Agricultural irrigation represents the main use of global water resources. Irrigation has an impact on the environment, and scientific evidence suggests that it inevitably leads to salinization of both soil and aquifers. The effects are most pronounced under arid and semi-arid conditions. In considering the varied impacts of irrigation practices on groundwater quality, these can be classed as either directthe direct result of applying water and accompanying agrochemicals to croplandor indirectthe effects of irrigation abstractions on groundwater hydrogeochemistry. This paper summarizes and illustrates through paradigmatic case studies the main impacts of irrigation practices on groundwater salinity. Typically, a diverse range of groundwater salinization processes operating concomitantly at different time scales (from days to hundreds of years) is involved in agricultural irrigation. Case studies suggest that the existing paradigm for irrigated agriculture of focusing mainly on crop production increases has contributed to widespread salinization of groundwater resources.

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The blind reverse Bajo Segura Fault is located at the eastern extreme of the Trans-Alboran shear zone (Betic Cordillera, southeast Iberian Peninsula). The surface expression of recent activity of this blind ENE–WSW fault is represented by coseismic surface anticlines and growth synclines on both sides of the anticlines. In the synclines, the deformation of the most recent Quaternary materials is obscured by a sedimentary unit more than 30 m thick which was deposited during the later part of the Late Pleistocene and the Holocene. The present study reports three high-resolution seismic profiles made in the northern growth syncline, which was the one developed most by the Bajo Segura Fault. In these seismic profiles we recognize the boundary between pre-growth strata and growth strata. This marker, Early Pliocene in age, dates the start of the activity of this blind reverse fault. The geometry observed in the seismic profiles of the syntectonic strata, dating from the Late Pliocene and Quaternary, indicates a limb rotation folding mechanism. On seismic profile 2, the complex geometry of the Benejúzar anticline forelimb can be attributed to several splay faults close to the surface of Bajo Segura Fault.

Please cite this article as: Touhami, I., Chirino, E., Andreu, J.M., Sánchez, J.R., Moutahir, H., Bellot, J., Assessment of climate change impacts on soil water balance and aquifer recharge in a semiarid region in south east Spain, Hydrology (2015), doi: http://dx.doi.org/10. 1016/j.jhydrol.2015.05.012 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Climate change forecasts in a semiarid region are of much interest to academics, managers 31 and governments. A significant decrease in annual precipitation and an increase in mean 32 annual air temperature are expected; consequently, changes in the soil water balance and 33 groundwater recharge to aquifers are expected as a response to climate change forecasts. In 34 this context, our study aimed to assess the impact of climate changes on the soil water balance 35 and natural groundwater recharge in a semiarid area (Ventós-Castellar aquifer, SE, Spain). To 36 this end, we selected Global Climate Model HadCM3 after comparing it with two other 37 models (ECHAM4 and CGCM2). The HadCM3 model climate data (air temperature and 38 precipitation in two emission scenarios: A2-high and B2-low; 2011-2099) were coupled to a 39 HYDROBAL hydrological model to determine the soil water balance. The HYDROBAL 40 model results showed that climate change will have a significant impact on the soil water 41 balance in the study area, especially on groundwater recharge during the latter period. In both 42 the A2-high and B2-low scenarios, the selected years to run the HYDROBAL model showed 43 a decrease in water balance components (Precipitation, actual evapotranspiration, aquifer 44 recharge and runoff) in relation to the baseline period . Over the projected period 45 (2011-2099), we expect fewer rainfall events (>15 mm), which promote aquifer recharge, 46 longer dry summer seasons and, consequently, reduced average annual recharge that ranged 47 from 3-17%; 10-49 mm, if compared to the baseline period. The methodology developed in 48 the present study can be beneficial for assessing the impact of predicted climate change on 49 groundwater recharge, and can help managers and planners to devise strategies for the 50 efficient use and conservation of freshwater resources. 51 52 Journal of

Abstract:Mediterranean aquifers are frequently subject to the joint effect of intensive exploitation and low recharge values. Besides, groundwater is the only available water resource in many Mediterranean regions. Groundwater recharge studies are therefore necessary to underpin water management practices. This manuscript presents a methodology to estimate groundwater recharge in a small limestone aquifer of southeastern Spain. The HYDROBAL model is used to calculate daily soil water balances on the basis of hydrological and soil data as well as on vegetation cover. Deep drainage model outputs are converted into water table variations using a lumped model add-on. The adjustment between observed and calculated water table levels is in the order of r 2 = 0.87. This correlation coefficient suggests that HYDROBAL is a useful tool to estimate groundwater recharge in the region. In addition, differences in groundwater recharge rates are observed for dry, average and wet years. Estimated recharge rates range between 0% and 18% of the mean annual rainfall, which corresponds to a net recharge of 0 to 59 mm year À1 . Recharge rates increase proportionally with precipitation (r 2 = 0.90).

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