Repositório Colecção: CEC_HID_ARI
https://hdl.handle.net/1822/1107
CEC_HID_ARI2024-03-29T01:23:26ZOptimal locations of groundwater extractions in coastal aquifers
https://hdl.handle.net/1822/6804
Título: Optimal locations of groundwater extractions in coastal aquifers
Autor: Silva, Júlio F. Ferreira da; Haie, Naim
Resumo: A regional water supply management model for coastal aquifers was developed.
One of its outcomes is the definition of the optimized locations for groundwater
withdrawal. Such a tool permits the analysis of alternative plans for groundwater extraction
and the sustainable use of water resources in a coastal aquifer subject to saltwater intrusion.
The principal components are the evolutionary optimization and the analytical/numerical
simulation models. The optimization technique looks for the best well locations taking into
consideration the economic results and the satisfaction of the societal water demand.
However these two concerns are conditioned by trying to control the saltwater intrusion,
i.e., preserving the environmental equilibrium. The simulation model uses the governing
mathematical equations for groundwater movement to find the interface between freshwater
and saltwater. Because of the non-linearity in the system and the possibility of a jumping
interface, a security distance was defined. This is a controlling variable which can be set by
the decision makers. The model was applied to a typical case with interesting results. For
example, diagrams showing the relationship between the location of the wells and the
security distance(s) are of importance to the managers. It was also crucial to have an
understanding of the tradeoffs between groundwater withdrawals, positions of the wells
from the coast line, and the security distance. The model was also applied to a real case in
order to relate the extractions, distances and artificial recharge (not presented in this paper).
<b>Tipo</b>: article2007-07-27T17:11:03ZEffect of residence times on river Mondego estuary eutrophication vulnerability
https://hdl.handle.net/1822/6147
Título: Effect of residence times on river Mondego estuary eutrophication vulnerability
Autor: Duarte, António A. L. Sampaio; Pinho, José L. S.; Pardal, Miguel A. C.; Neto, J. M.; Vieira, J. M. Pereira; Santos, Fernando S.
Resumo: The south arm of Mondego estuary, located in the central western Atlantic coast of Portugal, is almost silted up in the upstream area. So, the water circulation is mostly driven by tides and the tributary river Pranto discharges. Eutrophication has been taking place in this ecosystem during last twelve years, where macroalgae reach a luxuriant development covering a significant area of the intertidal muddy flat.
A sampling program was carried out from June 1993 to June 1994. Available data on salinity profiles and on nutrients loading into the estuary south arm are being used in order to get a better understanding of the ongoing changes. River Pranto flow discharges, controlled by a sluice, were also monitored.
Integral formulations are typically based on assumptions of steady-state and well mixed systems and thus cannot take into account the space and time variability of estuarine residence times, due to river discharge flow, tidal coefficients, discharge(s) location and time of release during the tidal cycle. This work presents the hydrodynamics modelling (2D-H) of this system in order to estimate the residence times variability and to assess their effect on the estuarine eutrophication vulnerability, contributing for proper environmental management strategies selection.
<b>Tipo</b>: conferencePaper2007-02-14T14:22:11ZEutrophication vulnerability analysis: a case study
https://hdl.handle.net/1822/6146
Título: Eutrophication vulnerability analysis: a case study
Autor: Vieira, J. M. Pereira; Pinho, José L. S.; Duarte, António A. L. Sampaio
Resumo: River Cavado water quality variability was studied for eutrophication vulnerability assessment at a new
surface water supply intake. Since the river flow regime is artificially controlled by upstream multipurpose
reservoirs, mathematical modelling was applied in evaluating alternative management scenarios. Due to the
fact that surface water quality at intake location is mainly affected by a 5 km upstream wastewater treatment
plant effluent discharge, algae and nutrients concentration simulations have been worked out in order to
identify critical situations. Different algal concentration profiles along the river were obtained for local
conditions of light energy, water temperature and estimated nutrient loads, showing high probability of
eutrophication occurrence for some of the simulated scenarios. The discussion of results of this study
appears to be very useful for river basin wide water management policies evaluation.
<b>Tipo</b>: article2007-02-14T14:07:50Z