Managed Aquifer Recharge in Los Arenales (Segovia, Spain)

NWRM

Application scale

Plot

Installation date

2002

Age

Performance timescale

< 1 year

Area (ha)

4800

Area subject to Land use change or Management/Practice change (ha)

7,55819988250732

Size

27960

Size unit

Design capacity description

The system was designed for a maximum water flow of 1000 l/s (or 1 m3/s) and a maximum annual volume of 8 hm3.

Basis of design

Peak flow (for a standard return period of 5 years) = 100 m3/s
Peak flow (for a return period of 500 years) = 560 m3/s

Constraints

In winter, water freezing reduce infiltration to the aquifer. This might be relevant considering that the concesion of water for this propose goes from November to April.
Some years have not been successful due to silting up in soakways and pond.
The water transfer from Voltoya River to the recharge channel needed to be stopped during heavy rain days in order to avoid flooding.
Additionally, the Lisse effect (excess of air trapped in to the aquifer reduces the infiltration capacity) has been a problem during the implementation, having to modify the design and structure of the devices.
Erotion of soakways/channels banksides, jeopardising stability.
The transfer of water to the recharge system was only allowed is the flow in Voltoya river was be above 600 l/s (in order to guarantee the ecological flow.

Favourable preconditions

The channel was designed to take advantage of the former route of the Ermita strem to enhance infiltration.

Essays and monitoring in the site of study showed that in areas were the aquifer was more than 3m deep, infiltration was more effective.

Literature lists favourable conditions for aquifer recharge: scant vegetation, permeable or fractured soil, high water table level, and aboundant rainfal (De Vries and Simmers, 2002).

Inflow volume

0,379999995231628

Inflow volume unit

m3/sec

Design contractual arrangement

No data

Design consultation activity

No data

Design land use change

No data

Design authority

Authority type	Role	Name	Comments
Other	Initiation of the measure	Ministry of Agriculture, Food and Enviromental Affairs, Spain	The ministry responsible for environmental affairs.
Other	Initiation of the measure	Castilla y Leí³n Regional Government (Agriculture and Livestock Office)	Is the regional authority for agricultural affairs.
	Other	Tragsa	Type: Public Company Role: Tragsa has been involved since the begining is most of the stages: Initiation of the measure; Determination of design details of the measure, Implementation, Financing (from 2007 to 2010) and Monitoring.
Local water authority	Other	Duero River Basin Authority	Supporting tragsa withdata collection and providing information.
	Other	Universidad Complutense de Madrid	Type: education and research institution Role: monitoring and field research
Farmers	Monitoring	Irrigators Community	Framers were actually involved in all the process. They were responsible for opening and closing the recharge devices following Tragsa instructions.

Key lessons

- It is important to involve irrigators in the process and the implementation of measures, especially to those Communities that use underground waters, since the withdrawal control is lower than for those using surface waters.
- It is important to improve economic and geopolitical indicators, apart from the hydrogeological ones, prior to the implementation of new devices.
- Monitoring is key to improve effectiveness, to improve the devices and to increase infiltration rates and the total volume infiltrated to the aquifer.
- Some key actions to ensure the proper functioning of the measure is the pre-treatment of water, the inflow regulation, reduction of suspended soils and air in water. Is advisable to avoid whipping of recharge water. Low flow speed is preferred.
- Some of the most common limitations are soil silting and increase of trapped air in the aquifer, which can be avoided with SAT techniques and the proper design of the channel.

Success factor(s)

Success factor type	Success factor role	Comments
Attitude of relevant stakeholders	main factor	Once the infiltration system started working, it was necessary the participation of the irrigator community to manage the entrance of water from Voltoya River. This procedure proved to be the most efficient to avoid excess of water and flooding in nearby areas, or to surpass the limit established by the River Basin Authority of 8,5hm3 to be used for recharge purposes. Mayors of related towns were always collaborative.
Public participation	secondary factor
Attitude of decision makers	secondary factor	Once the overexploitation problem was identified, local and national authorities reacted with a project of aquifer recharge, declaring the implementation of measures of "general interest". Mayors of related towns were always collaborative.
Successful coordination between authorities	secondary factor
Communication activities	secondary factor	The project has became a practice of interest in Spain and is often visited by students, other researcher, and even a dissemination plan has been implemented for the general public.
Existing staff and consultant knowledge	main factor	Some of the researchers involved in the project have been very committed to the continuation of monitoring and sampling to get additional data and results even when the budget was scant.

Financing

Financing type	Comments
National funds	The Ministry of Agriculture, Food and Environmental Affairs.
Sub-national funds	Castilla y León Regional Government (Agriculture and Livestock Office)
Other	European Agricultural Guarantee Fund
Other	Trasgsa (public company) financed an RTD programme (2007-2010) to continue the research activity regarding aquifer management activities. SEPI Group (Spanish Society of Industrial Participations) was the main shareholder

Barrier

Barrier type	Barrier role	Comments
Lacking financing sources	main barrier	The lack of financing actually became a barrier during the recharge cycles 2010/2011 and 2011/2012, when maintenance, new infraestructures and expansions were not possible, and the little activity that remained was thanks to private efforts (of researchers and irrigators)
Existing technical standards	secondary barrier	During the progress of the implementation silting was one of the major problems which reduded efective infiltration of water into the aquifer. Several studies were carried out in order to define best solutions and improve effectiveness of the measure.
Legal obligations / restrictions	secondary barrier	A "spill" authorization is needed to implement this measures in Spain (despite the fact that most activities result in an increased groundwater quality)

Driver

Driver type	Driver role	Comments
Balancing different objectives	main driver	A group of groundwater users posed their concern about the aquifer degradation to the local authorities, which enabled a serie of interventions.
Public pressure	main driver
Organisation committed to it	secondary driver

Policy description

The exploitation of the superficial aquifer, mainly for irrigated agriculture, has led to a 10 m fall of the water table, which has led to related salinization and pollution processes. [WFD pressure: 3.1 Abstraction, Agriculture]

Part of wider plan

Policy target

Target purpose
Groundwater Recharge
Increase Water Storage

Policy pressure

No data

Policy area

No data

Policy impact

No data

Policy wider plan

No data

Policy requirement directive

No data

Costs investment information

See total cost

Costs operation maintenance

3000

Costs operation maintenance

Each recharge cycle had maintenance works of the channel and basins depending on the results of the previous year. However, there is not a specific budget with details on these specific costs.

Costs total

4608946

Costs total information

Initial investmentuntil 2006:
Water intake: 409657 €
Transfer conveyance: 2641615 €
Recharge channel 1: 289940 €
Recharge channel 2: 606867 €

Investment in the second period: 660867€ (The amount was devoted to maintenance, studies and projects)

Compensations annual information

There is no specific records of compensation payments to landowners or irrigators affected by the measure. In fact, the implementation of the measure was originated from a social claim to recover a damage aquifer, and irrigators and landowners were involved in the petition.

Information on Economic costs - income loss

In very wet years, agricultural fields (generally with potato crops) have been occasionally flooded after the groundwater level reached the limit that should not be exceeded in aquifer managment and recharge practices (defined in 1.5m by Fernández Escalante, 2005).

Ecosystem improved biodiversity

Information on Ecosystem improved biodiversity

The implementation of the measures also included the restoration of La Iglesia lagoon, which has served as a refuge for bird life and as a nesting area.

Ecosystem impact climate regulation

No information available

Information on Ecosystem impact climate regulation

Not specific impacts are described in the literature on the case study.

Retained water

2555000

Retained water unit

m3/year

Information on retained water

Average value per recharge cycle calculated on the basis of the data obtained after 8 effective recharge cycles. Of the total volume derived to the infiltration devices, that is the volume that was actually infiltrated into the aquifer in each of the cycles in which the measure was working. Values obtained per cycle: 1300000 m3 (cycle 1; 2002/03); 1800000 m3 (cycle 2; 2003/04); 970000 m3 (cycle 3; 2004/05); 3560000 m3 (cycle 4; 2005/06); 12190000 m3 (cycle 5; 2007/08); 460000 m3 (cycle 6); 2500000 m3 (cycle 7; 2008/09); 640000 m3 (cycle 8; 2009/10); 2130000 m3 (cycle 9; 2010/11); 0 m3 (cycle 10; 2011/12).

Information on increased water storage

For each cycle of recharge was calculated the volumen of water devoted and the actual recharged volume. The following are the percentage of used volume vs recharged volume: 37,14% (cycle 1); 80% (cycle 2); 76,98% (cycle 3); 69,67% (cycle 4); 96,13% (cycle 5); 87,41% (cycle 6); 64,50% (cycle 7); 90,46% (cycle 8); 68,03% (cycle 9); 0% (cycle 10).

Increased groundwater level

1,23000001907349

Information on Increased groundwater level

Average value per recharge cycle on the basis of the the data obtained after 10 recharge cycles (and excluding cycle 6 value -see later-). These values show the variation in the groundwater level in the monitoring network. The value of the Cycle 6 cannot be only attribuible to the recharge as there was also abundant precipitation that year, and measurement could not differ between sources. Values obtained per cycle: 2,30 m (cycle 1); 2,10 m (cycle 2); 1,17 m (cycle 3); 3,36 m (cycle 4); 0,31m (cycle 5); 3,57*m (cycle 6); 0,62 m (cycle 7); 0,41 m (cycle 8); 0,54 m (cycle 9); 0,28 m (cycle 10).

Information on Water quality overall improvements

The hydrochemical evolution of groundwater has shown improvement in nitrate concentrations (which were very high at the beginning: 274 mg/L in the NE of the aquifer). On the other hand, some negative impacts occurred like the increased concentration of diluted iron in central-eastern areas of the aquifer, the creation of a reducing environment with calcium carbonate precipitation, and formation of imprevious crust.

Soil quality overall soil improvements

Not relevant for this application

Information on Soil quality overall soil improvements

Soil is relevant for this applicationonly regarding infiltration rates. Once the recharge has began, silting is one of the major constrains in terms of infiltration reduction. This is why Soil Aquifer Tecniques are applied in the channel /soakways and in the infiltration basins.

National Id

Spain_03

Site name

Segovia province, left bank of Voltoya and Eresma Rivers.

Summary

Managed Aquifer Recharge in Los Arenales (Segovia, Spain).
As showed by data obtained after 8 effective recharge cycles carried out in an experimental area (Cubeta de San Tiuste) at Los Arenales Aquifer (Segovia, Duero River Basin, Spain), Managed Aquifer Recharge can be more than an effective measure for storing large quantities of water in underground aquifers to naturally increase the quantity of groundwater in times of shortage: it can also result in an enhanced natural condition of aquifers and water availability. Also, the natural cleaning process of water percolating through the soils when entering the AGR showed its potential for providing improved water quality

NUTS Code

Castilla y León

RBD code

ES020

Transboundary

Data provider

Estefanía Ibáñez (IMDEA Water) in close cooperation with Enrique Fernández Escalante (TRAGSA-SEPI) whose valuable contribution is acknowledged and very much appreciated.

Longitude

-4.572

Latitude

41.1445

EEA core metadata

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