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Sustainable Water Resources Management

, Volume 4, Issue 2, pp 193–215 | Cite as

Characterization and benchmarking of seven managed aquifer recharge systems in south-western Europe

  • J. San-Sebastián-Sauto
  • E. Fernández-Escalante
  • R. Calero-Gil
  • T. Carvalho
  • P. Rodríguez-Escales
Original Article

Abstract

The European MARSOL project includes different examples of managed aquifer recharge (MAR) facilities in the Mediterranean area. A methodical characterization of the whole recharge process has been carried out to ensure that all functions and facilities are clearly comparable independent of size, budget or location. The seven selected MAR demo sites are located in two countries. Four are in Portugal—Rio Seco and Noras (Campina de Faro Aquifer), S. Bartolomeu de Messines and Cerro do Bardo (Querença-Silves) in Algarve, and three are in Spain—Llobregat (Catalonia), Santiuste and El Carracillo (Castilla y León). The systems have been defined using a form divided into four sections, including alpha-numerical data, orthophotographs, sketches and schedules. A first draft using a bibliography was reviewed by the authors, who recorded a detailed analysis and further reports to complete the characterization, as shown in several tables. The article covers MAR benchmarking serial steps for infrastructure measurements (surfaces, lengths, facilities, costs), functions categorization (transport, infiltration, treatment, restoration) and evolution in time and space (maps, sketches and calendars). MAR measuring displays contrasting interpretations depending on scale. The benchmarking process was found to be difficult to apply to seven sites with different sizes, aims, operational procedures and time scales. However, some parameters, such as mean infiltration rate, have shown their potential as management decision tools in the long term. Mediterranean areas, characterized by water supply irregularity, which is likely to be exacerbated by climate change models, can benefit from the use of MAR as a water management technique and from its diverse functions, although these objectives have not generally been attached to recharge. Null energy cost and low initial investment can also play important roles in boosting MAR development as a feasible alternative in short-term water planning.

Keywords

Managed aquifer recharge (MAR) Groundwater quality Benchmarking Mediterranean climate Water management Climate change 

Introduction

Benchmarking is a question of comparison. It deals with the process of comparing one’s business procedure and performance metrics to either industry bests or best practices from other firms (Camp 1989). Typically measured parameters are quality, time and cost. In benchmarking, management identifies the best facilities in their sector and compares the results and processes of those ‘targets’ to one’s own results and processes. Thus, they learn how well the targets perform and, more significantly, the business processes that clarify why these ‘firms’ are so successful (Larsson et al. 2002).

Specific indicators (cost per unit of product, productivity per unit of time) are used to measure performance, resulting in a metric of performance that is then compared to others (Fifer 1989). The goal of managed aquifer recharge (MAR) can apparently be as unrelated as water storage, water treatment or habitat rehabilitation. These key aims should also be measured in terms of indicators associated with water quantity, quality and efficiency.

Also referred to as ‘best practice benchmarking’ or ‘process benchmarking’, this procedure is used in management, particularly strategic management, in which organizations evaluate various aspects of their processes in relation to those of best practice companies, usually within a peer group defined for the purpose of comparison (Scanlon et al. 2002).

The strategic dimensions of recharge should be considered whenever looking for the role that a recharge facility can play in basin planning. Their different uses for winter water surplus storage, seawater intrusion barrier or sewage treatment could be appraised in comparison to other standard water management infrastructures such as dams, reservoirs and waste water treatment plants (WWTP) (Levantesi et al. 2010). Therefore, effectiveness should also consider the multipurpose capability of many MAR systems (Dillon et al. 2010). The broad variability of MAR facilities (e.g., infiltration pond, river bank filtration and deep injection), their different purposes and the local geological context, complicate the task of comparison. Consequently, it is imperative to begin with an exhaustive benchmark analysis and characterization of those different roles that an MAR system can simultaneously play. Only true comparable facilities should be assessed, so that the evaluation can be considered technically correct.

In this paper, we have analysed seven selected MAR demo sites located in Portugal and Spain through a methodical characterization of the whole recharge process. Thus, our goal has been to make them comparable through benchmark analysis. Furthermore, we have used detailed diagrams of the systems and their separated recharging facilities or sections can be clearly submitted to the same conditions considering their common characteristics, so consistency is guaranteed. This work was developed in the context of the MARSOL project (Managed Aquifer Recharge Solutions, an EU-FP7), which was aimed at demonstrating that MAR technology is a sound, safe and a sustainable strategy that can be applied with confidence.

Materials and methods

Characterization of the indicators

The usage of benchmark indicators for any water recharge system must, above all, evaluate the characterization of the framework itself, considering the broad variability of these schemes. Most of the processes that can be found in an MAR system are diverse and interconnected (Fig. 1). The benchmark indicators can be divided into those for evaluating the water quantity and its quality, and those for evaluating the cost and the energy of the MAR facility.

Fig. 1

Water recharge and recovery system sketch

Measuring water quantity

The volume of managed water should be quantified by considering the different phases that this bulk has passed through from its abstraction to its final use. Parameters collected for water quantity in the MAR framework are listed in Table 1.

Table 1

Main parameters for water quantity in an MAR system covering different phases

Phase

Quantitative parameter

Original source

Aquifer

End use

Resources

Water availability

m3

  

Abstraction

Water abstraction

m3

  

Pre-treatment

Pre-treated water

m3

  

Recharge

Recharged volume

 

m3

 
 

Recharge rate

 

m3/year; L/s

 
 

Volume/surface rate

 

m3/ha

 

Storage

Incremented store

 

m3

 
 

Water table

 

m

 

Recovery

Water availability

  

m3

 

Water recovery

  

m3

Use

Water use

  

m3

Measuring water quality

Once the flow pattern has been identified at every stage, the changes in quality must be monitored to check any possible (desired or undesired) change that could affect not only the final use but also the chemical evolution of the collected water or the stability of the aquifer (Sedighi et al. 2006).

The same parameters that are used in any water treatment quality control can be applied to MAR (Table 2). The general constraints are expected to be similar among European countries, although harmonization is still required (Miret et al. 2012). The list could be larger depending on the kind of pollution (industrial, agrarian, urban, etc.) and the expected role of the MAR facility (storage, dilution, filtering, etc.).

Table 2

Parameters for water quality in an MAR system

Qualitative parameter

Recharging water

Aquifer

Recovered water

Change

pH

pH

pH

pH

%

Biological oxygen demand (BOD)

BOD (mg/L)

BOD (mg/L)

BOD (mg/L)

%

Chemical oxygen demand (COD)

COD (mg/L)

COD (mg/L)

COD (mg/L)

%

Total suspended solids (TSS)

TSS (mg/L)

TSS (mg/L)

TSS (mg/L)

%

Total dissolved solids (TDS)

TDS (mg/L)

TDS (mg/L)

TDS (mg/L)

%

Dissolved organic carbon (DOC)

DOC (mg/L)

DOC (mg/L)

DOC (mg/L)

%

Ammonia (NH3)

NH3 (mg/L)

NH3 (mg/L)

NH3 (mg/L)

%

Total nitrogen (N)

N (mg/L)

N (mg/L)

N (mg/L)

%

Phosphorus (P)

P (mg/L)

P (mg/L)

P (mg/L)

%

Emerging organic compounds, pesticides

(ppm)

(ppm)

(ppm)

%

The change (in terms of %) refers to the relative change of quality in different water stages (before abstraction, aquifer, and before use)

Comparing efficiency in terms of cost and energy

Effectiveness can be quantified at every step (Table 3) using economic or energy references. Although the cost/effectiveness ratio could be associated with the volume managed in each phase, a more objective measure is usually calculated by considering the net volume of recovered water, as this is usually the final goal of the MARSOL schemes. In the case of a rising water table for energy saving as in Santiuste, water is finally pumped out for irrigation. MAR facilities dedicated to sea intrusion and wetland restoration goals opt out of this efficiency concept.

Table 3

Parameters for efficiency in an MAR system at every possible step of the recharge recovery cycle

Phase

Efficiency parameter

Original resource

Aquifer

End use

Abstraction

Energy cost

kWh/m3

  
 

Infrastructure cost

€/m3

  
 

Operation and maintenance (O&M) cost

€/m3

  

Pre-treatment

Energy cost

kWh/m3

  
 

Infrastructure cost

€/m3

  
 

O&M cost

 

€/m3

 

Recharge

Energy cost

 

kWh/m3

 
 

Infrastructure cost

 

€/m3

 
 

O&M cost

 

€/m3

 
 

Recharging rate

 

%

 
 

Filtration rate

 

m3/m2

 

Recovery

Energy cost

  

kWh/m3

 

Infrastructure cost

  

€/m3

 

O&M cost

  

€/m3

Use

Energy cost

  

kWh/m3

 

Infrastructure cost

  

€/m3

 

O&M cost

  

€/m3

An energy balance must be applied to compare passive and active systems. The economic cost should be calculated separately for the infrastructure investment and the Operation and Maintenance (O&M) costs. Even an internal rate of return could be estimated to appraise the recharging system as a progressive investment in time.

General procedure

In order to gather all the relevant data for each demo site, a form has been designed that is divided into four sections:

  • Main data and large numbers are enclosed in the first section, such as MAR class, functions, geology, water cycle, water quality, soil control and benchmark indicators as seen in Tables 5, 6 and 7 (Fig. 2 up). The first sheet where the main data reside contains the most important table, showing the approach of MAR to solve water management problems. The upper part of the table shows the features that illustrate the demo site with regard to local and technical details. Functions are then disclosed so performance rates can be assigned.

  • The second section shows the location of the demo site on orthophotographs using any GIS program or Google Earth. In the case of benchmarking, this process (Fig. 2 left) is not simply used to obtain location maps but also to obtain operational dimensions, e.g., the size of the recharging facilities (pond surface) is greater than the active dimensions (pond infiltrating bottom area).

  • The third section is a sketch of the demo site where Q0 to Qx represents the main inlets and outlets in order to determine which facility or stretch is playing a different role at each point of the recharge net (Fig. 3). The main aim is focused on identifying in and out flow directions (available points for future monitoring network), main functions (transport, recharge, recovery, etc.) and connectivity (leaks) for benchmark design (Fig. 2 right).

  • The fourth section is a calendar showing new works and changes of facilities over time (Table 4). As shown below, some of them can be enlarged and others can start from zero so functionality is not constant every season (Fig. 2 down).

Table 4

Example of the Santiuste MAR system development schedule from 2002 to 2015

Operative section

02/03

03/04

04/05

05/06

06/07

07/08

08/09

09/10

10/11

10/11

12/13

13/14

14/15

 

Diversion catchment

X

X

X

X

X

X

X

X

X

 

X

X

X

12

Diversion pipe

X

X

X

X

X

X

X

X

X

 

X

X

X

12

Infiltration pond

  

X

X

X

X

X

X

X

 

X

X

X

10

East infiltration canal (old)

X

X

X

X

X

X

X

X

X

 

X

X

X

12

East infiltration canal (new)

     

X

X

X

X

 

X

X

X

7

West infiltration canal

   

X

X

X

X

X

X

 

X

X

X

9

WWTP

    

X

X

X

X

X

X

X

X

X

9

Biofilter

    

X

X

X

X

X

X

X

X

X

9

Artificial wetlands

   

X

X

X

X

X

X

 

X

X

X

9

Salt lake diversion

   

X

X

  

X

X

 

X

X

X

7

Salt lake restoration

   

X

X

  

X

X

 

X

X

X

7

 

3

3

4

8

10

9

9

11

11

2

11

11

11

 

The first column indicates the operative sections. The total number of operative facilities per year is shown in the last row. The last column shows total operative years

Fig. 2

Methodology applied for data gathering. From MAR characterization to indicators (R/T/R: recharge/transport/recovery)

Table 5

Main features of the seven studied MAR demo sites

Demo site name

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Country

Portugal

Portugal

Portugal

Portugal

Spain

Spain

Spain

Demo location

Rio Seco (Algarve)

Campina do Faro (Algarve)

S. Bartolomeu de Messines (Algarve)

Cerro do Bardo (Algarve)

Santiuste (Segovia)

El Carracillo (Segovia)

Sant Vicenç dels Horts (Barcelona)

Aquifer

Campina de Faro

Campina de Faro

Querença-Silves

Querença-Silves

Los Arenales

Los Arenales

Llobregat

MAR class

Infiltration

Infiltration

Infiltration

Infiltration

Infiltration

Infiltration

Infiltration

MAR type

Infiltration ponds

Open infiltration wells

Infiltration/soil-aquifer treatment (SAT)

Well/dam

Infiltration/SAT basins

Infiltration/SAT basins

Infiltration/SAT basins

Fig. 3

Example of the Campina de Faro demo site network sketch

Results

The seven demo sites are located on four aquifers in two countries. All of them are basically surface infiltration facilities but there is a great variety because of the assorted combinations of ponds, canals, artificial wetlands or connections to WWTP (Table 5 and Fig. 4).

Fig. 4

Demo site locations in the Iberian Peninsula

Benchmarking in Portugal demo sites

The four Portuguese sites (Rio Seco, Noras, São Bartolomeu de Messines and Cerro do Bardo) were assessed for their preliminary benchmark results (Table 6). Only the first site (Rio Seco) shows two-year work performance indicators as the rest are only estimations based on the initial tests.

The main goal in Rio Seco is to improve the quality of the groundwater which is heavily contaminated with nitrates (vulnerable zone of Faro), mainly due to inappropriate agricultural practices. The water source will be the ephemeral stream/river bed (Rio Seco) and the infiltration will be carried out using gravel-filled basins in the river bed. This MAR facility shows a high potential for annual diversion (6.7 Mm3) when the project is totally developed, but it is only operative for a short time, not much longer than an average of 2 months (67 days) per year (Fig. 5), and infiltrates in only a short section. The site had been partially active since 2007 until it became fully operational in October 2014. The space was limited as the three infiltration ponds were located in the very narrow ephemeral river bed (Costa et al. 2015). The average infiltration rate was fairly good (22 m3/h) but, considering the diverted volume, the fraction was low (0.5%) for these initial campaigns. On the other hand, mainly due to the thickness of the confining material, the cost of the infrastructure was 86,000 €, which despite not being too high is the second highest cost in Portugal and almost twice the budget of the third highest. Considering the costs and the corresponding infiltrated volume, the Rio Seco ponds are the most expensive facilities (2.5 €/m3). However, this is expected to change in future campaigns as the long lifespan and low O&M charges of these infrastructures tend to level out the annual investment.

Fig. 5

Campina de Faro (Rio Seco) profile. Main processes (arrows) and MAR facilities (ponds and piezometers) are shown

Noras (Fig. 6) is an unconventional site as it is a rainwater harvest system in a rural area. Its huge gathering capacity (1,300,000 m2) comes from the surface of the greenhouse rooftops, and the old abandoned wells (large-diameter dug wells are named ‘noras’ in Portuguese) are the actual infiltration facilities (Ferreira and Leitão 2014). The infiltration speed is very high (max. 7200 m3/h, annual average 818 m3/h) for such short water availability. Consequently, a very good infiltration area rate (463 m3 per m2, considering the large ‘noras’ area) makes its efficiency adequate (27%). The cost of the infrastructure is very low as the greenhouses and old wells were established before recharge. The O&M cost is higher than expected because of the current low intensive recharge. The availability of pre-existing wells and no water transport requirements are good advantages for easy replication in many other areas with greenhouses (De Pascale and Maggio 2005) on the Mediterranean coast (e.g., Almería in Spain, Ragusa in Italy or Antalaya in Turkey).

Fig. 6

Campina de Faro profile. Rain on greenhouse roofs is harvested and directed to abandoned wells (Noras) to recharge the unconfined aquifer

S. Bartolomeu de Messines (Fig. 7) and Cerro do Bardo (Fig. 8) benchmarking are based only on projects in their preliminary states, so their results cannot be commented on in detail yet. The most remarkable facts are the low O&M cost for both sites and the high price of the infrastructure of Cerro do Bardo, due to its long water transport pipe (2230 m in length). S. Bartolomeu and Lobregat share some similarities in influent quality (urban polluted water) and design (biofilter in the bottom of a pond) although infiltration in Portugal takes place later, after discharge into a stream running on a karst (Fig. 7, right).

Fig. 7

São Bartolomeu de Messines MAR profile. Part of the outflow from a WWTP is infiltrated through a couple of SAT basins and spills into a stream

Fig. 8

Cerro do Bardo profile. Water from a dam network is diverted to an infiltration well and a weir where a submerged sinkhole recharges a karst

Table 6

Preliminary benchmarking indicators for Portuguese MAR sites

Benchmark indicators

Units

Campina de Faro (Rio Seco + Infiltration Ponds)

Campina de Faro (Noras Greenhouses + Infiltration Wells)

S. Bartolomeu de Messines

Cerro do Bardo

Water diversion

Mm3/campaign

6.7

1.6

0.3

14

Operation time

Days/campaign

67

22

365

365

Operation campaigns

Years

2

0

0

0

Infiltration surface

m2

401

950

210

Unknown

Infiltration volume

Mm3/campaign

0.035

0.4

0.03

1.7

Infiltration (volume/time) rate

m3/h (infiltrated volume/time)

22

818

3.5

190

Infiltration efficiency (infiltrated/diverted) rate

% (infiltrated volume/diverted volume)

0.5%

27%

10%

3.4%

Infiltration area (infiltrated volume/area) rate

m3/m2

87

463

142

--

Average infiltration rate

m/day

1.3

21

0.4

--

Pollutants concentration decrease (passive by dilution)

mg/L, %

50% lower nitrate concentration in a 100 m radius around the basins

Nitrate depletion (data for future collection)

Pharmaceutics decrease in % (active by biofilter)

--

Energy cost

kWh/m3

0

0

0

0

Infrastructure cost

86,000

32,000

15,000

1,154,000

Infiltration infrastructure cost

€/m3

2.5

0.07

0.5

0.7

O&M cost

4000

4000

1000

15,000

O&M cost (calculated)

€/m3 (cost/infiltrated)

0.11

0.04

0.03

0.006

In brief, the main functions at the Portuguese test sites are related to quality improvement. Unfortunately, the monitoring network of such a large body of groundwater is still not completely covered by sensors. Nitrogen depletion must be achieved with dilution processes thanks to the lower concentration in recharged water. However, alternatives such as pumping and treating the volume of groundwater to reduce the nitrate content from around 200 to 50 mg/L (legal limits) would be unaffordable. Pharmaceutical resilience associated with the outflow at S.B. de Messines implies very expensive and specific analyses, but there is also an emerging concern related to urban pollution and WWTP outflow (Drewes et al. 2003; Clara et al. 2004).

Benchmarking in Spain. Llobregat demo site (Catalonia)

The Llobregat demo site is based on two ponds—one for sedimentation processes and another for infiltration processes (Fig. 9). The MAR system has been placed at Sant Vicenç dels Horts (10 km from Barcelona) and is a component of the artificial recharge carried out in the Low Llobregat area for decades. The recharged water comes from the Llobregat River and the main goal is to increase the water storage in the aquifer as well as to improve the quality of recharged water. A reactive layer made up of organic matter was installed in the bottom of the infiltration pond (Fe oxides plus reactive layer with 49% green waste compost, 49% sand and 2% clay) (Valhondo et al. 2015). The objective of this reactive layer was to enhance the redox processes of the aquifer through the release of organic matter (acting as a potential electron donor). Previous laboratory studies concerning the dynamics of physical and biological processes concluded that microorganisms could reduce the infiltration rate as the flow patterns affect the special distribution of biological parameters (Rubol et al. 2014; Freixa et al. 2016). Alternation of short wetting and drying cycles allows microbial activity to be maintained in order to recover the infiltration rate and to minimize bio-clogging, respectively (Dutta et al. 2015; Rodríguez-Escales et al. 2016).

Fig. 9

Llobregat MAR demo site profile. A pipe from a weir in the Llobregat River fills a couple of ponds. The first acts as a sedimentation device and the second as an infiltrator with a reactive layer

The available data for benchmarking come from the past 6 years, when the MAR facility has been operative for 952 days with an average of 159 days per campaign. The infiltration pond covered an area of 5600 m2, although there are some discrepancies about such data (see CETaqua 2013; Valhondo et al. 2015). Some biological processes are probable, considering the flora and algae growing in the sedimentation pond although it was not surveyed during the infiltration process. Some infiltration volumes show different amounts in 2011 and 2012 depending on the source (Table 6).

Nevertheless, a volume up to 3.74 Mm3 was recharged during the 6 years with an average of 0.6 per campaign (2010 was an exceptionally dry year). The mean infiltration rate was approximately 0.75 ms per day. The decrease in the recharged volume has been attributed to the increased clogging effects on the infiltration pond. Of note, besides the total recharged volume the infiltration rate was also low and was comparable to 2013. After installation of the reactive layer and during the next 3 years the infiltration rate ranged between 0.89 and 0.94 m/day; in 2012 it decreased to 0.72 and in 2013 and 2014 it was between 0.48 and 0.5 m/day. This decrease in a benchmark parameter could be used as a pre-alarm signal, indicating the need of reactive layer renewal or the application of some counter-clogging measures.

The most important indicators are related to the removal of pollutants. Nitrate and sulfate (SO4) decrease whereas ferrous iron (Fe) and manganese II (Mn) increase as recharged water passes through the reactive layer modifying redox conditions and enhancing the emerging organic compound degradation (40–75% of reduction in CEC see Table 6) present in the river flow (atenolol, cetrizine, gemfibrozil) (Valhondo et al. 2014, 2015). Only carbamazepine stays imperturbable to the effect of the reactive layer. Denitrification (> 90%) is one of the most relevant achievements (Valhondo et al. 2014, 2015).

The investment seems to be too high when bearing in mind the recharged volume and rate; however, the ponds have been irregularly used (Table 7) because of litigation linked to rights on river water supply. Nevertheless, the effects of persistent pollutants should be considered in order to assess the real cost-benefit rate of this MAR system, especially in a high-demanding water supply area like Barcelona City, particularly during the dry and tourist seasons when surrounding WWTPs are overloaded by the increase in volume to treat, and secondary treatment cycles are therefore usually reduced.

Table 7

Preliminary benchmark indicators for the Llobregat MAR site

Benchmark

Units

Llobregat (Catalonia)

Water diversion

m3/h

710 (maximum)

Operation time

Days

952 days in 6 operative years

Operation flow

m3/h

200–500

Operation campaigns

Year

Days/year

2009

80

2010

14

2011

170

2012

258

2013

211

2014

219

Infiltration surface

m2 in ponds

5600

Sedimentation (microbiological active) surface

m2 in ponds

4000

Infiltration volume

Year

m3/year

2009

422,568

2010

49,950

2011

898,401

2012

1,038,295

2013

739,643

2014

592,760

Infiltration rate

Year

m/day

2009

0.94

2010

0.89

2011

0.94

2012

0.72

2013

0.50

2014

0.48

NO3 concentration decrease

%

>90%

SO4 decreasing %

%

5–15%

Fe (II) increasing factor

%

200–5000 times

Mn (II) increasing factor

%

80–1500 times

Energy cost

kWh/m3

No energy consumption

Infrastructure cost

1,107,807

O&M cost

€/m3

0.047

Seawater barrier effect

Change in meters, Chlorine concentration, interface location

No relevant effect

Others

Microbiological active volume (m3)

5600

Others

Pollutant depletion

33–100% (see below)

Anthropogenic contaminants (contaminants of emerging concern) decrease

Pharmaceuticals and personal care

% of inflow concentration (2011–2012)

Atenolol

100%

Cetirizine

33–77%

Gemfibrozil

34–64%

Carbamazepine

No (recalcitrant)

Benchmarking in Spain: the Los Arenales demo site

The most important current operative demo sites in Castilla y León are located on the same broad sandy aquifer and both have been recharging river water since 2002. El Carracillo could not get any supply for a couple of campaigns but Santiuste only failed in 2011–2012 for the same period. Thus, there are 11–12 recharging cycles to compare for consistent results (Fernández-Escalante 2005; Fernández-Escalante et al. 2015). The main differences between Santiuste (Fig. 10) and El Carracillo (Fig. 11) are:

Fig. 10

Santiuste MAR sketch. A complex MAR system conjugates up to four processes using water diverted from Voltoya River

Fig. 11

El Carracillo MAR sketch. A long (33 km) pipe carries water from the Cega River and supplies a series of infiltration facilities in the El Carracillo district

  • Both sites take water from river winter surplus but Santiuste has also had a complementary water source from a lagooning WWTP since 2005.

  • Canals are the main transport and infiltration facilities in Santiuste, while a pipeline and ponds perform those roles in El Carracillo.

  • Works in Santiuste have been constantly evolving since 2002, lengthening and broadening some facilities (canals) and building new ones (ponds, artificial wetlands), while El Carracillo has remained more stable with only minor changes.

In summary, these sites use a long pipe to transport water by gravitation from a river about 10 km from the irrigation area, where a series of canals and ponds enhance the recharge into the sandy aquifer by direct infiltration. Transport, infiltration, purification and restoration processes take place in different sections and to different extents in both areas.

The biofilter process in Santiuste is carried out by a vegetated canal and three artificial wetlands that improve the water quality of the WWTP sewage flow before infiltrating into the next canal section. El Carracillo has a similar small-scale triplet formed by a stagnation pond, a vegetated canal, and an artificial wetland with a spreading infiltration field at the end. However, water quality is still better than at the previous site, where current lagooning has proved not to be a very effective purification method.

Benchmark figures in the Los Arenales aquifer are shown in Tables 8 and 9. The availability of more than ten cycles at both demo sites permits the use of some averages as statistics with a greater relevance for characterization in Table 9.

Table 8

Preliminary benchmark indicators for the Los Arenales MAR site (indicators dependent on campaigns)

Benchmark

Demo site

2002/2003

2003/2004

2004/2005

2005/2006

2006/2007

2007/2008

2008/2009

2009/2010

2010/2011

2011/2012

2012/2013

2013/2014

2014/2015

Water diversion (Mm3)

S

3.5

2.3

1.3

5.1

12.7

0.5

3.9

0.7

3.1

0

3.5

2.0

3.6

EC

1.4

5.5

0

2.4

3.2

0

1.9

5.8

4.6

1.9

7.1

1.8

0.6

Operation time (days)

S

145

175

212

137

212

7

181

43

68

0

76

57

76

EC

149

149

0

149

149

0

149

89

90

60

119

89

27

Infiltration length (km)

S

7.2

7.2

7.2

17

17

25.7

25.7

25.7

25.7

1.1

25.7

25.7

25.7

EC

17.8

17.8

17.8

17.8

17.8

17.8

17.8

17.8

17.8

17.8

17.8

17.8

17.8

Infiltration surface (ha)

S

0

0

1.8

1.8

1.8

1.8

1.8

1.8

1.8

0.17

1.8

2.2

2.2

EC

60.2

60.2

60.2

60.2

60.2

60.2

60.2

60.2

60.2

60.2

60.2

60.2

60.2

Purification area (ha)

S

0

0

0

2

2.6

2.6

2.6

2.6

2.6

0.7

2.6

2.6

2.6

EC

0

0

0

0

0

0

0

0

0

0

0

0

0

Restoration area (ha)

S

0

0

0

8.7

8.7

0

0

8.7

8.7

0

0

0

0

EC

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

2.8

Infiltration volume (Mm3)

S

1.3

1.8

1

3.6

12.2

0.5

2.5

0.6

2.1

0

3.2

2

3.2

EC

1.4

5.5

0

2.4

3.2

0

1.9

5.8

4.6

1.9

7.1

1.8

0.6

Infiltration rate (m3/h)

S

374

429

191

1083

2396

2738

576

620

1305

1782

1462

1743

EC

391

1538

0

685

895

0

531

2715

2130

1319

2486

836

923

Infiltration rate (m/day)

S

2.2

1.2

0.3

2.0

3.3

4.0

1.2

0.9

2.5

0.000

2.6

1.6

2.2

EC

0.02

0.06

0.00

0.03

0.04

0.00

0.02

0.11

0.08

0.05

0.10

0.03

0.04

S Santiuste, EC El Carracillo

Table 9

Preliminary benchmark indicators for the Los Arenales MAR site (constant and average indicators)

Benchmark

Units

Santiuste (Castilla y León)

El Carracillo (Castilla y León)

Transport length

km in pipe

13.6

46.2

Purification length

m in canal

1129

138

NO3 concentration decrease

mg/L, %

NO3 reduction by dilution with river source (not measured)

NO3 reduction by dilution with river source (not measured)

Energy cost

kWh/m3

0

0

Infrastructure cost

3,948,079 €

5,273,999 €

O&M cost

€/m3

0.05

0.08

Irrigable area

ha

3061

7586

Original irrigated area

ha

515

3000

Current irrigated area

ha

790

3500

Increased irrigation land

ha

275

500

Mean annual aquifer extraction

Mm3/year

0.21

8

Farmers

Number

440

713

Effect of MAR in irrigation supply

m3/ha

853

314

Irrigated volume from MAR

%

28%

24%

Mean water table depth increase after MAR

M

1.5

2.3

Energy savings

kWh

27.10 (per well)

28,000 (total)

Energy savings

%

30%

36%

It is worth mentioning that the Santiuste Basin MAR plant has been extended at different stages. In 2004, new canal branches were built, especially in the extreme north, and minor adaptations have been conducted throughout the entire operative time (see Table 4). The high infiltration rate in the 2007/2008 hydrological year was due to the fact that the MAR cycle was only 7 days long (according to the precipitation in the area to satisfy legal constraints). In this situation, the scarce volume of diverted water easily penetrated into the aquifer. Desilting activities in all the MAR facilities was performed in 2005, 2010 and 2015, i.e., removing plants growing in the canals and renewing the biofilters. According to the previous conditions, there is a good correlation between the mean infiltration rate and the decrease in clogging in the canals and infiltration ponds.

In contrast, the Carracillo MAR plant has hardly changed as no general desilting campaign has been undertaken. Therefore, cleaning and maintenance are carried out according to the resources of the irrigation community.

Characterization of MARSOL demo sites

The seven studied demo sites have covered 13 of the 25 recorded MAR devices (Table 10). Infiltration ponds and open wells are the usual facilities. The array of working services at the Los Arenales sites contrasts with the specificity of Rio Seco, Messines and Llobregat.

Table 10

Types of MAR devices in the selected demo sites

MAR devices

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Infiltration ponds / artificial wetlands

3 IP

   

5  IP+ 23 AW

22 IP + 1 AW

1 (A W / SP) + 1 IP

Channels and infiltration ditches

    

27 km

40.7 km

 

Ridges/soil and aquifer treatment techniques (SAT)

  

2 SAT ponds

 

X

 

X

Infiltration fields (flood and controlled spreading)

     

1

 

Accidental recharge by irrigation return

 

X

  

X

X

 

Reservoir dams and dams

   

1 Weir

1

1

 

Qanats (underground galleries)

     

X

 

Open infiltration wells

 

60 dug wellsa

 

1 dug well

3

X

 

Sinkholes, collapses..

   

1 known sink hole

   

Aquifer storage, transfer and recovery

   

X

   

River bank filtration

    

1

  

Interdune filtration

     

Ditches

 

Rainwater harvesting in unproductive

 

Greenhouse roof harvest

     

Number of MAR devices

1

3

1

4

7

8

2

X existent but not specified

AW Artifitial Wetlands; IP Infiltration Ponds; SP Sedimenation pond

aOnly 11 of the 60 ‘noras’ were considered within the modelling area

The main problems reported for each aquifer area are similar and repetitive. Overexploitation and nitrate pollution from agricultural sources are common for most of the groundwater masses (Table 11). Llobregat and Messines have been unambiguously designed to treat only urban polluted water, and not to solve supply issues in the groundwater area.

Table 11

Main problems in the aquifer under the studied demo sites

Problems

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Scarcity (overexploitation)

  

X

X

X

X

X

Scarcity (climate change)

  

X

X

  

X

Salinity (seawater intrusion)

       

Heavy metals (mining, industry)

      

X

Contamination from agriculture source (mainly N)

X

X

  

X

X

 

Organic pollution (pesticides and antibiotics)

X

X

  

X

X

Xa

Wastewater discharge

  

X

 

X

 

X

Wetland desiccation

    

X

  

Floods

X

      

Total number

3

2

3

2

5

3

5

X existent but not specified, N nitrogen

aOrganic industrial residues (1,1,2-trichloroethane, TCA) have also been detected in Llobregat

A comparison between problems and functions shows the different approach of specialized facilities with extended sites (Table 12). This was expected as a result of the number of facilities cited in Table 10. However, quality improvement is a more recurrent function than storage for these recharging infrastructures.

Table 12

Attainable functions of the MAR demo sites

Functions

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Irrigation supply

   

X

X

X

X

Drinking water supply

   

X

X

 

X

Seawater barrier

 

X

 

X

   

Wastewater treatment

    

X

  

Wetland restoration

    

X

X

 

Water quality improvement

NO3

NO3

Pharmaceutics

 

NO3

NO3

X

Seasonal storage

   

X

X

X

 

Total number

1

2

1

4

6

4

3

X existent but not specified, NO3 nitrate

Considering their geological features, the seven sites have been located on aquifers that are as varied as their solutions (Table 13). Unconfined ones are still the most habitual kind as the vadose zone is going to play an essential role in water purification during the infiltration process.

Table 13

Geological features of the MAR demo sites

Geology

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Multi-aquifer

X

X

     

Single-aquifer

    

X

X

X

Coastal

X

X

    

X

Inland

    

X

X

 

Alluvial

X

X

  

X

X

X

Siliceous

X

X

  

X

X

X

Karst

  

X

X

   

Confined

  

X

X

   

Unconfined

X

X

  

X

X

X

X existent but not specified

Most of the selected demo sites are attached to other hydraulic infrastructures, such as dams, weirs and WWTP (Table 14) that can be seen as potential competitors from a benchmark point of view. Coordination of traditional and new MAR facilities is still necessary and helps to develop a more integrated network in watershed management. Among the selected sites in this paper, the only documented way to recover water is well pumping. This is not a disadvantage as the private energy cost becomes the best control mechanism to avoid overexploitation, as water pricing policies have proved not to be adequate (Kajisa and Dong 2015).

Table 14

MAR phases of the MAR demo sites

Water source

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Water source

       

 River

Rio Seco

  

Ribeira de Aivados

Voltoya (1000 L/s)

Cega

Llobregat

 Weir/dam

   

Foucho Dam

Voltoya Dam (60,000 m3)

Cega

Weir in Molins de Rei

 Sewage (WWTP)

  

S.B. de Messines

 

Santiuste de S. Juan Bautista

  

 Irrigation return flow

    

X

X

 

 Rainfall

 

X

     

 Outflows (spillways)

    

Eresma River

Pirón River

 

Water transport

       

 Canal

    

X

  

 Ditch

     

X

 

 Pipe

 

X

X

X

900 mm/9824 m

33,000 m

3200 m (pipe from Weir to first pond)

Water recovery

       

 Well

 

X

X

X

X

X

X

 Others

*

      

Water use

       

 Agriculture

 

X

X

X

X

X

X

 Industrial

      

X

 Ecological

X

X

X

X

X

X

 

 Urban

   

X

  

X

X existent but not specified

*The goal is to improve the water quality rather than recovery

Benchmarking in MARSOL demo sites

Long experience allows managers to try and test a range of techniques so benchmarking can also show comparison in time (performance/internal benchmarking) within the same demo site. Average measurements must be calculated to compare different demo sites using a single benchmark figure.

The main challenge is to achieve a good method to evaluate the economic effect of MAR. As different sites show dissimilar uses, water markets or demands, monetary calculations could be incomparable among diverse MAR systems.

Most of the time the prominence of recharge must be assessed as the percentage of improvement in some of the important features for users, such as pumping energy reduction, water table rise, irrigated area expansion, vegetable production increase, standard water purification cost, groundwater nitrate content dilution, etc.

Discussion

The main problems with benchmarking associated with recharge are related to the huge variety of demo sites and MARSOL facilities. Apart from local conditions such as pollution sources and geological backgrounds, there are some conditions that make the MAR sites difficult to evaluate for benchmarking:

  • Scale: the sites that have been compared using benchmark indicators show a great difference in extent. From the infiltration ponds of Llobregat or Rio Seco to the broad areas of canals in Santiuste, the MARSOL group needs to change from square meters to hectares (ha) as the surface used for infiltration varies from small pond bottoms to kilometers of channels. This change of size goes further than simply using different units of measure. It is also needs a different approach from intensive to extensive systems, each with their own technical and environmental advantages and disadvantages.

  • State of development: some demo sites such as Cerro do Bardo are almost in the conceptual stage, while others have been working for decades. Consequently, the availability of data and the consistency of the figures are unequal. This initial stage is an important inconvenience when the aim is a long-term target such as nitrate dilution or seawater intrusion barrier effectiveness. None of them can be immediately tested by simple quantification of the volume of groundwater storage or water purification through the soil.

  • Complexity: the demo sites that have been selected can be as simple as an infiltration pond system in either Portugal or Spain or as complicated as a network of canals, ponds and wetlands in the Santiuste basin in Los Arenales. The connected facilities need to be evaluated according to their separated sections to get an appropriate comparison based on similar aims and processes instead of an appraisal as a whole.

  • Main target: the array of recharging facilities covers many different aims, from nitrate dilution to environmental recovery. Although complexity and multifunctionality are usually linked, even the basic sites such as Rio Seco can play different roles at the same time (infiltration, nitrate dilution and flood control). That flexibility and multiplicity of roles are perfect examples of the reasons why recharge could be easily used as a water management tool adapted to different situations within a basin planning framework.

The benchmark results and trends provide the main MAR figures (Table 15) showing different features, such as:

Table 15

Preselected indexes as benchmark indicators for MAR systems

Country

 

Portugal

Portugal

Portugal

Portugal

Spain

Spain

Spain

Benchmark indicators:

Units

Rio Seco

Noras

S.B. de Messines

Cerro do Bardo

Santiuste

El Carracillo

Llobregat

Characteristics

        

 MAR type

Text

Infiltration ponds

Open Infiltration wells

Infiltration/SAT

Well/dam

Infiltration/SAT basins

Infiltration/SAT basins

Sedimentary pond & infiltration pond (reactive layer)

 Water source

Text

River

Rainfall

WWTP

River

River + WWTP

River

River

 Performance campaigns

Years

2 (2014–2015)

0

0

0

12 (2002–2015)

11 (2002–2015)

6 (2009–2014)

 Soil type

Text

Siliceous unconfined

Siliceous unconfined

Confined Karst

Confined Karst

Siliceous unconfined

Siliceous unconfined

Siliceous unconfined

Diversion

        

 Annual volume water diversion

Mm3/year

6.7

1.6

0.1

14

3.2

2.4

0.6

 Max potential diverted water (authorized)

Mm3/year

6.7

1.6

0.3

50

8.5

14.2

1

 Annual % of potential diverted water

%

100%

100%

36%

38%

20%

0.1–0.3%

 Operation time

Days

67

0

0

0

107

94

159

 Max potential operational time

Days

67

22

365

365

182

149

365

 Annual % of potential operational time

%

100%

0%

0%

59%

63%

43%

 Diversion rate

m3/h

22

7200

12

190

1482

1112

169

 Diversion rate

L/s

6

2000

3.5

523

412

309

47

 Potential diversion rate (technical)

L/s

50 Mm3

1000

197

Recharge

        

 Annual recharged volume

Mm3/year

0.03

0.4

0.03

1.7

2.6

2.4

0.6

 Annual recharging rate

%

0.5%

27%

10%

100%

73%

63%

100%

 Total recharged volume

Mm3

0.03

0

0

0

34

31

3.7

Dimensions

        

 Transport length

M

0

3000

20

2230

13,598

46,192

3200

 Recharging length

M

0

0

0

0

25,720

17,765

0

 Purification length

M

0

0

0

0

1129

138

0

 Restoration length

M

0

0

0

0

0

0

0

 Diversion area

m2

0

1.3 × 106

0

0

27,778

25,803

0

 Recharging area

m2

401

950

0

??

22,342

602,416

5600

 Purification area

m2

0

0

210

0

26,066

0

4000

 Restoration area

m2

0

0

0

0

86,654

27,838

0

 Infiltration rate

m/day

1.3

21

0.4

1.9

0.04

0.7

Costs

        

 Total investment

M€

0.086

0.032

0.015

1.15

3.9

5.2

1.1

 Current investment

€/campaign

43,000

 

329,007

479,454

184,634

 Lifespan

Years

35

35

35

35

35

35

35

 Lifespan investment

€/year

2475

914

429

32,971

112,802

150,686

31,652

 Relative investment (total recharge volume)

€/m3

2.46

0.07

0.50

0.68

0.12

0.17

0.30

 Relative investment (max. potential recharge volume)

€/m3

0.02

0.05

0.02

0.04

0.06

0.05

 O&M cost

4000

4000

1000

15,000

177,249

 O&M cost per volume

€/m3

0.11

0.04

0.03

0.006

0.050

0.080

0.05

 Energy cost

kWh/m3

0

0

0

0

0

0

0

Benefits

        

 Quality improvement

Nitrates

–50%

??

??

??

− 90%

 

Pharmaceutics

??

− 100% to − 33% *

 Total MAR population

Inhabitants

2953

10,958

27,961

 Served population (farmers)

Inhabitants/year

440

713

230

 Served irrigation area

ha

130

3061

7586

1383

 Irrigated area

ha

130

1520

3500

254

?? Probable but not measured, – unknown

* Depending on Contaminants of Emerging Concern

  • Operational dimensions should not always be inferred from geometrical measurements (real meter ≠ operative meter). The infiltration surface or length is limited by clogging and/or other processes (clay layers, turbid water, etc.). These figures may change in time depending on management operations such as weeding or soil ploughing. Consequently, canals are divided into stretches with high or low infiltration/distribution rates (Santiuste) or ponds can be used as wetlands for environmental or purification purposes (Santiuste and El Carracillo) rather than as infiltrating spots.

  • Diversion flow/volume is usually the most reliable data based on flowmeters and volume/flow legal limitations (maximum potential diverted water authorized). Infiltration is more often deduced, especially in broad areas. Global figures in extended areas are worth studying in detail to develop the best possible improvements in recharge.

  • Flows through canals or infiltration rates are usually deduced (transpiration, lateral and deep losses are inferred or neglected). It is necessary to install more control points to develop mathematical models to analyse quantitative and qualitative MAR performances on a more solid foundation.

  • Water quality enhancement (S. Bartolomeu, Llobregat, Santiuste) has a very interesting and contrasting role (Maeng et al. 2011), as reclaimed water could play an essential part in the future during the dry seasons in the Mediterranean sites. Nitrate reduction has been proved in-site (Llobregat) but dilution effects are difficult to prove when agriculture inputs are not often monitored (Portugal, Los Arenales). Nevertheless, legal, technical (clogging) and sanitary issues should be solved before sewage could be generally accepted as a standard recharging source by water authorities.

  • Costs should be shared through the whole operational lifespan (unfinished, refurbished, etc.) and compared to the cost of their analog facilities (dams for storage, WWTP for purification, injection wells for recharge). Some experiences seem to sustain positive MAR results (Khan et al. 2008). However, these calculations sometimes imply too many deductions, as not many MAR facilities have been running for a sufficient amount of time to check their profitability (Maliva 2014).

  • Relative investment is extremely variable (mean: 0.613 €/m3) as the scale and state of the development of each site differ. Nevertheless, considering the maximum diverted water as the maximum recharged volume per year, the potential cost per recharged volume would be 0.06–0.02 €/m3. O&M rates are much more variable with a wide range from 0.13 to 0.006 €/m3.

  • The best economic indicator would be the cost of a recharged cubic meter of water according to the current water price in the local market, especially for agrarian use; however, that also may imply many unreliable and undesirable inferences. For instance, in Los Arenales the price for water can fluctuate from 0.0017 to 0.0036 €/m3 depending on the system of application (ITA 2013). However, for Cerro do Bardo and S.B. Messines the pumping cost can range from 300 €/ha for citrus fruits to 700 €/ha for vegetables, according to the local Irrigation Association.

  • Efficiency measures are usually limited to total recharge of water in the form of water table rise over the irrigated area, and the increasing availability of groundwater supplies. More diverse and open MAR systems require a broader range of measures related to functional objectives (Santiuste and El Carracillo). Multifunctionality must be considered to assess the whole MAR system performance, especially when compared to dams and reservoirs.

  • Environmental functions such as habitat restoration or passive water quality improvement should also be considered in assessment of MAR systems (San-Sebastián-Sauto et al. 2015), but the way they can be evaluated as a local enhancement is difficult to compare with other ecosystems.

Conclusions

In summary, the main aims of MAR are the amount and the quality of the resource recovered after passing through the system. Therefore, these two variables must be the focus of the benchmarking when matching the different cases of MAR under consideration. However, quantity and quality may also be measured in many ways.

To be able to compare the efficiency and efficacy of the MAR based in terms of energy balance or cost/benefit, a methodical characterization of the whole process must be carried out to ensure that functions and facilities are clearly comparable independent of size, budget or location.

Benchmarking MAR facilities should comprise a series of steps. This article proposes at least three:

  • Characterization of MAR functions (transport, recharge, treatment, restoration) divided into homogeneous operational sections.

  • MAR infrastructure measurements (surfaces, lengths, facilities, costs).

  • MAR evolution in time (data series and schedules) and space (maps and sketches).

Measuring MAR could be relatively easy on a small scale with a specific function (Llobregat, S. Bartolomeu), but not in open extended multipurpose areas (Los Arenales, Noras). This is the reason why the largest MARSOL demo sites need to be studied following a more subdivided and multifaceted approach. The benchmark system proposed and applied to medium-scale sites may best be used to compare only similar tested facilities (infiltration ponds, infiltration canals, purifying canals, artificial wetlands, etc.) with comparable purposes.

In general, there is a good correlation between the mean infiltration rate and the desilting activities accomplished in the Santiuste basin (with a general cleaning in 2005, 2010 and 2015 plus isolated maintenance activities). However, El Carracillo has never been desilted in its totality and the variations in the infiltration rate are somewhat attributable to environmental conditions.

Mediterranean water supply irregularity, amplified by climate change, can be mitigated by MAR techniques in very different ways, such as sea water intrusion barrier (Reichard and Johnson 2005), sewage treatment (Bekele et al. 2011) or ecological restoration (Esteban and Dinar 2013). These roles are not generally seen as goals to be solved by means of induced recharge activities and their benefits are not usually assessed when they are compared to other infrastructures. For instance, problems with persistent organic pollutants are undeniable during filtration but they show a similar behavior in nature (Hamann et al. 2016) and after WWTP processes (Petrovic et al. 2009). Therefore, it is a common issue for all procedures, not just an MAR restraint. On the other hand, the small land use and their location out of riverbeds of infiltration ponds and the maintenance of biological corridors through infiltration canals of MAR are, to an extent, environmental advantages on behalf of recharge if they are compared to dams or canals. Unfortunately, these low impact MAR techniques are less positively appraised during the Environmental Impact Assessment (EIA) processes of infrastructures for water storage purposes.

The reuse of previous structures (sandpits in El Carracillo, wells in Noras, dry stream beds in Santiuste and weir in Cerro do Bardo), its adaptability to local usages (agricultural, rural, urban) and consequent savings provide a broader variety of solutions within a MAR ‘recycling spirit’. The design of passive systems (no energy costs after the initial construction at the seven sites) and their low initial investment (minimized by means of refurbishing former infrastructures such as sand pits for artificial wetlands, etc.) seem to be key factors for boosting MAR acceptance (Escalante and Sauto 2012).

Some demo sites are placed near very popular tourist destinations like Barcelona and Algarve, where the increasing population requires large amounts of drinking water in summer (dry season) and simultaneously produces high discharge rates of sewage. The high price of urban land is also an issue to consider when building an above-ground water storage facility in these areas.

Benchmark indicators can help to assemble didactic material for the printed and social media, as guidelines on points of interest in water management issues (Fernández-Escalante et al. 2013. Thus, the performance of MAR techniques may become common knowledge in both technical and inexperienced circles (Lyytimäki and Assmuth 2015).

MAR must play a central role in the recycling process (Dillon et al. 2010) as an affordable option in a climate change scenario where extreme episodes (such as floods and droughts) are expected to happen more frequently (Giorgi and Lionello 2008).

Notes

Acknowledgements

This article has been developed and written within the framework of the MARSOL project (Demonstrating Managed Aquifer Recharge as a Solution to Water Scarcity and Drought FP7, http://www.marsol.eu, GA 119120), financed by the European Commission and Tragsa Group. The authors wish to thank Ms. Miren San-Sebastián and Mr. James Haworth who assisted in proof-reading the manuscript.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

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Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Building and EngineeringTragsatecMadridSpain
  2. 2.Department of R&D Integrated Water ManagementTragsaMadridSpain
  3. 3.TARH Terra, Ambiente e Recursos Hídricos, LdaSacavémPortugal
  4. 4.Hydrogeology Group (UPC-CSIC), Civil and Environmental Engineering DepartmentUniversitat Politècnica de Catalunya-BarcelonaTechBarcelonaSpain

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