In semi-arid areas, agricultural practices have been found to significantly alter groundwater quality. Although significant research has been conducted on the impacts of the intensification of irrigated agriculture, many pivotal questions relating to the impact of traditional agricultural practices on groundwater quality remain unanswered. In this study, the results of major ions analysis of 91 water samples collected in the semi-arid piedmont of the High Atlas Mountains, central Morocco, are used to assess the impact of traditional irrigation practices on groundwater quality. Despite the use of organic fertilizer in the irrigated area, the NO3 groundwater concentrations remain low (median = 9 mg/L) and only increase on average by 3.6 mg/L during the irrigation season. All groundwater sampled in the irrigation area has an excellent quality for both drinking and irrigation purposes based on the chemical indices. Overall, groundwater chemistry is controlled by geogenic processes. Relationships between major ion in groundwater reflects the mineral dissolution and ion exchange processes during the trajectory of the streamwaters from the mountain to the alluvial plain via irrigation practices. In comparison, in the non-irrigated area, halite dissolution and/or transpiration processes results in increases in electrical conductivity values that were over twice the values in the irrigated area. The seasonal decrease of electrical conductivity values in groundwater beneath the irrigated area (on average from 841 to 692 mu S/cm) is a result of irrigation recharge, which counterbalances effects of salinization mechanisms that can often characterize irrigated arid zones. These results highlight the low impacts of this ancestral hydro-agro system on groundwater quality. Such a traditional irrigation system provides a nexus between food production, low energy costs (streamflow diversions by gravity-fed channels), and low environmental impacts. In the context of accelerations in global change impacts via the rapidly expanding modern irrigation practices, such traditional hydroagro systems, where possible, should be highlighted and preserved.
Plan de classement
Hydrologie [062]
;
Sciences du monde végétal [076]
