Modeling rock weathering in small watersheds
| Autor: | Pacheco, F.A.L., van der Weijden, C.H., Marine geochemistry & chemical oceanography, Marine geochemistry |
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| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Hydrology
geography geography.geographical_feature_category Groundwater flow Soil production function Modeling Aquifer Weathering Rock weathering Groundwater recharge Bimodal landscape Structural basin Infiltration (hydrology) Groundwater flow system Geomorphology Geology Groundwater Water Science and Technology |
| Zdroj: | Journal of Hydrology, 513, 13. Elsevier |
| ISSN: | 0022-1694 |
| Popis: | Summary Many mountainous watersheds are conceived as aquifer media where multiple groundwater flow systems have developed (Toth, 1963), and as bimodal landscapes where differential weathering of bare and soil-mantled rock has occurred (Wahrhaftig, 1965). The results of a weathering algorithm (Pacheco and Van der Weijden, 2012a, 2014), which integrates topographic, hydrologic, rock structure and chemical data to calculate weathering rates at the watershed scale, validated the conceptual models in the River Sordo basin, a small watershed located in the Marao cordillera (North of Portugal). The coupling of weathering, groundwater flow and landscape evolution analyses, as accomplished in this study, is innovative and represents a remarkable achievement towards regionalization of rock weathering at the watershed scale. The River Sordo basin occupies an area of approximately 51.2 km 2 and was shaped on granite and metassediment terrains between the altitudes 185–1300 m. The groundwater flow system is composed of recharge areas located at elevations >700 m, identified on the basis of δ 18 O data. Discharge cells comprehend terminations of local, intermediate and regional flow systems, identified on the basis of spring density patterns, infiltration depth estimates based on 87 Sr/ 86 Sr data, and spatial distributions of groundwater pH and natural mineralization. Intermediate and regional flow systems, defined where infiltration depths >125 m, develop solely along the contact zone between granites and metassediments, because fractures in this region are profound and their density is very large. Weathering is accelerated where rocks are covered by thick soils, being five times faster relative to sectors of the basin where rocks are covered by thin soils. Differential weathering of bare and soil-mantled rock is also revealed by the spatial distribution of calculated aquifer hydraulic diffusivities and groundwater travel times. |
| Databáze: | OpenAIRE |
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