Testing the ability of an empirical hydrological model to verify a knowledge-based groundwater potential zone mapping methodology

Abstract

Groundwater potential characterization is a major component of the developmental strategies required for sustainable management of the water resources of a country. This study explores the potential of Natural Resources Conservation Service (NRCS-CN) estimated runoff/infiltration to verify a knowledge-based groundwater potential zone mapping methodology using remote sensing and GIS. Eight criteria/factors regarded as positive indicators to the existence of groundwater in the study area were mapped and weighted based on the knowledge of the local geology using analytical hierarchy process (AHP). The results from AHP were integrated using Weighted Index Overlay Analysis in a GIS environment to delineate the groundwater potential map of the area. Five classes consisting of very good, good, moderate, fair and poor groundwater potentials, each occupying 4.6, 53.3, 82.22, 37.47, and 0.43 km 2 , respectively, were delineated. They were found to be in agreement with the borehole information of the area. Curve number (CN) for the various land cover types was generated using the NRCS-CN approach. CN was used to compute a qualitative, terrain-based, runoff/infiltration response for rainfall events in the study area, from which a terrain-based runoff map of the area was computed. A comparison between the groundwater potential map and terrain-based runoff map was done using linear regression analysis. The coefficient of determination (R 2) obtained was 0.80. The result indicates a high application efficiency of NRCS-CN method in verifying the accuracy of a GIS-based qualitative groundwater potential mapping.

Investigation of the influence of lineaments, lineament intersections and geology on groundwater yield in the basement complex terrain of Ondo State, Southwestern Nigeria

“…This shows that boreholes located on lineaments are expected to give relatively high groundwater yield due to the enhanced groundwater flow through the lineaments. Similar experiences have been reported by Edet et al (1994), Edet (1996), Adiat et al 2012, Yene et al (2015, Aladejana et al (2016). Figure 11 shows the spatial distribution of boreholes on the hydrointersection map.…”

“…Mabee et al 1994;Masoud and Koike 2006;Ekwe et al 2010;Adiat et al 2012;Akinluyi 2013;Dasho et al 2017).Figure 8depicts a characteristic feature of the occurrence of underlying structures in the basement complex of Ondo State. It shows the fracture distribution and pattern in the study area on a scale of 1:200,000 as exhibited in each of the sixteen (16) local government areas (LGA).…”

“…Basement aquifers constitute relevant sources of water in the hard rock terrain of Ondo State in which groundwater occurs mainly in fractured zones, with or without saturated weathered zones (Olorunfemi and Olorunniwo 1985;Olorunfemi 1990;Olorunfemi et al 1991;Olorunfemi and Okhue 1992;Idornigie and Olorunfemi 1992;Olorunfemi and Fasuyi 1993;Olorunfemi 2007;Ekwe et al 2010;Bayowa et al 2014;Akinlalu et al 2017). However, the development of crystalline bedrock aquifers is highly complex, and groundwater occurrence is spatially variable due to many factors (Satpathy and Kanungo 1976;Mabee et al 1994;Mabee 1999;Mabee et al 2002;Ojo et al 2015;Aladejana et al 2016). Though tectonic history, geomorphology and climatic conditions play prominent role in the development of weathered and fractured aquifer systems, in this kind of terrain, water percolation and accumulation is essentially controlled by fractures and other rock discontinuities (Lattman et al 1964;Siddiqui and Parizek 1971;Edet et al 1994;Edet 1996;Sander 1997;Taylor andHoward 2002, Anifowose et al 2012;Akinlalu et al 2017).…”

Pollution potential and causative hydrogeochemical processes in unconfined aquifer systems in a typical urban setting: emphasis on recharge and discharge areas

“…Overburden of thick weathered regoliths which varies from place to place overlay these rocks in some places. These rocks generally lack primary porosity but possess secondary porosity due to weathering and fracturing activities (Acworth 1987;Olorunfemi et al 1999;Owoseni et al 2013;Aladejana et al 2016). Groundwater recharge is primarily through infiltration by direct precipitation with mean annual value of about 1350 mm.…”

“…Many researchers (Olorunfemi et al 1999; Akintorinwa and Olowolafe 2012; Anifowose and Kolawole 2012;Asiwaju-Bello et al 2013;Owoseni et al 2013;Owoseni and Komolafe 2014;Aladejana et al 2016;Yenne et al 2018) have worked on the several aspects of groundwater resources of Akure area for different purposes. However, they did not consider the identification and assessment of the groundwater recharge and discharge areas in Akure area.…”