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Analysis of spatiotemporal relationships between irrigation water quality and geo-environmental variables in the Khanmirza Agricultural Plain, Iran

Shahabeddin Taghipour Javi, Hadi Mokhtari, Ahad Rashidi, Hojjatolah Taghipour Javi

Faculty of Environment, University of Tehran, Tehran, Iran

College of Agriculture, Shahid Chamran University of Ahvaz. Ahvaz, Iran

Faculty of Geography, University of Tehran, Tehran, Iran

Key words: Irrigation water quality index (IWQI), Geo-environmental variables, Spatial and temporal relationship, Statistical analysis, Khanmirza agricultural plain.

environmentalAbstract

The goal of this work was to explore spatiotemporal relationships between irrigation water quality index (IWQI) and geo-environmental variables in the Khanmirza agricultural plain, Iran. Data from 1987 to 2013 was applied to analyses of local statistics by geographically weighted regression (GWR). For this purpose, a statistics index was used to generate IWQI maps applying ionic composition of the water used for agriculture. Geo-environmental variables such as, electrical conductivity soil (EC), changes in water table, aquifer thickness and changes of land cover were applied in the current research. Data for all variables were acquired from field observations, lab analysis, and from several local projects in the region. According to IWQI outputs, throughout the study area, and particularly in the central parts of the plain, groundwater quality had gradually declined over the past 26 years. All results for spatial distribution of local R2 determined by the GWR approach showed that relationships between IWQI and the four geo-environmental variables were consistent over space; this result was attributed to natural characteristics and from groundwater management in the region. Likewise, results of t values for local parameter estimates revealed both positive and negative relationships with higher significance (p≤0.01 and p≤0.05) between IWQI and geo-environment variables, which were mainly centralized in central parts of the study area. The current study provides essential information for groundwater resources planning in regions with a severe decrease of water quality and in regions where agricultural land is mainly irrigated by groundwater.

Get the original articles in Source: Volume 6, Number 6, June 2015 – JBES

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