Your search found 6 records
1 Smakhtin, Vladimir; Eriyagama, Nishadi. 2011. Simulating discharge time series in regions with contrasting seasons using duration curves. In Yang, D.; Marsh, P.; Gelfan, A. (Eds.). Cold regions hydrology in a changing climate: proceedings of the Symposium HS02 held during the IUGG GA, Melbourne, Australia, 28 June - 7 July 2011. Wallingford, UK: International Association of Hydrological Sciences (IAHS). pp.65-70. (IAHS Publication 346)
(Location: IWMI HQ Call no: e-copy only Record No: H044286)
(0.30 MB) (97.32KB)
Continuous discharge time series in ungauged basins where winter and summer flow generation mechanisms are distinctly different are simulated from limited observed meteorological data (rainfall, snow, temperature). Duration curves are used to convert the precipitation data from source gauges into a continuous hydrograph at an ungauged destination site. Temperature data is used as a control variable which determines whether precipitation is in a liquid (rainfall) or solid (snow) state, and whether the catchment is currently “active” to generate flow. The method is tested in several small catchments in Ontario, Canada, and is designed primarily for application at ungauged sites in data poor regions where the use of more complex and information consuming techniques of data generation may be difficult to justify.
2 Ward, R. C. 1967. Principles of hydrology. 2nd ed. Boston, UK: McGraw-Hill. 367p.
(Location: IWMI HQ Call no: 551.48 G000 WAR Record No: H045969)
(0.58 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H049320)
(3.63 MB) (3.63 MB)
Debris is known to influence the ablation, topography and hydrological systems of glaciers. This paper determines for the first time how these influences impact on bulk water routing and the proglacial runoff signal, using analyses of supraglacial and proglacial water chemistry and proglacial discharge at Miage Glacier, Italian Alps. Debris does influence the supraglacial water chemistry, but the inefficient subglacial system beneath the debris-covered zone also plays a role in increasing the ion contribution to the proglacial stream. Daily hydrographs had a lower amplitude and later discharge peak compared to clean glaciers and fewer diurnal hydrographs were found compared to similar analysis for Haut Glacier d’Arolla. We attribute these observations to the attenuating effect of the debris on ablation, smaller input streams on the debris-covered area, a less efficient subglacial system, and possible leakage into a raised sediment bed beneath the glacier. Strongly diurnal hydrographs are constrained to periods with warmer than average conditions. ‘Average’ weather conditions result in a hydrograph with reverse asymmetry. Conductivity and discharge commonly show anti-clockwise hysteresis, suggesting the more dilute, rapidly-routed melt component from the mid-glacier peaks before the discharge peak, with components from higher up-glacier and the debris-covered areas arriving later at the proglacial stream. The results of this study could lead to a greater understanding of the hydrological structure of other debris-covered glaciers, with findings highlighting the need to include the influence of the debris cover within future models of debris-covered glacier runoff.
(Location: IWMI HQ Call no: e-copy only Record No: H049457)
(28.30 MB) (28.3 MB)
(Location: IWMI HQ Call no: e-copy only Record No: H050278)
(6.91 MB) (6.91 MB)
Climate change is recognized as one of the greatest challenges of 21st century. This study investigated climate and hydrological regimes of the high-altitude Indus basin for the historical period and extreme scenarios of future climate during 21st century. Improved datasets of precipitation and temperature were developed and forced to a fully-distributed physically-based energy-balance Variable Infiltration Capacity (VIC) hydrological model to simulate the water balance at regional and sub-basin scale. Relative to historical baseline, the results revealed highly contrasting signals of climate and hydrological regime changes. Against an increase of 0.6 °C during the last 40 years, the median annual air temperature is projected to increase further between 0.8 and 5.7 °C by the end of 21st century. Similarly, a decline of 11.9% in annual precipitation is recorded, but future projections are highly conflicting and spatially variable. The Karakoram region is anticipated to receive more precipitation, while SW-Hindukush and parts of W-Himalayan region may experience decline in precipitation. The Model for Interdisciplinary Research On Climate version-5 (MIROC5) generally shows increases, while Max Planck Institute Earth System Model at base resolution (MPI-ESM-LR) indicates decreases in precipitation and river inflows under three Representative Concentration Pathways (RCPs) of 2.6, 4.5 and 8.5. Indus-Tarbela inflows are more likely to increase compared to Kabul, Jhelum and Chenab river inflows. Substantial increase in the magnitudes of peak flows and one-month earlier attainment is projected for all river gauges. High flows are anticipated to increase under most scenarios, while low flows may decrease for MPI-ESM-LR in Jhelum, Chenab and Kabul river basins. Hence, hydrological extremes are likely to be intensified. Critical modifications in the strategies and action plans for hydropower generation, construction and operation of storage reservoirs, irrigation withdrawals, flood control and drought management will be required to optimally manage water resources in the basin.
(Location: IWMI HQ Call no: e-copy only Record No: H050290)
(9.44 MB)
A reliable estimation of hydrological extremes with potentially severe socio-economic impacts is of crucial importance for efficient planning and design of hydraulic structures. Extreme value theory provides a firm theoretical foundation for the statistical modelling of extreme hydrological events. The dilemma in the modelling is on whether to use block maxima (BM) or peak-over-threshold (POT) method, each with its own cons and pros. It remains unexplored to what extent future projected changes in extreme hydrological events are influenced by the method choice, especially when some simplifications are made to lessen the computational burden for large-scale studies. This study addresses this research question by a comparative analysis between the BM and POT methods on future climate change impact on global flood and extreme precipitation. The extreme precipitation analysis is performed using 24 CMIP5 general circulation models (GCMs), while the flood analysis is based on a multi-model ensemble of 20 members including five global impact models forced by four CMIP5 GCMs. The results reveal that the BM and POT methods agree on the sign of changes in flood and extreme precipitation intensities, but disagree on the magnitude. The discrepancy between the BM and POT results increases with event extremity. The difference also varies with season, where the difference in the global land area with increasing signals peaks in winter at the rates of 11% for extreme precipitation and in summer at the rates of 3.5% for flood.
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