Details

Autor(en) / Beteiligte

• Santos, R.M.B.
• Sanches Fernandes, L.F.
• Moura, J.P.
• Pereira, M.G.
• Pacheco, F.A.L.

Titel

The impact of climate change, human interference, scale and modeling uncertainties on the estimation of aquifer properties and river flow components

Ist Teil von

• Journal of hydrology (Amsterdam), 2014-11, Vol.519, p.1297-1314

Ort / Verlag

Kidlington: Elsevier B.V

Erscheinungsjahr

2014

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• •Describe the impact of climate change in aquifer properties in the 20th century.•Describe the impact of climate change in river flow components in a small watershed.•Validate GIS-based watershed models, such as Mike Basin, with specific settings. Within the period 1978–2006, climate change and human interferences produced noticeable impacts on the hydrology of a small watershed, known as the Beça River basin. Climate change was characterized by a persistent raise in temperature (+0.78°Cdecade−1) and a drop in the annual rainfall (−300mmdecade−1). Human interferences included the construction of a dam for electric power generation, in 1998, and since then the transference of Beça River flows from the dam lake to the adjacent Tâmega River. The impacts on catchment hydrology comprised a decline of aquifer hydraulic conductivity and effective porosity, by approximately one order of magnitude, related to a water table lowering of about 17m within the bedrock aquifer composed of weathered and fractured Hercynian granites and Paleozoic metassediments and of saprolite layers derived therefrom. Aquifer property estimates were compared across spatial scales, namely the Beça River and the nested sub-basins scale. Sub-basin aquifers are more porous and permeable than the basin aquifer because corresponding hydraulic circuits are shallower. Comparisons were also made between aquifer properties derived from measured and simulated stream flows, which revealed effects of modeling uncertainties on the results. River flows also suffered a substantial decrease in the course of climate change and human interference, especially the overland flows (4/5 decrease) and the base flows (2/3 decrease). The inter flows were less affected (1/3 decrease) because they were partly fed with water from the aquifer storage, which in turn underwent depletion. The hydrologic changes in the Beça River basin anticipate important impacts on the local use of natural water. In this context, the aforementioned water table lowering may have caused limited access to shallow groundwater for activities such as crop irrigation from dug wells, whereas the severe decline in overland flows and base flows had certainly reduced the availability of surface water for the refilling of dam lakes and of groundwater for the supply of public and private boreholes.