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Sustainable Water Resources Management

, Volume 5, Issue 1, pp 175–186 | Cite as

Demonstrative actions of spring restoration and groundwater protection in rural areas of Abegondo (Galicia, Spain)

  • A. Naves
  • J. SamperEmail author
  • A. Mon
  • B. Pisani
  • L. Montenegro
  • J. M. Carvalho
Original Article

Abstract

There is an increasing concern about the chemical and microbiological quality of spring waters in Galicia (Spain) due to bacteriological and nitrate contamination. Demonstrative actions of spring restoration and groundwater protection were implemented in five selected springs and fountains in the municipality of Abegondo. These actions include the cleaning and disinfection of the fountains, the restoration of the spring catchments and the definition and the implementation of the spring protection zones. Available topographic, geological, meteorological, hydrological, hydrogeological and hydrochemical data of the area were used to: (1) elaborate the hydrogeological conceptual model of the study area; (2) assess the groundwater chemical and microbial status; and (3) define the spring protection zones with a numerical groundwater flow and solute transport model solved with the CORE2D code. Spring protection zones include: (1) an immediate zone of absolute restrictions around the spring with a radius of 3 m; (2) an intermediate zone of maximum restrictions where potential contamination activities are restricted; this zone has a radius of 30 m and is defined on the basis of a 50 days transit time; and (3) a remote zone which includes the rest of the contributing groundwater basin where restrictions are moderate. The protection zones defined in the project were included in the general development plan of the municipality. The chemical and microbial data of the springs were monitored during 3 years after the restoration actions. The cleaning and disinfection of the fountains and spring catchments were efficient in dropping noticeably the microbiological contamination and reducing mildly the nitrate concentrations (from 10 to 20%). The efficiency of the restoration measures was partially reduced by: (1) the low frequency of the cleaning and disinfection of the fountains; and (2) the lack of actions to enforce the restrictions in the protection zones to prevent the excessive use of manure as fertilizer in the surroundings of some springs.

Keywords

Groundwater quality Spring catchment Spring protection zones Fractured aquifer Galicia 

Introduction

Water supply in dispersed rural communities is a great challenge for the implementation of the European regulations concerning water protection and management (Directive 2000/60/EC) and the quality of water for human consumption (Directive 98/83/EC). Agricultural contamination is often the pressure that results in poor groundwater chemical status in Europe where nitrate is the main concern for groundwater quality (EC 2010).

About 650,000 people in Galicia (Spain) rely on groundwater supply through autonomous solutions. The technical and economic feasibility of centralized infrastructures in this region is severely limited by the distance to highly populated areas and the large investments required to undertake them. Local people developed spontaneously autonomous systems in response to the historic shortcomings of local administrations. A large part of the public-use springs in Galicia do not meet the sanitary standards for water supply due to bacteriological and nitrate contamination. This situation is propitiated by the lack of adequate water and land use plans in the spring catchments.

Potential sources of contamination to springs and wells are prohibited from being located within their capture zones to protect their water quality. A capture zone is an area around a spring or a drinking water supply well that contributes water to the spring or the well. The purpose of delineating a capture zone is to ensure that the chemical and microbiological concentrations in the spring or in the water extracted from a water supply pumping well are below the drinking water standards. Capture zone delineation is often done by using approaches based on the advective travel time such as the particle tracking method, the uniform flow field equations (U.S. EPA 1994) and the HYBRID method (Paradis and Martel 2007). Other methods to delineate capture zones account for both advection and dispersion (Uffink 1989; Chin and Chittaluru 1994; Paradis et al. 2007; Tosco and Sethi 2010). Difficulties in the delineation of protection zones are often due to the complexities in the flow field due to the uncertainties in the hydraulic conductivity and the transport processes (Okkonen and Neupauer 2016).

More than the 50% of the population of the municipality of Abegondo rely on autonomous private systems with groundwater supply from spring catchments. Spring catchments also feed many public fountains throughout the municipality. The Abegondo municipality compiled nearly a hundred public fountains and traditional wash houses within the framework of the Life Aqua Plann project (Ameijenda et al. 2013). The recovery of water quality and the assurance of the potability of public springs in the municipality of Abegondo were also undertaken in the Aqua Plann project (Aqua Plann 2011). Here, we report the demonstrative actions of groundwater quality restoration implemented in five pilot springs in the municipality of Abegondo (Galicia, Spain) to clean and disinfect the fountains, restore the spring catchments and define and implement spring protection zones. The spring protection zones were defined with a numerical groundwater flow and solute transport model solved with the CORE2D code (Dai and Samper 2004; Samper et al. 2011b). The protection zones defined in the project were included in the development plan of the municipality. We present also the data collected during the 3 years monitoring period after the restoration actions.

The paper starts with a description of the study area and its hydrogeological conceptual model. The springs selected for demonstrative actions and their groundwater quality data are presented next. The paper continues with the demonstrative actions and the definition of the protection zones. Then, the results of the groundwater quality monitoring are presented. The paper ends with the main conclusions and recommendations.

Description of the study area

The study area is located in the Abegondo municipality, south of A Coruña in northwest Spain (Fig. 1). Its surface area is 83.9 km2. The average altitude is 174 m a.m.s.l. It is located in a rural area with dispersed and low-density population (~66 inhabitants per km2). The economy depends on agriculture, livestock and forestry with a few derived industries. The main land uses include pastures, thickets, forests and crops.
Fig. 1

Location and landscape view of the study area in the Abegondo municipality (Galicia, Spain)

The climate in Abegondo is wet oceanic with relatively abundant rainfall. The climate is classified as Csb, temperate with dry or temperate summer, according to the Köppen Climate Classification System (AEMET and IM 2011). The complete weather station at the Agricultural Research Center of Mabegondo is located in the center of the study area. The average annual temperature is 12.3 °C. The precipitation shows a clear seasonal character. The autumn and the winter are the rainy seasons. The precipitation decreases in the spring. The summers are often dry. The average annual precipitation is equal to 1169 mm.

The main water courses of the study area are the Mero River and its tributaries, Gobia and Barcés rivers (Fig. 2). The drainage network is very dense including also many streams and brooks. A small area in the south of the municipality drains to the south and belongs to the Tambre River basin. However, most of the study area drains to the north to the Mero and the Barcés river basins.
Fig. 2

Location of the selected springs on: (1) a topographic and drainage basin map with the main rivers (left) and (2) geological map (right) showing the schists of the complex of Ordes, the alluvial Quaternary deposits and the intercalated phyllite (Galán et al. 1978)

The study area is mostly framed in High-Precambrian metapsamites and metapelites of the Ordes Complex (Galán et al. 1978). It is a schist–graywacke substrate. The weathered layer of schists has a spatially variable thickness which ranges from 1 to 5 m, reaching sometimes 15 m. Narrow intercalated phyllite can be found in the southern part of the study area. The longest is about 4 km long. Quaternary deposits are found in the lowest areas and in the flood plains of the main water courses (Fig. 2).

Hydrogeological conceptual model

The conceptual model of the groundwater flow in the metamorphic rocks of the study area assumes an equivalent porous medium and accounts for an upper layer of weathered rock (regolith), an intermediate layer of fractured rock and a deep layer of slightly fractured rock (Fig. 3). This model shares some similarities with that proposed by Lubczynski and Gurwin (2005) for the Sardón basin (Salamanca, Spain) and provides a simplified representation of the spatial heterogeneity and the spatial variability of the hydraulic conductivity of the fracturing, the tectonic processes and the rock weathering. The layer of weathered rock has a large spatial extent with a small thickness which varies spatially. The available data do not allow distinguishing the hydrogeological parameters of the regolith and the fractured rock layers because most of the existing wells tap the two shallowest layers. The deepest layer plays a less relevant hydrogeological role because groundwater flows mostly through the regolith and the fractured rock layers. Springs are not related to geological contacts, quartz dikes or other rock singularities. On the other hand, many springs are located at the contact between the regolith and the fractured rock layer.
Fig. 3

Hydrogeological block diagram of the fractured schists of Abegondo which illustrates the hydrogeological conceptual model. The upper layer of weathered rock (regolith) overlies the fractured rock. The slightly fractured rock is the deepest

A pumping test was carried out in a 30 m-deep well near the Presedo fountain, one of the selected fountains for demonstrative actions. Its location is shown in Fig. 2. The interpretation of the test shows that the weathered and fractured schist layers have an equivalent transmissivity of ~20 m2/d. This value is consistent with the transmissivities reported by Carvalho et al. (2003) for fractured schists in the north of Portugal. They reported transmissivities ranging from 20 to 40 m2/d in the surroundings of the springs and equal to 2 m2/d in the rest of the schist formations.

The water table is generally shallow. Available data show that the depth to the water table is less than 10 m in most of the study area and greater than 20 m in the highest areas. Hydraulic heads were monitored from March 2011 to April 2012 in two dug wells located near the Vilanova public fountain. Measured depths of the water table range from 4 to 9 m and their fluctuations are smaller than 3 m.

The aquifer is recharged from rainfall infiltration in most of the study area. Irrigation is not relevant because crops occupy small tracks located at the bottom of the valleys. Groundwater discharges along the lower parts of the creeks and valleys. The discharge is evenly distributed or focused on springs and seepage areas.

Selected springs for demonstrative actions

The following criteria were used to select the fountains for demonstrative actions: (1) wide use of the fountain; (2) the need for restoration actions; and (3) fountains distributed throughout the study area. The selected fountains include: Vilanova, Outeiro, Villardel, Beldoña and Presedo. Figure 4 shows the pictures of the fountains. Their location is shown in Fig. 2.
Fig. 4

Pictures of the selected public fountains after the restoration actions: 1 Vilanova fountain, 2 Outeiro fountain, 3 Villardel fountain, 4 Villardel catchment, 5 Presedo  fountain, and 6 Beldoña fountain

The groundwater basin of each selected spring was defined from the Digital Terrain Model by assuming that the groundwater basin coincides with the surface water basin. This assumption is supported by the low to medium hydraulic conductivity of the subsurface and, also, by the similarity between the shape of the topographic surface and the shape of the phreatic surface in the study area. The surface areas of groundwater basins of the Vilanova, Outeiro, Villardel, Beldoña and Presedo fountains are equal to 4, 29, 11, 38 and 31 ha, respectively.

The selected fountains are widely used for drinking and traditional washing. Drinking water from public fountains is a very firm custom in the region because of its good taste without chlorination, and the popular belief that spring water is healthier than the water from the public supply network. The Villardel and Outeiro fountains are widely used by local people who often fill water containers for their drinking needs. The Vilanova fountain is along the “Camino de Santiago” (The Way of Saint James) and is used by the local people and by the numerous pilgrims. The Presedo and Beldoña fountains serve also as traditional washing places for older neighbors.

A detailed compilation of the fountain characteristics was performed, including: the location of the capture point, the design and materials of the catchment, the pipelines, the water tanks, the connection boxes, the valves and the taps. Fountain functioning and conservation conditions were also recorded. A detailed inventory of the current land uses and the foreseen land uses in the general development plan of the municipality in the surroundings of the springs was also performed. This inventory included also the infrastructures or activities likely to cause groundwater contamination in the spring basins.

The flow rate of the fountains was monitored from September 2010 to April 2012 (Fig. 5). The average flow rate of the Vilanova and Villardel fountains is approximately equal to 0.5 L/s, while that of the Outeiro, Presedo and Beldoña fountains is 0.2 L/s. The water flow of the fountain is smaller than the spring flow when the spring flow exceeds the conveyance capacity of the pipeline which feeds the fountain. The overflow is important in some springs such as the Villardel spring for which the average spring flow is estimated to be equal to 1 L/s. The spring flow increases in response to the rainfall events and decreases in dry periods. The Presedo and Beldoña springs dried in the summer of 2011. Physical and chemical spring parameters such as the water temperature, the pH, the electrical conductivity and the total dissolved solids were monitored in situ during this period. In addition, spring water samples were taken for chemical and bacteriological analyses.
Fig. 5

Measured flow rates at the selected fountains from September 2010 to April 2012

Spring water quality and contamination

The natural chemical properties of the shallow groundwaters of the Mero and Mandeo river basins were established within the framework of the Aqua Plann project (Aqua Plann 2011). The pH of natural groundwater is slightly acidic and ranges from 5.7 to 6.5. The electrical conductivity is also low and ranges from 40 to 110 μS/cm. The ranges of the concentrations of the main anions and cations are listed in the last column of Table 1. The concentration of chloride in pristine groundwater varies from 11 to 15.5 mg/L. The range of nitrate concentrations is from 1 to 10.4 mg/L. The concentration of iron ranges from 0.01 to 0.23 mg/L, while that of manganese ranges from 5 to 67 μg/L. The maximum concentrations of Fe and Mn exceed the European drinking water standards (Directive 98/83/EC). These high concentrations of Fe and Mn have a natural origin associated with the contact zones of shales and granites. The concentrations of other metals such as aluminum, arsenic, copper, cadmium, nickel, mercury, lead and zinc are very low (not shown here).
Table 1

Chemical and microbiological data from groundwater samples taken  in the selected springs/fountains in 2011 before the demonstrative actions

 

Villardel fountain

Outeiro fountain

Vilanova fountain

Presedo fountain

Beldoña fountain

Reference ranges

pH at 25 °C

6.9

6.9

6.9

6.0

6.1

5.7–6.5

Electrical conductivity (μS/cm)

116

225

235

244

246

41.6–108

Dry residue (mg/L)

80

145

140

160

155

n.d.

Total alkalinity (mmol/L)

35.7

44

32.4

18

24

n.d.

Chloride (mg/L)

16.0

20.5

27.4

27.3

41.7

11–15.5

Sulfate (mg/L)

3.13

10.6

11.4

10.0

7.22

1.3–10.4

Phosphate (mg/L)

<0.2

<0.2

<0.2

<0.15

<0.15

15–88

Fluoride (mg/L)

0.05

0.06

<0.05

0.06

<0.06

n.d.

Nitrite (mg/L)

<0.10

<0.10

<0.10

<0.06

<0.06

n.d.

Nitrate (mg/L)

2.54

29.3

33.9

47.1

21.3

1.2–9.9

Sodium (mg/L)

13.3

20.2

23.9

n.a.

n.a.

8.8–12.2

Calcium (mg/L)

5.92

12.35

9.42

n.a.

n.a.

2.5–4.0

Magnesium (mg/L)

2.84

6.74

6.95

n.a.

n.a.

n.d.

Potassium (mg/L)

0.75

0.77

1.63

n.a.

n.a.

0.21–1.88

Total coliform (ufc/100 mL)

1–3

84

1–3

1–3

0

0

E. coli (ufc/100 mL)

1–3

84

1–3

1–3

0

0

Intestinal enterococci (ufc/100 mL)

0

0

0

0

0

0

The estimated ranges of natural conditions were established within the framework of the Aqua Plann project (Aqua Plann 2011)

n.d. not defined, n.a. not available

Table 2 lists the average values of the chemical parameters monitored in situ from February 2011 to March 2012. The pH, the electrical conductivity and the total dissolved solids were almost constant in this period. Therefore, no major changes in the chemical composition of the spring waters were observed. Table 1 presents also the chemical and microbiological data from water samples taken from the selected fountains in the spring of 2011 before the demonstrative actions. In general, the chemical composition of the waters of the five fountains is very similar. However, the electric conductivity and the concentrations of the major ions in the Villardel fountain are smaller than those of the other fountains.
Table 2

Average values of the chemical parameters measured in situ at the selected fountains from February 2011 to March 2012

 

Villardel fountain

Outeiro fountain

Vilanova fountain

Presedo fountain

Beldoña fountain

In situ pH

6

6.2

5.8

5.7

5.8

In situ electric conductivity (μS/cm)

85

170

180

170

180

In situ TDS (mg/L)

40

95

85

85

85

The number of measurements in this period ranges from 9 to 19

The measured concentrations were compared to the reference values corresponding to natural conditions and to the parametric values established by the European drinking water regulations (Directive 98/83/EC). The pH of natural groundwater is slightly more acidic than the parametric pH. The measured electrical conductivities are low and slightly larger than the reference values for this aquifer. The concentration of chloride ranges from 16 to 42 mg/L. Spring waters present a low alkalinity. Sodium is the dominant cation. Evidences of nitrate contamination were found in all the fountains except the Villardel fountain. The measured nitrate concentrations do not exceed the maximum admissible concentration for drinking water (50 mg/L). The measured metal concentrations are very low (not shown here). No evidences of metal contamination were found.

The microbiological data confirm the presence of coliforms and E. coli in low concentrations (1–3 cfu/100 mL) in the Vilanova, Villardel and Presedo fountains and show a high concentration (up to 84 cfu/100 mL) in the Outeiro fountain. No microbial contamination was found in the Beldoña fountain.

The possible reasons and sources of nitrate and bacteriological contamination include: (1) the lack of maintenance and cleanliness of the fountains and spring catchments; (2) the leaking septic tanks near the springs; and (3) the inadequate management of the manure in the neighboring fields.

Demonstrative actions

Restoration of the fountains

The demonstrative actions for the recovery of the water quality in the selected fountains include (Samper et al. 2011a): (1) the cleaning and disinfection of the fountain and the spring catchment; (2) the replacement of pipelines, water tanks, inspection boxes and other elements in bad condition; (3) the fencing and sanitary sealing of the catchment area; (4) the cleaning of weed of the surroundings of the spring and the fountain; and (5) the construction of drainage ditches to divert the surface runoff. These actions were carried out by Espina and Delfin S.L. in January and February 2012.

Definition of the intermediate protection zone with a numerical model

The demonstrative actions included also the definition of the spring protection zones. The spring intermediate protection zone was estimated with a two-dimensional horizontal numerical flow model of the Villardel fountain. The model was performed with the CORE2D code (Samper et al. 2009, 2011b). CORE2D V4 is a code for transient saturated and unsaturated water flow, heat transport and multicomponent reactive solute transport under both local chemical equilibrium and kinetic conditions in heterogeneous and anisotropic media. The flow and transport equations are solved with Galerkin finite elements and a Euler scheme for time discretization. The code has been used extensively to model aquifer flow and solute transport (Dai and Samper 2006), to conduct laboratory and in situ experiments for radioactive waste disposal (Yllera et al. 2004; Zheng et al. 2010), perform coupled models of geochemical reactions and microbial processes on the subsurface (Yang et al. 2007, 2008), evaluate the long-term geochemical evolution of repositories in granite and clay (Samper et al. 2008, 2016; Mon et al. 2017), model groundwater flow and solute transport in granitic rocks (Molinero and Samper 2004), assess the impact of CO2 leakage on groundwater quality (Yang et al. 2015) and evaluate the impact of climate change on groundwater heads and spring flows (Stigter et al. 2014; Samper et al. 2015).

The numerical model domain coincides with the groundwater drainage basin which has a surface area of 0.112 km2. The domain was discretized with an irregular triangular finite element mesh. Groundwater recharge is uniform throughout the domain and equal to 280 mm/year. All the boundaries are impervious except the node where the spring is located from which groundwater discharges with an estimated mean flow equal to 1 L/s. The model considers two hydraulic conductivity zones, one of them around the spring and the other in the rest of the domain (Fig. 6). The numerical model was calibrated to ensure that the computed hydraulic heads are below the ground surface. The computed water table near the spring is very shallow and nearly coincides with the topographic surface. The depth to the water table far from the spring increases up to 40 m in the highest points. The calibrated transmissivity is equal to 40 m2/d near the spring, while it is equal to 1.2 m2/d in the rest of the model domain. These values are within the range of the expected transmissivities.
Fig. 6

Groundwater flow numerical model of the Villardel groundwater spring basin: (1) model domain which coincides with the groundwater spring basin and finite element mesh (left); (2) hydraulic conductivity zones (intermediate) and (3) computed steady-state hydraulic heads (right)

The mean transit time, τ (days) from a point located upstream of the spring to the spring, was calculated for various locations by simulating the transport of a conservative tracer injected continuously at a constant concentration. The background concentration of the tracer in the aquifer is negligible. The accessible porosity was taken equal to 0.07. The diffusion coefficient is equal to 10−7 m2/d. Molecular diffusion is much less relevant than hydrodynamic dispersion in this aquifer. The longitudinal dispersivity was assumed to be equal to 15 m and the transverse dispersivity to 10 m.

The breakthrough curve for an instantaneous tracer injection, c(t), is obtained from the time derivative of the breakthrough curve for a continuous tracer injection, c(t). The mean transit time, τ, can be calculated from c(t) according to:
$$\tau = \frac{{\mathop \smallint \nolimits_{0}^{\infty } t\;c(t)\;{\text{d}}t}}{{\mathop \smallint \nolimits_{0}^{\infty } c(t)\;{\text{d}}t}}.$$

The mean transit time was calculated for injection points located at distances from 25 to 50 m upstream of the spring at several orientations. The mean transit time increases linearly with the increasing distance from the spring for injection points located along a given orientation. The computed mean transit time is about 50 days for tracer injection points located about 30 m from the spring, regardless of the orientation.

A sensitivity analysis of the transit time to changes in the porosity and dispersivity was performed to evaluate the uncertainty in the estimation of the distance for a 50 days transit time. The transit times are significantly sensitive to changes in the porosity within the range (0.05, 0.1). The smaller the porosity, the faster is the groundwater flow and the smaller is the transit time from the injection point to the spring. The distance to the spring for a transit time of 50 days is equal to 35 m for a porosity equal to 0.05. Figure 7 shows the steady-state concentration contour plot for a continuous tracer injection in a point located approximately 30 m from the spring and the sensitivity of the computed breakthrough curves for an instantaneous tracer injection to changes in porosity from 0.05 to 0.1.
Fig. 7

Steady-state concentration contour plot for a continuous tracer injection in a point transit located approximately at 30 m from the spring (left) and sensitivity of the computed breakthrough curves to changes in porosity  for an instantaneous tracer injection

The sensitivity analysis to changes in the dispersivities considers a range between 10 and 20 m for the longitudinal dispersivity, while the ratio between the longitudinal and the transverse dispersivities is maintained constant. The results are slightly sensitive to the changes in the dispersivities. The computed transit time decreases when dispersivities increase. The distance to the spring for a transit time of 50 days is nearly 33 m when the longitudinal dispersivity is equal to 10 m. On the other hand, the computed transit times are not sensitive to the ratio between the longitudinal and the transverse dispersivities. The results of the sensitivity runs allow concluding that the distance to the spring for a transit time of 50 days is most likely to range from 25 to 35 m with a most likely value of 30 m.

Proposal of the spring protection zones

The immediate zone is defined as the closest area around the spring. As an educated guess, it was defined as a circle with a radius of 3 m. The size of the intermediate protection zone was defined based on a transit time of 50 days which according to the results of the numerical model leads to a distance of 30 m. The intermediate protection zone is the intersection of the groundwater basin of the spring and a circle centered at the spring with a radius of 30 m. The moderate restriction zone is protected against more persistent pollutants such as nitrates. This proposal of spring protection zones was included in the general development plan of the municipality of Abegondo. Figure 8 shows the defined protection zones for the Villardel fountain.
Fig. 8

Protection zones for  the Villardel public fountain including: (1) the immediate zone, in which all the activities are restricted (red circle), (2) the intermediate zone, in which all polluting activities are forbidden to prevent bacteriological contamination (thick red lines), and (3) the remote zone with moderate restrictions (thick blue line)

Post-restoration spring water quality monitoring

After the restoration of the selected springs and fountains, a periodic monitoring of the spring water quality was carried out to test the efficiency of the restoration measures. Four water sampling campaigns were performed in March, June, August and October 2012 for chemical and microbiological analyses. An additional sampling campaign was performed 3 years later in May 2015.

Chemical and microbiological data after the restoration were compared with those collected before the restoration. The main chemical parameters, such as pH and electrical conductivity, remained stable (Table 3). The measured concentrations of the major anions and cations (not shown here) remained also stable except for some fluctuations in the concentrations of sulfate and some cations, which were probably due to the fact that the chemical and microbiological analyses were performed in different laboratories. Therefore, no significant changes in water chemistry were observed.
Table 3

Chemical and microbiological data from groundwater samples in the selected springs/fountains taken in 2011 before the demonstrative actions and during the post-restoration monitoring period from March 2012 to May 2015

 

Date

pH (25 °C)

Conductivity (μS/cm)

Chloride (mg/L)

Nitrate (mg/L)

Total coliform (ufc/100 mL)

E. coli (ufc/100 mL)

Intestinal enterococci (ufc/100 mL)

Villardel fountain

2011

6.9

116

16.0

2.54

1–3

1–3

0

March 2012

6.6

120

16.4

3

7

0

0

June 2012

6.2

125.1

16.1

3

3

0

0

August 2012

6.5

142.6

15.3

2

10

6

0

October 2012

6.3

114.2

16.1

4

0

0

0

May 2015

6.1

98.6

18.8

<0.4

3

0

n.a.

Outeiro fountain

2011

6.9

225

20.5

29.3

1–3

1–3

0

March 2012

6.5

220

21.7

29

0

0

0

June 2012

6.2

233

20.8

29

8

1

0

August 2012

6.7

249

19.9

27

11

7

0

October 2012

6.2

225

23.6

30

29

2

24

May 2015

6.2

192

21.2

28.8

12

0

n.a.

Vilanova fountain

2011

6.9

235

27.4

33.9

84

84

0

March 2012

6.8

225

26.1

38

0

0

0

June 2012

5.8

244

26.6

37

0

0

0

August 2012

6.1

258

25.2

38

0

0

0

October 2012

6.3

227

29.7

38

0

0

0

May 2015

5.9

197

48.1

34.6

0

0

n.a.

Presedo fountain

2011

6.0

244

27.3

47.1

1–3

1–3

0

March 2012

6.5

203

27.6

40

0

0

0

June 2012

5.8

219

26.4

39

12

0

0

August 2012

6.1

238

25.6

39

1

0

0

October 2012

5.5

194.6

26.1

39

11

4

3

May 2015

5.8

197

48.1

41.6

3

0

n.a.

Beldoña fountain

2011

6.1

246

41.7

21.3

0

0

0

March 2012

6.9

215

42.7

15

0

0

0

June 2012

6.7

239

41.4

17

2

0

0

August 2012

6.2

253

34.3

17

1

0

0

October 2012

6.0

244

37.6

15

0

0

0

May 2015

6.0

189

56.5

17.9

0

0

n.a.

n.a. not available

A slight decrease in nitrate contamination in the Presedo and Beldoña fountains was observed after the restoration measures, even after 3 years. On the other hand, the concentration of nitrate in the Outeiro and Vilanova fountains remained constant. No evidences of nitrate contamination were found in the Villardel spring water which has nitrate concentrations lower than 4 mg/L. The microbial contamination disappeared completely in the Villardel, Vilanova and Beldoña fountains a year after the restoration. The microbial contamination, on the contrary, persisted in the Outeiro and Presedo fountains. The microbial contamination reappeared in the Villardel fountain 3 years after the restoration.

Although the protection zones were included in the municipality development plan, no action was taken to enforce the restrictions imposed in the protection zones. The fertilization of the orchards and the crops with manure in the surroundings of the Outeiro and Presedo fountains continued after their restoration. The persistence of the bacteriological contamination in some fountains could be explained by an insufficient periodic cleaning and disinfection of the fountains and the lack of enforcement of the protection zone with an efficient control and a restriction of the manure application.

Conclusions

Available topographic, geological, meteorological, hydrological and hydrochemical data of the municipality of Abegondo have been used to develop a hydrogeological conceptual model of the study area and to evaluate the groundwater quality. Groundwater flows mostly through the weathered and more intensely fractured rock. Its equivalent transmissivity ranges from 20 to 40 m2/d. The aquifer recharge occurs due to infiltration of rainwater and the discharge of the groundwater flow occurs in the lower parts of the creeks and valleys.

Five widely used public fountains distributed throughout the study area were selected to implement restoration activities. All the fountains except for the Villardel fountain show evidences of nitrate contamination. The measured concentrations are below the parametric value for drinking water. All the fountains except the Beldoña fountain are affected by microbial contamination. The demonstrative actions for the recovery of the water quality of the five fountains include: (1) the cleaning and disinfection of the fountain and the spring catchment; (2) the replacement of pipelines, water tanks, inspection boxes and other elements in bad condition; (3) the fencing and sanitary sealing of the catchment area; (4) the cleaning of weed of the surroundings of the spring and the fountain; and (5) the construction of drainage ditches to divert the surface runoff. These actions were successfully carried out in January and February 2012. The demonstrative actions included also the definition of spring protection zones. The immediate protection zone was defined as a circle centered in the spring with a radius of 3 m. The intermediate protection zone was defined as the intersection of the groundwater basin and a circle centered in the spring with a radius of 30 m. The moderate restriction zone of each spring coincides with the spring groundwater basin. This proposal of spring protection zones was included in the general development plan of the municipality of Abegondo.

The chemical and microbial data of the springs were monitored during 3 years after restoration actions. No significant changes in the water chemistry were observed in the post-restoration phase. However, a clear reduction in the microbial contamination and a mild reduction of nitrate contamination were achieved in some fountains. The efficiency of the restoration measures was partially reduced by: (1) the low frequency of the cleaning and disinfection of the fountains; and (2) the lack of actions to enforce the restrictions in the protection zones and prevent the excessive use of manure as fertilizer in the surroundings of some springs.

An appropriate periodic maintenance of the fountains and spring catchments is strongly recommended to maintain good water quality in the springs over time. The definition of the protection zones and their implementation in the general development plan is not enough to ensure good spring water quality. An efficient control of the restricted activities, especially of the excessive manure application, is recommended to reduce the nitrate concentrations and prevent microbial contamination.

The lessons learned in the rural areas of Abegondo and the conclusions of our study should be of great relevance for the proper groundwater protection, use and governance in the rural areas of metamorphic and plutonic regions which occupy large parts of the world.

Notes

Acknowledgements

This work was carried out within the framework of the AQUA PLANN Project of the LIFE+ Programme (07/ENV/E/000826) funded by the European Commission. We acknowledge the support provided by Carlos Ameijenda from the Secretariat of the Project in the Municipality of Abegondo and Roberto Arias from Aguas de Galicia (Xunta de Galicia). This work was also partly funded by the Spanish Ministry of Economy and Competitiveness (Project CGL2016-78281), FEDER funds and the Galician Regional Government, Xunta de Galicia (Fund 2012/181 from “Consolidación e estruturación de unidades de investigación competitivas”, Grupos de referencia competitiva). We thank the comments, corrections and suggestions of the two anonymous reviewers of the manuscript which contributed to improving it.

References

  1. AEMET and IM (2011) Iberian Climate Atlas. Air temperature and precipitation (1971–2000). In: Agencia Estatal de Meteorología de España (AEMET) of Ministerio de Medio Ambiente y Medio Rural y Marino and Instituto de Meteorología de Portugal (IM). ISBN: 978-84-7837-079-5. AEMET website. http://www.aemet.es/documentos/es/divulgacion/publicaciones/Atlas-climatologico/Atlas.pdf. Accessed 24 July 2017
  2. Ameijenda C, Martínez A, Giménez M, Manteiga I, Manteiga A, Iglesias MC, Santiso JA (2013) Traditional washing places and fountains in Abegondo municipality. Legal Deposit: C-563-2013 (in Spanish) Google Scholar
  3. Aqua Plann (2011) Diagnosis and detailed study of the current state of groundwater quality in the Mero-Barcés basin. Proyecto Aqua Plann Porject. Final Report of Activity A.3-Municipality of Abegondo (in Spanish) Google Scholar
  4. Carvalho JM, Chaminé HI, Plasencia N (2003) Caracterização dos recursos hídricos subterrâneos do maciço cristalino do Norte de Portugal: implicações para o desenvolvimento regional. In: A Geologia de Engenharia e os Recursos Geológicos: recursos geológicos e formação. Volume de Homenagem ao Prof. Doutor Cotelo Neiva. Série Investigação Imprensa da Universidade de Coimbra, vol 2, pp 245–264. ISBN: 972-8704-15-1. doi:http://dx.doi.org/10.14195/978-989-26-0322-3_18 (in Portuguese)
  5. Chin DA, Chittaluru PVK (1994) Risk management in wellhead protection. J Water Resour Plann Manag 120(3):294–315CrossRefGoogle Scholar
  6. Dai Z, Samper J (2004) Inverse problem of multicomponent reactive chemical transport in porous media: formulation and applications. Water Resour Res 40:W07407. doi: 10.1029/2004WR003248 CrossRefGoogle Scholar
  7. Dai Z, Samper J (2006) Inverse modeling of water flow and multicomponent reactive transport in coastal aquifer systems. J Hydrol 327(3–4):447–461CrossRefGoogle Scholar
  8. EC (2010) Report from the Commission in accordance with Article 3.7 of the Groundwater Directive 2006/118/EC on the establishment of groundwater threshold values. 5.3.2010 C, 1096 final, European Commission, BrusselsGoogle Scholar
  9. Galán J, Aldaya F, Ruiz F, Huerga A (1978) Mapa geológico y Memoria de la Hoja nº 45 (5-5) Betanzos. Mapa Geológico de España, E. 1:200.000, ITGE. Legal Deposit: M-24423-1989. NIPO: 232-89-011-1Google Scholar
  10. Lubczynski MW, Gurwin J (2005) Integration of various data sources for transient groundwater modeling with spatio-temporally variable fluxes—Sardon study case, Spain. J Hydrol 306:71–96CrossRefGoogle Scholar
  11. Molinero J, Samper J (2004) Groundwater flow and solute transport in fracture zones: an improved model for a large-scale field experiment at Äspö (Sweden). J Hydraul Res 42:57–172CrossRefGoogle Scholar
  12. Mon A, Samper J, Montenegro L, Naves A, Fernández J (2017) Long-term nonisothermal reactive transport model of compacted bentonite, concrete and corrosion products in a HLW repository in clay. J Contam Hydrol 197:1–16CrossRefGoogle Scholar
  13. Okkonen J, Neupauer RM (2016) Capture zone delineation methodology based on the maximum concentration: preventative groundwater well protection areas for heat exchange fluid mixtures. Water Resour Res 52:4043–4060CrossRefGoogle Scholar
  14. Paradis D, Martel R (2007) HYBRID: a wellhead protection delineation method for aquifers of limited extent. Tech. Note 1. Geological Survey of Canada, OttawaCrossRefGoogle Scholar
  15. Paradis D, Martel R, Karanta G, Lefebvre R, Michaud Y, Therrien R, Nastev M (2007) Comparative study of methods for WHPA delineation. Ground Water 45(2):258–267CrossRefGoogle Scholar
  16. Samper J, Lu C, Montenegro L (2008) Reactive transport model of interactions of corrosion products and bentonite. Phys Chem Earth 33(Suppl 1):S306–S316. doi: 10.1016/j.pce.2008.10.009 CrossRefGoogle Scholar
  17. Samper J, Xu T, Yang C (2009) A sequential partly iterative approach for multicomponent reactive transport with CORE2D. Comput Geosci. doi: 10.1007/s10596-008-9119-5 Google Scholar
  18. Samper J, Mon A, Naves A, Pisani B (2011a) Obras de protección y mejora de las fuentes y manantiales de Abegondo. Proyecto constructivo para Aguas de Galicia. Grupo de hidrología superficial y del subsuelo, ETSI Caminos, Canales y Puertos, Universidade da Coruña (in Spanish) Google Scholar
  19. Samper J, Yang C, Zheng L, Montenegro L, Xu T, Dai Z, Zhang G, Lu C, Moreira S (2011b) CORE2D V4: a code for water flow, heat and solute transport, geochemical reactions, and microbial processes, chapter 7. In: Zhang F, Yeh G-T, Parker C, Shi X (eds) Electronic book groundwater reactive transport models. Bentham Science Publishers, Sharjah, pp 161–186Google Scholar
  20. Samper J, Li Y, Pisani B (2015) An evaluation of climate change impacts on groundwater flow in the La Plana de la Galera and Tortosa alluvial aquifers (Spain). Environ Earth Sci 73:2595–2608CrossRefGoogle Scholar
  21. Samper J, Naves A, Montenegro L, Mon A (2016) Reactive transport modelling of the long-term interactions of corrosion products and compacted bentonite in a HLW repository in granite: uncertainties and relevance for performance assessment. Appl Geochem 67:42–51CrossRefGoogle Scholar
  22. Stigter TY, Nunes JP, Pisani B, Fakir Y, Hugman R, Li Y, Tomé S, Ribeiro L, Samper J, Oliveira R, Monteiro JP, Silva A, Tavares PCF, Shapouri M, Cancela da Fonseca L, Himer El (2014) Comparative assessment of climate change impacts on coastal groundwater resources and dependent ecosystems in the Mediterranean. Reg Environ Change 14(Suppl 1):S41–S56CrossRefGoogle Scholar
  23. Tosco T, Sethi R (2010) Comparison between backward probability and particle tracking methods for the delineation of well head protection areas. Environ Fluid Mech 10:77–90CrossRefGoogle Scholar
  24. Uffink GJM (1989) Application of Kolmogorov’s backward equation in random walk simulations of groundwater contaminant transport. In: Kobus HE, Kinzelbach W (eds) Contaminant transport in groundwater. A. A. Balkema, Brookfield, pp 283–289Google Scholar
  25. U.S. EPA (1994) Handbook: ground water and wellhead protection, EPA/625R94001. U.S. Environmental Protection Agency, WashGoogle Scholar
  26. Yang C, Samper J, Molinero J, Bonilla M (2007) Modelling geochemical and microbial consumption of dissolved oxygen after backfilling a high level radioactive waste repository. J Contam Hydrol 93:130–148CrossRefGoogle Scholar
  27. Yang C, Samper J, Molinero J (2008) Inverse microbial and geochemical reactive transport models in porous media. Phys Chem Earth 33(12–13):1026–1034. doi: 10.1016/j.pce.2008.05.016 CrossRefGoogle Scholar
  28. Yang C, Hovorka SD, Treviño RH, Delgado-Alonso J (2015) Integrated framework for assessing impacts of CO2 leakage on groundwater quality and monitoring-network efficiency: case study at a CO2 enhanced oil recovery site. Environ Sci Technol 49(14):8887–8898CrossRefGoogle Scholar
  29. Yllera A, Hernández A, Mingarro M, Quejido A, Sedano LA, Soler JM, Samper J, Molinero J, Barcala JM, Martín PL, Fernández M, Wersin P, Rivas P, Hernán P (2004) DI-B Experiment: planning, design and performance of an in situ diffusion experiment in the opalinus clay formation. Appl Clay Sci 26:181–196CrossRefGoogle Scholar
  30. Zheng L, Samper J, Montenegro L, Fernández AM (2010) A coupled THMC model of a heating and hydration laboratory experiment in unsaturated compacted FEBEX bentonite. J Hydrol 386:80–94CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Centro de Investigaciones Científicas Avanzadas (CICA), E.T.S. Ingenieros de Caminos, Canales y Puertos, Campus de ElviñaUniversidad de A CoruñaA CoruñaSpain
  2. 2.Laboratory of Cartography and Applied Geology (LABCARGA), School of Engineering (ISEP), Polytechnic of PortoPortoPortugal

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