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Hydrological changes in Lerma creek (Zaragoza) after the implementation of irrigation

Abstract:

Irrigation expands without a real knowledge of its impacts and dynamics. This work aims to analyze changes in a natural creek's hydrology as a consequence of receiving irrigation return flows from a newly-irrigated area. To this end, trends and seasonal patterns of flow, electrical conductivity and nitrate concentration were studied in Lerma creek (Zaragoza) from unirrigated conditions (2004) until the new irrigation area was completely transformed (2011). Irrigation resulted in an increase in flow (4.2 L/s·year) and nitrate concentration (5.6 mg/L·year) values. Although electrical conductivity decreased (-0.4 mS/cm·year), the increase in flow resulted in an increase of the mass of salt exported from thearea (232 kg/year). Irrigation management and hydro geological conditions produced annual, weekly and daily cycles of the studied variables. The results provided an insight on hydrological changes and their dynamics after implementation of irrigation, which should be taken into account for an adequate water resources management. © Universidad de La Rioja.