Kali Gandaki Research Articles

Construction of road bridges without consideration of geo-hazards and river-flow dynamics – A case study from Ghatte Khola, Myagdi, Nepal

In the past 20 years, motor road and bridge construction works have increased significantly in Nepal, in most cases with poor consideration of geo-hazards (rockfalls, landslides, debris flows) and river-flow dynamics. The National Road Construction (NRC) is further fostered by China’s Belt and Road Initiative (BRI). Currently, the Kali Gandaki (KG) road corridor is being upgraded to a 2-way black-top road as a project under BRI. The river dynamics of the KG sub-catchments is rarely considered by engineers despite it represents a common threat to the KG road, road bridges, and human lives. Here we study the Ghatte Khola (GK) sub-catchment that is located along the KG corridor in Dana, Myagdi district, West Nepal. From hydro-geomorphological mapping, hydrological and HEC–RAS analysis, historical archives and interviews, several questions have arisen regarding to the size of the under-construction GK motor bridge. The water way and freeboard of this bridge were found to be insufficient to safely pass the highest flood discharge for 100 years return-period, hence the bridge was found to be vulnerable to extreme floods. Actually, the nearly completed GK bridge was destroyed by a severe hyper-concentred flood on May 25, 2019. Active geo-hazards (rock falls, landslides) in the upper GK catchment appear as persistent drivers susceptible to aggravate sporadically the GK flows, and may pose serious threat to the future GK road bridge and to nearby infrastructure and settlements. We discuss these issues and eventually propose new technical, more sustainable solutions (e.g., fords).

Major geomorphic events and natural hazards during monsoonal precipitation 2018 in the Kali Gandaki Valley, Nepal Himalaya

Highest geomorphic activity in the central Nepal Himalayas is mainly driven by monsoonal precipitation. In contrast, the northern flanks of the Nepal Himalaya lay in the relative dry rain shadow of the mountain range.During the monsoon 2018, major floods and geomorphic events occurred in the Kali Gandaki (KG) valley impacting both the monsoon-affected and the dry parts of the catchments. We analyze the events and its triggers based on field observations, multiple satellite image interpretation, climatological analysis using Global Precipitation Measurement and MODIS snow cover data, hydrological analysis and media analysis.The hydro-meteorological triggers are complex. Exceptional precipitation in April and May 2018 occurred in the entire study area, followed by a rather dry period. Precipitation in August was exceptional in the northern part whereas below average in the South. We argue that dynamics of snow accumulation and delayed melting contributed significantly to flooding and increased geomorphic activity in the southern part in August whereas flooding in the northern part was mainly triggered by rainfalls. We thus define 2018 as an abnormal (pre-)monsoon year with less rainfall than average but being more catastrophic.Sediment dynamics in the study area are still controlled by the Dhampu rock avalanche dam and the braided river floodplain north of this knickpoint, where sediment pulses delivered from tributaries are rarely connected from the main river. During the monsoon floods 2018 sediment connectivity was given for most tributaries due to the steepness of the catchments.The study area is subject to major human impact. Mostly in the south, numerous hillslopes have been undercut by road construction, leading to higher geomorphic sensitivity. Severe landslides might thus be triggered in future even by less intense rainfall events.Magnitude and frequency of such abnormal (pre-)monsoon precipitation are highly relevant for sediment flux and natural hazards studies.

Integrated assessment of extreme events and hydrological responses of Indo-Nepal Gandak River Basin

Changes in climate cause significant alterations in morphometric parameters and may lead to hydro-meteorological hazards. In this study, an attempt has been made to identify drainage morphometric characteristics through topographic, geologic and hydrological information to assess the extreme weather events (flood) over the Gandak River Basin (GRB). The standardized precipitation index (SPI) and rainfall anomaly index (RAI) were used for deducing extreme rainfall incidences derived from the Tropical Rainfall Measuring Mission precipitation datasets. An assembled frequency distribution as well as trends in RAI and SPI was calculated to understand the hydro-climatological behaviour of the basin. During the monsoon season, the years 1998, 2007, 2011, 2013 and 2017 witnessed the extreme flood events. The variations in heavy and intense rainfall in short time can be linked to extreme flood events, which leads to channel shifting and modifications, can be deduced from provided asymmetric factors and sinuosity index. The results illustrated that both the monsoonal rainfall and the frequency of extreme rainfall over the basin are increasing, which could be a reason for a high severity and frequency of flood events in the GRB.

Variations in organic carbon sourcing along a trans-Himalayan river determined by a Bayesian mixing approach

Rivers transfer particulate organic carbon (POC) from eroding mountains into geological sinks. Organic carbon source composition and selective mobilization have been shown to affect the type and quantity of POC export, but their combined effects across complex mountain ranges remain underexplored. Here, we examine the variation in organic carbon sourcing and transport in the trans-Himalayan Kali Gandaki River catchment, along strong gradients in precipitation, rock type and vegetation. Combining bulk stable nitrogen, and stable and radioactive organic carbon isotopic composition of bedrock, litter, soil and river sediment samples with a Bayesian end-member mixing approach, we differentiate POC sources along the river and quantify their export. Our analysis shows that POC export from the Tibetan segment of the catchment, where carbon bearing shales are partially covered by aged and modern soils, is dominated by petrogenic POC. Based on our data we re-assess the presence of aged biospheric OC in this part of the catchment, and its contribution to the river load. In the High Himalayan segment, we observed low inputs of petrogenic and biospheric POC, likely due to very low organic carbon concentrations in the metamorphic bedrock, combined with erosion dominated by deep-seated landslides. Our findings show that along the Kali Gandaki River, the sourcing of sediment and organic carbon are decoupled, due to differences in rock organic carbon content, soil and above ground carbon stocks, and geomorphic process activity. While the fast eroding High Himalayas are the principal source of river sediment, the Tibetan headwaters, where erosion rates are lower, are the principal source of organic carbon. To robustly estimate organic carbon export from the Himalayas, the mountain range should be divided into tectono-physiographic zones with distinct organic carbon yields due to differences in substrate and erosion processes and rates.

Assimilation of Snowmelt Runoff Model (SRM) Using Satellite Remote Sensing Data in Budhi Gandaki River Basin, Nepal

The Himalayan region, a major source of fresh water, is recognized as a water tower of the world. Many perennial rivers originate from Nepal Himalaya, located in the central part of the Himalayan region. Snowmelt water is essential freshwater for living, whereas it poses flood disaster potential, which is a major challenge for sustainable development. Climate change also largely affects snowmelt hydrology. Therefore, river discharge measurement requires crucial attention in the face of climate change, particularly in the Himalayan region. The snowmelt runoff model (SRM) is a frequently used method to measure river discharge in snow-fed mountain river basins. This study attempts to investigate snowmelt contribution in the overall discharge of the Budhi Gandaki River Basin (BGRB) using satellite remote sensing data products through the application of the SRM model. The model outputs were validated based on station measured river discharge data. The results show that SRM performed well in the study basin with a coefficient of determination (R2) >0.880. Moreover, this study found that the moderate resolution imaging spectroradiometer (MODIS) snow cover data and European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological datasets are highly applicable to the SRM in the Himalayan region. The study also shows that snow days have slightly decreased in the last three years, hence snowmelt contribution in overall discharge has decreased slightly in the study area. Finally, this study concludes that MOD10A2 and ECMWF precipitation and two-meter temperature products are highly applicable to measure snowmelt and associated discharge through SRM in the BGRB. Moreover, it also helps with proper freshwater planning, efficient use of winter water flow, and mitigating and preventive measures for the flood disaster.

Flood Frequency Analysis for Burhi Gandak River Basin

The study is aimed at finding the best distribution to match the steam flow and calculation of magnitude and frequency of flow. In the current study, we have used several statistical distributions to find the best fit distribution for stream flow and used flood frequency analysis techniques to find the magnitude and frequency of stream flow and non-exceedance probability of peak discharge. The study has been performed at Sikandarpur and Rosera gauging sites of BurhiGandak River. Historical (50 years) maximum annual peak discharge data of each station are used for statistical analysis for estimating maximum peak discharge in 5, 10, 25, 50, 100 year return period. In this study, Lognormal distribution, Galton distribution, Gamma distribution, Log Pearson Type III distribution, Gumbell distribution, Generalised extreme values distribution have been considered to describe the annual maximum stream flow. Flood frequency analysis methods were used for estimating the magnitude of the extreme flow events and their associated return periods. For both Sikandarpur and Rosera stations, Log Pearson type III distributions showed the lowest value of K–S and Chi-square test statistic. The annual probable peak discharge for 5, 10, 25, 50, and 100 years return period is calculated for each distribution. The most suitable distribution for both the stations is found to be the log-Pearson type III distribution.

Physical and chemical characteristics of soils in Ephedra gerardiana and E. pachyclada habitats of Kali Gandaki Valley in Central Nepal

In the Kali Gandaki Valley in Central Nepal, Ephedra gerardiana and E. pachyclada show species specificity for physical and chemical characteristics of soils. Here, the relationship between soil characteristics and ephedrine and pseudoephedrine contents was examined. E. gerardiana grew in moist alpine scrub and upper alpine meadow from 3735 to 4156m a.s.l., while E. pachyclada grew in the lower Caragana steppe and dry alpine scrub from 2629 to 3671m a.s.l. The soil texture of E. gerardiana and E. pachyclada collection sites were classified as loam or sandy loam mainly composed of sand and silt. Loss on ignition (%) of soil in E. gerardiana habitats (28.4-35.0%) was markedly higher than for that in E. pachyclada habitats (14.2-17.2%). E. pachyclada soil (pH 8.4-9.2) was more alkaline than that for E. gerardiana (pH 8.5). The five ions (Cl-, SO42-, Ca2+, Mg2+, and Na+) in soil of E. pachyclada (Cl-, 0.01-18.97mmol/100g dry soil weight; SO42-, 1.95-83.33; Ca2+, 3.79-77.91; Mg2+, 1.28-27.9; Na+, 0.94-34.49) were markedly higher than those of E. gerardiana (Cl-, 0.18-0.29; SO42-, 0.07-0.08; Ca2+, 4.19-4.59; Mg2+, 0.22-0.58; Na+, 0.93-1.40). The main factor contributing to strongly alkali soils for each species was different between E. gerardiana and E. pachyclada: CaCO3 for E. gerardiana and CaSO4, MgSO4, NaCl, or a combination of these for E. pachyclada. The total ephedrine and pseudoephedrine content in E. gerardiana and E. pachyclada ranged from 1.67-1.88%DW and 1.95-4.80%DW, respectively. Both E. gerardiana and E. pachyclada were amenable for use a raw material source for extraction of ephedrine and pseudoephedrine, and the ephedrine content of both species showed a statistically significantly positive correlation with Mg2+ and Na+ contents of the soil.

Change in the Distribution of National Bird (Himalayan Monal) Habitat in Gandaki River Basin, Central Himalayas

Gandaki River Basin (GRB) is part of the central Himalayan region, which provides habitat for numerous wild species. However, due to changes in climate and land cover, the habitats of many protected species are at risk. Based on the maximum entropy (MaxEnt) model, coupled with bioclimatic layers, land cover and DEM data, the impacts of environmental factors on habitat suitability of Himalayan Monal (Lophophorus impejanus), a national bird of Nepal, was quantified. This study further assessed the present and future habitat and distribution of the Himalayan Monal in the context of climate and land cover changes. The results of this study show that the highly suitable habitat of Himalayan Monal presently occupies around 749 km2 within the northern, eastern and western parts, particularly protected areas such as Langtang National Park, Manaslu Conservation Area and Annapurna Conservation Area, while it is likely to decrease to 561 km2 by 2050, primarily in the northern and northwestern parts (i.e., Chhyo, Tatopani, Humde and Chame). These expected changes indicate increasing risk for Himalayan Monal due to a decline in its suitable habitat area.

Assessment of agricultural potential of a river command using geo-spatial techniques: a case study of Himalayan river project in Northern India

Agriculture and associated sectors are one of the primary sources of living for the global population. Sustainability in agriculture will yield long-term benefits requisite to accomplish development and mitigation of resource scarcity. Hence, realistic assessment of water requirement for agricultural use or alternatively agricultural potential from available water resources is imperative to sustainable water management keeping in view of possible scarce situation in relation to freshwater availability across the Globe. The present study focuses on assessment of the water requirement for potential agricultural use for the command area of a Himalayan river project, namely Gandak river project in Northern India using extensive geo-spatial techniques. Detailed information of extensive canal network is derived from high-resolution satellite images using GIS tools, along with other spatially distributed information for relevant parameters such as rainfall, temperature, soil type, elevation, water-holding capacity and agricultural productivity. The study reasonably identifies the spatial variability in water requirement potential in the project command with rational indication of maximum water demand in north-central section of the study area where the lowest aridity index characterized by very low slope and deep sandy loam soil is recorded. Efficient usage with growing scarcity of this essential natural resource warrants efficiency optimization of water usage with realistic assessment. This approach unlike traditional method uses high-resolution satellite data that are more scientific and accurate and will undoubtedly facilitate development of rational decision support system for efficient management of available surface water use for different purposes in the region.

Evaluation of global forcing datasets for hydropower inflow simulation in Nepal

AbstractDischarge over the Narayani river catchment of Nepal was simulated using Statkraft's Hydrologic Forecasting Toolbox (Shyft) forced with observations and three global forcing datasets: (i) ERA-Interim (ERA-I), (ii) Water and Global Change (WATCH) Forcing Data ERA-I (WFDEI), and (iii) Coordinated Regional Climate Downscaling Experiment with the contributing institute Rossy Centre, Swedish Meteorological and Hydrological Institute (CORDEX-SMHI). Not only does this provide an opportunity to evaluate discharge variability and uncertainty resulting from different forcing data but also it demonstrates the capability and potential of using these global datasets in data-sparse regions. The fidelity of discharge simulation is the greatest when using observations combined with the WFDEI forcing dataset (hybrid datasets). These results demonstrate the successful application of global forcing datasets for regional catchment-scale modeling in remote regions. The results were also promising to provide insight of the interannual variability in discharge. This study showed that while large biases in precipitation can be reduced by applying a precipitation correction factor (p_corr_factor), the best result is obtained using bias-corrected forcing data as input, i.e. the WFDEI outperformed other forcing datasets. Accordingly, the WFDEI forcing dataset holds great potential for improving our understanding of the hydrology of data-sparse Himalayan regions and providing the potential for prediction. The use of CORDEX-SMHI- and ERA-I-derived data requires further validation and bias correction, particularly over the high mountain regions.

HYDROBIOLOGICAL STUDY OF BURHI GANDAK RIVER NEAR URBAN AREA AT SAMASTIPUR (BIHAR)

Hydrobiological studies of Burhi Gandak river were carried out for a period of one year from March, 2019 to February, 2020 at two stations of urban area of Samastipur town, Bihar. The parameters taken included the water temperature, transparency, pH, dissolved oxygen, magnesium, and calcium. These properties were analyzed and compared with standard values recommended by bureau of Indian standards and world health organization. Present investigation was undertaken to ascertain the water quality status of Burhi Gandak river at Samastipur town. The results revealed that there were significant seasonal variations in most of the parameters; water was found to be hard, polluted and not suitable for domestic, agricultural and fish growth.

Assessment of Land Use/Land Cover Change using Geo-informatics in Catchment of Burhi Gandak River, Bihar

Land use/land cover (LULC) information is essential for proper management, planning and monitoring of natural resources of any region. The present study delineated the catchment of a part-length of Burhi Gandak river falling under Samastipur district of Bihar, estimated its area and LULC change over a period of ten years (2008-2018) using Remote Sensing (RS) and Geographic Information System (GIS) techniques. LULC mappings were done by supervised classification technique using GIS. Overall accuracy of image classification processes was 79.07 % and 75 %, whereas Kappa coefficients were found to be 0.71 and 0.68 for the year 2008 and 2018, respectively. Over the 10-year period, the area under agricultural land increased by 3,329 ha (6.51 %), settlement increased by 4,554 ha (58.20 %), and wasteland (barren and sand) increased by 685 ha (34.05 %); while natural vegetation cover reduced by 6,523 ha (33.58 %) and water bodies reduced by 2,045 ha (54.23 %). Hence, a significant portion of land under natural vegetation and water bodies in the catchment had been converted into either agricultural land or settlement (e.g. buildings) during the period. This change might affect the ecosystem of the area.

Assessment of Land Use/Land Cover Change using Geo-informatics in Catchment of Burhi Gandak River, Bihar

Land use/land cover (LULC) information is essential for proper management, planning and monitoring of natural resources of any region. The present study delineated the catchment of a part-length of Burhi Gandak river falling under Samastipur district of Bihar, estimated its area and LULC change over a period of ten years (2008-2018) using Remote Sensing (RS) and Geographic Information System (GIS) techniques. LULC mappings were done by supervised classification technique using GIS. Overall accuracy of image classification processes was 79.07 % and 75 %, whereas Kappa coefficients were found to be 0.71 and 0.68 for the year 2008 and 2018, respectively. Over the 10-year period, the area under agricultural land increased by 3,329 ha (6.51 %), settlement increased by 4,554 ha (58.20 %), and wasteland (barren and sand) increased by 685 ha (34.05 %); while natural vegetation cover reduced by 6,523 ha (33.58 %) and water bodies reduced by 2,045 ha (54.23 %). Hence, a significant portion of land under natural vegetation and water bodies in the catchment had been converted into either agricultural land or settlement (e.g. buildings) during the period. This change might affect the ecosystem of the area.

Climate change and biodiversity in Narayani river ecosystem and ecosystem services

Climate change and biodiversity in Narayani river ecosystem and ecosystem services

Groundwater Flow Modeling in Chitwan Dun Valley (Between Narayani River and Lothar Khola), Nepal

Models are simplification of reality to investigate certain phenomena or to predict future behavior and always tries to generate scenario that is close to the real condition. Groundwater flow models are computer models generated through using established flow equations that simulate and predict aquifer conditions. The result of groundwater modeling is used for groundwater management and remediation. In the present study, hydrostratigraphic units were identified through interpreting the lithological logs of the drilled wells then fence diagram was prepared with three major aquifer horizons, namely unconfined, shallow confined and deep confined aquifers. In addition, hydrogeologic data were integrated to develop a conceptual hydrogeologic model of the aquifer system of the Chitwan Dun valley, which was the basis for the development of the numerical model. The aquifer system was modeled numerically using MODFLOW-2005 numerical modeling, which was further calibrated and an acceptable numerical model was obtained which showed different flow direction in each aquifer layer. The model was validated by comparing the observed and simulated heads. The result shows that in each of the aquifer layers, the general flow direction is towards west and south-west.

Spatiotemporal characterization of dissolved trace elements in the Gandaki River, Central Himalaya Nepal

A comprehensive investigation was conducted on trace elements (TEs) in the glacier-fed Gandaki River Basin, Central Himalayas Nepal. A total of 93 water samples were collected from 31 locations in pre-monsoon, monsoon and post-monsoon seasons in 2016 to evaluate the concentrations of TEs. Multivariate statistical techniques such as analysis of variance, cluster analysis, principal component analysis, and correlation analysis were applied to investigate the spatiotemporal variations and identify the major sources of the TEs. The results classified most of the TEs into two groups. Group 1 including Cs, Li, Ni, Rb, Sc, Sr, Tl, U and V were from geogenic sources, while Group 2 including Cd, Co, Cr, Cu, Pb, Ti, Y and Zn were impacted by anthropogenic activities. Group 1 showed lower concentrations in the lower-middle and downstream segments with higher precipitation and the highest concentrations during pre-monsoon. In contrast, Group 2 demonstrated higher concentrations in the densely populated lower segments with more agriculture and industries, and the highest concentrations during the post-monsoon season. Comparing to the drinking water limits suggested that special attention should be paid to the elevated concentrations of Zn and As. The results of the study provide a basic guideline for future environmental protection in the Himalaya.

Late Holocene Landscape Collapse of a Trans‐Himalayan Dryland: Human Impact and Aridification

AbstractSoil degradation is a severe and growing threat to ecosystem services globally. Soil loss is often nonlinear, involving a rapid deterioration from a stable eco‐geomorphic state once a tipping point is reached. Soil loss thresholds have been studied at plot scale, but for landscapes, quantitative constraints on the necessary and sufficient conditions for tipping points are rare. Here, we document a landscape‐wide eco‐geomorphic tipping point at the edge of the Tibetan Plateau and quantify its drivers and erosional consequences. We show that in the upper Kali Gandaki valley, Nepal, soil formation prevailed under wetter conditions during much of the Holocene. Our data suggest that after a period of human pressure and declining vegetation cover, a 20% reduction of relative humidity and precipitation below 200 mm/year halted soil formation after 1.6 ka and promoted widespread gullying and rapid soil loss, with irreversible consequences for ecosystem services.

Cost effective adaptation to flood: sanitation interventions in the Gandak river basin, India

ABSTRACT The Hindu Kush Himalayan (HKH) region comprises of areas which are highly vulnerable to flood risks. The region faces challenges from multiple non-climate stressors such as poverty, environmental and climate shocks, and inadequate infrastructure. Addressing these deprivations in ways that reduce vulnerability associated with a changing climate are critical for the communities that live here. This paper combines data on flood risks derived from a climate–hydrology model under two future scenarios of RCP 4.5 and 8.5, with socio-economic data from communities in the Gandak basin, to demonstrate how mainstreaming climate change impacts into decision-making for sanitation interventions can reduce socio-economic vulnerability to flooding. A Cost-effectiveness analysis of the alternative interventions for sanitation reveals that gains are substantially higher under an intervention that takes note of climatic events, both for the present and in the future. Substantial health costs and inconvenience losses that are particularly acute for women during floods can be averted by investing in climate-friendly options. Climate adaptation (SDG goal 13 on climate action) can be synergistic with the achievement of other SDGs (Goal 6 on sanitation, goal 3 on health and well-being, goal 5 on gender).

Nutritive values of fodders at different seasons and altitudes in Gandaki River Basin of Nepal

This study aimed to assess the seasonal and ecological variation of chemical and nutritional values of locally preferred fodders in Gandaki River Basin (GRB) areas. The study was conducted in four altitudinal gradients viz. <400m, 400-800m, 800-1200m and 1200–1600m altitude above sea level in different looping seasons: rainy, spring and winter seasons. The most important five species of fodder trees Artocarpus lakoocha, Ficus roxburghii, Thysanolaena maxima, Ficus semicordata and Bauhinia purpurea were selected based on farmers’ preferences in nutritional values. Fodder samples comprised young leaves, old leaves and young twigs that were taken in July, September and December. It was revealed that nutritive value is not very much influenced by altitude but it is strongly influenced by lopping seasons. Among Thysanolaena maxima, Artocarpus lakoocha, Ficus roxburghii and Bauhinia purpurea the cellulose contents were significantly different (p<0.001) with seasons but there was no significant variation with altitudes. Similarly, Acid Detergent Fibre (ADF) contents in Thysanolaena maxima, Ficus roxburghii and Bauhinia purpurea were found significantly different with seasons. Ficus roxburghii fodder tree was found significantly different in Neutral Detergent Fibre (NDF), ADF, Cellulose and Potassium content with seasons. Similarly, fodder tree Bauhinia purpurea was found significant on Dry matter (DM), Crude fibre (CF), NDF, ADF, cellulose, tannin and potassium with seasons. The study hinted how careful planning of species selection and prudent decision in scheduling looping and feeding fodder trees can help improve animal metabolism, health, growth and productivity.

Geochemistry of Eocene-Early Oligocene low-temperature crustal melts from Greater Himalayan Sequence (Nepal): a nanogranitoid perspective

Despite melt inclusions in migmatites and granulites provide a wealth of information on crustal anatexis in different geological scenarios, a complete compositional study (including trace elements and H2O) is yet to be made for the Himalayan rocks. In this contribution, we focus on nanogranitoids occurring in peritectic garnet of migmatites from Kali Gandaki valley in central Nepal (Greater Himalayan Sequence, GHS). The microstructural position of the nanogranitoids proves that these melts were produced at 650–720 °C and 1.0–1.1 GPa, during the Eohimalayan prograde metamorphism (41–36 Ma) associated with crustal thickening. Nanogranitoid compositions (mostly granodiorites, tonalities and trondhjemites) resemble those of experimental melts produced during H2O-present melting of meta-sedimentary rocks. They have variable H2O concentrations (6.5–14.4 wt%), which are similar to the expected minimum and maximum values for crustal melts produced at the inferred P–T conditions. These compositional signatures suggest that melt formation occurred in the proximity of the H2O-saturated solidus, in a rock-buffered system. The low-to-very low contents of Zr (3–8 ppm), Th (0.1–1.2 ppm) and LREE (4–11 ppm) along with the weak-to-moderate positive Eu anomalies (Eu/Eu* = 1.2–3.3), the high B concentrations (200–3400 ppm) and the high U/Th ratio (up to 21) point to the lack of equilibration between melt and accessory minerals and are consistent with melting of plagioclase at low temperature. Kali Gandaki nanogranitoids record the beginning of melting in a H2O-present system that, in other GHS localities, may have produced voluminous crustal melts. We demonstrate that compositional comparison with nanogranitoids may be useful to reconstruct the petrogenesis of Eohimalayan granitoids.