Hydrogeochemistry as a tool for coastal aquifers management

The case of the Bou Areg aquifer and the Nador Lagoon (Morocco)

Re Viviana, PhDCa' Foscari University of Venice (Italy) & National Engineering School of Sfax (Tunisia)re@unive.it

The Study Area

• Semi-arid climate (300mm/y)• No regular rain season• Agricultural activities cover more than 62% of the Bour-Areg plain area

Issues

Increase in water demand /Overexploitation

Water Scarcity

Saline Water Intrusion

Water Pollution

Food Security

Coastal AquiferArid/ Semi-Arid climate

Population Growth• Internal migration• Tourism

Agricultural Activities

Urban and Industrial development

Project Goals• Overall objectives

– Support science based management practices– Provide data on water quality in the Bou-Areg coastal aquifer and the

Lagoon of Nador

• Specific objectives – Assessment of the natural groundwater quality (baseline conditions)– Evaluation of deviations from the natural conditions – Assessment of aquifer/lagoon interactions, evaluation of groundwater

quality discharging in the lagoon

Methods– Hydrogeological investigation– Geochemical analysis of major and trace element– Isotope geochemistry (δ18O, δ2H, δ18ONO3 ,δ15NNO3, δ13CDIC, δ11B) – Statistical data treatment

Work performed with contribution of:Prof.G.M. Zuppi (Scientific Coordinator)Prof. N. El Hamouti and Mr. R. Bouchnan Faculté pluridisciplinaire de Nador,

Universitè de Oujda (Morocco)Prof. N. El Amrani, Universitè Hassan I Settat (Morocco)Prof. E. Sacchi, Università degli studi di Pavia (Italy)Dr. E. Allais and ISO4 s.n.c. (Italy)Dr. T. Lovato, Euro Mediterranean Center For Climate Change (Italy)Prof. J.Mas-Pla and Dr. A Menciò, University of Girona (Spain)And with the support of the Italian Ministry for the Environment Land and Sea

Results• Sodium-chloride type• High natural salinity,

mainly due to water-rock interaction processes (dissolution of evaporative rocks and carbonates)

• Agricultural return flow: main contribution to groundwater salinization especially in the central part of the aquifer

• [NO3-] often exceeding

WHO limits• High dependency on

seasonal variations

Results

Oued SelouaneIrrigation Channel

Agricultural return flowWater-rock interactions

Results

URBAN

RURAL

Identify the main anthropogenic sources of groundwater pollution

Understand the governing factors of groundwater vulnerability

UNDERSTANDING THE HYDROGEOLOGYC SYSTEM & THE ASSOCIATED BEHAVIOR OF CONTAMINANTS: A NECESSARY STEP IN GROUNDWATER VULNERABILITY ASSESSMENT

Conclusions• HIGH AQUIFER SALINITY due to the coexistence of dissolution processes,

water-rock interactions, and human impacts due to agricultural return flows

Saline water intrusion from the lagoon in the shallow aquifer is negligible, while discharge of polluted groundwater into the lagoon has been found to partially alter its quality

• HIGH NITRATE CONCENTRATIONS associated with two main drivers for human induced pollution: (i) manure and septic effluents, (ii) synthetic fertilizers

• HIGH AQUIFER VULNERABILITY • HIGH DEPENDENCY ON SEASONAL VARIATIONS

Management implications• Need for improving the understanding of groundwater quality• Control of applied irrigation volumes and identification alternative

irrigation sources to improve groundwater quality

• Enhance public participation and the involvement of local farmer associations to enforce adequate groundwater protection

Re V., 2011

Hydrogeochemistry as a management tool

Water quality assessment

Pollution sources

identification

Vulnerability assessment

Science based

management pracrices

• Identification of recharge processes • Separating baseline conditions from anthropogenic

impacts• Identification of groundwater and surface water

Interaction• Identification of mixing processes

• Contaminant-specific vulnerability assessment

• Support the development of effective (science-based) policies for reducing contaminant loads and protecting water resources

• Promotion of stakeholder engagement and public participation

• Development of participatory monitoring assessment

Thank you for your attention

Merci pour votre attention

النتباهكم شكرًا

In loving memoriy of Prof. Gian Maria Zuppi