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Fluvial terraces of the northwest Iberian lower Miño River. Viveen, W. ; Schoorl, J.M. ; Veldkamp, A. ; Balen, R.T. van; Vidal-Romani, J.R. - \ 2013
Journal of Maps 9 (2013)4. - ISSN 1744-5647 - p. 513 - 522. sea-level change - tectonic activity - portugal - uplift - climate - reconstruction - pleistocene - evolution - incision - deposits
A new fluvial terrace map with a tectonic framework for the northwest Iberian lower Miño River is presented. It is the first integrated map to cover the entire lower, 67-km reach of the Miño River, and to cover both the Spanish and Portuguese side of the river. The map is presented at a scale of 1:200,000, although its features were mapped at a scale of 1:5000. Various map layers can be viewed, such as a digital elevation model (DEM), fluvial sediment thickness layers, a palaeoflow direction layer, a lineament and fault layer, and two terrace and tectonic basin layers, showing up to 10 fluvial terraces and a floodplain level. Interpretation of the map shows that next to regional tectonic uplift and glacioeustacy, local basin subsidence and small-scale block movement are very important for the fluvial network, localised fluvial terrace formation, and preservation.
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Holocene dynamics of the salt-fresh groundwater interface under a sand island, Inhaca, Mozambique Vaeret, L. ; Leijnse, A. ; Cuamba, F. ; Haldorsen, S. - \ 2012
Quaternary International 257 (2012). - ISSN 1040-6182 - p. 74 - 82. last glacial maximum - sea-level change - southern africa - aquifers - climate
The configuration of coastal groundwater systems in southeast Africa was strongly controlled by the Holocene sea-level changes, with an Early Holocene transgression ~15 m (10,000–5000 cal BP), and two assumed high-stand events in the Middle and Late Holocene with levels higher than the present. The fluctuation of the salt–fresh groundwater interface under Inhaca Island in Mozambique during the Holocene has been studied using an adapted version of the numerical code SUTRA (Saturated-Unsaturated Transport). In this study, small-scale variations such as tidal effects have not been considered. A number of transient simulations were run with constant boundary conditions until the steady state condition was reached in order to study the sensitivity of response time, salt–fresh interface position, and thickness of the transition zone to different parameters such as hydraulic conductivity, porosity, recharge, and dispersivity. A 50% increase in horizontal hydraulic conductivity yields a rise in the location of the interface of >15 m, while an increase in recharge from 8% to 20% of mean annual precipitation (MAP) causes a downward shift in the interface position of >40 m. A full transient simulation of the Holocene dynamics of the salt–fresh groundwater interface showed a response time of several hundred years, with a duration sensitive to porosity, hydraulic conductivity and recharge and a position determined by the recharge rate and the hydraulic conductivity. Dispersivity controls the thickness of the transition zone in this non-tidal model. Physical processes, such as changes in recharge and/or the sea level, may cause rapid shifts in the interface position and affect the thickness of the transition zone
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