Your search found 21 records
(Location: IWMI HQ Call no: e-copy only Record No: H042330)
(2.48 MB)
Performance of process-based hydrological models is usually assessed through comparison between simulated and measured streamflow. Although necessary, this analysis is not sufficient to estimate the quality and realism of the modelling since streamflow integrates all processes of the water cycle, including intermediate production or redistribution processes such as snowmelt or groundwater flow. Assessing the performance of hydrological models in simulating accurately intermediate processes is often difficult and requires heavy experimental investments. In this study, conceptual hydrological modelling (using SWAT) of a semi-arid mountainous watershed in the High Atlas in Morocco is attempted. Our objective is to analyse whether good intermediate processes simulation is reached when global-satisfying streamflow simulation is possible. First, parameters presenting intercorrelation issues are identified: from the soil, the groundwater and, to a lesser extent, from the snow. Second, methodologies are developed to retrieve information from accessible intermediate hydrological processes. A geochemical method is used to quantify the contribution of a superficial and a deep reservoir to streamflow. It is shown that, for this specific process, the model formalism is not adapted to our study area and thus leads to poor simulation results. A remote-sensing methodology is proposed to retrieve the snow surfaces. Comparison with the simulation shows that this process can be satisfyingly simulated by the model. The multidisciplinary approach adopted in this study, although supported by the hydrological community, is still uncommon.
(Location: IWMI HQ Call no: e-copy only Record No: H044438)
(6.47 MB) (6.46MB)
All major rivers in Bhutan depend on snowmelt for discharge. Therefore, changes in snow cover due to climate change can influence distribution and availability of water. However, information about distribution of seasonal snow cover in Bhutan is not available. The MODIS snow product was used to investigate snow cover status and trends in Bhutan. Average snow cover area (SCA) of Bhutan estimated for the period 2002 to 2010 was 9030 sq. km, about 25.5% of the total land area. SCA trend of Bhutan for the period 2002–10 was found to decrease (–3.27 ± 1.28%). The average SCA for winter was 14,485 sq. km (37.7%), for spring 7411 sq. km (19.3%), for summer 4326 sq. km (11.2%), and for autumn 7788 sq. km (20.2%), mostly distributed in the elevation range 2500–6000 m amsl. Interannual and seasonal SCA trend both showed a decline, although it was not statistically significant for all sub-basins. Pho Chu sub-basin with 19.5% of the total average SCA had the highest average SCA. The rate of increase of SCA for every 100 m elevation was the highest (2.5%) in the Pa Chu sub-basin. The coefficient of variance of 1.27 indicates high variability of SCA in winter.
3 Chemin, Yann. (Ed.) 2012. Remote sensing of planet earth. Rijeka, Croatia: InTech. 240p.
(Location: IWMI HQ Call no: IWMI Record No: H044692)
(28.13 MB) (28.13MB)
(Location: IWMI HQ Call no: 621.3678 G000 WAR Record No: H045035)
(0.46 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H045039)
(1.65 MB)
This paper addresses a snow-mapping algorithm for the Tibetan Plateau region using Moderate Resolution Imaging Spectroradiometer (MODIS) data. Accounting for the effects of the atmosphere and terrain on the satellite observations at the top of the atmosphere (TOA), particularly in the rugged Tibetan Plateau region, the surface reflectance is retrieved from the TOA reflectance after atmospheric and topographic corrections. To reduce the effect of the misclassification of snow and cloud cover, a normalized difference cloud index (NDCI) model is proposed to discriminate snow/cloud pixels, separate from the MODIS cloud mask product MOD35. The MODIS land surface temperature (LST) product MOD11 L2 is also used to ensure better accuracy of the snow cover classification. Comparisons of the resulting snow cover with those estimated from high spatial-resolution Landsat ETM+ data and obtained from MODIS snow cover product MOD10 L2 for the Mount Everest region for different seasons in 2002, show that the MODIS snow cover product MOD10 L2 overestimates the snow cover with relative error ranging from 20.1% to 55.7%, whereas the proposed algorithm estimates the snow cover more accurately with relative error varying from 0.3% to 9.8%. Comparisons of the snow cover estimated with the proposed algorithm and those obtained from MOD10 L2 product with in situ measurements over the Hindu Kush-Himalayan (HKH) region for December 2003 and January 2004 (the snowy seasons) indicate that the proposed algorithm can map the snow cover more accurately with greater than 90% agreement.
6 Mukhopadhyay, B.; Singh, V. P. 2011. Hydrological modelling at mesoscopic scales using global data sets to derive stream water availability models of river basins. In Shukla, M. K. (Ed.) Soil hydrology, land use and agriculture: measurement and modelling. Wallingford, UK: CABI. pp.24-74.
(Location: IWMI HQ Call no: e-copy SF Record No: H045774)
(Location: IWMI HQ Call no: IWMI Record No: H045908)
(1.75MB)
This paper presents a comprehensive assessment of the water storage properties of glaciers and seasonal snow, carried out for the first time at a major river basin scale, for the Indus, Ganges, Brahmaputra, Amu Darya, Syr Darya and Mekong basins. It analyzes the changes of glaciers and snow under recent climate change, i.e., between the baseline (1961-1990) and current (2001-2010) periods. The paper also addresses climate change sensitivity of glacier systems and the changes that might be expected under a warming scenario for the end of the twenty-first century.
(Location: IWMI HQ Call no: IWMI Record No: H045909)
(1.12MB)
The hydrological roles of glaciers and seasonal snow in the Indus, Ganges, Brahmaputra, Amu Darya, Syr Darya and Mekong basins are, for the first time, assessed comprehensively at a major river basin scale in this paper. Contribution of glacier runoff, subdivided into renewable and nonrenewable components, and seasonal snowmelt to mean annual flow is evaluated for two time slices: 1961-1990 and 2001-2010. The recent changes of the hydrological roles of glaciers and snow, and the most likely changes of those under future climate change are analyzed.
(Location: IWMI HQ Call no: e-copy only Record No: H046051)
(1.86 MB)
Greater Himalayan glaciers are retreating and losing mass at rates comparable to glaciers in other regions of the world 1–5. Assessments of future changes and their associated hydrological impacts are scarce, oversimplify glacier dynamics or include a limited number of climate models6–9. Here, we use results from the latest ensemble of climate models in combination with a high-resolution glacio-hydrological model to assess the hydrological impact of climate change on two climatically contrasting watersheds in the Greater Himalaya, the Baltoro and Langtang watersheds that drain into the Indus and Ganges rivers, respectively. We show that the largest uncertainty in future runoff is a result of variations in projected precipitation between climate models. In both watersheds, strong, but highly variable, increases in future runoff are projected and, despite the different characteristics of the watersheds, their responses are surprisingly similar. In both cases, glaciers will recede but net glacier melt runoff is on a rising limb at least until 2050. In combination with a positive change in precipitation, water availability during this century is not likely to decline.We conclude that river basins that depend on monsoon rains and glacier melt will continue to sustain the increasing water demands expected in these areas.
10 Kogan, F.; Powell, A. M. Jr.; Fedorov, O. (Eds.) 2009. Use of satellite and In-Situ data to improve sustainability: Proceedings of the NATO Advanced Research Workshop on Using Satellite Data and In-Situ Data to Improve Sustainability, Kiev, Ukraine, 9-12 June 2009. 313p. (NATO Science for Peace and Security Series - C: Environmental Security)
(Location: IWMI HQ Call no: 384.51 G000 KOG Record No: H046311)
(0.46 MB)
(Location: IWMI HQ Call no: 363.34929 G000 SHE Record No: H046319)
(0.46 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H046709)
(4.13 MB)
A large proportion of Pakistan's irrigation water supply is taken from the Upper Indus River Basin (UIB) in the Himalaya–Karakoram–Hindukush range. More than half of the annual flow in the UIB is contributed by five of its snow and glacier-fed sub-basins including the Astore (Western Himalaya — south latitude of the UIB) and Hunza (Central Karakoram — north latitude of the UIB) River basins. Studying the snow cover, its spatiotemporal change and the hydrological response of these sub-basins is important so as to better managewater resources. This paper compares new data from the Astore River basin (mean catchment elevation, 4100 m above sea level; m asl afterwards), obtained using MODIS satellite snow cover images, with data from a previouslystudied high-altitude basin, the Hunza (mean catchment elevation, 4650 m asl). The hydrological regime of this sub-catchment was analyzed using the hydrological and climate data available at different altitudes from the basin area. The results suggest that the UIB is a region undergoing a stable or slightly increasing trend of snow cover in the southern (Western Himalayas) and northern (Central Karakoram) parts. Discharge from the UIB is a combination of snow and glacier melt with rainfall-runoff at southern part, but snow and glacier melt are dominant at the northern part of the catchment. Similar snow cover trends (stable or slightly increasing) but different river flow trends (increasing in Astore and decreasing in Hunza) suggest a sub-catchment level study of the UIB to understand thoroughly its hydrological behavior for better flood forecasting and water resources management.
(Location: IWMI HQ Call no: e-copy only Record No: H047603)
(1.47 MB)
Although vital for millions of inhabitants, Himalayan water resources remain currently poorly known, mainly because of uncertainties on hydro-meteorological measurements. In this study, the authors propose a new assessment of the water budget components of the Dudh Koshi River basin (3720 km2 , Eastern Nepal), taking into account the associated uncertainties. The water budget is studied through a cross analysis of field observations with the result of a daily hydrological conceptual distributed snow model. Both observed datasets of spatialized precipitations, interpolated with a co-kriging method, and of discharge, provided by the hydrological agency of Nepal, are completed by reanalysis data (NCEP/NCAR) for air temperature and potential evapotranspiration, as well as satellite snow products (MOD10A2) giving the dynamics of the snow cover area. According to the observation, the water budget on the basin is significantly unbalanced; it is attributed to a large underestimation of precipitation, typical of high mountain areas. By contrast, the water budget simulated by the modeling approach is well balanced; it is due to an unrealistic overestimation of the glacier melt volume. A reversing method led to assess the precipitation underestimation at around 80% of the annual amount. After the correction of the daily precipitation by this ratio, the simulated fluxes of rainfall, icemelt, and snowmelt gave 63%, 29%, and 8% of the annual discharge, respectively. This basin-wide precipitation correction is likely to change in respect to topographic or geographic parameters, or in respect to seasons, but due to an insufficient knowledge of the precipitation spatial variability, this could not be investigated here, although this may significantly change the respective proportions for rain, ice or snow melt.
(Location: IWMI HQ Call no: e-copy only Record No: H048190)
(4.76 MB)
Recharge assessment is a challenge in snow and glacier dominated Himalayan basins. Quantification of recharge to karst springs in these complex geological environments is important both for hydrologic understanding and for effective water resource management. We used spring hydrographs and environmental tracers (isotopes and solutes) to distinguish and estimate the sources of spring water and to identify the flow paths of the recharging waters in three mountainous basins of the western Himalaya. The karst springs are perennial with high discharge amplitudes. The results indicate that ambient temperature has a strong influence on the hydrological behavior of the springs. Although the spring flow is dominantly controlled by the melting of snow and/or glaciers, rain events produce sharp spikes in spring hydrographs. The facies patterns in springs within the Bringi basin (Ca-HCO3) and the Liddar basin (Ca-HCO3 and Ca-Mg-HCO3) suggest flow dominantly through limestone and dolomite. Higher concentrations of SO4 2 and Na+ in warm springs of the Kuthar basin indicate flow through carbonate, silicate and other rocks. The isotopic composition (d18O, d2 H) of precipitation, snowpacks, glacier melt and karst springs show wide variation both in space and time, and are strongly influenced by the basin relief and meteorology. The tracer-based two- and three-component mixing models suggest that the snowmelt dominantly contributes to the spring flow (55–96%), followed by glacier melt (5–36%) and rain (4–34%). Based on tracer tests with good recovery rates, springs are dominantly recharged through point sources rather than by diffuse infiltration. Changes in the timing, form, and amount of winter precipitation substantially affect the timing and magnitude of spring discharge during the rest of the year.
(Location: IWMI HQ Call no: e-copy only Record No: H048714)
(0.37 MB)
The Himalayan rivers are recognized as a reliable source of water supply in the countries of the Hindu Kush Himalayan (HKH) region. Increasing need for food and energy for the growing population of the HKH region has stimulated water harvesting from the transboundary rivers and triggered water conflict, environmental degradation and socio-economic turmoil among the riparian nations. Teesta is one such mighty trans-Himalayan river flowing through India and Bangladesh and is recognized as a basin where there is increasing tension between these two nations. Due to upstream interventions including barrage, dam and hydropower construction, the lower riparian region of Bangladesh faces acute water stresses, which hamper the agricultural, fisheries and livelihood activities of the river-dependent communities and impede the economic prosperity of the greater north-west region. The study provides a robust outline of the transboundary nexus between India and Bangladesh, and identifies upstream intervention-induced economic loss and ecological deterioration in the lower Teesta basin. To encourage water collaboration between the riparian states, the study estimates the benefit of transboundary co-operation for the larger socio-economic prosperity and environmental sustainability in the Teesta basin of the Himalayan region, which is decidedly applicable to similar basins in the HKH region and the rest of the world.
16 Chamine, H. I.; Barbieri, M.; Kisi, O.; Chen, M.; Merkel, B. J. (Eds.) 2019. Advances in sustainable and environmental hydrology, hydrogeology, hydrochemistry and water resources. Proceedings of the 1st Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Hammamet, Tunisia, 12-15 November 2018. Cham, Switzerland: Springer. 449p. (Advances in Science, Technology and Innovation: IEREK Interdisciplinary Series for Sustainable Development) [doi: https://doi.org/10.1007/978-3-030-01572-5]
(Location: IWMI HQ Call no: e-copy SF Record No: H049482)
(Location: IWMI HQ Call no: e-copy only Record No: H050209)
(4.20 MB) (4.20 MB)
The frozen water reserves on the Earth are not only very dynamic in their nature, but also have significant effects on hydrological response of complex and dynamic river basins. The Indus basin is one of the most complex river basins in the world and receives most of its share from the Asian Water Tower (Himalayas). In such a huge river basin with high-altitude mountains, the regular quantification of snow cover is a great challenge to researchers for the management of downstream ecosystems. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) daily (MOD09GA) and 8-day (MOD09A1) products were used for the spatiotemporal quantification of snow cover over the Indus basin and the western rivers’ catchments from 2008 to 2018. The high-resolution Landsat Enhanced Thematic Mapper Plus (ETM+) was used as a standard product with a minimum Normalized Difference Snow Index (NDSI) threshold (0.4) to delineate the snow cover for 120 scenes over the Indus basin on different days. All types of errors of commission/omission were masked out using water, sand, cloud, and forest masks at different spatiotemporal resolutions. The snow cover comparison of MODIS products with Landsat ETM+, in situ snow data and Google Earth imagery indicated that the minimum NDSI threshold of 0.34 fits well compared to the globally accepted threshold of 0.4 due to the coarser resolution of MODIS products. The intercomparison of the time series snow cover area of MODIS products indicated R2 values of 0.96, 0.95, 0.97, 0.96 and 0.98, for the Chenab, Jhelum, Indus and eastern rivers’ catchments and Indus basin, respectively. A linear least squares regression analysis of the snow cover area of the Indus basin indicated a declining trend of about 3358 and 2459 km2 per year for MOD09A1 and MOD09GA products, respectively. The results also revealed a decrease in snow cover area over all the parts of the Indus basin and its sub-catchments. Our results suggest that MODIS time series NDSI analysis is a useful technique to estimate snow cover over the mountainous areas of complex river basins.
(Location: IWMI HQ Call no: e-copy only Record No: H050398)
(4.00 MB) (4.00 MB)
The hydrological response to climate change in mountainous basins manifests itself at varying spatial and temporal scales, ranging from catchment to large river basin scale and from sub-daily to decade and century scale. To robustly assess the 21st century climate change impact for hydrology in entire High Mountain Asia (HMA) at a wide range of scales, we use a high resolution cryospheric-hydrological model covering 15 upstream HMA basins to quantify the compound effects of future changes in precipitation and temperature based on the range of climate change projections in the Coupled Model Intercomparison Project Phase 6 climate model ensemble. Our analysis reveals contrasting responses for HMA's rivers, dictated by their hydrological regimes. At the seasonal scale, the earlier onset of melting causes a shift in the magnitude and peak of water availability, to earlier in the year. At the decade to century scale, after an initial increase, the glacier melt declines by the mid or end of the century except for the Tarim river basin, where it continues to increase. Despite a large variability in hydrological regimes across HMA's rivers, our results indicate relatively consistent climate change responses across HMA in terms of total water availability at decadal time scales. Although total water availability increases for the headwaters, changes in seasonality and magnitude may diverge widely between basins and need to be addressed while adapting to future changes in a region where food security, energy security as well as biodiversity, and the livelihoods of many depend on water from HMA.
19 Steiner, J. F.; Gurung, T. R.; Joshi, S. P.; Koch, I.; Saloranta, T.; Shea, J.; Shrestha, A. B.; Stigter, E.; Immerzeel, W. W. 2021. Multi-year observations of the high mountain water cycle in the Langtang Catchment, Central Himalaya. Hydrological Processes, 35(5):e14189. [doi: https://doi.org/10.1002/hyp.14189]
(Location: IWMI HQ Call no: e-copy only Record No: H050411)
(1.22 MB) (1.22 MB)
The Langtang catchment is a high mountain, third order catchment in the Gandaki basin in the Central Himalaya (28.2°N, 85.5°E), that eventually drains into the Ganges. The catchment spans an elevation range from 1400 to 7234 m a.s.l. and approximately one quarter of the area is glacierized. Numerous research projects have been conducted in the valley during the last four decades, with a strong focus on the cryospheric components of the catchment water balance. Since 2012 multiple weather stations and discharge stations provide measurements of atmospheric and hydrologic variables. Full weather stations are used to monitor at an hourly resolution all four radiation components (incoming and outgoing shortwave and longwave radiation; SWin/out and LWin/out), air temperature, humidity, wind speed and direction, and precipitation, and cover an elevational range of 3862–5330 m a.s.l. Air temperature and precipitation are monitored along elevation gradients for investigations of the spatial variability of the high mountain meteorology. Dedicated point-scale observations of snow cover, depth and water equivalent as well as ice loss have been carried out over multiple years and complement the observations of the water cycle. All data presented is openly available in a database and will be updated annually.
(Location: IWMI HQ Call no: e-copy only Record No: H051235)
(1.25 MB) (1.25 MB)
Quantifying water-related ecosystem services (WES) helps to secure limited and valuable water resources sustainably. Mainstreaming these ecosystem services into policy and decision-making requires accurate information at the local level. This paper aims to quantify provisioning and regulating freshwater ecosystem services potential in the Kangchenjunga Landscape using a hydro-ecological model. This study is the first to use the J2000 hydrological model to estimate annual and seasonal WES. The model output was validated against snow-cover and river discharge, after conducting a sensitivity analysis of the input parameter. High precipitation and low evapotranspiration resulted in rich water availability in the landscape. It was found that the precipitation amount in the landscape is highly seasonal, resulting in high variation in water availability. Snowfall, accounting for 4% of the total precipitation still plays an important role in regulating water resources. Nearly 100% of the discharge during the dry period originates from groundwater and melt runoff. This study highlights the importance of the presence of snow and glacier to sustain the ecosystem in the landscape. This model-derived information could further be used for decision-making and evaluating the impact of climatic and land use changes.
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