Estimation of the Quantity of Surface Runoff to Determine Appropriate Location and Size of Drainage Structures in Jimeta Metropolis, Adamawa State, Nigeria
Idowu, T. O., Edan, J. D., Damuya, S. T.
Journal of Geography and Earth Science, 1(1), 19-29

Abstract
This study attempts to determine the appropriate locations and sizes of drainage structures that can handle surface runoff in all watersheds of the study area (i. e. Jimeta Metropolis) without endangering lives and properties. Surface runoff is the excess water that flows over the land after the soil is infiltrated as a result of heavy rainfall while a watershed is defined as the area of land that drains to a particular point. Among various methods of determining the quantity of surface runoff, rational method is considered for this study. This is because previous attempts have shown that the concept of rational method is simple and good for relatively small watersheds as those covered in this study. The data used are the rectangular coordinates of points and the rainfall data of the study area for the year 2011. The method includes the determination of the locations and volumes of the drainage structures, Time of Concentration (ToC), Rainfall Intensity (I), Runoff Coefficient (C) and hence the estimated quantities of the surface runoff. Analyzing the results obtained, it was observed that the locations of the drainage structures are appropriate. However, the drainage structures of some watersheds are smaller than the required sizes thereby posing the risk of endangering lives and properties. That is, the existing volumes of the structures are smaller than the estimated volumes of the surface runoff. Therefore, it is recommended that the estimated quantity of surface runoff in a particular watershed should serve as a bench mark for the determination of appropriate location and size of drainage structure to be constructed for such watershed.

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Idowu, T. O., Edan, J. D. & Damuya, S. T. (2013). Estimation of the Quantity of Surface Runoff to Determine Appropriate Location and Size of Drainage Structures in Jimeta Metropolis, Adamawa State, Nigeria. Journal of Geography and Earth Science, 1(1), 19-29

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Idowu, T. O. is a Nigerian, about 54years old and an Associate Professor of Surveying and Geoinformatics. He obtained B. Sc, M. Sc and Ph. D in Surveying and Geoinformatics and he is the Head of Department of Surveying and Geoinformatics, Modibbo Adama University of Technology, Yola, Nigeria. He has research experience in geodetic network adjustment, gravimetric techniques, determination of geoid and datum transformation parameters. Also, his activities include membership of professional bodies and editorship to academic journals.

Contact numbers of corresponding author ( Idowu, T. O.) are +2348034269273, +2347080251351.

Edan, J. D.
Department of Surveying and Geoinformatics
Modibbo Adama University of Technology
Yola, Nigeria

Damuya, S. T.
Department of Surveying,
Adamawa State Ministry of Land and Survey
Yola, Nigeria.