Water in Celtic Countries: Quantity

Key words drinking-water quality; multiple barriers; risk management; source water protection

_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 71-77.
Implications of climate change for river regimes in Wales: a comparison of scenarios and models

J. A. A. JONES¹, N. C. MOUNTAIN², C. G. PILLING³ &
C. P. HOLT⁴

1 Institute of Geography and Earth Sciences, University of Wales, Aberystwyth SY23 3DB, UK

[e-mail]

2 Environment Agency, Rivers House, East Quay, Bridgwater TA6 4YS, UK

3 Meteorological Office, Fitzroy Road, Exeter EX1 3PB, UK

4 Division of Environmental Science, University of Northampton, Park Campus, Boughton Green Road, Northampton NN2 7AL, UK
Abstract The paper compares the results from a range of GCM scenarios, downscaling methods and hydrological simulation techniques that have been applied to assess the impact of climate change on rivers in Wales. In spite of wide differences in scenarios and the sophistication of the methodology, there is broad agreement.

Key words climate change impacts; downscaling; river regimes; Wales
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 78-85.
An assessment of runoff trends in undisturbed catchments in the Celtic regions of North West Europe

JAMIE HANNAFORD, CEDRIC L. R. LAIZE & TERRY J. MARSH

National River Flow Archive, Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB, UK

[e-mail]
Abstract This study presents results of trend tests applied to annual and seasonal runoff time series from a network of catchments across the Celtic regions of the northwest European Atlantic margin, namely northern and western areas of the British Isles and Brittany. The aim is to provide an overview of natural, climate-driven runoff trends across the Celtic region by focusing on catchments undisturbed by artificial influences (e.g. impound­ments and hydropower development) on flow regimes. Strong evidence of increasing runoff over the 40 years from 1964 to 2003 was found for Scotland and Ireland, and there were some significant increases in Wales, western England and Brittany. The regional signals are less compelling in these areas, but the predominance of positive trends observed in this study suggests a tendency towards a region-wide increase. Annual runoff trends were associ­ated with increases in winter runoff; there was no evidence for any decline in summer runoff over the period. The findings have some parallels with climate change scenarios, although there were also strong associations with the North Atlantic Oscillation Index over the timescale used in this study. The study provides a baseline against which to assess historical variability and future runoff trends in the Celtic region.

Key words climate change; monitoring networks; natural catchments; North Atlantic Oscillation; resampling; river flow; runoff; trend
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 86-93.
The impact of changes in the weather on the surface temperatures of Lake Windermere (UK) and Lough Feeagh (Ireland)

GLEN GEORGE¹, DIANE HEWITT², ELEANOR JENNINGS³, NORMAN ALLOTT³ & PHILIP McGINNITY⁴

1 CEH Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK

[e-mail]

2 Freshwater Biological Association, The Ferry House, Far Sawrey, Ambleside, Cumbria LA22 OLP, UK

3 Trinity College, College Green, Dublin 2, Ireland

4 Marine Institute, Newport, County Mayo, Ireland
Abstract The surface temperatures of Lake Windermere (UK) and Lough Feeagh (Ireland) have been recorded every day since 1960. Here, we examine the factors influencing these measurements and their associated weekly variability. At both sites there was a progressive increase in the measured temperature, but the rate of increase was very much greater in Lake Windermere. The variance of the Lake Windermere temperatures was negatively correlated with the cloud cover, but there was no corresponding relationship in Lough Feeagh. Comparisons with the Lamb system of weather classification showed that the lake temperatures were closely correlated with these synoptic conditions. The highest winter temperatures were recorded during “westerly” conditions and the highest summer temperatures under “southerly” conditions. The most striking difference between the lakes was their response to cold winters and windy summers. Such results demonstrate that lakes that are topographically different “filter” the imposed climate signal in subtly different ways.

Key words climate change; Ireland; lake temperatures; UK; weather patterns
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 94-102.
Precipitation trends in mainland Portugal in the period 1941–2000

M. ISABEL P. DE LIMA^1,2, ANA C. P. MARQUES¹, JOÃO L. M. P. DE LIMA^1,3 & M. FÁTIMA E. S. COELHO⁴

1 Institute of Marine Research/IMAR-Sea, Environment and Territory Research Centre, Portugal

2 Forestry Department, ESAC/Polytechnic Institute of Coimbra, Bencanta, 3040-316 Coimbra, Portugal

[e-mail]

3 Department of Civil Engineering, FCTUC, University of Coimbra, Pólo II, 3030-290 Coimbra, Portugal

4 Institute of Meteorology, Rua C ao Aeroporto, 1749-077 Lisboa, Portugal
Abstract The presence of a trend in hydrological parameters can result from the highly variable nature of hydrological processes or be related to climate variations. The purpose of this work is to contribute to a better understanding of the variability of precipitation by investigating recent trends in the temporal structure of this process in mainland Portugal. The study uses annual and monthly precipitation data from 107 locations scattered over the territory. The time span of the records is 60 years, from 1941 to 2000. The data are analysed using statistical methods (e.g. Mann-Kendall trend test). In order to take into account seasonality and serial correlation, the months of the year were analysed separately. The analyses of both annual and monthly data led to a characterization of changes in the distribution of precipitation over mainland Portugal and within the year.

Key words climate change; mainland Portugal; precipitation; seasonality; trend
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 103-110.
Models to predict the impact of the climate changes on aquifer recharge

MANUEL MENDES OLIVEIRA¹, MARIA EMÍLIA NOVO² & JOÃO PAULO LOBO FERREIRA¹
1 Laboratório Nacional de Engenharia Civil (LNEC), Hydraulics and Environment Department (DHA), Groundwater Division (NAS), Av. do Brasil, 101, 1700-066 Lisboa, Portugal

[e-mail]

2 Parque Natural do Douro Internacional, Largo do Outeiro, no. 6, 5810-118 Freixo de Espada à Cinta, Portugal
Abstract Climate change is a statistically significant alteration of the climate variables in terms of their distribution both in time and in space. These changes will have a direct impact on the hydrological system and an indirect impact on the quality of the surface and groundwater resources. This paper deals with the impact of climate change on groundwater recharge. Several models to estimate recharge are presented, among them the daily sequential water balance model is the most appropriate to attain this goal. Climate changes may be predicted using climate models. Average precipitation and temperature values are outputs of these models. For a case study area of north Portugal, theoretical forecasted precipitation and reference evapotranspiration series are used to study the impact of precipitation change in groundwater recharge. For a scenario of 70% of actual precipitation, recharge would decrease to 45% of the estimated actual recharge.

Key words climate change; Portugal; recharge; recharge assessment; water balance models
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 113-119.
Aluminium contents in drinking water from public water supplies of Galicia (northwest Spain)

DAVID A. RUBINOS¹, MANUEL ARIAS², CARLOS AYMERICH³ & FRANCISCO DÍAZ-FIERROS¹

1 Dpto. Edafoloxía e Química Agrícola, Facultade de Farmacia, Universidade de Santiago de Compostela,
ES-15785 Santiago de Compostela, Spain

[e-mail]

2 Dpto. Bioloxía Vexetal e Ciencias do Solo, Facultade de Ciencias, Campus Ourense, Universidade de Vigo, Spain

3 Espina y Delfín, S. L. Polígono do Tambre, Santiago de Compostela, Spain
Abstract Aluminium (Al) salts are used extensively as coagulants in drinking water treatment. Since several research works have linked Al levels in drinking water to elevated risks of Alzheimers disease, we have studied the Al content in drinking water from populations in Galicia (NW Spain). Drinking water from 35 cities and villages in Galicia were analysed for dissolved Al and other relevant parameters (pH, turbidity, sulphate, fluoride and DOM) for the period 1997–2003. The results obtained showed an average aluminium content of 126 µg L^-1, but the variability was high, with Al levels ranging from 8 to 650 µg L^-1. Of the waters studied, 19% and 34% contained Al above 0.2 and 0.1 mg L^-1, respectively. Speciation studies performed using the WHAM computer model showed that most dissolved Al was DOM-complexed, although some waters contained significant amounts of labile Al, mainly as hydroxo and fluoride complexes.

Key words aluminium; Alzheimer’s disease; drinking water; speciation; WHAM
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 120-127.
1Constructions cyanobactériennes calcaires dans les rivières de Haute-Normandie: perspectives de gestion

FREDERIC PITOIS¹, ALAIN JIGOREL² & PAUL FERLIN³

1 36 rue de Piré, 35000 Rennes, France

[e-mail]

2 INSA de Rennes, GCGM–Géologie, 20 avenue des Buttes de Coësmes, CS 14315, 35043 Rennes cedex, France,

3 DIREN Haute-Normandie, 1 rue Dufay, 76100 Rouen, France
Résumé La précipitation de calcite à la surface des films cyanobactériens benthiques est à l’origine du colmatage des fonds de nombreuses rivières calcaires dans le nord ouest de la France. L’intensité du phénomène dépend essentiellement de la composition du film et de l’hospitalité du milieu pour la microflore incrustante. Les études menées depuis 10 ans ont permis d’identi­fier les seuils d’apparition et de développement optimal de la microflore incrustante (conditions trophiques, température, éclairement, granulométrie des fonds, profondeur et vitesse du courant). Un grille d’évaluation de l’intensité du concrétionnement intégrant les paramètres déterminants a été validée par des mesures in situ. Elle permet de connaître dès le printemps et avec une incertitude raisonnable, le taux de précipitation prévisible par site et par an. Elle est aussi un outil d’aide à la gestion qui permet d’évaluer les conséquences sur le milieu des travaux d’entretien couramment pratiqués dans les cours d’eau affectés par le phénomène.

Mots cléf calcite, cyanobactéries, entretien des cours d’eau, rivières calcaires

Management perspectives of the calcareous cyanobacterial build-ups in the hardwater rivers of Haute-Normandie (France)
Abstract Calcite precipitation on cyanobacterial benthic films is the cause of the cementing of many calcareous river beds in northwest France. The extent of this phenomenon depends both on the composition of the film and on how favourable the local conditions are to the encrusting microflora. The surveys carried out over the past 10 years have determined the thresholds at which the phenomenon appears and those allowing the most favourable development of the encrusting microflora (trophic conditions, temperature, exposure to light, grain size of the river bed, depth and speed of current). An assessment grid for the intensity of the phenomenon, which takes into account the determining factors, has been confirmed by on site measurements. As early as the spring, this grid makes it possible to forecast with a reasonable degree of error the precipitation rate for each site during the course of the coming year. It is also a useful tool for the management of the regular maintenance work carried out on the rivers affected by this phenomenon.

Key words calcite; management of the rivers; hardwater rivers
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 128-138.
An indicator system for surface water quality in river basins

R. E. S. Oliveira, M. M. C. L. Lima & J. M. P. Vieira

Departamento de Engenharia Civil, Escola de Engenharia da Universidade do Minho,
4800-058 Guimarães, Portugal

[e-mail]
Abstract Public utilities, agricultural and industrial economic sectors, and ecosystems depend on the water supplied by the natural environment. The European Water Framework Directive requirements, water demands and key surface water pollution problems identified in a river basin, lead to the need to develop a surface water quality indicator system. This tool allows the assessment of the pressure-state-impact of human activities on natural waters. This paper presents a methodology used for the development and application of an indicator system in the Portuguese River Ave basin, based on the conceptual Pressure-State-Response model, and on chemical and hydro-morphological water quality parameters. It is shown that the most relevant questions for the implementation of an indicator system for the surface waters of this river basin are: eutrophication, bacterial contamination, presence of organic mater, oxidation state and organic metals coming from industrial wastewater discharges.

Key words Ave River basin; European Water Framework Directive; surface waters; water quality indicators; water resources management
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 139-147.
Eutrophication in the River Vouga basin—impacts on the quality of water for public supply

J. FIGUEIREDO DA SILVA¹ & FAUSTO OLIVEIRA²

1 Departamento de Ambiente, Universidade de Aveiro, 3810-193 Aveiro, Portugal

[e-mail]

2 Águas do Vouga,3850 Albergaria a Velha, Portugal
Abstract The aim of this paper is to make a characterization of water quality problems in the River Vouga, regarding its use for public water supply. The River Vouga basin is located in a mountainous area, draining to the coastal lagoon of the Ria de Aveiro. Other medium size rivers also contribute to the pollution load entering the estuarine system of the Ria de Aveiro. Two major impacts of the pollution in the River Vouga basin were identified. One is the eutrophication process of the lower reach of the river, including the Ria de Aveiro; the other is the occasional deterioration in the quality of the water from the medium reach of the River Vouga. The causes of this deterioration are related to the enrichment of the river water with organic material. To improve the river water quality, both urban wastewater and agriculture related sources must be controlled.

Key words filtration; nutrients; suspended solids; water quality; water treatment
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 148-158.
Stockage du phosphore dans les sédiments d’un réservoir eutrophe (Gouet, Bretagne, France)

ALAIN JIGOREL¹, ANNICK BOUEDO², REMY NICOLAS² & JEAN PIERRE MORIN²

1 INSA de Rennes, LGCGM—Géologie, 20 Avenue des Buttes de Coësmes, CS 14315, F-35043 Rennes Cedex, France

[e-mail]

2 Conseil Général des Côtes d'Armor Direction de l'Agriculture et de l'Environnement (DAE) 2 rue Kuster—BP 2375, F-22023 Saint-Brieuc cedex 1, France
Résumé Un bilan du stockage du phosphore a été effectué dans le réservoir du Gouet d’un volume 7.9 × 106 m³ (Côtes d’Armor, France) par l’évaluation des flux entrants et sortants et par le suivi en continu de la sédimentation. La dynamique des apports du phosphore particulaire (Pp) est identique à celle du phosphore soluble (Ps) et liée à l’importance relative des écoulements. Les apports de Pp ont été 2 fois plus élevés que ceux de Ps (9.2 vs 4.2 t an^-1). La moitié du Ps et les 2/3 du Pp ont été stockés dans la retenue. Pour la même période de suivi, la quantité de phosphore accumulé dans les sédiments a été estimée à 5.6 t, alors que l’examen comparé des flux a donné un stock de phosphore de 6.6 t dans la retenue. Les apports de phosphore dans la retenue sont liés aux cycles hydrologiques (crues hivernales et printanières) tandis que l’accumulation du phosphore dans les sédiments s’accorde bien aux cycles biologiques (proliférations algales).

Mots clés flux; phosphore; retenue; sédiment; stockage
Phosphorus storage in sediments of an eutrophic reservoir (Gouet, Britanny, France)
Abstract A phosphorus budget was established for the 7.9 × 10⁶ m³ Gouet reservoir (Côtes d’Armor, France) by measuring inflow and outflow of phosphorus, and sedimentation processes. The dynamic of input of particulate phosphorus (pP) was identical to the dynamic of input of dissolved phosphor­us (dP), and both were linked to the relative importance of inflow. The inputs in pP were twice as much as the input of dP (9.2 vs 4.2 t year^-1). Half of dP and two-thirds of pP remained within the reservoir. During the same period, the amount of phosphorus accumulated in the sediment was estimated at 5.6 t, whereas the mass balance between inflow and outflow suggested that 6.6 t of phosphorus was stored in the reservoir. The input of phosphorus to the reservoir depends on the hydrological cycle (floods during winter and spring) while the storage of the phosphorus by sedimentation is according to the biological cycles (algal blooms).

Key words flow; phosphorus; reservoir; sediment; storage
_____________________________________________________________________________________________________Water in Celtic Countries: Quantity, Quality and Climate Variability (Proceedings of the Fourth InterCeltic Colloquium on Hydrology and Management of Water Resources, Guimarães, Portugal, July 2005). IAHS Publ. 310, 2007, 161-171.
Assessing aquifer vulnerability to seawater intrusion using the GALDIT method: part 1—application to the Portuguese Monte Gordo aquifer

JOÃO PAULO LOBO FERREIRA¹, A. G. CHACHADI², CATARINA DIAMANTINO¹ & M. J. HENRIQUES¹
1 Laboratório Nacional de Engenharia Civil (LNEC), Hydraulics and Environment Department (DHA), Groundwater Division (NAS), Av. do Brasil, 101, 1700-066 Lisboa, Portugal

[e-mail]

2 Goa University, Dept. of Earth Science, Goa University, Goa–403 206, India
Abstract This paper is divided into two parts. Part 1 presents the first application in Europe of an index developed in the framework of the EU-India INCO-DEV COASTIN project that aims to assess coastal aquifer vulnerability to seawater intrusion. The most important factors controlling seawater intrusion were found to be: Groundwater occurrence (aquifer type; unconfined, confined and leaky confined); Aquifer hydraulic conductivity; height of groundwater Level above the sea level; Distance from the shore (distance inland perpendicular from shoreline); Impact of existing status of seawater intrusion in the area; and the Thickness of the aquifer that is being mapped. The acronym GALDIT is formed from the highlighted letters of the parameters for ease of reference. These factors, in combination, were found to include the basic requirements needed to assess the general seawater intrusion potential of each hydrogeological setting. GALDIT factors represent measurable parameters for which data are generally available from a variety of sources without detailed examination. A numerical ranking system to assess seawater intrusion potential in hydrogeological settings has been devised using GALDIT factors. The application of the method is exemplified in the paper for the assessment of aquifer vulnerability to seawater intrusion in Portugal (Monte Gordo aquifer in the Portuguese southern Algarve region). The system contains three significant parts: weights, ranges, and ratings. Each GALDIT factor has been evaluated with respect to the others to determine their relative importance. In Part 2 of the paper the method for assessing GALDIT index parameters is fully explained.