Salinity contamination response to changes in irrigation management. Application of geochemical codes

Abstract

Salinity contamination caused by irrigation has been widely studied but the analysis of geochemical processes regarding agronomic variables has not adequately been considered yet. The research presented here analyzes the influence of changes in irrigation management on salinity contamination, through the use of geochemical modeling techniques, in an agricultural basin during the hydrological year of 2001 and within the period 2005-2008. The results indicate that the changes implemented in irrigation management reduced the masses of salts exported in 72%, although water salinity increased by 25% (this salinity level does not restrict its use for irrigation). The different ionic ratios in drainage water, the results of the salinity balances, and the results of geochemical calculations (mass balances and speciation-solubility) indicate, mainly, precipitation of calcite, dissolution of gypsum and halite and cation exchange. The salt contamination index decreased from approximately 70% to levels close to those presented in modern irrigation areas, indicating that the changes in irrigation management were effective. Petrocalcic genesis and punctual sodification of soils can constitute an agroenvironmental problem that requires adequate management of irrigation and drainage considering future modernization of irrigation areas.

Geochemical Modeling of Systems Affected by Irrigation: The Case of Lerma Basin (Spain, 2004-2020)

“…The excess of Na + and deficiency of Ca 2+ observed in the waters suggests a Na -Ca cationic exchange process that supplies Na + to water and removes Ca 2+ from it to a solid phase. This process has been previously mentioned in other geochemical studies in the zone (Causapé et al, 2004;García-Garizábal et al, 2014;Merchán et al, 2015).…”

“…In this sense, Causapé et al (2004) started an investigation line based on the geochemical modeling of irrigation zones, which enabled the simulation of modernization scenarios for the Bardenas I irrigation zone and the verification of the environmental effects associated with the implementation of irrigation in Bardenas II. García-Garizábal et al (2014) also successfully employed geochemical modeling to analyze the salinity dynamics of irrigation return flows associated with changes in irrigation management at the Irrigation Community n • V at Bardenas. Merchán et al (2015) presented an initial assessment of the geochemical processes at a new irrigation zone of the Lerma basin (Fig.…”

Geochemical processes controlling water salinization in an irrigated basin in Spain: Identification of natural and anthropogenic influence

“…Applications reported in the literature include the use of multivariate analysis to understand the main factor explaining the chemical evolution of waters in regional alluvial aquifers (Acero et al, 2013;Lorite-Herrera et al, 2008). For geochemical modeling, some examples of application are the use of inverse modeling approaches to elucidate the net geochemical reactions occurring in a water flow line from irrigation water to drainage water (Causapé et al, 2004a;García-Garizábal et al, 2014) or the use of direct modeling approaches to reproduce observed patterns in groundwater and to develop simulations in which different hypotheses can be tested (Kim et al, 2005;Stigter et al, 2006). However, both approaches are seldom applied to the same study area, which could improve the knowledge on the processes controlling the hydrological system.…”