Abstract
ABSTRACTDroughts can have serious negative impacts on the water quality needed for irrigated agriculture. The Metropolitan region of Chile is a relevant producer of high-value crops and is prone to droughts. Standardized Drought Indices were used to characterize meteorological and hydrological droughts for the period from 1985 to 2015. To understand the relationship between droughts and water quality, we evaluated the correlations between daily discharge and surface water quality observations. The threshold level method was used to compare physicochemical parameters during hydrological drought periods with the Chilean water quality thresholds for agricultural uses. A significant (p < 0.05) negative relationship between discharge and electrical conductivity and major ions was found in most of the basin. Hydrological stations located in irrigation districts exceeded the official thresholds for these parameters during hydrological drought periods seriously threatening irrigated agriculture of the region.
Highlights
Drought is a natural phenomenon that can occur in all climatic zones and is defined as a sustained and regionally extensive occurrence of below-normal natural water availability (Tallaksen and van Lanen 2004)
The longest drought periods in most of the basin occurred in recent years (2010–2015), while in meteorological droughts, the longest and most intense droughts were in the period of 2010–2013 and 1988–1999
The electrical conductivity and major ions analyzed in the irrigation districts increase during drought periods, reaching values that had surpassed the Chilean regulation for agricultural water uses
Summary
Drought is a natural phenomenon that can occur in all climatic zones and is defined as a sustained and regionally extensive occurrence of below-normal natural water availability (Tallaksen and van Lanen 2004). In the context of climate change, an increase in global temperatures is projected that will impact evapotranspiration and specific humidity of the air, affecting the ability of the atmosphere to store water, with direct effects on the magnitude, frequency, intensity and spatio-temporal distribution of precipitation (Wang et al 2016 and references therein). According to Iglesias and Garrote (2015), the potential impacts on the agricultural production in these areas are: (a) an increase in water demand due to higher rates of crop evapotranspiration in response to rising temperatures; (b) intensification of water shortages, especially in the spring and summer due to increased irrigation requirements; and (c) deterioration of water quality due to high temperatures and low levels of runoff in some regions, inducing additional stress to irrigated areas, among others
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