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"Shrestha, B."
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Climate Change Impacts on the Upper Indus Hydrology: Sources, Shifts and Extremes
2016
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.
Journal Article
Consistent increase in High Asia's runoff due to increasing glacier melt and precipitation
by
Shrestha, A. B.
,
Lutz, A. F.
,
Immerzeel, W. W.
in
704/106/242
,
704/106/694/1108
,
704/106/694/2739
2014
The impact of climate change on the water resources and hydrology of High Asia is uncertain. This work uses a cryospheric hydrological model to quantify the hydrology of five major rivers in the region and project future water availability. Runoff is expected to increase until at least 2050 due to an increase in precipitation in the upper catchment of four rivers and increased melt entering the fifth river.
Rivers originating in the high mountains of Asia are among the most meltwater-dependent river systems on Earth, yet large human populations depend on their resources downstream
1
. Across High Asia’s river basins, there is large variation in the contribution of glacier and snow melt to total runoff
2
, which is poorly quantified. The lack of understanding of the hydrological regimes of High Asia’s rivers is one of the main sources of uncertainty in assessing the regional hydrological impacts of climate change
3
. Here we use a large-scale, high-resolution cryospheric–hydrological model to quantify the upstream hydrological regimes of the Indus, Ganges, Brahmaputra, Salween and Mekong rivers. Subsequently, we analyse the impacts of climate change on future water availability in these basins using the latest climate model ensemble. Despite large differences in runoff composition and regimes between basins and between tributaries within basins, we project an increase in runoff at least until 2050 caused primarily by an increase in precipitation in the upper Ganges, Brahmaputra, Salween and Mekong basins and from accelerated melt in the upper Indus Basin. These findings have immediate consequences for climate change policies where a transition towards coping with intra-annual shifts in water availability is desirable.
Journal Article
Climate change‐induced distributional change of medicinal and aromatic plants in the Nepal Himalaya
by
Dhakal, Sajita
,
Atreya, Kishor
,
Shrestha, Bharat B.
in
Biodiversity
,
Climate adaptation
,
Climate change
2022
Medicinal and aromatic plants (MAPs) contribute to human well‐being via health and economic benefits. Nepal has recorded 2331 species of MAPs, of which around 300 species are currently under trade. Wild harvested MAPs in Nepal are under increasing pressure from overexploitation for trade and the effects of climate change and development. Despite some localized studies to examine the impact of climate change on MAPs, a consolidated understanding is lacking on how the distribution of major traded species of MAPs will change with future climate change. This study identifies the potential distribution of 29 species of MAPs in Nepal under current and future climate using an ensemble modeling and hotspot approach. Future climate change will reduce climatically suitable areas of two‐third of the studied species and decrease climatically suitable hotspots across elevation, physiography, ecoregions, federal states, and protected areas in Nepal. Reduction in climatically suitable areas for MAPs might have serious consequences for the livelihood of people that depend on the collection and trade of MAPs as well as Nepal's national economy. Therefore, it is imperative to consider the threats that future climate change may have on distribution of MAPs while designing protected areas and devising environmental conservation and climate adaptation policies. This figure provides climatically suitable habitats of various species of Medicinal and Aromatic Plants of Nepal along with extent of the species and hotspots of the studied species
Journal Article
Future changes in hydro-climatic extremes in the Upper Indus, Ganges, and Brahmaputra River basins
2017
Future hydrological extremes, such as floods and droughts, may pose serious threats for the livelihoods in the upstream domains of the Indus, Ganges, Brahmaputra. For this reason, the impacts of climate change on future hydrological extremes is investigated in these river basins. We use a fully-distributed cryospheric-hydrological model to simulate current and future hydrological fluxes and force the model with an ensemble of 8 downscaled General Circulation Models (GCMs) that are selected from the RCP4.5 and RCP8.5 scenarios. The model is calibrated on observed daily discharge and geodetic mass balances. The climate forcing and the outputs of the hydrological model are used to evaluate future changes in climatic extremes, and hydrological extremes by focusing on high and low flows. The outcomes show an increase in the magnitude of climatic means and extremes towards the end of the 21st century where climatic extremes tend to increase stronger than climatic means. Future mean discharge and high flow conditions will very likely increase. These increases might mainly be the result of increasing precipitation extremes. To some extent temperature extremes might also contribute to increasing discharge extremes, although this is highly dependent on magnitude of change in temperature extremes. Low flow conditions may occur less frequently, although the uncertainties in low flow projections can be high. The results of this study may contribute to improved understanding on the implications of climate change for the occurrence of future hydrological extremes in the Hindu Kush-Himalayan region.
Journal Article
SpatialData: an open and universal data framework for spatial omics
by
Marconato, Luca
,
Stockhaus, Sonja
,
Treis, Tim
in
631/114/2398
,
631/114/2401
,
631/1647/245/2160
2025
Spatially resolved omics technologies are transforming our understanding of biological tissues. However, the handling of uni- and multimodal spatial omics datasets remains a challenge owing to large data volumes, heterogeneity of data types and the lack of flexible, spatially aware data structures. Here we introduce SpatialData, a framework that establishes a unified and extensible multiplatform file-format, lazy representation of larger-than-memory data, transformations and alignment to common coordinate systems. SpatialData facilitates spatial annotations and cross-modal aggregation and analysis, the utility of which is illustrated in the context of multiple vignettes, including integrative analysis on a multimodal Xenium and Visium breast cancer study.
SpatialData is a user-friendly computational framework for exploring, analyzing, annotating, aligning and storing spatial omics data that can seamlessly handle large multimodal datasets.
Journal Article
South Asian agriculture increasingly dependent on meltwater and groundwater
2022
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.South Asian agriculture depends on water from rains, meltwater and groundwater, but climate change impacts the timing of these water sources’ availability. Projections indicate that meltwater and groundwater will become more important and will need to offset reduced rainfall during drier years.
Journal Article
Climate change in Nepal and its impact on Himalayan glaciers
2011
Climate change can be particularly hard-hitting for small underdeveloped countries, relying heavily on natural resources for the economy and livelihoods. Nepal is one among these countries, being landlocked, with diverse physiographical characteristics within a relatively small territory and with rugged terrain. Poverty is widespread and the capacity of people and the country to cope with climate change impact is low. The country is dominated by the Asian monsoon system. The main occupation is agriculture, largely based on rain-fed farming practices. Tourism based on high altitude adventures is one of the major sources of income for the country. Nepal has a large hydropower potential. While only 0.75% of the theoretical hydropower potential has been tapped, Nepal can greatly benefit from this natural resource in the future. Climate change can adversely impact upon water resources and other sectors of Nepal. The source of water is mainly summer monsoon precipitation and the melting of the large reserve of snow and glaciers in the Himalayan highlands. Observations show clear evidences of significant warming. The average trend in the country is 0.06°C per year. The warming rates are progressively higher for high elevation locations. The warming climate has resulted in rapid shrinking of majority of glaciers in Nepal. This paper presents state-of-knowledge on the glacial dynamics in the country based on studies conducted in the past in Shorong, Khumbu, Langtang, Dhaulagiri and Kanchenjunga regions of Nepal. We present recent trends in river flow and an overview of studies on expected changes in the hydrological regime due to climate change. Formation, growth and likely outburst of glacial lake are phenomena directly related to climate change and deglaciation. This paper provides a synopsis of past glacial lake outburst floods impacting Nepal. Further, likely impacts of climate change on other sectors such as agriculture, biodiversity, human health and livelihoods are discussed.
Journal Article
Diversity of use and local knowledge of wild edible plant resources in Nepal
2012
Background
Wild edible plants (WEP) provide staple and supplement foods, as well as cash income to local communities, thus favouring food security. However, WEP are largely ignored in land use planning and implementation, economic development, and biodiversity conservation. Moreover, WEP-related traditional knowledge is rapidly eroding. Therefore, we designed this study to fulfill a part of the knowledge gap by providing data on diversity, traditional knowledge, economic potential, and conservation value of WEP from Nepal.
Methods
The information was collected through focus group discussions and key informant interviews. Percentage of general utility of the plants among the study communities was evaluated using the Chi-square (
χ
2
) test of homogeneity. High priority species were identified after consultation with the local stakeholders followed by scoring based on defined criteria. Pairwise ranking was used to assess ethnoecological knowledge to identify the threats to WEP.
Results
We documented 81 species belonging to Angiosperms (74), Pteridophytes (5), and Fungi (2). Most of the species were used as fruits (44 species) followed by vegetables (36). Almost half of the species (47%) were also used for purposes other than food. From the species with market value (37% of the total), 10 were identified as high priority species. Pairwise ranking revealed that WEP are threatened mostly by habitat destruction, land-use change and over-harvesting. Some of these plants are crop wild relatives and could thus be used for crop improvement. Interestingly, our study also revealed that young people who spend most of the time in the forest as herdsmen are particularly knowledgeable of wild fruit plants.
Conclusion
We provide empirical evidence from a relatively large area of Nepal about diversity and status of WEP, as well as methodological insights about the proper knowledge holders to consult. Regarding the unique and important knowledge they have on WEP, young people should be included when recruiting participants to ethnobotanical studies or to any type of consultation about WEP. The habit of using wild edible plants is still alive and is a traditional culinary practice that demonstrates rich traditional knowledge of local people. WEP were found to be important for livelihood as well as showing great potential for crop improvement. Priority species should be promoted for income generation activities through sustainable collection and trade. Communities should engage in minimizing the threats to these valuable resources.
Journal Article
Multifractal Behavior of Energetic Neutral Atom Time Series from IBEX
by
Schwadron, N. A
,
Shrestha, B. L
,
Sarlis, N. V
in
Fluctuations
,
Fractal analysis
,
Neutral atoms
2026
Energetic neutral atom (ENA) flux time series measured by the Interstellar Boundary Explorer (IBEX) from the north and south polar regions have recently revealed persistence, which is in accord with the persistence in the solar wind (SW) flow pressure at 1 au. This is not unexpected since the SW is involved in the generation of ENAs. Here, we further explore the origins of this similarity by studying for the first time the multifractal character inherent to these time series. We show that even when removing periodic trends from the time series, the remaining fluctuations exhibit rich multifractality. The multifractality reflects the existence of multiple long-range correlations in the ENA fluctuations. The north polar region presents wider multifractality than the south, exhibiting higher complexity. This is compatible with the fact that the northern region is much more affected than the southern from the IBEX Ribbon, an unanticipated ENA source discovered by IBEX. The ENA flux time series multifractal spectra (MFS) show a clear tendency (>70%) to be right-skewed. SW flow pressure MFS is also right-skewed, indicating the influence of the SW pressure on the ENAs. The analysis relies on two modern techniques commonly used in fractal analysis: the multifractal detrended fluctuation analysis (MFDFA) and the Multiscale Multifractal Analysis (MMA), which is a generalization of MFDFA, both of order m = 3 (determined in our previous study as optimal for detrending). Finally, the MMA of ENA flux time series indicates persistence in 97% of the cases studied, generalizing our previous results.
Journal Article
Projected changes in climate over the Indus river basin using a high resolution regional climate model (PRECIS)
2015
A regional climate modelling system, the Providing REgional Climates for Impacts Studies developed by the Hadley Centre for Climate Prediction and Research, has been used to study future climate change scenarios over Indus basin for the impact assessment. In this paper we have examined the three Quantifying Uncertainty in Model Predictions simulations selected from 17-member perturbed physics ensemble generated using Hadley Centre Coupled Module. The climate projections based on IPCC SRES A1B scenario are analysed over three time slices, near future (2011–2040), middle of the twenty first century (2041–2070), and distant future (2071–2098). The baseline simulation (1961–1990) was evaluated with observed data for seasonal and spatial patterns and biases. The model was able to resolve features on finer spatial scales and depict seasonal variations reasonably well, although there were quantitative biases. The model simulations suggest a non-uniform change in precipitation overall, with an increase in precipitation over the upper Indus basin and decrease over the lower Indus basin, and little change in the border area between the upper and lower Indus basins. A decrease in winter precipitation is projected, particularly over the southern part of the basin. Projections indicate greater warming in the upper than the lower Indus, and greater warming in winter than in the other seasons. The simulations suggest an overall increase in the number of rainy days over the basin, but a decrease in the number of rainy days accompanied by an increase in rainfall intensity in the border area between the upper and lower basins, where the rainfall amount is highest.
Journal Article