Eastern Algarve
Hydro-Agricultural Project
of the Eastern Algarve Hydro-Agricultural Development.
Overall characterisation
The Eastern Algarve Hydro-Agricultural Project is part of an overall hydraulic system consisting of the Odeleite-Beliche multi-purpose scheme for irrigation and urban supply.
The system, covering an area of approximately 35,000 ha, along the coastline between Vila Real de Santo António and Almancil, including the Campina de Faro, is divided into two phases, only the first of which has been implemented. In this phase, the system also supplies seven municipalities in the Faro district, for a floating population estimated at 800,000 inhabitants in 2020 (250,000 permanent).
Included in the agro-ecological zone known as ‘Sotavento’ and dominated by traditional Mediterranean crops such as almond, fig and carob trees, the first phase of improvement in the eastern Algarve covers a total area of around 8,600 ha, which extends along the coastline (where greenhouses and open-air horticulture prevail) and the barrocal lands (where irrigation has allowed orchards to be established), south of the Algarve Longitudinal Way (Via do Infante), between the town of Altura to the east and the Fuseta-Moncarapacho road to the west, in the municipalities of Vila Real de Santo António, Castro Marim and Tavira.
The land structure is essentially characterised by small and medium-sized properties.
The Odeleite/Beliche Hydraulic Utilisation Centre
The construction of the Odeleite/Beliche Hydraulic Utilisation Center has satisfied the wishes of the farmers of this coastal region, who for many years have been calling for the construction of hydraulic infrastructures that make water available in quantity and quality, in order to guarantee the water needs of their crops. This project covers an area with excellent climatic conditions and the availability of soils suitable for irrigation, favourable for horticulture, fruit growing, floriculture and subtropical crops which, due to their earliness, offer competitive advantages even in a wider market.
We believe that making the water resource available will enable rural development to be energised and supported, unequivocally contributing to improving the standard of living of the population involved in this process.
Thus, and as a logical follow-up to the construction of the irrigation infrastructures and because hydro-agricultural development should be geared towards the real involvement of potential beneficiaries, IHERA promoted the formation of the Associação de Beneficiários do Plano de Rega do Sotavento Algarvio, as an organisation representing farmers and which will be responsible for managing the agricultural component of the development.
The public notarial deed took place on 17 November 1992 and was formally recognised by the Ministry of Agriculture on 26 January 1993 through Ministerial Order 44/93 published in the Diário da República (II’ Série) on 5 February 1993.
It is with great satisfaction that we present the Eastern Algarve Hydraulic Development in its agricultural component, for which IHERA has mobilised significant material and technical resources in order to support the necessary changes in this sector.
Promoting Entities of the Project
The launch of the implementation of the multi-purpose Odeleite/Beliche Hydraulic Development, which will irrigate the eastern Algarve and supply urban water, took place with the signing of a protocol in March 1989 at the Civil Government of Faro between the ex-Direcção-Geral de Hidráulica e Engenharia Agrícola (now IHERA), the ex-Direcção-Geral dos Recursos Naturais (now INAG), the Direção Regional de Agricultura do Algarve and the Comissão de Coordenação da Região do Algarve.
In December 1991, the former DGRN and former DGHEA, as the project owners, and the Odeleite Consortium, as the contractor, signed the contract for the execution of the Odeleite Dam, the Odeleite-Beliche Tunnel, the Beliche ETA (Water Treatment Plant) Adduction System in Tavira, the Tavira Water Treatment Plant (under the responsibility of INAG), as well as the Irrigation Networks, Drainage Networks, and Agricultural Roads (under the responsibility of IHERA). Subsequently, IHERA awarded the works for the pumping stations EE3, EE4, and EE5, as well as the Filtration Stations.
It should be emphasised that for IHERA this was the first contract adjudicated in the design-build modality, since according to the technical clauses ‘the contract involves the conception, by the bidders, and the preparation of the execution projects, by the Contractor, of all the works and details that are not sufficiently detailed in the patented parts.
This was the case in particular with the irrigation networks, drainage and farm tracks, which were only project bases for the tender, with approximate volume calculations. The plans for the agricultural component were then developed by the project design company Prosistemas, Consultores S.A., based on the proposal submitted by the contractor and called Variant B.
The cultivation plan includes:
The system also includes an important environmental component by preventing soil salinisation. In fact, the farmers concerned by the irrigation perimeter will no longer be using groundwater that drags in large quantities of salts, but will have good quality surface water at their disposal. At the same time, the drainage water will act as a vehicle for eliminating soluble elements stored in the soil.
Main System Components
The cultivation plan includes:
- Odeleite Dam
- Beliche Dam
- Tunnel linking the Odeleite and Beliche reservoirs
- Pipeline
- 5 Pumping Stations
- Water Treatment Station
- Santo Estevão Reservoir
- Irrigation, Drainage and Agricultural Path Networks
Odeleite Dam
River: Odeleite
Year of completion: 1996
Type: Rockfill with upstream concrete lining
Foundation: On schist and greywacke
Height (m): 65
Crest length (m): 347
Reservoir:
Area (ha): 720
Capacity (hm³): 130
Beliche Dam
River: Beliche
Year of completion: 1986
Type: Earthfill, with zoned profile and clay core
Foundation: On schist and greywacke
Height (m): 54
Crest length (m): 527
Reservoir:
Area (ha): 292
Capacity (hm³): 48
TUNNEL
Approximately 3 km long, 3.3 metres high and 3.3 metres wide, the horseshoe-shaped, concrete-lined tunnel allows the transfer of 25 m3/s (maximum value for the second phase).
PIPELINE
The connection between the Beliche reservoir and the Santo Estevão Distribution Center is ensured by a prestressed reinforced concrete pipeline with a diameter of 2500 mm, approximately 28 km long, which transports a maximum flow of 10.4 m³/s, pumped using two pumping stations.
Along the adduction pipeline, several protection devices were installed, such as a surge shaft (at the beginning) and air valves at high points.
The pipeline simultaneously ensures direct supply to Blocks D1 to D4.1.
Santo Estevão Reservoir
Located 28 km west of the Beliche Dam, the Distribution Center consists of an open-air, hillside-type reservoir designed for storage during periods of low demand, both for irrigation and urban supply. It is equipped with a set of hydraulic safety structures and two water intakes: one for supplying the Water Treatment Plant (Tavira ETA) on the northern side, and another for irrigating Blocks D4.2 and D4.3 on the southern side.
The Reservoir, with a capacity of 130,000 m³ between elevation 100.0 and 105.0 (crest at elevation 106.0), provides a volume corresponding to approximately 50% of the daily irrigation consumption of Blocks D4.2 and D4.3
Filtration Stations
The water transported by the adduction pipeline contains a variety of solid particles of different types and sizes, which could damage certain elements of the secondary irrigation network, particularly the air valves and the meters.
On the other hand, clogging is one of the most widespread issues in localized irrigation systems.
To avoid these problems, each irrigation block directly supplied by the adduction pipeline will perform a pre-filtration through its own primary filtration station, consisting of a series of self-cleaning mesh filters, 14 inches in diameter, installed in parallel.
These filters are ineffective for colloidal particles, organic matter, and microorganisms; therefore, farmers using drip irrigation will necessarily need to carry out a different filtration method.
For Blocks D4.2 and D4.3, supplied by the Santo Estêvão Reservoir, three filtration units were chosen in parallel for the project flow rate of 3 x 1.2 m³/s. The proposed screen filters are of the roller-belt (or rotary) type, supported by a rigid structure in the shape of a balance, resting on a single point. Each screen consists of a series of filter panels with a fixed stainless steel mesh mounted in a reinforced frame.
CHART I
Characteristic elements of the filtration stations directly supplied from the Adduction Pipeline
(*) — According to the flow/pressure loss curve obtained in a specific test conducted in an official laboratory, on one of the filters intended for installation
Santo Estevão Reservoir
Located 28 km west of the Beliche Dam, the Distribution Center consists of an open-air, hillside-type reservoir designed for storage during periods of low demand, both for irrigation and urban supply. It is equipped with a set of hydraulic safety structures and two water intakes: one for supplying the Water Treatment Plant (Tavira ETA) on the northern side, and another for irrigating Blocks D4.2 and D4.3 on the southern side.
The Reservoir, with a capacity of 130,000 m³ between elevation 100.0 and 105.0 (crest at elevation 106.0), provides a volume corresponding to approximately 50% of the daily irrigation consumption of Blocks D4.2 and D4.3
CHART II
Characteristics of the Pumping Stations
Irrigation Network
The four irrigation blocks that make up the irrigation system, with an equipped area of 8,100 ha, are spread over two distinct zones separated by the Séqua river: the eastern and central one, elongated in shape, includes Blocks D1, D2 and D3 and Sub-Block D4. 1, with the secondary irrigation network being fed through bypasses in the water pipeline, in the area where it borders the perimeter; the west, more compact, encompasses Sub-Blocks D4.2 and D4.3, further away from the water source, with the secondary irrigation network being fed from the Santo Estevão Distribution Centre. Covering 3,900 farmers, the pressure irrigation network is approximately 271 km long.
The pipes used in Estearn Algarve are made of ductile iron, fibre cement and PVC, selected according to the conditions of construction and use; however, as a reference, it can be said that:
Material | ∅ (mm) |
PVC | < = 350 |
Fiber cement | 350 – 1000 |
Ductile iron | > = 1000 |
Crossings of railways, water lines and main roads (e.g. EN 125) were generally made with ductile iron pipes.
The pipelines are equipped with a large number of control devices suitable for this type of network: shut-off valves (wedge and butterfly), bottom discharges, air valves to prevent the formation of air pockets and, consequently, flow reductions and water hammer, safety valves to prevent overpressure, and irrigation hydrants.
These can have one to four irrigation outlets, each distributing water to different buildings, which implies the flow rate of different volumes, but always with a minimum pressure of 3.5 bar, sufficient for the operation of the tertiary irrigation network (sprinklers or drip irrigation). Each outlet has a flow limiter, a water meter, a pressure reducer, and, in some cases, a micro-air valve.
The irrigation water supply will be “on demand,” allowing the farmer to use the irrigation outlet at any time without needing to inform the irrigation technician. At the end of the irrigation season, the farmer will pay for the volume of water supplied/consumed. Chart III presents the detailed characteristics of the irrigation network.
CHART III
Characteristics of the Irrigation Network
Climate
Semi-arid with Mediterranean characteristics typical of the Eastern region.
Precipitation
Coast: < 400 mm
Mountains: > 1200 mm
November to March: rainiest
(- 70% of annual average)
Temperature
Annual average ~ 17 °C
August – 24 °C
January – 11 °C
Solar Radiation
> 160 Kcal/cm2/year
Sun Exposure
3100 h/year
IRRIGATION METHOD RECOMMENDED FOR THE ENTIRE PERIMETER
Localised irrigation
Total Water Requirements
Average year – 8276 m3/ha/year
Critical Year – 8823 m3/ha/year Peak Month – 1696 m3/ha
SIZING FLOW RATE
(Clement Method):
1.00 l/s·ha (± 5%)
NUMBER OF BENEFICIARIES
3900
Material Used
PVC (PN10 and PN16 Kg/cm2)
∅ 110 a ∅ 315 mm
Fiber ciment (c1.18 e cl. 24)
∅ 350 to ∅ 900 mm
Ductile iron
(K7)-D4LR
(main ducts originating from the Santo Estevão Reservoir
∅ 500 mm (Cond. A) -> D4.3
∅ 1000 mm (Cond. B) ->D4.2
∅1000 mm (Cond. A1) ->D4.3 L
∅1200 mm (Cond. A2) ->D4.30
Project Area (1st phase)
From near the village of S. Bartolomeu, located 6 km west of V. R. S. António, to about 10 km west of Tavira, more precisely to near the village of Fuseta, with the EM-514-1 as its boundary;
Municipalities concerned:
Vila Real de St° António, Castro Marim, Tavira.
Blocks D1, D2, D3 and D4.1 have been in operation since September 1998; blocks D4.2 and D4.3 are currently being trialled.
The longitudinal drainage of the paths is ensured by ditches of various types depending on the width of the available platform.
For transverse drainage, aqueducts, pontoons and ford crossings have been built, the latter for small flows.
Agricultural paths
Some irrigation plots were difficult to access, which made it difficult to mechanise certain activities, including transporting produce to the market.
Building a good network of agricultural accesses will not only prevent the risk of farmers losing income in the future, but will also be useful for utilising and maintaining the irrigation network.
Thus, intervention in the network of farm tracks generally consisted of improving the network of existing tracks, since the area to be irrigated is already reasonably served by communication routes.
The aim was to adapt the new routes to the existing ones, avoiding expropriation and demolition of existing infrastructures.
The road network was prioritised and various types of road were defined according to the expected traffic intensity, corresponding to different platform widths and different types of pavement. Based on these assumptions, within the irrigation perimeter, 78 km of agricultural roads were built, repaired and covered with bituminous matting, according to the following criteria:
Project Speed: 50 km/h
Minimum radius of curvature: 20 – 25 m
Maximum Gradient: 10%
Lane: 3 – 4 m
Berms: 0,5 – 0,75 m
Drainage network
Some say that drainage is the price to pay for sustainable irrigated agriculture; however, it seems to be a fair price, since a good drainage network results in lower production costs through:
- Improved soil structure
- Flood protection
- Improved accessibility
- Salinity control
To this purpose, the existing drainage systems were rationalised and improved, complemented by the opening of ditches in the most deprived areas. The main work carried out consisted of cleaning (by removing fallen trees, logs, stones and rubble), vegetation control and re-profiling of water lines in order to maintain the flow capacity of the streams or ditches, opening new ditches, executing engineering works (aqueducts, pontoons to allow machinery access, falls, confluences, etc.), protecting banks with reinforced rockfill and torrential correction works.
Contractors and Costs
Contract for the construction of the Odeleite Dam, the Odeleite-Beliche Tunnel, the Beliche-ETA Tavira Pipeline, the Tavira Water Treatment Plant, and the Irrigation Networks, Drainage Networks and Agricultural Path Networks:
Contractor: Odeleite-Beliche Consortium, consisting of the companies Mota & Companhia, S.A. (consortium leader), Engil – Sociedade de Construção Civil, S.A., Tâmega – Construtora, S.A., A. Silva & Silva – Indústria e Comércio, S.A., Carlos Eduardo Rodrigues, S.A. and Setal Degrèmont – Tratamento de Águas, Lda.
Designer: ProSistemas, S.A.
Value of Works Executed – (Irrigation Networks, Drainage, and Agricultural Roads): 11.433.135.096$00 (VAT included)
Duration of contract: December 1991 (consignment) – March 1998 (provisional acceptance)
Conception Contract - Construction of the Filtration Stations for the Secondary Irrigation Networks of the Eastern Algarve Hydro-agricultural Project:
Contractor: OIKOS — Construções, Lda
Designer: (HERA / OIKOS — Construções, Lda (filters)
Value of work completed (VAT included): 329.704.473$00
Duration of contract: December 1997 (consignment) – May 1999 (provisional acceptance)
Contract for the construction of the EE3, EE4 and EE5 pumping stations for the Eastern Algarve hydro-agricultural project:
Contractor: OIKOS — Construções, Lda
Designer: ProSistemas, S.A.
Contract value (excluding VAT): 529.927.036$00
Duration of contract: October 1998 (consignment) – June 2000 ( scheduled)
