Journal of Range and Watershed Managment

Spatial variation of nitrate concentrations in groundwater by Geostatistics (Case Study: Kurdan Plain)

Document Type : Research Paper

Authors

Kh. Osati 1
A. Salajegheh 2
S. Arekhi 3

1 *Ph.D. student, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran.

2 Associate Professor, Faculty of Natural Resources, University of Tehran, Karaj, I.R. Iran.

3 Assistant Professor, College of Agriculture, Ilam University, Ilam, I.R. Iran.

https://doi.org/10.22059/jrwm.2012.32045
Abstract
Spatiality assessment of groundwater pollution is very important to determine water quality condition, pollution sources and management decisions. In this case, GIS and geostatistics methods can be useful tools. Spatiality of groundwater quality parameters, in relation with various land uses, can be very extremely. Therefore water samples from 52 wells in the Kurdan area were analyzed in this study. The results show that nitrate concentrations are less than maximum acceptable concentration in drinking water (i.e. 50 mg/L as nitrate recommended by ISIRI and WHO guideline values) except to  one sample  (2 percent of samples) in the study area. Various geostatistics methods, e.g. IDW (power 1-4), ordinary Kriging and RBF (five Kernel functions) were compared after assessing the variograms and the spatiality of nitrate samples. Then the model parameters were calibrated and through the specific methods, predicted and standard errors maps were prepared. Errors criteria show that Kriging is the best fitting model in the study area. Finally, probability map of NO3 concentrations exceeding the threshold value of 50 mg/L, is generated using the Indictor Kriging method. Spatiality of NO3 show that Nitrate concentration is increased where the rock type is permeable, land use is agriculture and slope is enough low to infiltrate polluted water into the wells. This research also tries to describe how to assess the spatiality of groundwater parameters by GIS.

Keywords

Nitrate
Ground water quality
Human activities
Geostatistics
Kriging
Kurdan
Journal of Range and Watershed Managment
Volume 65, Issue 4 - Serial Number 4
Winter 2013
Pages 461-472

  • Receive Date 20 April 2010
  • Revise Date 14 July 2013
  • Accept Date 16 May 2011
  • Publish Date 21 December 2012

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