@article {Levenson2015, title = {Calcite dissolution rates in texturally diverse calcareous rocks}, journal = {Geological Society, London, Special Publications}, volume = {406}, number = {1}, year = {2015}, pages = {81{\textendash}94}, abstract = {

The injection of reactive fluids into carbonate reservoirs during enhanced recovery operations can induce important changes in rock permeability. However, reliably predicting these changes requires accurate knowledge of calcite reaction rates. While numerous studies have examined calcium carbonate dissolution rates, most have focused on pure calcite crystals rather than actual rocks. In this study, two types of flow-through experiments were carried out to determine the calcite dissolution rates in texturally diverse calcareous rocks: the first type of experiment had a duration of 3 days, while the second type ran for 3 months. Our experiments show that rocks with differing textures and roughness (samples included coarse-grained oolitic limestone, fine-grained Solnhofen limestone, marble and calcite spar) do in fact dissolve by different mechanisms. However, despite these differences, bulk reaction rates were found to be remarkably similar (with a relative standard deviation of {\textless}20{\%}) and consistent with previously reported reaction rates for calcite. Thus, our results suggest that textural differences between rock types are unlikely to have an important impact on overall reaction rates in fractured carbonate reservoirs.

}, issn = {0305-8719}, doi = {10.1144/SP406.14}, url = {http://sp.lyellcollection.org/content/406/1/81.abstract}, author = {Levenson, Yael and Schiller, May and Kreisserman, Yevgeny and Emmanuel, Simon} } @article {Oz2015, title = {Saltwater circulation patterns within the freshwater-saltwater interface in coastal aquifers: Laboratory experiments and numerical modeling}, journal = {Journal of Hydrology}, volume = {530}, year = {2015}, pages = {734{\textendash}741}, publisher = {Elsevier B.V.}, abstract = {

Groundwater flow patterns within the freshwater-saltwater interface in coastal aquifers include rotation in the flow direction of saltwater that originates from the sea and circulates in the aquifer. Using two types of tracer experiments we analyze the configuration of the rotating flow-lines. The experimental results are numerically reconstructed and quantitatively compared to the salinity distribution along the interface. The results show that the rotation in the direction of the saltwater flow-lines begins at the lowermost part of the interface (i.e. contour C/Cmax=99{\%}), and completes within its lower tenth (contour C/Cmax=94{\%}). At the upper part of the interface, after the rotation is completed, the flow is dictated by the freshwater flow seaward. Based on these results, the well-known chemical freshwater-saltwater interface is divided into two different parts, defined by their physical properties: (1) the lower part is the "Flow Rotation Region", defined by convective circulating flow-lines; and (2) the upper part is the "Dispersive Region", defined by dispersive dilution. Sensitivity analysis shows that the physical configuration of the interface depends on the transversal dispersivities. At higher dispersivities the rotation width increases, but completes within the lower third of the interface, at most. The sensitivity analysis also shows that the rotation begins at the lowermost part of the interface for dispersivities. Therefore, since no flow occurs below a line of 99{\%}, the saline water that flows seaward is always diluted with respect to its original salinity. These flow patterns might affect coastal processes such as submarine groundwater discharge (SGD) and chemicals transport through the aquifer.

}, keywords = {Circulation, Freshwater-saltwater interface, Laboratory experiment, Numerical model, Rotation, Tracers}, issn = {00221694}, doi = {10.1016/j.jhydrol.2015.10.033}, url = {http://dx.doi.org/10.1016/j.jhydrol.2015.10.033}, author = {Oz, Imri and Shalev, Eyal and Yechieli, Yoseph and Gvirtzman, Haim} } @article {Peleg2015, title = {A framework for assessing hydrological regime sensitivity to climate change in a convective rainfall environment: a case study of two medium-sized eastern Mediterranean catchments, Israel}, journal = {Hydrology and Earth System Sciences}, volume = {19}, number = {1}, year = {2015}, pages = {567{\textendash}581}, abstract = {

A modeling framework is formulated and applied to assess the sensitivity of the hydrological regime of two catchments in a convective rainfall environment with respect to projected climate change. The study uses likely rainfall scenarios with high spatiotemporal resolution that are de- pendent on projected changes in the driving regional meteorological synoptic systems. The framework was applied to a case study in two medium-sized Mediterranean catchments in Israel, affected by convective rainfall, by combining the HiReS-WG rainfall generator and the SAC-SMA hydrolog- ical model. The projected climate change impact on the hy- drological regime was examined for the RCP4.5 and RCP8.5 emission scenarios, comparing the historical (beginning of the 21st century) and future (mid-21st-century) periods from three general circulation model simulations available from CMIP5. Focusing on changes in the occurrence frequency of regional synoptic systems and their impact on rainfall and streamflow patterns, we find that the mean annual rain- fall over the catchments is projected to be reduced by 15\% (outer range 2{\textendash}23\%) and 18\%(7{\textendash}25\%) for the RCP4.5 sand RCP8.5 emission scenarios, respectively. The mean annual streamflowvolumes are projected to be reduced by 45\%(10{\textendash} 60\%) and 47\% (16{\textendash}66 \%). The average events{\textquoteright} streamflow volumes for a given event rainfall depth are projected to be lower by a factor of 1.4{\textendash}2.1. Moreover, the streamflow sea- son in these ephemeral streams is rojected to be shorter by 22\%and 26{\textendash}28\%for the RCP4.5 and RCP8.5, respectively. The amplification in reduction of streamflow volumes relative to rainfall amounts is related to the projected reduction\ in soil moisture, as a result of fewer rainfall events and longer dry spells between rainfall events during the wet sea- son. The dominant factors for the projected reduction in rainfall amount were the reduction in occurrence of wet synop- tic systems and the shortening of the wet synoptic systems durations. Changes in the occurrence frequency of the two dominant types of the regional wet synoptic systems (active Red Sea trough and Mediterranean low) were found to have a minor impact on the total rainfall.

}, issn = {1607-7938}, doi = {10.5194/hess-19-567-2015}, url = {http://www.hydrol-earth-syst-sci.net/19/567/2015/}, author = {Peleg, N. and Shamir, E. and Georgakakos, K. P. and Morin, E.} }