Temporal dynamics of soil water balance components in a karst range in southeastern Spain: estimation of potential recharge

Abstract

This paper analyses the temporal dynamics of soil water balance components in a representative recharge area of the Sierra de Gádor (Almeria, southeastern Spain) in two hydrological years. Two approaches are used to estimate daily potential recharge (PR): Approach 1 based on deriving PR from the water balance as the difference between measurements of rainfall (P) and actual evapotranspiration (E) obtained by eddy covariance; and Approach 2 with PR obtained from the dynamic pattern of the soil moisture (y) recorded at two depths in the site's thin soil (average 0.35 m thickess). For the hydrological year 2003/04, which was slightly drier than the 30-year average, E accounted for 64% of rainfall and occurred mainly in late spring and early summer. The PR estimated by Approach 1 was 181 AE 18 mm year -1 (36% of rainfall), suggesting an effective groundwater recharge in the study area. In the unusually dry hydrological year 2004/05, E was about 215 mm year -1 , close to the annual rainfall input, and allowing very little (8 AE 12 mm year -1 ) PR according to Approach 1. Estimation of PR based on Approach 2 resulted in PR rates lower than those found by Approach 1, because Approach 2 does not take into account the recharge that occurs through preferential flow pathways (cracks, joints and fissures) which were not monitored with the y probes. Moreover, using Approach 2, the PR estimates differed widely depending on the time scale considered: with daily mean y data, PR estimation was lower, especially in late spring, while y data at 30 min resolution yielded a more reliable prediction of the fraction of total PR resulting from the downward movement of soil water by gravity.Key words potential recharge; evapotranspiration; soil moisture; soil water balance; Mediterranean; Sierra de Gádor Dynamique temporelle des composantes du bilan hydrique du sol dans une chaine karstique du sud-est de l'Espagne: estimation de la recharge potentielle Résumé Ce travail analyse la dynamique temporelle des composantes du bilan hydrique du sol dans une zone de recharge représentative de la Sierra de Gador (Almeria, SE de l'Espagne) pendant deux années hydrologiques. Deux approches ont été utilisées pour estimer la recharge potentielle journalière (RP): dans l'approche 1, RP est calculée à partir de la différence entre les mesures de pluie (P) et d'évapotranspiration réelle (E) obtenues par la méthode de la covariance turbulente; dans l'approche 2, RP est obtenue à partir de l'humidité du sol (y) mesurée à deux profondeurs dans les sols peu profonds du site (épaisseur moyenne de 0.35 m). Pendant l'année hydrologique

Recharge estimation and soil moisture dynamics in a Mediterranean, semi-arid karst region

“…The observed seasonal dynamics of soil moisture, dominated by short wetting phases during single rainfall events and a rapid decrease after the rainfall season, are comparable with observations reported in other studies in the Mediterranean region (Cantón et al, 2010;Ruiz-Sinoga et al, 2011). At all soil moisture plots, our soil moisture data suggested fast infiltration into deeper sections of the soil profile during rainfall events with high intensities and amounts (e.g.…”

“…very close to the long-term average calculated by Schmidt et al (2014) for the same area. Our values also fall into the range of Cantón et al (2010), who derived annual effective evapotranspiration rates of more than 64 % of annual rainfall based on eddy covariance measurements in southeastern semi-arid Spain. Our simulated percolation rates ranged between 0 and 45 % of precipitation (arithmetic mean: 28 %) indicating strong inter-annual variability and a strong dependency on depth and temporal distribution of precipitation.…”

Groundwater intensive use and mining in south-eastern peninsular Spain: Hydrogeological, economic and social aspects

“…They have been carried out in Sierra de Gádor (Alcalá et al, 2011;Cantón et al;, Campo de Cartagena (Baudron et al, 2014;Jiménez-Martínez et al, 2010), highlands of the Río Mundo , and some of the karstic formations in the north-eastern sector (Andreu Rodes, 2011;Martínez-Santos and Andreu Rodes, 2010;Touhami et al, 2012;. Only a few times results have been calibrated against groundwater level and spring flow data, mostly because these data are not available or too sparse.…”

Regional spatial pattern of deep soil water content and its influencing factors

“…However, SWC exhibits a high degree of spatial and temporal variability and this variability is scale-dependent (Blöschl and Sivapalan 1995, Western et al 2002, Cantón et al 2010. Understanding the distribution and variability characteristics of SWC is necessary for sustainable land management evaluation, developing farm-specific best management plans and hydrology and climate modelling (Qiu et al 2003, Western et al 2004, Ampofo 2006.…”