacier mass balance and runoff. The Upper Indus Basin is predominantly influenced by winter precipitation; similar trend analysis applied to summer-monsoon-dominated catchments of the central Himalaya is recommended.

scholarly journals Trends in timing and magnitude of flow in the Upper Indus Basin

2012 ◽  
Vol 9 (9) ◽  
pp. 9931-9966 ◽  
Author(s):  
M. Sharif ◽  
D. R. Archer ◽  
H. J. Fowler ◽  
N. Forsythe
Keyword(s):  
Mass Balance ◽  
Trend Analysis ◽  
River Flow ◽  
Annual Runoff ◽  
Indus Basin ◽  
Onset Date ◽  
Trend Test ◽  
Glacier Mass Balance ◽  
Climate Trends ◽  
Upper Indus Basin

Abstract. River flow is a reflection of the input of moisture and its transformation in storage and transmission over the catchment. In the Upper Indus Basin (UIB), since high altitude climate measurement and observations of glacier mass balance are weak or absent, analysis of trends in magnitude and timing in river flow provides a window on trends and fluctuations in climate and glacier outflow. Trend analysis is carried out using a Mann-Kendall nonparametric trend test on records extending from 1960 to 1998. High level glacial catchments show a falling trend in runoff magnitude and a declining proportion of glacial contribution to the main stem of the Indus. Elsewhere annual flow has predominantly increased with several stations exhibiting statistically significant positive trends. Analysis of timing using spring onset date (SOT) and centre of volume date (CoV) indicated no clear trends – in direct contrast to what has been observed in Western North America. There is, however, a consistent relationship between CoV and annual runoff volume. A consistently positive correlation was also found between SOT and CoV for all the stations implying that initial snowpack conditions before the onset of runoff influence timing throughout the season. The results of the analysis presented here indicate that the magnitude and timing of streamflow hydrograph is influenced both by the initial snowpack and by seasonally varied trends in temperature. The study contributes to the understanding of the links between climate trends and variability and river runoff and glacier mass balance and runoff. The Upper Indus Basin is predominantly influenced by winter precipitation; similar trend analysis applied to summer monsoon dominated catchments of the Central Himalaya is recommended.

scholarly journals Analysis of the Spatio-Temporal Variability of Precipitation and Drought Intensity in an Arid Catchment in South Africa

Climate ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 70
Author(s):  
Achamyeleh G. Mengistu ◽  
Weldemichael A. Tesfuhuney ◽  
Yali E. Woyessa ◽  
Leon D. van Rensburg
Keyword(s):  
South Africa ◽  
Temporal Variability ◽  
Assessment Tool ◽  
Winter Season ◽  
Aridity Index ◽  
Annual Precipitation ◽  
Trend Test ◽  
Monthly Precipitation ◽  
Drought Intensity ◽  
Spatio Temporal

Water deficit is high and precipitation varies spatio-temporally in arid areas. This study was conducted to analyse the spatio-temporal variability of precipitation and drought intensity in an arid catchment in South Africa. The Soil and Water Assessment Tool (SWAT) was used to estimate the spatio-temporal precipitation where nine meteorological stations were used as input to the model. The model was calibrated and validated by regionalization with a physical similarity approach. SWAT only predicts precipitation at sub-basin level. Hence, the mean precipitation was further interpolated by using the inverse distance weighted method (IDW). The Mann–Kendall trend test shows that there was no trend in annual precipitation whereas in the monthly precipitation there was a 0.01 mm decrease. Daily precipitation varied from 0.1 to 4 mm whereas in a monthly basis, it varied from 6 mm (September) to 43.4 mm (February). The annual precipitation varied from 169 mm (1983) to 415 mm (2003) with a long-term mean of 280.8 mm. Precipitation is also highly variable in space throughout the catchment. Generally, annual precipitation decreased from north to south; however, during the winter season, the reverse was true due to the influence of rain-bearing condition from the south- western direction. Based on the aridity index (AI), the catchment is categorized as arid. The SPI shows that the 1983 drought was the worst whereas the 2003 and 2004 years were relatively wet. The results from this study provide baseline information for further research in climate change adaptation and environmental monitoring programs in the region.

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