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A semi-distributed hydrological model of the Niger River above and including the Inner Delta is developed. GCM-related uncertainty in climate change impacts are investigated using seven GCMs for a 2°C increase in global mean temperature, the hypothesised threshold of "dangerous" climate change. Declines in precipitation predominate, although some GCMs project increases for some subcatchments, whilst PET increases for all scenarios. Inter-GCM uncertainty in projected precipitation is three to five times that of PET. With the exception of one GCM (HadGEM1), which projects a very small increase (3.9%), river inflows to the Delta decline. There is considerable uncertainty in the magnitude of these reductions, ranging from 0.8% (HadCM3) to 52.7% (IPSL). Whilst flood extent for HadGEM1 increases (mean annual peak +1405 km 2 /+10.2%), for other GCMs it declines. These declines range from almost negligible changes to a 7903 km 2 (57.3%) reduction in the mean annual peak.ARTICLE HISTORY

Section: Introductionmentioning

confidence: 99%

GCM-related uncertainty for river flows and inundation under climate change: the Inner Niger Delta

Thompson

Crawley

Kingston

2016

“…Therefore, some detected short-term trends could be unrepresentative of long-term changes. In addition, European regions based on the correlation between a set of streamflow percentiles were identified by Gudmundsson et al (2011), who found that low flows have lower spatial correlations than mean and high flows for shorter distances, though this pattern is reversed for longer distances (>800 km), as well as by Mediero et al (2015), who identified five regions across Europe based on the monthly frequency of flood occurrence.…”

Section: Identification Of Homogeneous Regionsmentioning

confidence: 99%

Trends in low flows in Spain in the period 1949–2009

Coch

Mediero

2016

This study analyses trends in low flows in Spain in the period 1949-2009, based on daily flow data collected at 60 gauging stations located in near-natural catchments. Two low-flow indicators were considered: (i) the seven-day annual minimum streamflow and (ii) the 10th percentile of the yearly flow duration curve. Catchments were clustered into three regions in terms of monthly mean flows. The Mann-Kendall test was used considering four periods between 1949 and 2009. A multi-temporal trend analysis was also applied to the longest series to identify wet and dry periods that could influence the results. Lastly, a field significance test provided a regional assessment of the at-site detected trends at each region. The results for each indicator reveal a clearly decreasing trend in low flows throughout the northern half of Spain that was found to be field-significant over the (Atlantic and Mediterranean) regions.

“…It has been shown that the selection of meteorological forcing can be equally or more important than the choice of model (Guo et al 2006, Mo et al 2012 and that different forcing data can produce substantially different calibrated parameter sets (Elsner et al 2014). Differences in precipitation forcing often have the greatest influence on runoff sensitivity (Materia et al 2010, Nasonova et al 2011 and differences in shortwave radiation forcing can have a large impact on snowmelt and runoff fluxes in high altitude regions (Mizukami et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Comparison of land surface scheme simulations with field observations versus atmospheric model output as forcing

MacDonald

Davison

Mekonnen

et al. 2016

The low density of meteorological stations in parts of Canada necessitates using numerical weather prediction (NWP)/assimilation output for hydrological modelling. In this study, comparisons are made of simulated land surface variables when using field observations versus NWP output as forcing for two well-instrumented sites: the mountainous and forested Marmot Creek Basin (MCRB) in the Canadian Rocky Mountains, and a prairie cropland/grassland site (Kenaston). The Canadian Land Surface Scheme 3.6 (CLASS) was used for modelling. The Global Environmental Multiscale (GEM) model with Canadian Precipitation Analysis (CaPA) was also used as forcing. There was good agreement between observed meteorology and GEM/CaPA, though some deficiencies in GEM/CaPA were identified: the effects of subgrid topography on incoming radiation and wind speed were not accounted for at MCRB, and CaPA did not capture some convective rainfall events at Kenaston. CLASS simulations using both sets of forcing showed difficulties in simulating snow depth, soil moisture and evapotranspiration; certain difficulties were linked to GEM/CaPA deficiencies and/or CLASS. Both sets of forcing tended to overestimate the duration of snow cover at MCRB, but during different years. With GEM/CaPA as forcing, CLASS overestimated the duration of frozen soils. The GEM/CaPA precipitation difficulties at Kenaston degraded soil moisture simulations.