Evaluation of Horizontal and Vertical Accuracies of SRTM and ASTER GDEMs for Topographic and Hydrological Modeling in Onitsha, South East Nigeria

Ejikeme, J.O; Igbokwe, J.I; Igbokwe, E.C; Aweh, D.S

doi:10.21276/ijirem.2017.4.2.5

Abstract

Digital Elevation Models (DEMs) are essential in the analysis and modeling of different topographical, hydrological and ecological phenomena on the Earth surface. The Shuttle Radar Topography Mission (SRTM) DEM and Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) are the most widely available global digital elevation model (DEM) dataset. In Nigeria, due to the lack of up-to-date topographic map and high cost of obtaining elevation data using conventional techniques, Map users often resort to the use of these freely available global datasets for their topographic information. However, the vertical accuracy of these global DEM varies depending on the terrain characteristics and land cover types, and may affect the quality of products such as slope, aspect and stream channels derived from these data needed for topographic and hydrologic modeling. This study deals on a comparative analysis of SRTM and ASTER GDEM version1 and version2 in topographical and hydrological modeling of Onitsha and environs using 1:50000 topographic map of the study area as the reference DEM. The validity of the topographic map was confirmed on the ground. The contour lines of the topographic map were digitized and their equivalent values used to generate the topographic DEM. The vertical and horizontal accuracies of the global datasets were evaluated using the reference topographic DEM. The results showed that ASTER ver1 has a vertical accuracy of 13.987m while that of ASTER ver2 is 12.558m. SRTM has a vertical accuracy of 14.125m. Horizontal accuracy of 18.240m and 27.341m was obtained for ASTER ver1 and ASTER ver2 respectively. Horizontal accuracy of 27.092m was obtained for SRTM. The study recommends the use of SRTM for topographic and hydrologic modeling of Onitsha and Environs and other areas of similar topography representation.

Keywords

Accuracy, SRTM, ASTER GDEM, Hydrological Modeling,

Reference

1) Bluman, A.G (2009). Elementary Statistics: A Step by Step Approach (7th eds). New York: McGraw-Hill.

2) Ejikeme, J.O (2013). Revision and Analysis of Medium-Scale Topographic Map Using Remote Sensing and GIS Techniques. M.Sc Thesis, Department of Surveying and Geoinformatics, Nnamdi Azikiwe University, Awka.

3) Ejikeme, J.O (2016). Comparative Analysis of SRTM and ASTER GDEM in topographic and hydrologic modeling of Onitsha and Environs. Ph.D Thesis, Department of Surveying and Geoinformatics, Nnamdi Azikiwe University, Awka.

4) Gamett, B.J (2010). An Accuracy Assessment of Digital Elevation Data and Subsequent Hydrologic Delineations in Low Relief Terrain: An Analysis for Idaho’s Little Lost River Valley. M.Sc Thesis, Idaho State University

5) Nikolakopoulos, K.G; Kamaratakis, E.K & Chrysoulakis, N(2006). SRTM vs ASTER Elevation Products. Comparison for two regions in Crete, Greece. International Journal of Remote Sensing. 27(21), 4819–4838.

6) Obasi, L.O., Okoroigwe, D.S and Ogbuagu, N (2015). Evaluation of the Erosion Prevention and Control Measures in Obosi, Anambra State, Nigeria. Proceedings of 1st Nnational Conference of Faculty of Environmental Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.

7) Ofomata, G.E.K (1975). Nigeria in Maps Eastern States. Benin City: Ethiope Publishing Houses.

8) Onwuka, S.U., Okoye, C.O and Ikekpeazu, F.O (2015). Effect of rural household income on biodiversity conservation, A Study of Awka South Local Government Area of Anambra State, Nigeria. Proceedings of 1st Nnational Conference of Faculty of Environmental Sciences, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.

9) Orajaka,S.O (1975). “Geology” In Ofomata, GEK. (ed) Nigeria in Maps Eastern States, Benin City: Ethiope Publishing House.

10) Ozah, A.P & Kufoniyi, O (2008). Accuracy Assessment of Contour Interpolation from 1:50000 Topographic Maps and SRTM Data for 1:25000 Topographical Mapping. International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. XXXVII(B7).

11) Singh, S.K (2005). Analysis of Uncertainties In Digital Elevation Models in Flood (Hydraulic) Modelling. M.Sc Thesis, International Institute for Geo-information Science and Earth Observation, Enschede, Netherland.

12) USGS (1998). GLSDEM. Global Land Cover Facility. University of Maryland, College Park, Maryland.

13) Uzodinma, N.V & Ezenwere, O.C (1993). Map Projections Practical Computations On The Transverse Mercator Projection. Enugu: El’Demak Publishers.

14) Uzodinma, V.N, Oguntuase, J.O, Alohan, N.O, & Dimgba, C.N (2013). Practical GNSS Surveying. Enugu: Professor’s Press Limited.

Cites this article as

[Ejikeme, J.O , Igbokwe, J.I , Igbokwe, E.C , Aweh, D.S (2017), Evaluation of Horizontal and Vertical Accuracies of SRTM and ASTER GDEMs for Topographic and Hydrological Modeling in Onitsha, South East Nigeria, International Journal of Innovative Research in Engineering & Management (IJIREM), Vol-4, Issue-2, Page No-634-643], (ISSN 2347 - 5552). www.ijirem.org