Evaluation of Hydrological Data Collection Challenges and Flood Estimation Uncertainties in Nigeria

Iguniwari Thomas Ekeu-Wei

doi:10.5539/enrr.v8n2p44

Iguniwari Thomas Ekeu-Wei

Open Access

https://doi.org/10.5539/enrr.v8n2p44

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Abstract

In recent years, flooding has become a recurring problem in many regions including Nigeria, owing to changing climatic conditions, as well as anthropogenic factors such as poor land use management and urbanization that aggravate flood impact. To effectively manage and mitigate flood impact, hydrological data is required, and in many developing regions gauging stations are established, and gauge readers recruited and trained to collect and transmit such data to designated hydrological or water resource management agencies. This study focuses on understanding the challenges associated with hydrological data collection in Nigeria, using the Ogun-Osun River as a typical case, while analytically assessing how these challenges result in uncertainties that propagate unto flood frequency estimates that are used to inform flood management decisions. The findings reveal that (i) capacity and institutional gaps; lack of maintenance of hydrological infrastructure and surrounding landscape; poor data management architecture; and floods events that destroy hydrological equipment and inundate roads thereby restricting access to collected data during peak floods, are some of the challenges associated with hydrological data collection in developing regions; (ii) these conditions result in gaps in and shortened length of annual maximum hydrological time series required for flood frequency estimation, consequently leading to under or overestimation of low and high flood quantiles such as 1-in-2year and 1-in-100year floods, to levels of 0.67 m and 0.9 m respectively for the Ogun Osun River Basin. The need for improved data collation, management and adaptation of new technologies such as radar or sonar by the Ogun-Osun River Basin Development Authority is recommended in this study, to ensure sustainable and improved hydrological data collection, management, transferability and usability for flood management.

Highlights

Floods are one of the most devastating natural hazards, increasing in frequency, magnitude and impact in recent decades (Aerts et al, 2014; Di Baldassarre et al, 2010), owing to changing climatic conditions and anthropogenic factors such as poor land use management and urbanization (Lavender & Matthews, 2009)
The five (5) gauge readers interviewed were responsible for Ajilete, Ebute – Igbooro, Eggua, Idogo and Ijaka – Oke hydrological gauging stations located along the Yewa River, one of the major rivers in Ogun state Nigeria
This study evaluated the challenges associated with hydrological data collection in a typical developing region based on gauge readers testaments, field observations and hydrological analysis, identifying capacity and institutional gaps; poor maintenance of hydrological equipment and surrounding landscape; poor data management architecture; and floods events that destroy hydrological equipment and inundate roads restricting access to data collection during peak floods, as factors that hamper seamless and sustainable data collection

Summary

Introduction

Floods are one of the most devastating natural hazards, increasing in frequency, magnitude and impact in recent decades (Aerts et al, 2014; Di Baldassarre et al, 2010), owing to changing climatic conditions and anthropogenic factors such as poor land use management and urbanization (Lavender & Matthews, 2009). Networks of Hydro-Meteorological (HYDROMET) gauging stations are established for systematic data collection (Herschy, 2008; Hipel, 1995), distributed across locations of interest for continuous and long-term data collection Operating these stations, especially in developing regions is challenging, as factors such as poor financing by the government (Starrett et al, 2010), poor institutions, lack of commitment, lack of capacity, logistical and technical challenges (Ampadu, Chappell, & Kasei, 2013; Olayinka, Nwilo, & Emmanuel, 2013) hamper seamless data collection. This paucity of data is severe in developing countries, thereby further limiting these nations capacity to mitigate and cope with the impact of flooding on people, environment, infrastructure and socio-economic activities (Komi, Neal, Trigg, & Diekkrüger, 2017)

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