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Upstream-downstream linkages of hydrological processes in the Himalayan region

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Ecological Processes 2014年第1期3卷 51-66页

作者： Santosh Nepal Wolfgang-Albert Flugel arun bhakta shrestha International Centre for Integrated Mountain Development(ICIMOD) KathmanduNepal Department of Geoinformatics Hydrology and ModellingFriedrich Schiller UniversityJena(FSU-Jena)Germany

Understanding the upstream-downstream linkages in hydrological processes is essential for water resources planning in river basins.Although there are many studies of individual aspects of these processes in the Himalayan region,studies along the length of the basins are limited.This study summarizes the present state of knowledge about linkages in hydrological processes between upstream and downstream areas of river basins in the Himalayan region based on a literature review.The paper studies the linkages between the changes in the physical environment of upstream areas(land use,snow storage,and soil erosion)and of climate change on the downstream water availability,flood and dry season flow,and erosion and sedimentation.It is argued that these linkages are complex due to the extreme altitudinal range associated with the young and fragile geology,extreme seasonal and spatial variation in rainfall,and diversity of anthropogenic processes.Based on the findings,the paper concludes that integrated systems analysis is required to understand the holistic complexity of upstream-downstream linkages of hydrological processes in the river basin context.The integrated land and water resources management(ILWRM)approach can be instrumental in developing adaptive solutions to problems and can also enable stakeholders of upstream and downstream areas with various interests and needs to work together for the better utilization and management of land and water resources.As a part of this,the specific circumstances of the upstream communities,who live in fragile and inaccessible mountain areas with limited resource opportunities,should be taken into account so that incentive mechanisms can be established to encourage and acknowledge their contribution.

关键词： Integrated land and water resources management Himalayan region Integrated systems analysis Geoinformatics Physical linkages Value of environmental services

Downscaled climate change projections for the Hindu Kush Himalayan region using CORDEX South Asia regional climate models

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Advances in Climate Change Research 2017年第3期8卷 185-198页

作者： Jayanarayanan SANJAY Raghavan KRISHNAN arun bhakta shrestha Rupak RAJBHANDARI REN Guo-Yu Centre for Climate Change Research Indian Institute of Tropical Meteorology Pune 411008 India International Centre for Integrated Mountain Development Kathmandu 3226 Nepal Department of Meteorology Tri-Chandra Campus Tribhuvan University Kathmandu 3226 Nepal Laboratory for Climate Studies National Climate Center China Meteorological Administration Beijing 100081 China

This study assessed the regional climate models (RCMs) employed in the Coordinated Regional climate Downscaling Experiment (CORDEX) South Asia framework to investigate the qualitative aspects of future change in seasonal mean near surface air temperature and precipitation over the Hindu Kush Himalayan (HKH) region. These RCMs downscaled a subset of atmosphere ocean coupled global climate models (AOGCMs) in the Coupled Model Intercomparison Project phase 5 (CMIP5) to higher 50 km spatial resolution over a large domain covering South Asia for two representation concentration pathways (RCP4.5 and RCP8.5) future scenarios. The analysis specifically examined and evaluated multi-model and multi-scenario climate change projections over the hilly sub-regions within HKH for the near-future (2036e2065) and far-future (2066e2095) periods. The downscaled multi-RCMs provide relatively better confidence than their driving AOGCMs in projecting the magnitude of seasonal warming for the hilly sub-region within the Karakoram and northwestern Himalaya, with higher projected change of 5.4 C during winter than of 4.9 C during summer monsoon season by the end of 21st century under the high-end emissions (RCP8.5) scenario. There is less agreement among these RCMs on the magnitude of the projected warming over the other sub-regions within HKH for both seasons, particularly associated with higher RCM uncertainty for the hilly sub-region within the central Himalaya. The downscaled multi-RCMs show good consensus and low RCM uncertainty in projecting that the summer monsoon precipitation will intensify by about 22% in the hilly subregion within the southeastern Himalaya and Tibetan Plateau for the far-future period under the RCP8.5 scenario. There is low confidence in the projected changes in the summer monsoon and winter season precipitation over the central Himalaya and in the Karakoram and northwestern Himalaya due to poor consensus and moderate to high RCM uncertainty among the downscaled multi-RCMs. Finally, the RCM related uncerta

关键词： CMIP5 CORDEX South Asia Regional climate models Hindu Kush Himalayan Climate change projections

Extreme climate projections over the transboundary Koshi River Basin using a high resolution regional climate model

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Advances in Climate Change Research 2017年第3期8卷 199-211页

作者： Rupak RAJBHANDARI arun bhakta shrestha Santosh NEPAL Shahriar WAHID REN Guo-Yu Department of Meteorology Tri-Chandra Campus Tribhuvan University Kathmandu Nepal International Centre for Integrated Mountain Development Kathmandu Nepal National Climate Center China Meteorological Administration Beijing 100081 China

The high-resolution climate model Providing REgional Climates for Impacts Studies (PRECIS) was used to project the changes in futureextreme precipitation and temperature over the Koshi River Basin for use in impact assessments. Three outputs of the Quantifying Uncertaintiesin Model Prediction (QUMP) simulations using the Hadley Centre Couple Model (HadCM3) based on the IPCC SRES A1B emission scenario were used to project the future climate. The projections were analysed for three time slices, 2011e2040 (near future), 2041e2070 (mid-century), and 2071e2098 (distant future). The results show an increase in the future frequency and intensity of climate extremes events such as dry days, consecutive dry days, and very wet days (95th percentile), with greater increases over the southern plains than in the mountainous area to the north. A significant decrease in moderate rainfall days (75th percentile) is projected over the middle (high) mountain and trans-Himalaya areas. Increases are projected in both the extreme maximum and extreme minimum temperature, with a slightly higher rate in minimum temperature. The number of warm days is projected to increase throughout the basin, with more rapid rates in the trans-Himalayan and middle mountain areas than in the plains. Warm nights are also projected to increase, especially in the southern plains. A decrease is projected in cold days and cold nights indicating overall warming throughout the basin.

关键词： Climate change Climate projection Koshi basin PRECIS Extreme climate

An overview of studies of observed climate change in the Hindu Kush Himalayan (HKH) region

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Advances in Climate Change Research 2017年第3期8卷 141-147页

作者： YOU Qing-Long REN Guo-Yu ZHANG Yu-Qing REN Yu-Yu SUN Xiu-Bao ZHAN Yun-Jian arun bhakta shrestha Raghavan KRISHNAN Key Laboratory of Meteorological Disaster Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environmental Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD) Nanjing University of Information Science Laboratory for Climate Studies National Climate Center China Meteorological Administration Beijing 100081 China Department of Atmospheric Science School of Environmental Studies China University of Geosciences Wuhan 430074 China International Centre for Integrated Mountain Development Kathmandu 3226 Nepal Indian Institute of Tropical Meteorology Pune 411008 India

The Hindu Kush Himalayan (HKH hereafter) region is characterized by mountainous environments and a variety of regional climatic conditions. High-altitude regions in the HKH have the recent warming amplifications, especially during the global warming hiatus period. The rapid warming cause solid state water (snow, ice, glacier, and permafrost) to shrink, leading to increase in meltwater and there have been found more frequent incidences of flash floods, landslides, livestock diseases, and other disasters in the HKH region. Increasing awareness of climate change over the HKH region is reached a consensus. Meanwhile, the HKH region is often referred to as the water towers of Asia as many highaltitude regions store its water in the form of snow and/or glacier, feeding ten major large rivers in Asia. Therefore, the impacts of climate change on water availability in these river basins have huge influences on the livelihood of large number of population, especially in downstream regions. However, the scarcity of basic hydro-meteorological observations particularly in high-altitude regions of HKH limits rigorous analysis of climate change. Most studies used reanalysis data and/or model-reconstructed products to explore the spatial and temporal characteristics of hydro-meteorological processes, especially for extreme events. In this study, we review recent climate change in the HKH region, and the scientific challenges and research recommendations are suggested for this high-altitude area.

关键词： Climate change Hindu Kush Himalayan Tibetan Plateau Hydrological cycles

Observed changes in surface air temperature and precipitation in the Hindu Kush Himalayan region over the last 100-plus years

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Advances in Climate Change Research 2017年第3期8卷 148-156页

作者： REN Yu-Yu REN Guo-Yu SUN Xiu-Bao arun bhakta shrestha YOU Qing-Long ZHAN Yun-Jian Rupak RAJBHANDARI ZHANG Pan-Feng WEN Kang-Min Laboratory for Climate Studies National Climate Center China Meteorological Administration Beijing 100081 China Department of Atmospheric Science School of Environmental Studies China University of Geosciences Wuhan 430074 China College of Atmospheric Science Nanjing University of Information Science & Technology Nanjing 210044 China International Centre for Integrated Mountain Development Kathmandu 3226 Nepal National Meteorological Information Center China Meteorological Administration Beijing 100081 China Chinese Academy of Meteorological Sciences China Meteorological Administration Beijing 100081 China Department of Meteorology Tri-Chandra Campus Tribhuvan University Kathmandu 3226 Nepal

In this paper, we analyzed the long-term changes in temperature and precipitation in the Hindu Kush Himalayan (HKH) region based on climate datasets LSAT-V1.1 and CGP1.0 recently developed by the China Meteorological Administration. The analysis results show that during 1901e2014 the annual mean surface air temperature over the whole HKH has undergone a significant increasing trend. We determined the change rates in the mean temperature, mean maximum temperature, and mean minimum temperature to be 0.104 C per decade, 0.077 C per decade, and 0.176 C per decade, respectively. Most parts of the HKH have experienced a warming trend, with the largest increase occurring on the Tibetan Plateau (TP) and south of Pakistan. The trend of precipitation for the whole HKH is characterized by a slight decrease during 1901e2014. During 1961e2013, however, the trend of the annual precipitation shows a statistically significant increase, with a rate of 5.28% per decade and has a more rapid increase since the mid-1980s. Most parts of northern India and the northern TP have experienced a strong increase in the number of precipitation days (daily rainfall 1 mm), whereas Southwest China and Myanmar have experienced a declining trend in precipitation days. Compared to the trends in precipitation days, the spatial pattern of trends in the precipitation intensity seems to be more closely related to the terrain, and the higher altitude areas have shown more significant upward trends in precipitation intensity during 1961e2013.

关键词： Climate change Temperature Precipitation Trend Hindu Kush Himalayan Tibetan Plateau

Projection of Future Climate over the Koshi River Basin Based on CMIP5 GCMs

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Atmospheric and Climate Sciences 2016年第2期6卷 190-204页

作者： Rupak Rajbhandari arun bhakta shrestha Santosh Nepal Shahriar Wahid Department of Meteorology Tri-Chandra Campus Tribhuvan University Kathmandu Nepal International Centre for Integrated Mountain Development Kathmandu Nepal

This paper analyses the climate projections over the Koshi river basin obtained by applying the delta method to eight CMIP5 GCMs for the RCP4.5 and RCP8.5 scenarios. The GCMs were selected to cover the full envelope of possible future ranges from dry and cold to wet and warm projections. The selected coarse resolution GCM outputs were statistically downscaled to the resolution of the historical climate datasets. The scenarios were developed based on the anomaly between the present reference period (1961-1990) and the future period (2021-2050) to generate transient climate change scenarios for the eight GCMs. The analyses were carried out for the whole basin and three physiographic zones: the trans-Himalaya, high-Himalaya and middle mountains, and southern plains. Future projections show a 14% increase in rainfall during the summer monsoon season by 2050. The increase in rainfall is higher over the mountains than the plains. The meagre amount of rainfall in the winter season is projected to further decrease over both the mountain and southern plains areas of the basin for both RCPs. The basin is likely to experience warming throughout the year, although the increase in winter is likely to be higher. The highest increase in temperature is projected to be over the high Himalayan and middle mountain area, with lower increases over the trans-Himalayan and southern plains areas.

关键词： Climate Projection Climate Change Himalaya Koshi Future Scenario

Projection of Future Precipitation and Temperature Change over the Transboundary Koshi River Basin Using Regional Climate Model PRECIS

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Atmospheric and Climate Sciences 2018年第2期8卷 163-191页

The Koshi river basin sustains the livelihoods of millions of people in the upstream and downstream areas of the basin. People rely on monsoon rainfall for agricultural production, hydropower generation and other livelihood activities. Climate change is expected to have serious implication on its environment. To reduce the adverse impacts of disasters and to better understand the implication of climate change for the sustainable development, initiative in this regard is necessary. Analysis of past meteorological trends and future climate projections can give us a sense of what to expect and how to prepare ourselves and manage available resources. In this paper, we have used a high-resolution climate model, viz., Providing REgional Climates for Impacts Studies (PRECIS), to project future climate scenario over the Koshi river basin for impact assessment. Three outputs of the Quantifying Uncertainties in Model Prediction (QUMP) simulations have been used to project the future climate. These simulations were selected from the 17-member Perturbed Physics Ensemble (PPE) using Hadley Centre Couple Model (HadCM3) based on the IPCC SRES A1B emission scenario. The future projections are analysed for three time slices 2011-2040 (near future), 2041-2070 (middle of the century) and 2071-2098 (distant future). Despite quantitative wet and cold bias, the model was able to resolve the seasonal pattern reasonably well. The model projects a decrease in rainfall in the near future and a progressive increase towards the end of the century. The projected change in rainfall is non-uniform, with increase over the southern plains and the middle mountains and decrease over the trans-Himalayan region. Simulation suggests that rainy days will be less frequent but more intense over the southern plains towards the end of the century. Further, the model projections indicate significant warming towards the end of the century. The rate of warming is slightly higher over the trans-Himalayan region during summer and over the southern plains durin

关键词： Future Climate Climate Projection PRECIS Koshi Himalaya

澜沧江和怒江流域的气候变化及其对径流的影响

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气候变化研究进展 2017年第4期13卷 356-365页

作者：刘苏峡丁文浩莫兴国王盛刘昌明罗贤何大明 Sagar Ratna Bajracharya arun bhakta shrestha Nand Kishor Agrawal 中国科学院地理科学与资源研究所陆地水循环及地表过程重点实验室北京100101 中国科学院大学资环学院/中丹学院北京100049 云南大学昆明650091 International Centre for Integrated Mountain Development Kathmandu 100023Nepal

采用VIP(Vegetation Interface Processes)模型和HIMS(Hydro-Informatic Modeling System)模型,模拟分析了1957—2012年澜沧江和怒江流域(简称两江流域)水资源量的演变。根据CMIP5 RCP2.6,RCP4.5和RCP8.5情景预测,模拟了2030年代和2050年代流域水资源的变化。研究发现,过去50年间,两江流域的气温都呈升高趋势,但海拔较高的上游地区升幅大于下游。年总降水量的变化趋势不明显,但春季降水增加趋势明显。两江流域年总水资源量为650亿~850亿m^3,水资源总量长期变化趋势不明显,其中澜沧江的波动性(1.884,最大与最小之比)大于怒江。空间上水资源量呈现北低-南高的格局。在未来,两江流域气温仍呈增加趋势,降水呈增加趋势,径流呈增加趋势,空间变异性趋小,但较强的季节性变化对水资源安全仍具有较大的挑战性。

关键词：径流气温降水 VIP模型 HIMS模型