Geostatistical Mapping and Assessment of Iron Concentrations in Groundwater

Abstract

Iron can often be a problematic substance in water resources; its presence in water causes unpleasant odours, taste, colour, and staining on clothes. In this study, water samples (n = 70) were collected from existing boreholes within the Yenagoa area and subjected to laboratory analysis in order to examine the spatial distribution and trends of iron concentration in groundwater. Landuse/landcover (LULC) was also acquired from the Environmental Systems Research Institute (Esri) via Sentinel-2 10-Meter LULC, utilizing the geostatistical method. The distribution analysis, including the histogram and Q-Q plot, indicates a positively skewed distribution, potentially normal. A quadratic pattern in iron concentration trends was revealed using the ArcGIS 10.5 application tool. From the results, descriptive statistics present a mean of 0.35 mg/L, a standard deviation of 0.17 mg/L, and a positive skewness of 0.88. The spatial distribution map highlights areas below and above the WHO permissible concentration of 0.3 mg/L, while hotspot analysis identifies regions exceeding the standard stipulated guideline with confidence levels ranging from 90% to 99%. Comparative analysis of geostatistical models favors the Gaussian model for accurate predictions due to its low standardized mean error. The non-normally distributed iron concentration in Yenagoa suggests localized areas with elevated concentration levels. In addition, spatial analysis and LULC analysis conducted based on the laboratory results distinguished regions adhering to and those deviating from WHO guidelines, underscoring the need for targeted intervention and the importance of tailored strategies for areas with elevated accumulations. Understanding iron concentration distribution and trends is imperative for devising strategies to mitigate potential environmental and health risks.

Keywords: Geostatistics; Iron; Hotspot analysis, GIS; Groundwater; LULC

DOI: 10.7176/JEES/14-3-03

Publication date: April 30^th 2024