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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. Plain Language Summary: The mountains of Asia have large reservoirs of snow and ice, which are the source of water to the people living in the mountains and downstream, mainly during the dry season. However, due to recent warming, these reserves are melting faster and depleting year by year. We use a computer model to understand what will happen to these volumes of snow and ice and the total volume of water, which also includes rain and groundwater, in the 15 main rivers under future climate change scenarios. We find that the water generated upstream will increase for all the rivers in the future. However, there would be either too little or too much water for different seasons in the future. The peak volume of water will increase in magnitude and the peak time will shift to earlier in the season (in the month of May instead of current June or July) for most rivers in the western part of Asia. This change in the timing of water will have severe impacts on the livelihoods of mountain communities as well as populations downstream where food production, energy production as well as biodiversity depend on the amount and timing of mountain water supply. Key Points: Contrasting seasonal responses are observed for High Mountain Asia's (HMA) rivers, dictated by their hydrological regimesThe onset of early snow and glacier melt in the spring season affects the magnitude and peak water availabilityA relatively consistent decadal climate change responses across HMA, despite a large variability in hydrological regimes [ABSTRACT FROM AUTHOR]

ABSTRACT The main windiness index in the Netherlands (Windex-CBS) has been subject to a decreasing trend since the systematic recording started in 1988. This seriously complicates the estimation of future long-term wind supply. Therefore, it is necessary to know the main causes of the reported decline. For this purpose, Windex-CBS, derived from actual wind turbine yields, is compared with two alternative windiness indices. The first index is based on wind speed observations Wland and the second on geostrophic wind speed Gland. Similar indices are formulated for offshore wind supply in the North Sea, Woff and Goff. High mutual correlations between the indices indicate that they do efficiently account for natural variability. Yet, the trends of the different indices do substantially differ from each other. The decrease of Windex-CBS is twice as large as (200%) the decrease of Wland. The trend of the difference between both indices is highly significant. This suggests that the Windex-CBS is contaminated by operational or methodological factors. Wland does not suffer from such factors and is therefore the preferred measure of wind supply. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The ECMWF land surface hydrology has been revised in the last 3 years in its soil and snow hydrological components, leading to improvements in weather and seasonal predictions. It has been shown that efforts devoted to the improvement of land surface processes can lead to a more accurate representation of the global water cycle on monthly timescales. In this paper, we analyse the impact of land hydrology revisions at daily timescales on both atmospheric near-surface quantities and river discharges by coupling the ECMWF land surface model (HTESSEL) to a river routing scheme total runoff integration pathways (TRIP2). This application defines a hydro-meteorological verification for land surface models and it shows the usefulness of river discharge observations for quantitative evaluation of the global water cycle at daily timescales. The relative contributions of the soil and snow hydrology revisions on atmospheric state, in particular for temperature, and the predicted river discharge are evaluated showing a significant incremental performance with the land surface updates. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The temporal signature of terrestrial storage changes inferred from the Gravity Recovery and Climate Experiment (GRACE) has been assessed by comparison with outputs from a calibrated hydrological model (lumped elementary watershed (LEW)) of the upper Zambezi and surroundings and an inspection of the within-month ground track coverage of GRACE together with spatial-temporal rainfall patterns. The comparison of the hydrological model with GRACE reveals temporal inconsistencies between both data sets. Because the LEW model has been calibrated and validated with independent data sources, we believe that this is a GRACE artifact. The within-month ground track coverage shows an irregular orbit behavior which may well cause aliasing in the GRACE monthly deconvolutions. This aliasing is the most probable cause of observed temporal inconsistencies between GRACE and other data sets. [ABSTRACT FROM AUTHOR]

Large evaporation occurs over the Sudd wetland, a huge swamp located on the upper Nile. Historically, water resources planners have had the intention to reduce the Sudd evaporation by shortcut channels (e.g., Jonglei canal). The question is: What is the effect of draining the Sudd wetland on the regional water cycle and on the Nile water flow? A regional climate model has been applied to the Nile Basin, with a special modification to include routing of the Nile flood over the Sudd. The impact of the wetland on the Nile hydroclimatology has been studied by comparing two model scenarios: the present climatology and a drained Sudd scenario. The results indicate that draining the entire Sudd has negligible impact on the regional water cycle owing to the relatively small area covered by the wetland. The runoff gain would then be up to ∼36 Gm3 yr−1. However, the impact on the microclimate is large. The relative humidity will drop by 30-40% during the dry season, and temperature will rise by 4°-6°C. The impact during the wet season is small. [ABSTRACT FROM AUTHOR]