Streamflow Composition and Water "Imbalance" in the Northern Himalayas

Fan, Linfeng1,2; Kuang, Xingxing1; Or, Dani3,4; Zheng, Chunmiao1,5

2023-10-01

10.1029/2022WR034243

WATER RESOURCES RESEARCH   Impact Factor & Quartile

0043-1397

1944-7973

The Yarlung Zangbo River (YZR) is the largest river in the northern Himalayas, providing crucial water resources for downstream. A full understanding of the streamflow dynamics and regional water budget is critical to secure water security of the Himalayan water tower. Here we establish a comprehensive hydrological model to simulate the precipitation-runoff-evapotranspiration-groundwater-streamflow complex in the YZR basin. We decipher contributions of different water sources (e.g., precipitation, meltwater, groundwater) to YZR's streamflow and estimate that groundwater sustains similar to 36% of annual streamflow in the YZR, while precipitation and melt surface runoff contribute 40% and 24%, respectively. Combining modeling, observation and reanalysis data, our results reveal a water "imbalance" that similar to 31% of annual precipitation and meltwater (similar to 333 mm yr(-1) or similar to 85 km(3) yr(-1)) is unaccounted for in the YZR basin. We propose that the "excess water" discharges to deep fractured bedrock aquifers, which is promoted by widespread permeable active structures (e.g., faults, fractures). This hypothesis is supported by groundwater storage (GWS) estimates where inclusion of the deep groundwater bridges the discrepancy between baseflow-derived (shallow) GWS and those derived from the Gravity Recovery and Climate Experiment satellite data. The deep groundwater most likely flows across basins, bypasses streams, and finally discharges to downstream aquifers in the Indo-Gangetic Plain as mountain block recharge. This study not only provides a comprehensive analysis of the streamflow composition in the YZR, but also contributes to shaping a more complete picture of the functionality of the Himalayan water tower, highlighting the importance of groundwater in regional water transfers.

streamflow groundwater water budget Himalaya

SCI

English

First ; Corresponding

This work was supported by the National Natural Science Foundation of China (Grants 92047202, 41861124003, 41807288). The authors are grateful to Xiuyu Liang, Yong Tian, Kewei Chen, Zhilin Guo, Yinlei Hao, Fang Ji, and Yiguang Zou for helpful discussions a["92047202","41861124003","41807288"]

Environmental Sciences & Ecology ; Marine & Freshwater Biology ; Water Resources

Environmental Sciences ; Limnology ; Water Resources

WOS:001081529100001

AMER GEOPHYSICAL UNION

ENVIRONMENT/ECOLOGY

Web of Science

1.Southern Univ Sci & Technol, Sch Environm Sci & Engn, Shenzhen, Peoples R China
2.Chinese Acad Sci, Inst Mt Hazards & Environm, Key Lab Mt Hazards & Earth Surface Proc, Chengdu, Peoples R China
3.Swiss Fed Inst Technol, Dept Environm Syst Sci, Zurich, Switzerland
4.Desert Res Inst, Div Hydrol Sci, Reno, NV USA
5.Eastern Inst Technol, Eastern Inst Adv Study, Ningbo, Peoples R China

Fan, Linfeng,Kuang, Xingxing,Or, Dani,et al. Streamflow Composition and Water "Imbalance" in the Northern Himalayas[J]. WATER RESOURCES RESEARCH,2023,59(10).

Fan, Linfeng,Kuang, Xingxing,Or, Dani,&Zheng, Chunmiao.(2023).Streamflow Composition and Water "Imbalance" in the Northern Himalayas.WATER RESOURCES RESEARCH,59(10).

Fan, Linfeng,et al."Streamflow Composition and Water "Imbalance" in the Northern Himalayas".WATER RESOURCES RESEARCH 59.10(2023).