Hydrosaline Balance in and Nitrogen Loads from an irrigation district before and after modernization

Abstract

The stress on water resources and the need to maintain water quality and to protect the environment push for an efficient use of natural resources: irrigation water and nutrients (particularly nitrogen). Traditional surface irrigation areas (frequently located on saline materials) use huge amounts of these resources, contributing to the degradation of water bodies by salts and nitrate loads in Irrigation Return Flows (IRF), and also to soil salinization when salt leaching is constrained. In this respect, 1.5 Mha of irrigated lands in Spain have been modernized recently to more efficient systems. Such is the case of the Violada Irrigation District (VID; 4880ha; Northeast Spain) modernized from surface to sprinkler irrigation. The availability of historical data under both irrigation systems in VID offered an ideal scenario to analyze the impact of the modernization process on water consumption and nitrogen management. The analysis was based on the water and salt balances, which showed that irrigation modernization triggered an alteration of the hydrological regime of the VID controlled by the irrigation system. The transformation to sprinkler irrigation resulted in high quality non-diverted water savings of 5536 m 3 /ha•yr (19 hm 3 /yr for the whole VID) available for other uses downstream, triggering a reduction of the IRF from the VID to the Ebro River. In general, the modernization has brought about a clear reduction of all flows in the water balance (except ETa), together with a slight increase in salt and nitrate concentrations in IRF. Both changes entailed a reduction in salt and nitrate loads of 11.5 Mg/ha•yr (44889 Mg/yr;-60.4%) and 82.2 kg N/ha•yr (301 Mg N/yr;-70.4%), respectively. The modernization also resulted in better water use and agronomic indices (drainage fraction, consumptive fraction and irrigation fraction). It was also concluded that at the moment, there is no risk of soil salinization in VID. Hydrosaline Balance in and Nitrogen Loads from an irrigation district before and after modernization.

A Legacy of Quantitative and Qualitative Data for the Irrigated Violada Area and Conterminous Lands in Aragon, Spain

“…Several studies were conducted involving the ecology of Violada, such as those mentioned by [9]. More recent studies have been devoted to the soil and water salinity of Violada, as is the case in [10][11][12][13][14][15]. A comparison of these studies against the data contained in the IRYDA report [1] can highlight the decadal effects of irrigation, as was done for another irrigation area [16].…”

Water Balance and Nitrate and Salt Exports from a Saline–Sodic Irrigation District in Castelflorite (Huesca, NE Spain)

“…Total water volume usage data were obtained from the records of the Irrigation Community. Irrigation data per crop were estimated from surveys to local farmers, as in Jiménez-Aguirre et al [26]. These surveys (n = 36) also helped to determine agronomic practices, fertilization, type of fertilizers and dates of application, and to estimate crop yields.…”

“…Newly modernized irrigation communities offer a suitable scenario to evaluate the impact of aforementioned transformation on the use of water and to assess its effects on the quantity and quality of water. An example of a long-term monitoring of one of those irrigation communities, that of La Violada, has been reported in [20][21][22][23][24][25][26][27].…”

Simulation of Flow and Agricultural Non-Point Source Pollutant Transport in a Tibetan Plateau Irrigation District

“…The use of fertilizers in irrigation districts is considered as one of the most common sources of environmental pollution [1,2]. With low fertilizer recovery efficiency of nitrogen in the field, a major portion of applied fertilizers is lost due to various processes [3].…”