Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.5194/hessd-11-83-2014 |
| Title (Primary) | Is the groundwater reservoir linear? A mathematical analysis of two limiting cases |
| Author | de Rooij, G.H. |
| Journal | Hydrology and Earth System Sciences Discussions |
| Year | 2014 |
| Department | BOPHY |
| Volume | 11 |
| Issue | 1 |
| Page From | 93 |
| Page To | 108 |
| Language | englisch |
| UFZ wide themes | RU1 |
| Abstract | Storage–discharge relationships of the groundwater reservoirs of several catchments in
a temperate-humid climate were reported in the literature to be seemingly non-linear. Once
recharge was adequately accounted for during model calibration they turned out to be linear. The
question was posed if this linearity was a fundamental property of groundwater reservoirs in
general. A mathematical analysis based on analytical solutions for several cases involving
parallel flow in horizontal aquifers shows that this is not the case when the surface water level
is close to the aquifer bottom. When the aquifer is of constant thickness, linear-reservoir
behaviour arises when the forcings remain constant for a sufficiently long time. This can range
from a few weeks for aquifers with a dense drainage network of streams or ditches to years or
centuries for large aquifers drained by rivers many kilometers apart. The characteristic time of
the groundwater reservoir depends on whether or not the aquifer is leaky and recharge is
non-zero. It is concluded that groundwater reservoirs can only be linear if their thickness can be
assumed independent of the hydraulic head, and if they have a dense drainage network. Even then,
they behave non-linearly up to several weeks after a change in recharge. Models that conceptualize
the catchment as a configuration of coupled reservoirs will normally assign the groundwater
discharge surplus generated because of the initially non-linear behaviour of the groundwater to
their fast-responding reservoirs, thereby exaggerating the importance of fast-responding flow
routes in a catchment. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=14746 |
| de Rooij, G.H. (2014): Is the groundwater reservoir linear? A mathematical analysis of two limiting cases Hydrol. Earth Syst. Sci. Discuss. 11 (1), 93 - 108 |
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