Individual and combined effects of land use/cover and climate change on Wolf Bay watershed streamflow in southern Alabama

Land use/cover (LULC) and climate change are two main factors affecting watershed hydrology. In this paper, individual and combined impacts of LULC and climate change on hydrologic processes were analysed applying the model Soil and Water Assessment Tool in a coastal Alabama watershed in USA. Temporally and spatially downscaled Global Circulation Model outputs predict a slight increase in precipitation in the study area, which is also projected to experience substantial urban growth in the future. Changes in flow frequency and volume in the 2030s (2016–2040) compared to a baseline period (1984–2008) at daily, monthly and annual time scales were explored. A redistribution of daily streamflow is projected when either climate or LULC change was considered. High flows are predicted to increase, while low flows are expected to decrease. Combined change effect results in a more noticeable and uneven distribution of daily streamflow. Monthly average streamflow and surface runoff are projected to increase in spring and winter, but especially in fall. LULC change does not have a significant effect on monthly average streamflow, but the change affects partitioning of streamflow, causing higher surface runoff and lower baseflow. The combined effect leads to a dramatic increase in monthly average streamflow with a stronger increasing trend in surface runoff and decreasing trend in baseflow. Copyright © 2013 John Wiley & Sons, Ltd.     

Reconstructing deep‐time histories from integrated thermochronology: An example from southern Baffin Island,Canada

We present a multi‐chronometric approach for reconstructing deep‐time thermal histories using southern Baffin Island as a case study. This continuous thermal history begins with the Palaeoproterozoic Trans‐Hudson Orogeny and is derived from inverse and forward models that integrate thermochronometers spanning some 500°C: new apatite U–Pb ages and K‐feldspar ⁴⁰Ar/³⁹Ar multi‐diffusion domain data, published (U–Th)/He zircon ages and new multi‐kinetic fission‐track results. Integration of data from a wider temperature range reduces ambiguities in thermal‐history modelling and permits us to constrain the timing of geological processes including, extended post‐orogenic cooling, enhanced later Proterozoic cooling, and then episodic burial and exhumation in the Palaeozoic–Mesozoic.     

Relations between the emplacement and fabric-forming conditions of the Kapitan-Dimitrievo pluton and the Maritsa shear zone (Central Bulgaria): magnetic and visible fabrics analysis

The Kapitan-Dimitrievo pluton was emplaced within the 15 km wide Maritsa shear zone during the Late Cretaceous. It has well-known U–Pb zircon age (78.54 ± 0.13 Ma) and appears as a late-syntectonic intrusion that marked the last ductile deformation in the Maritsa shear zone. Magnetite is believed to be the main carrier of the magnetic fabric in this pluton, and crystallized mainly late, after the main rock-forming minerals. Two fabrics are recorded, a visible syn-magmatic fabric (due to magma flow) and magnetic late-magmatic fabric (related to regional stresses). Although different, both are mainly related to the shearing along this shear zone. These results constrain in age the dextral strike-slip controlled emplacement and evolution of the Late Cretaceous plutons from Central Bulgaria.     

A warm-season comparison of WRF coupled to the CLM4.0, Noah-MP,and Bucket hydrology land surface schemes over the central USA

In climate modeling studies, there is a need to choose a suitable land surface model (LSM) while adhering to available resources. In this study, the viability of three LSM options (Community Land Model version 4.0 [CLM4.0], Noah-MP, and the five-layer thermal diffusion [Bucket] scheme) in the Weather Research and Forecasting model version 3.6 (WRF3.6) was examined for the warm season in a domain centered on the central USA. Model output was compared to Parameter-elevation Relationships on Independent Slopes Model (PRISM) data, a gridded observational dataset including mean monthly temperature and total monthly precipitation. Model output temperature, precipitation, latent heat (LH) flux, sensible heat (SH) flux, and soil water content (SWC) were compared to observations from sites in the Central and Southern Great Plains region. An overall warm bias was found in CLM4.0 and Noah-MP, with a cool bias of larger magnitude in the Bucket model. These three LSMs produced similar patterns of wet and dry biases. Model output of SWC and LH/SH fluxes were compared to observations, and did not show a consistent bias. Both sophisticated LSMs appear to be viable options for simulating the effects of land use change in the central USA.     

Comparative assessment of two distributed watershed models with application to a small watershed

Distributed watershed models are beneficial tools for the assessment of management practices on runoff and water‐induced erosion. This paper evaluates, by application to an experimental watershed, two promising distributed watershed‐scale sediment models in detail: the Kinematic Runoff and Erosion (KINEROS‐2) model and the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model. The physics behind each model are to some extent similar, though they have different watershed conceptualizations. KINEROS‐2 was calibrated using three rainfall events and validated over four separate rainfall events. Parameters estimated by this calibration process were adapted to GSSHA. With these parameters, GSSHA generated larger and retarded flow hydrographs. A 30% reduction in both plane and channel roughness in GSSHA along with the assumption of Green‐Ampt conductivity K_G‐A = K_s, where K_s is the saturated conductivity, resulted in almost identical hydrographs. Sediment parameters not common in both models were calibrated independently of KINEROS‐2. A comparative discussion of simulation results is presented. Even though GSSHA's flow component slightly overperformed KINEROS‐2, the latter outperformed GSSHA in simulations for sediment transport. In spite of the fact that KINEROS‐2 is not geared toward continuous‐time simulations, simulations performed with both models over a 1 month period generated comparable results. Copyright © 2006 John Wiley & Sons, Ltd.     

Late Cretaceous porphyry Cu and epithermal Cu–Au association in the Southern Panagyurishte District,Bulgaria: the paired Vlaykov Vruh and Elshitsa deposits

Vlaykov Vruh–Elshitsa represents the best example of paired porphyry Cu and epithermal Cu–Au deposits within the Late Cretaceous Apuseni–Banat–Timok–Srednogorie magmatic and metallogenic belt of Eastern Europe. The two deposits are part of the NW trending Panagyurishte magmato-tectonic corridor of central Bulgaria. The deposits were formed along the SW flank of the Elshitsa volcano-intrusive complex and are spatially associated with N110-120-trending hypabyssal and subvolcanic bodies of granodioritic composition. At Elshitsa, more than ten lenticular to columnar massive ore bodies are discordant with respect to the host rock and are structurally controlled. A particular feature of the mineralization is the overprinting of an early stage high-sulfidation mineral assemblage (pyrite ± enargite ± covellite ± goldfieldite) by an intermediate-sulfidation paragenesis with a characteristic Cu–Bi–Te–Pb–Zn signature forming the main economic parts of the ore bodies. The two stages of mineralization produced two compositionally different types of ores—massive pyrite and copper–pyrite bodies. Vlaykov Vruh shares features with typical porphyry Cu systems. Their common geological and structural setting, ore-forming processes, and paragenesis, as well as the observed alteration and geochemical lateral and vertical zonation, allow us to interpret the Elshitsa and Vlaykov Vruh deposits as the deep part of a high-sulfidation epithermal system and its spatially and genetically related porphyry Cu counterpart, respectively. The magmatic–hydrothermal system at Vlaykov Vruh–Elshitsa produced much smaller deposits than similar complexes in the northern part of the Panagyurishte district (Chelopech, Elatsite, Assarel). Magma chemistry and isotopic signature are some of the main differences between the northern and southern parts of the district. Major and trace element geochemistry of the Elshitsa magmatic complex are indicative for the medium- to high-K calc-alkaline character of the magmas. ⁸⁷Sr/⁸⁶Sr_(i) ratios of igneous rocks in the range of 0.70464 to 0.70612 and ¹⁴³Nd/¹⁴⁴Nd_(i) ratios in the range of 0.51241 to 0.51255 indicate mixed crustal–mantle components of the magmas dominated by mantellic signatures. The epsilon Hf composition of magmatic zircons (+6.2 to +9.6) also suggests mixed mantellic–crustal sources of the magmas. However, Pb isotopic signatures of whole rocks (²⁰⁶Pb/²⁰⁴Pb = 18.13–18.64, ²⁰⁷Pb/²⁰⁴Pb = 15.58–15.64, and ²⁰⁸Pb/²⁰⁴Pb = 37.69–38.56) along with common inheritance component detected in magmatic zircons also imply assimilation processes of pre-Variscan and Variscan basement at various scales. U–Pb zircon and rutile dating allowed determination of the timing of porphyry ore formation at Vlaykov Vruh (85.6 ± 0.9 Ma), which immediately followed the crystallization of the subvolcanic dacitic bodies at Elshitsa (86.11 ± 0.23 Ma) and the Elshitsa granite (86.62 ± 0.02 Ma). Strontium isotope analyses of hydrothermal sulfates and carbonates (⁸⁷Sr/⁸⁶Sr = 0.70581–0.70729) suggest large-scale interaction between mineralizing fluids and basement lithologies at Elshitsa–Vlaykov Vruh. Lead isotope compositions of hydrothermal sulfides (²⁰⁶Pb/²⁰⁴Pb = 18.432–18.534, ²⁰⁷Pb/²⁰⁴Pb = 15.608–15.647, and ²⁰⁸Pb/²⁰⁴Pb = 37.497–38.630) allow attribution of ore-formation in the porphyry and epithermal deposits in the Southern Panagyurishte district to a single metallogenic event with a common source of metals.