General Characterization
The Silves, Lagoa and Portimão Hydro-Agricultural Developments and the Várzea do Benaciate Hydro-Agricultural Development constitute two of the principal public irrigation systems in the western Algarve (Barlavento Algarvio).
This Association is integrated into the Algarve Rivers hydrographic basin, while Várzea do Benaciate Hydro-Agricultural Development is adjacent to the Querença–Silves aquifer system.
Both are managed by the Association of Irrigators and Beneficiaries of Silves, Lagoa and Portimão.
These multipurpose developments are primarily intended for agricultural irrigation, while also contributing to industrial water supply and to the environmental stabilization of the floodplains of the lower Arade and Odelouca rivers.
Aproveitamento Hidroagrícola de Silves, Lagoa e Portimão - AHSLP
The Silves, Lagoa and Portimão Hydro-Agricultural Development was conceived out of the need to secure water of adequate quantity and quality for the most fertile agricultural areas of the region, characterized by the alluvial floodplains of the Arade and Odelouca rivers.
Construction took place between 1944 and 1956, covering agricultural areas within the municipalities of Silves (1,458 ha), Lagoa (704 ha), and Portimão (138 ha).
The beneficiary area was progressively updated: initially comprising 1,900 hectares, it increased to 2,370 ha in 1974 and stabilized at 2,300 ha from 1982 onward — corresponding to 1,155 ha in the Silves Block and 1,145 ha in the Lagoa Block.
Operation of the scheme began in 1956 under the Directorate-General of Hydraulic Services and was transferred in 1959 to the Association of Irrigators and Beneficiaries of Silves, Lagoa and Portimão, an entity established by charter on November 27, 1951, which has since been responsible for its management, maintenance, and modernization. The system currently serves approximately xxx farmers.
The main water supply source is the Arade Reservoir, located on the river of the same name. The Arade Dam, an earthfill structure with a clay core, has a height of 42.5 m, a crest length of 246 m, and a useful storage capacity of 26.7 hm³, with a catchment area of 229 km².
The dominant soils are Recent Alluvial Soils (A), Moderately Saline Soils (As) and, in the Barrocal areas, Calcareous and Mediterranean Soils (Aac, Atac, Sr). Agricultural suitability is high, with a strong vocation for citrus crops, orchards, vegetables, and vineyards.
In 2006, ARBSLP promoted the Rehabilitation and Modernization Project of the Irrigation Network of the Silves Block, which was completed in the same year.
In 2012, ARBSLP requested the design team (Consultores de Engenharia e Arquitetura, S.A.) to revise Sub-Block 1, as significant changes had meanwhile occurred in land use and in the originally planned hydraulic configuration.
Studies carried out identified localized salinization phenomena in the low-lying floodplains of Silves, associated with groundwater abstraction practices and inadequate drainage, as well as the predominant influence of tidal effects in relation to the natural flow of the Arade River.
Within the scope of the development, three hydroelectric power plants — Arade, Pinheiro, and Vila Fria — were installed, none of which is currently operational.
The modernization of the hydraulic infrastructure in Lagoa was carried out through the Detailed Design for the Rehabilitation and Modernization of the Irrigation Network of the Lagoa Block, which covered the sub-blocks of Vila Fria, Lagoa, and Quinta da Vala – Alagoas.
These interventions aimed to increase water and energy efficiency, reduce conveyance and distribution losses, and enable the integration of a potential remote management and automation system. Technical alternatives were studied, culminating in the implementation of pressurized systems, ensuring minimum service pressures suitable for localized irrigation (3.5–4 bar). Hydraulic sizing was performed using the Clément method, ensuring uniformity and optimization of the pressure regime. The network was constructed using PVC piping (PN10/PN16) and ductile cast iron, and equipped with sectional valves, air release valves, bottom outlets, and multi-outlet hydrants.
In Lagoa, the Vila Fria and Lagoa pumping stations, together with the Vila Fria Balancing Reservoir, form the core of the modern pumping and distribution system.
Silves, Lagoa e Portimão Exploração
Characterization
DRAP: Algarve
Location:
District: Faro
Municipalities: Silves, Lagoa and Portimão
Parishes: Silves, Alcantarilha, Lagoa, Porches, Estombar, Carvoeiro and Portimão
Hydrographic Region: RH8
Hydrographic Basin: Algarve Rivers
Watercourse: Arade River
Military Map 1:25,000 nos: 595, 596 and 604
Objective:
Agriculture and supply to industry
Year of completion: 1956
Total irrigated area of the project: 2,300 ha
Number of beneficiaries planned: 1,482
Area under cultivation: 2,300 ha
Number of current beneficiaries: 1,465
Solos
| Dominant Soils | 73.01% of the total area of the AH | Classification | Suitability for irrigation |
|---|---|---|---|
| Aac | 14,59 | Incipient Soils - Modern Alluvial, Calcareous (Para-Calcareous Soils), with a heavy texture. | 1, 2 |
| Atl | 12,90 | Incipient Soils - Ancient, Non-Calcareous Alluvial Soils with a light texture. | 2, (3) |
| Atac | 9,29 | Incipient Soils - Ancient Alluvial Soils, Calcareous (Para-Calcareous Soils), with a heavy texture. | 2, 1, (3) |
| Sr | 7,55 | Slightly Unsaturated Clayey Soils - Mediterranean, Red or Yellow Soils, Normal Non-Calcareous Materials, from "rañas" or similar deposits | 3, (4) |
| As | 7,18 | Halomorphic Soils - Saline Soils, with Moderate Salinity, from Alluvial Deposits, with a medium texture. | 3, 4 (resistant crops) |
| A | 6,93 | Incipient Soils - Modern, Non-Calcareous Alluvial Soils of medium texture | 1, (2) |
| Vac | 5,48 | Calcareous, red soils of normal xeric climate regimes, from calcareous clayey detrital rocks (with a clayey-loam to clayey texture) | 2, (3) |
| Aa | 5,13 | Incipient Soils - Modern, Non-Calcareous Alluvial Soils with a heavy texture | 2 |
| Cbc | 3,96 | Reddish-brown clays, limestone, not decarbonated, of basalts or dolerites or other basic eruptive or crystalline rocks associated with friable limestone. | 2 |
Potential suitability for irrigation:
1-High
2-Moderate
3-Marginal
4-Conditioned for restricted uses
6-Totally unsuitable
Cultural occupation: Orchard (consisting almost exclusively of citrus fruits, largely grown in association with other crops such as corn and beans), and rice
Water source: Surface water
Water supply to farms: Gravity
Management: Association of Irrigators and Beneficiaries of Silves, Lagoa and Portimão
Tariff system: Exploitation and conservation fee per hectare benefited
Existing infrastructure in 2008
Barragem do Arade
Maximum height above the riverbed: 42.5 m
Crest length: 246.00 m
Reservoir capacity: 26,744,000 m3
Pumping Station: 1
Primary Irrigation Network: 45,746 m
Irrigation Networks: 82,700 m
Power Generation Plant: 3 (Arade, Pinheiro and Vila Fria)
There was no intervention during the period 2000-2008 (QCA III)
Modernization/rehabilitation needs
— Rehabilitation and modernization of the irrigation network in the Lagoa Block
— Rehabilitation and modernization of the irrigation network in the Silves Block
Barragem do Arade - Adaptation of the dam to the RSB (ProDeR application):
-
Repair of hydraulic structures (water intake tower equipment and spillway gates);
-
Restoration of the internal drainage system as well as the dam's observation equipment.
Observations
. Alvará de 1951-11-27, publicado no Diário do Governo n.º 283, IIª Série, de 10-12-1951.
Portaria n.º 1078/2000 (2ª Série) de 27 de Junho de 2000, publicada no D.R. n.º 171, IIª Série de 26 de Julho de 2000.
Escritura dos Estatutos da ARBSLP no Cartório Notarial de Lagoa Algarve, realizada no dia 29 de Setembro de 1998 e alterada no dia 23 de Março de 1999.
Regulamento da Obra de Rega das Campinas de Silves, Lagoa e Portimão de 18-04-1972, publicado no Diário do Governo n.º 115, IIIª Série, de 16-05-1972.
Declaração de Utilidade Pública do Plano Geral do aproveitamento das ribeiras de Odelouca e Arade, que compreende as barragens de Odelouca e do Funcho, vias de comunicação, túnel de interligação Odelouca-Funcho, a estação elevatória do Funcho e o canal de adução Funcho-Benaciate, de 06-11-1980, publicada D.R. n.º 276, IIª Série, 28-11-1980, na sequência do Despacho do Ministro Equipamento Social Ambiente de 07-01-1975, exarado sobre o parecer n.º 4674, emitido pelo Conselho Superior de Obras Públicas e Transportes em 19-12-1974.
Resolução do Conselho de Ministros n.º 48/2003, de 29 de Março de 2003, publicada no Diário da República n.º 75, Iª Série-B de 29 de Março de 2003, que ratifica o PU do Núcleo DT do Morgado da Lameira, que inclui o “Amendoeira Golf Resort”.
Aproveitamento Hidroagrícola da Várzea do Benaciate - AHVB
Water supply is provided through groundwater abstraction via nine wells, connected by a primary network of 5.8 km, a secondary network of 13.5 km, and a drainage network of 18.2 km, complemented by 27 km of agricultural access roads.
The system operates under pressure with a central pumping station and was classified as a Group III Project under Order No. 9550/2010 of May 27, succeeding a previous Group II classification established by Council of Ministers Resolution No. 125/97.
Groundwater is used primarily for irrigation and, to a lesser extent, for urban water supply. As the system required modernization—particularly the rehabilitation of the irrigation network and abstraction wells, as well as the renewal of electromechanical installations—the Directorate- General for Agriculture and Rural Development carried out the modernization of the hydro- agricultural development, which was completed in 2022.
Technical and administrative management of the development was concessioned to the Association of Irrigators and Beneficiaries of Silves, Lagoa and Portimão in 2023, which currently ensures the integrated operation of both irrigation developments/perimeters.