Impact of anthropogenic activities on the groundwater resources of the unconfined aquifer of Triffa plain (Eastern Morocco) Abdelhafid Fekkoul, Yassine Zarhloule, Mimoun Boughriba, Alae-eddine Barkaoui, Abdelhakim Jilali & Salem Bouri Arabian Journal of Geosciences ISSN 1866-7511 Arab J Geosci DOI 10.1007/s12517-012-0740-1
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Author's personal copy Arab J Geosci DOI 10.1007/s12517-012-0740-1
ORIGINAL PAPER
Impact of anthropogenic activities on the groundwater resources of the unconfined aquifer of Triffa plain (Eastern Morocco) Abdelhafid Fekkoul & Yassine Zarhloule & Mimoun Boughriba & Alae-eddine Barkaoui & Abdelhakim Jilali & Salem Bouri
Received: 6 November 2011 / Accepted: 31 October 2012 # Saudi Society for Geosciences 2012
Abstract Located at the northeastern part of Morocco, the plain of Triffa is characterized by a semi-arid climate where water resources are rather fragile and influenced by a highly irregular rainfall distribution, both in time (annual and interannual distribution) and in space. The mean annual rainfall does not exceed 240 mm. In the Triffa plain, the impact of anthropogenic activities on the groundwater resources is reflected both by (a) the decrease in the piezometric level due to the over exploitation and droughts and (b) the deterioration of the chemical quality of water. Currently, this situation is felt mainly by the farmers. The unconfined aquifer is under stress due to the increase of the pollution rate, especially by nitrates that are above the WHO standards, and salinity. Organochlorine pesticides are ubiquitous and persistent organic pollutants used widely in agriculture. Due to their extensive use in agriculture, organic environment contaminants such as hexachlorocyclohexane, DDT, and DDD along organochlorine pesticides are distributed globally by transport through water. Pesticides such as aldrin, lindane, and heptachlor have also been detected and were considered as indicators showing the need to inform and to train farmers on the pesticides and fertilizers use in order to reduce the threat of groundwater contamination. Keywords Anthropogenic activities . Groundwater contamination . Aquifer . Triffa plain A. Fekkoul : Y. Zarhloule : M. Boughriba : A.-e. Barkaoui (*) : A. Jilali Laboratory of Hydrogeology and Environment, Faculty of Sciences, University Mohammed I, Oujda, Morocco e-mail:
[email protected] S. Bouri Laboratory of Water-Energy-Environment, ENI Sfax, Sfax, Tunisia
Introduction Water resources are considered as the first priority by the Moroccan national strategy for sustainable development. The economy of the country is mainly based on agriculture, which is reflected on water use. Not surprisingly, irrigation is responsible for 90 % of water consumption in Morocco; thus, water resources management is a fundamental variable for the present and the future of Morocco, regardless of climate change. The Triffa plain, located in the northeast of Morocco and not far from the Mediterranean coast, is an important agricultural area (36,060 ha) composed of 33 % fruit (citrus), 24 % cereals, and 13 % industrial crops plantations, 7 % fodder farming, and 3 % manufacturing of various agricultural products (Fig. 1). Irrigation is essential due to the semi-arid climate conditions, with rainfall being dominated by a strong variability both in space and time, often resulting in water scarcity. Water demand is high for agriculture and for drinking water supply. Unfortunately, there has been a recently perceived quantitative and qualitative deterioration of groundwater resources. The Triffa plain is characterized by two aquifers; a shallow and unconfined in the Plio-Quaternary layers, generally with poor groundwater quality, and a deep Liasic carbonate with good groundwater (Zarhloule et al. 2009). Excessive use of pesticides and groundwater for the agriculture may lead to the contamination of groundwater of the unconfined aquifer by drift, vertical drainage, and leaching. The groundwater contamination in Triffa plain may cause a continuous human exposure since it represents the most important source of drinking water supply. This survey highlights the water stress as well as water contamination by the nitrates, the salinity, and the presence of the pesticides. The objective of this survey is to identify the influence of the human activity on the groundwater resources due to intense agricultural activity and uncontrolled use of
Author's personal copy Arab J Geosci
Fig. 1 Location of the study area
fertilizers and pesticides. For this purpose, 700 wells have been inventoried and 251 have been selected for the acquirement of data such as water table, TDS, major elements, nitrates, and pesticides. The sampling was conducted in 2007.
Study area The Triffa plain is situated at the northeastern part of Morocco (Fig. 1) with 750 km2 surface area. It is limited by Ouled Mansour hills in the north, Beni Snassen Mountains and Cherra river in the south and, respectively, in the east and the west by Kiss river and Moulouya River. The plain constitutes a vast synclinal depression formed by secondary and Quaternary geological formations (Fig. 2). The plain is characterized by two types of aquifers; the Liasic limestone and dolomites which host a confined aquifer that is the Fig. 2 Geological map of the studied area
origin of the thermal water in the region and an unconfined aquifer in the Quaternary heterogeneous layer system. A flexure running approximately east-west direction (Fig. 2) divides the unconfined aquifer in two distinct parts: The north of the flexure where the aquifer is composed by Villafranchian limestone, while south of it where the aquifer is formed by Quaternary layers is composed mainly by silt and conglomerate overlying the Villafranchian limestone (Fig. 3). The transmissivity coefficient in the south of the flexure varies between 10−2 and 5 10−3 m2/s for the Quaternary layers and 2.10−4 and 4.10−5 m2/s for the Villafranchian layers. The substratum is formed by marls dating from the Pliocene period (Zarhloule et al. 2009). The climate in this area is generally semi-arid. The total rainfall does not exceed 327 mm/year, being concentrated between January and April. The yearly temperature average is 17.40 °C, but seasonal variability is high, with a minimum of 11 °C and a maximum of 25 °C. The average annual evapotranspiration is about 300 mm/year. Water budgets estimate an infiltration rate of 14 % of the precipitation. The overall volume of water extraction for irrigation from the unconfined aquifer is approximately estimated at 55.17 Mm3/year in 2004, and the returns of irrigation water are the main source of groundwater recharge of the unconfined aquifer. They represent 30 to 55 Mm3/year from pump irrigation, 140 Mm3/year from water irrigation dam, and 5–10 Mm3/ year from irrigation by springs (Zarhloule et al. 2009).
Data acquisition and processing The sampled sites in this study include observation wells, springs, and wells for irrigation. Water samples were collected
Author's personal copy Arab J Geosci Fig. 3 North-south geological cross section
from the 251 existing wells (Fig. 4). Choice of the wells to sample was based on the following criteria:
3. Location of the wells with respect to the main agricultural areas.
1. Spatial distribution, to ensure appropriate coverage of the aquifer; 2. Location of the wells with respect to regional groundwater flow direction; and
For the pesticides, 15 wells were selected in an area with uncontrolled fertilizer use associated to intensive agricultural systems (citrus, vegetables, cereals, and various tree crops) (Fig. 4, Table 1).
Fig. 4 Land use map (modified after Mairess 2011) with the sampled wells
Author's personal copy Arab J Geosci Table 1 List and content of the required active matters. Nd not detected
Active matters
Limit of quantification
Concentration detected in μg/l
Maximum permissible concentration in μg/l
Aldrin Endosulfan sulfate Lindane Dieldrin Endrin
