Sensitivity analysis of main variables present in flash flood processes. Application in two Spanish catchments: Arás and Aguilón

The program Simulation of Hydrological Extreme Events provides a set of functionalities that combined together allows constructing, manipulating, analyzing and comparing the hydrological processes involved in flash flood generation. The program makes use of existing databases of interest in hydrology and available in Spain, such as digital terrain models, coverage of rainfall or curve number. Two pilot watersheds from Spain were selected, Arás and Aguilón, where flash flood episodes have taken place. A sensitivity analysis of the flash flood episodes in response to changes in the main hydrological processes involved has been made, such as spatial and temporal distribution of rainfall, soil moisture status and water flow through channel network. In this work, we found that the antecedent moisture condition is the most influential factor in the magnitude of flash floods produced by the same amount of rain. The temporal distribution of the storm represents the second characteristic in order of relevance. In addition, terrain morphology (specially the slope) is found to be decisive in the results differences obtained.     

The 2012/2014 swarmquakes of Jaen,Spain: a working hypothesis involving hydroseismicity associated with the hydrologic cycle and anthropogenic activity

A total of 2,300 swarmquake-type seisms have been striking the Torreperogil–Sabiote Hill (TSH) in southern Spain (Jaen) from October 2012 to the present, involving a major seismic crisis with six subseries until May 2013 (TSH seismic series, TSHS), followed by seven final series (FS). Two mild premonitory events occurred nearby in 2010–2011. Several evidences suggest cause–effect relationships between water and seismicity at the TSH: (1) The characteristics of seisms with a vast majority of ill-defined shallow/small events, spatial/temporal variations of the better constrained diffuse swarmquakes, increasing seismic velocities preceding stronger events, marked periodicities, abundant hydro-tremors, etc. (2) A series of spatial/temporal relationships between water and seismicity: Time lags between rainfall/reservoir peaks and seismic peaks; spatial links between swarmquakes and several factors (underground hydrogeology, reservoirs, etc.); etc. (3) From May 2013 to January 2014 evolution of rainfall and FS seismicity declined drastically at the same time. We suggest a hydroseismic hypothesis for TSH swarmquakes resulting from a complex series of cumulative factors: (1) A million-years natural setting involving geological, hydrogeological, geomorphological and tectonic elements. (2) A decades-long series of natural and anthropogenic factors are as follows: the 2012/2013 meteorological change, the massive overexploitation of the confined aquifers and alternating impoundment/emptying of the Giribaile reservoir.     

The Science Operations Centre of MINISAT-01

The Scientific Operations Centre (C.O.C.) takes care of all aspects of theMinisat-01 Mission related to the payload and its scientific instruments. Operations planning, preparation of commands, monitoring of the scientific instruments and data processing and distribution are the daily tasks carried out at the COC. We review these tasks along the operational life of Minisat-01 and we present a summary of the science operations andsome statistics on the usage of the satellite.     

Spatial and temporal variation of natural recharge in the semi-arid valley of Aguascalientes,Mexico

The investigation involves a temporal and spatial analysis to characterize recharge in the Aguascalientes valley in central Mexico. The results are based on a two-part methodological strategy using a geospatial and numerical analysis. Results from the geospatial analysis are based on the analytical hierarchical process (AHP) method, which involves developing a zoning map that qualifies the conditions for groundwater recharge in the valley. In addition, one-dimensional numerical modeling based on the van Genuchten equation was applied for various soil column configurations to estimate the transit time of recharge through the vadose zone. The analysis was performed over a 20-year period from 1995 to 2015. The results of the geospatial analysis indicate that the optimal area for groundwater recharge is the lower zone of the valley, particularly the portion influenced by surface discontinuities. The shortest estimated period of recharge for water to pass through the vadose zone is approximately 4.25 years.     

Spatial distribution of surgeonfish and parrotfish in the north sector of the Mesoamerican Barrier Reef System

Surgeonfish and parrotfish play an important role in structuring the benthic communities of coral reefs. However, despite their importance, little is known about their distribution patterns in the north sector of the Mesoamerican Reef System. This study evaluated the distribution of these fish in 34 sites in four habitats (lagoon, front, slopes and terrace) along a depth gradient (c 0.5–20 m). These herbivorous fish were assessed by visual censuses. Species dominance was evaluated for each habitat using SIMPER analysis. Habitat characteristics data were collected to determine the relationship between habitat conditions and spatial variations in herbivorous fish (using abundance and biomass as a proxy) via redundancy analysis. The herbivorous fish assemblage had a low density (fish per 100 m²) and biomass (g·100 m^?2) in comparison with assemblages in similar studies. In contrast, species richness was high compared with other studies in the Caribbean. Spatial variation of the abundance, biomass and size of herbivorous fish was strongly related to coral and seagrass cover, as well as to depth and rugosity. These four variables were critical in controlling the distribution patterns of the herbivorous fish assemblages. No associations were found between fish and macroalgae or any other benthic group. The present study indicates that the species richness of surgeonfish and parrotfish was not regionally affected by the dominance of macroalgae in the habitats studied. Seagrass beds and the coral reef matrix need to be preserved for the herbivorous fish assemblages to remain healthy and capable of controlling excess macroalgae growth.     

Intramontane basin development related to contractional and extensional structure interaction at the termination of a major sinistral fault: The Huércal-Overa Basin (Eastern Betic Cordillera)

Among the classical minor structural associations on the termination of transcurrent faults are horsetail splays formed by reverse, normal or strike-slip faults developing duplexes. However, temporal and spatial coexistence of contractional and extensional structures is very rarely documented. We discuss the relationships of contractional and extensional structures and associated sedimentary depocenters at the termination of a major strike-slip fault in the Eastern Betic Cordillera. Field mapping, kinematic fault analysis, paleostress determination and gravity prospecting in the Huércal-Overa Basin, at the southern termination of the NE–SW Alhama de Murcia transcurrent fault (AMF), are used to establish the relationships of tectonic structures and associated sedimentary depocenters. Here, ENE–WSW and WNW–ESE folds interact with two sets of normal faults having the same orientation as well as ENE–WSW reverse faults. Progressive unconformities associated with folds reveal that the beginning of the AMF activity occurred in the Tortonian. The folds progressively grew and rotated from ENE–WSW up to WNW–ESE close to the transcurrent fault. We propose that the development of the normal faults developed during short-term episodes characterized by vertical major stress axis and are, in turn, related to gravitational instability linked to the thickening of a crust relatively hot at depth. This setting may have become predominant in between the main activity, compressive pulses along transcurrent faults.     

PS-InSAR processing methodologies in the detection of field surface deformation—Study of the Granada basin (Central Betic Cordilleras,southern Spain)

Differential SAR interferometry (DInSAR) is a very effective technique for measuring crustal deformation. However, almost all interferograms include large areas where the signals decorrelate and no measurements are possible. Persistent scatterer interferometry (PS-InSAR) overcomes the decorrelation problem by identifying resolution elements whose echo is dominated by a single scatterer in a series of interferograms.Two time series of 29 ERS-1/2 and 22 ENVISAT ASAR acquisitions of the Granada basin, located in the central sector of the Betic Cordillera (southern Spain), covering the period from 1992 to 2005, were analyzed. Rough topography of the study area associated to its moderate activity geodynamic setting, including faults and folds in an uplifting relief by the oblique Eurasian–African plate convergence, poses a challenge for the application of interferometric techniques. The expected tectonic deformation rates are in the order of ～1 mm/yr, which are at the feasibility limit of current InSAR techniques.In order to evaluate whether, under these conditions, InSAR techniques can still be used to monitor deformations we have applied and compared two PS-InSAR approaches: DePSI, the PS-InSAR package developed at Delft University of Technology (TU Delft) and StaMPS (Stanford Method for Persistent Scatterers) developed at Stanford University. Ground motion processes have been identified for the first time in the study area, the most significant process being a subsidence bowl located at the village of Otura.The idea behind this comparative study is to analyze which of the two PS-InSAR approaches considered might be more appropriate for the study of specific areas/environments and to attempt to evaluate the potentialities and benefits that could be derived for the integration of those methodologies.