A Hydrological Model to Evaluate Environmental Impacts due to Extensive Irrigation. Case study: Basin of the Ludueña Stream, Santa Fe, Argentina.

ZIMMERMANN, ERIK DANIEL; GERARDO RICCARDI; MARGARITA PORTAPILA

WIT Transactions on Ecology and the Environment

WIT

Lugar: Southampton; Año: 2007 vol. 1 p. 457 - 468

1743-3541

A mathematical model of hydrological simulation quasi-3D is described. Themodel is suitable to simulate the hydrological behaviour in flat lands consideringinteractions between the surface zone ? vadose zone (UZ) ? saturated zone (SZ).The space domain is discretized in layers of surface and underground cells. Ineach cell, the model can quantify state variables dynamically (interception,surface storage, UZ and SZ storages) and exchange flows (evapotranspiration,infiltration, surface and groundwater flows, flow through constrictions). Thisaptitude of connecting surface and groundwater hydrology, enables the model topredict changes in the hydrological process due to human activities at basin scaleas well as long term impacts. In this paper results of the application andcalibration of the model for the Ludueña Stream System (Santa Fe, Argentina)are described.The model was run to evaluate the hydrological effects that ariseout of four extensive irrigation scenarios in the Ludueña Stream basin. Thesimulation is done for a period of twenty years. The considered scenarios are asfollows: #0 corresponds to the present situation in the basin, for which the modelwas calibrated. #1, #2 and #3 are three hypothetical scenarios where the soilmoisture level ranges from 60% to 75% and to 90% of the field capacity, in thisorder. It is demonstrated that scenario #1 has not great consequences for thehydrological process and does not contribute to groundwater vulnerability. Theresults for scenario #2 present important consequences for the hydrologicalprocess of the real system. An increment in the recharge of the aquifer is found,modifying the groundwater table, with higher impact in low areas. Thevulnerability to the contamination processes rises considerably towards the basinhead. For scenario #3, the hydrological process has a very significant variation,not only for the mean and extreme hydrological values but also for the spacepatterns. The groundwater level is greatly increased reaching a situation of highvulnerability in terms of contamination processes. From these results, weconclude that scenarios #2 and #3 are unfeasible as far as sustainable irrigation isconcerned.