Impacts of changing climate on the hydrology and hydropower production of the Tagus River basin

Abstract

The Tagus River basin is an ultimately important water source for hydropower production, urban and agricultural water supply in Spain and Portugal. Growing electricity and water supply demands, over‐regulation of the river and construction of new dams, as well as large inter‐basin and intra‐basin water transfers aggravated by strong natural variability of climate in the catchment, have already imposed significant pressures on the river. The substantial reduction of discharge is observed already now, and projected climatic change is expected to alter the water budget of the catchment further.In this study, we address the effects of projected climate change on the water resources availability in the Tagus River basin and influence of potential changes on hydropower generation of the three important reservoirs in the basin. The catchment‐scale, process‐based eco‐hydrological model soil and water integrated model was set up, calibrated and validated for the entire Tagus River basin, taking into account 15 large reservoirs in the catchment. The future climate projections were selected from those generated within the Inter‐Sectoral Impact Model Intercomparison Project. They include five bias‐corrected climatic datasets for the region, obtained from global circulation model runs under two emissions scenario – moderate and extreme ones – and covered the whole century. The results show a strong agreement among model runs in projecting substantial decrease of discharge of the Tagus River discharge and, consequently, a strong decrease in hydropower production under both future climate scenarios. Copyright © 2016 John Wiley & Sons, Ltd.

Climate change effects on the hydrology of the headwaters of the Tagus River: implications for the management of the Tagus–Segura transfer

“…The hydrological modelling carried out with the AR5 CC scenarios predicts a sharp decrease in the water resources of the THRB. These results are in line with the previous simulations made on the same scale (Lobanova et al, 2018), as well as on a larger scale (Guerreiro et al, 2017;CEDEX, 2011b;Lobanova et al, 2018). The hydrological modelling indicated that the increase in temperature would generate a decline in snowfall, which would lead to a reduction in the snow cover period of 2 months.…”

“…These alterations of the hydrological processes will probably generate a change in the fluvial regime. In relative terms, the months of autumn (October, November, December) would suffer the major decrease, this change being consistent with the results of Lobanova et al (2018). At the annual level, these alterations would result in greater variability of the surface flows of the basin due to increases in the relative difference between the maximum and minimum flows of spring and summer, respectively.…”

“…The average annual precipitation is 620 mm and the minimum values occur in summer (June-August). While the average annual temperature is 11 • C, in the coldest months there are values less than zero (November-April), so snowfalls are frequent at the higher altitudes (Lobanova et al, 2016). Moreover, much of the THRB extends over karst aquifers, meaning that groundwater exerts an important influence on the surface flows that circulate along the main river streams .…”

Retrospective analysis of published hydrological researches: models, trends and geographical aspects over the last two decades of hydrological modelling

“…This shows, a more frequent use of the models in Cluster A.1 in complex studies focusing on hydrological researches in large areas. On the other hand, the percentage of applications with the spatial category Regional is much lower in Cluster A.1 in comparison with Cluster A.2 (6.8% versus 43.7%; e.g., SWIM in Lobanova et al 2016). Also, the proportion of spatial category Catchment in Cluster A.1 is lower than in Cluster A.2 (4.5% versus 12.1%).…”

Challenges and Proposals for Socio-Ecological Sustainability of the Tagus–Segura Aqueduct (Spain) under Climate Change

“…Table 5 summarises the data on the evolution of water demands in the Tagus and Segura basins, as well as the available resources (taking into account the contemplated reduction from the HPI and District Plans) using what is known as the short series , the statistical trend that projects a greater reduction of supplies. It should be pointed out that in the Tagus basin, the situation of surface resources is compromised with regard to the satisfaction of demands of the basin in years of drought, and will be more so in view of the reduction in precipitation forecast by the climate change model [25]. Two other aspects of rainwater behavior that would also be altered (seasonality and irregularity) also cause concern in terms of water planning.…”