Impacts of intensive agricultural irrigation and livestock farming on a semi-arid Mediterranean catchment

Abstract

Irrigation return flows (IRF) are a major contributor of non-point source pollution to surface and groundwater. We evaluated the effects of irrigation on stream hydrochemistry in a Mediterranean semi-arid catchment (Flumen River, NE Spain). The Flumen River was separated into two zones based on the intensity of irrigation activities in the watershed. General linear models were used to compare the two zones. Relevant covariables (urban sewage, pig farming, and gypsum deposits in the basin) were quantified with the help of geographic information system techniques, accompanied by ground-truthing. High variability of the water quality parameters and temporal dynamics caused by irrigation were used to distinguish the two river reaches. Urban activity and livestock farming had a significant effect on water chemistry. An increase in the concentration of salts (240-541 microS.cm(-1) more in winter) and nitrate (average concentrations increased from 8.5 to 20.8 mg.l(-1) during irrigation months) was associated with a higher level of IRF. Those river reaches more strongly influenced by urban areas tended to have higher phosphorus (0.19-0.42 mg.l(-1) more in winter) concentrations. These results support earlier research about the significant consequences to water quality of both urban expansion and intensive agricultural production in arid and semi-arid regions. Data also indicate that salinization of soils, subsoils, surface water, and groundwater can be an unwelcome result of the application of pig manure for fertilization (increase in sodium concentration in 77.9 to 138.6 mg.l(-1)).

Identifying spatial and seasonal patterns of river water quality in a semiarid irrigated agricultural Mediterranean basin

“…Our results were consistent with those reported by Martín-Queller et al (2010), who indicated that the primary sources of contamination in the Flumen River were the discharges from the city of Huesca and those from the agricultural area. Group 2 contained sampling stations located in urban areas (I3, I4, and I5).…”

“…In this final route, the river crosses quaternary glacis and alluvial fans that overlay a tertiary structure composed of conglomerates, sandstones, and clays (Quirantes 1978). Saline mudstones and gypsum deposits observed in the lower part of the basin influence the water quality of the river at lower reaches (Martín-Queller et al 2010). The Isuela River, which runs parallel to the Flumen River for one third of its length, is the only perennial tributary and joins the Flumen River in the flat area of the basin.…”

Multivariate analysis of soil salination-desalination in a semi-arid irrigated district of Spain

“…This evolution can be attributed to a two-step process: first, irrigation with water of very low ionic content promoted the leaching of salts, and second, the water table rose as a result of overabundant irrigation, leading to a rebound in salinity. This explanation agrees with the magnitude of the irrigation return flows in this district and its impact on the volume and quality of the surficial waters (Isidoro and Aragüés, 2007;Martín-Queller et al, 2010). Under similar conditions, Badía et al (2011) recommended irrigating the soils of platforms and slopes with small water volumes at frequent intervals to decrease the hazard of water table rise and salination in the soils of the bottoms.…”

Changes in precipitation recycling over arid regions in the Northern Hemisphere

“…This irrigation impact on PRR can be explained in a sense that irrigation increases soil moisture and supplies abundant vapor for evapotranspiration, which enhances the precipitation recycling and precipitation. The observations show that the irrigation areas are intensively expanding from 1960s in arid region of North Africa and West Asia (Jomaa et al 2015;Martín-Queller et al 2010), which consist with PRR increases in this study. In additional, according to Eqs.…”