Geostatistical study of the spatial variability of groundwater parameters in Afikpo and Ohaozara, Southeastern Nigeria

Abstract

Abortive boreholes and parched wells, ascribed to the difficulty in understanding the hydrogeology of the aquifer by water borehole drillers, pose great concern to the people of the region. Mapping the spatial variability of water table depth (WTD) (m) and aquifer thickness H (m) is a vital step in optimal utilization of groundwater resources. Thus, the aim of this paper is to investigate the spatial variability of the groundwater parameters, H (m) and WTD (m) in the study area located in Nigeria, using geostatistical method of Ordinary Kriging, based on data estimated from interpreted results of fifty (50) Schlumberger Vertical Electrical Sounding (VES) curves. To attain this aim, the spatial variability of the groundwater parameters was analyzed. The result shows that the difference in directional behavior is not significant. Thus, the WTD and H were assumed as isotropic, and experimental semivariograms of logH and log(WTD) were calculated and modeled with the GS + software. It was found that, H and (WTD) data are moderately spatially correlated over the study area, and the spatial structures follow exponential model for H and spherical model for (WTD). According to the generated maps of kriged estimates of logH and log(WTD), the southern part of the study area with higher prolific aquiferous zone, shows higher kriged H-values, relative to the northern zone. The variation in the distribution of kriged WTD-values in the study region is asymmetrical. These results compare favorably in the trend patterns of distribution of the parameter values, with contour maps of a previous study in the region that indicates the distribution of H and WTD parameters. The parameters of the semivariogram models used for the analysis of the data, give insight into the spatial pattern of the groundwater parameters, H and WTD. This knowledge has improved the ability to understand the hydrogeology of the aquifer. The generated spatial variability maps of H and WTD will assist water resource managers and policymakers in the development of guidelines in judicious management of groundwater resources for drinking purposes in the study area.

Statistical Assessment of the Difference between the Height Differences Obtained by Spirit and Trigonometric Leveling Techniques

“…The area lies mostly in the (Eboine) River Basin and the Cross River plains (Figure 1). The area has an undulating terrain and an elevation of about 170 m above mean sea level (Iduma, Abam, & Uko, 2017).…”

Assessment of Spatial Variability of Groundwater Levels in Moroto District, Uganda

“…In line with Ahmadi & Sedghamiz, (2007), the primary root of facts on impact of hydrologic pressure on groundwater is usually associated with monitoring of groundwater levels. However, most areas lack effective groundwater monitoring networks (Alexander et al, 2017;Egwu et al, 2017). Geostatistics as a tool within GIS given methods has proven to be useful in interpolating discrete spatial data in order to generate optimum surfaces (Alexander et al, 2017;Delbari et al, 2013;Egwu et al, 2017;Sastre-Merino, 2011;Taghizadeh-Mehrjardi et al, 2008).…”

“…However, most areas lack effective groundwater monitoring networks (Alexander et al, 2017;Egwu et al, 2017). Geostatistics as a tool within GIS given methods has proven to be useful in interpolating discrete spatial data in order to generate optimum surfaces (Alexander et al, 2017;Delbari et al, 2013;Egwu et al, 2017;Sastre-Merino, 2011;Taghizadeh-Mehrjardi et al, 2008). The study by Egwu et al, (2017) utilized this technique to analyse the spatial variability connected with groundwater levels in Darab plains of southern Iran.…”

“…Geostatistics as a tool within GIS given methods has proven to be useful in interpolating discrete spatial data in order to generate optimum surfaces (Alexander et al, 2017;Delbari et al, 2013;Egwu et al, 2017;Sastre-Merino, 2011;Taghizadeh-Mehrjardi et al, 2008). The study by Egwu et al, (2017) utilized this technique to analyse the spatial variability connected with groundwater levels in Darab plains of southern Iran. Furthermore, Taghizadeh-Mehrjardi et al, (2008) used this method in order to predict the spatial distribution regarding groundwater parameters of Yazd-Ardkan in Iran.…”

“…The end result revealed that, the method may be appropriate throughout in preparation of groundwater variability maps. Also Egwu et al, (2017) recommended that, to understand the variations in groundwater level measurements as a result of excessive extraction, it is significant to measure the spatial pattern of groundwater levels. Equally, Bohling & Wilson, (2012) employed the geostatistical technique to analyse the variations in water levels of 70 water points in Kansas high plains during winter season and it presented a drop-in groundwater level.…”