The impact of droughts and water management on various hydrological systems in the headwaters of the Tagus River (central Spain)

Abstract

Abstract. The influence of climate variation on the availability of water resources was analyzed in 15 the headwaters of the Tagus River basin using two drought indices, the standardized precipitation 16 index (SPI) and the standardized precipitation evapotranspiration index (SPEI). This basin is highly 17 regulated and strategic, and contains two hyperannual reservoirs that are the origin of the water 18 supply system for Mediterranean areas of southeast Spain. The indices confirmed that drought 19 conditions have prevailed in the headwaters of the Tagus River since the 1970s. The responses in 20 river discharge and reservoir storage were slightly higher when based on the SPEI rather than the 21 SPI, which indicates that although precipitation had a major role in explaining temporal variability 22 in the analyzed parameters, the influence of temperature was not negligible. Moreover, the greatest 23 response in hydrological variables was evident over longer timescales of the climatic drought 24 indices. Although the effect of climate variability on water resources was substantial during the 25 analyzed period, we also showed a major change in hydrological-climatic relationships in regulated 26 systems including reservoir storage and outflow. These were closely related to changes in external 27 demand following commencement of the water transfer system to the Júcar and Segura basins after 28 the 1980s. The marked reduction in water availability in the basin, which is related to more frequent 29 droughts, contrasts with the amount of water transferred, which shows a clear upward trend 30 associated with increasing water demand in the Mediterranean basin. 31 32 33

Automatic design of basin-specific drought indexes for highly regulated water systems

“…Precipitation is always the core variable to characterize this drought type, with most meteorological drought indexes based on precipitation only (Byun and Wilhite, 1999;McKee et al, 1993). In some cases, especially in regions where droughts can be strongly influenced by evapotranspiration, additional variables such as temperature trends are also considered Lorenzo-Lacruz et al, 2010).…”

The contrasted evolution of high and low flows and precipitation indices in the Duero basin (Spain)

“…In regions with a Mediterranean climate, including the Iberian Peninsula, river regulation is a key factor in water management (Iglesias et al 2005). Reservoirs can collect water during high flows, ensure water supply during drought periods, minimize the risk of floods, and maintain the base flow of rivers (López-Moreno et al 2002, Lorenzo-Lacruz et al 2010. The management of reservoirs depends greatly on the occurrence of floods and the magnitude and duration of high and low flow episodes (Batalla et al 2004, López-Moreno et al 2004.…”

Comparison of Meteorological Drought and Hydrological Drought Index

“…그 중에서 SPI(Standardized Precipitation Index; Mckee et al, 1993) (Zhai et al, 2010;Lorenzo-Lacruz et al, 2010;Kauffmann and Vonck, 2011;McEvoy et al, 2012).…”