Open Access Open Access  Restricted Access Subscription or Fee Access

Thornthwaite’s Potential Evapotranspiration Rate Assessment and Implication on Rainfall Induced Floods in a Coastal Expanse of Nigeria

David O. Edokpa, Precious N. Ede, Susan I. Ajiere, Bridget E. Diagi

Abstract


This study examined the potential evapotranspiration (PET) rate effects on rainfall-induced floods within Port Harcourt, a coastal city in Nigeria. Mean monthly rainfall and air temperature data for 39 years (1979–2018) was sourced from the Nigerian Meteorological Agency and used to evaluate the potential evapotranspiration (PET) of the area using the Thornthwaite’s method. Results revealed that the mean rainfall and PET values for Port Harcourt during the periods under review were 192.2 mm and 112.2 mm with a range of 145.3–238.8 mm and 94.6–131.8 mm,respectively. The total mean annual values for rainfall and PET for the years analyzed for the study area were from 1743.1–2866.0 mm and 1135.6–1581.3 mm respectively. The years 2006 and 2017 had the highest and lowest total mean PET, i.e., 1581.3 mm and 1135.6 mm, respectively while 2007 and 2011 had the highest and lowest rainfall amount, i.e., 2866.0 mm and 1743.1 mm, respectively. The mean monthly maximum temperature of 31.3°C for the area is enough to cause considerable evaporation of water from surfaces. The study showed that 58 % of PET was generated from the total mean annual rainfall amount for the period under review. This indicates that PET for the area is substantial and contributes significantly to the very humid environment. The values of the correlation coefficient (R) and the coefficient of determination (R2 ) for the relationship between air temperature and PET are 0.92 and 0.85 respectively indicating a strong relationship. The total mean annual PET for the domain, which is less than the mean annual rainfall value shows that excess rainwater will enhance enormous flood buildup in the domain. Also, the build-up of more moisture in the area will lead to increased rainfall amount with impact on flooding in the area. It is important to note that Port Harcourt city must be adequately drained to avoid increasing overwhelming flood events being witnessed presently.

Full Text:

PDF

References


Luo Y, Gao P, Mu X. Influence of meteorological factors on the potential evapotranspiration in

Yanhe River Basin, China. Water. 2021;13(9):1–13. doi: 10.3390/w13091222.

Tukimat NNA, Harun S, Shahid S. Comparison of different methods in estimating potential

evapotranspiration at Muda Irrigation Scheme of Malaysia. J Agric Rural Dev Tropics Subtrop.

;113(1):77–85.

Wang H, Zheng J. Assessing the effects of surface conditions on potential evapotranspiration in a

humid subtropical region of China. Front Clim. 2022;4:(813787). doi: 10.3389/fclim.2022.813787.

Ndiaye PM, Bodian A, Diop L, Dezetter A, Guilpart E, Deme A et al. Future trend and sensitivity

analysis of evapotranspiration in the Senegal River Basin. J Hydrol Reg Stud. 2021;35:1–23. doi:

1016/j.ejrh.2021.100820.

Ogolo EO. Regional trend analysis of pan evaporation in Nigeria (1970–2000). J Geogr Reg Plan.

;4(10):566–77.

Al-Sudani HIZ. Temperature–Potential Evapotranspiration Relationship in Iraq Using

Thornthwaite Method. J Univ Babylon Eng Sci. 2019;27(1):16–25. doi:

29196/jubes.v27i1.1968.

Obada E, Alamou EA, Chabi A, Zandagba J, Afouda A. Trends and changes in recent and future

Penman-Monteith potential evapotranspiration in Benin (West Africa). Hydrology. 2017;4(3):1–

doi: 10.3390/hydrology4030038.

Ndiaye PM, Bodian A, Diop L, Deme A, Dezetter A, Djaman K et al. Trend and sensitivity analysis

of reference evapotranspiration in the Senegal River Basin using NASA meteorological data. Water.

;12(7):1–19. doi: 10.3390/w12071957.

Pravalie R. Analysis of temperature, precipitation and potential evapotranspiration trends in

southern Oltenia in the context of climate change. Geogr Tech. 2014;9(2):68–84.

Dong Q, Wang W, Shao Q, Xing W, Ding Y, Fu J. The response of reference evapotranspiration to

climate change in Xinjiang, China: historical changes, driving forces, and future projections. Int J

Climatol. 2020;40(1):235–54. doi: 10.1002/joc.6206.

Umego OM, Ewemoje TA, Alabi HA. Trend analysis of reference evapotranspiration: case study

of Asaba and Uyo, South-South Nigeria. CIGR J. 2020;22(4):1–8.

Dong W, Li C, Hu Q, Pan F, Bhandari J, Sun Z. Potential evapotranspiration reduction and its

influence on crop yield in the North China plain in 1961-2014. Adv Meteorol. 2020;2020:1–10.

doi: 10.1155/2020/3691421.

Zeng Z, Wu W, Zhou Y, Li Z, Hou M, Huang H. Changes in reference evapotranspiration over

Southwest China during 1960-2018: attributions and implications for drought. Atmosphere.

;10(11):1–24. doi: 10.3390/atmos10110705.

Abiye OE, Matthew OJ, Sunmonu LA, Babatunde OA. Potential evapotranspiration trends in West

Africa from 1906 to 2015. SN Appl Sci. 2019;1(11):1434. doi: 10.1007/s42452-019-1456-6.

Hounnou FE, Dedehouanou H. Variability of temperature, precipitation and potential

evapotranspiration time series analysis in Republic of Benin. Int J Agric Environ Res.

;4(4):991–1019.

Koudahe K, Djaman K, Bodian A, Irmak S, Sall M, Diop L et al. Trend Analysis in Rainfall,

Reference Evapotranspiration and Aridity Index in Southern Senegal: Adaptation to the

Vulnerability of Rainfed Rice Cultivation to Climate Change. Atmos Clim Sci. 2017;07(4):476–

doi: 10.4236/acs.2017.74035.

Trambauer P, Dutra E, Maskey S, Werner M, Pappenberger F, van Beek LPH et al. Comparison of

different evaporation estimates over the African continent. Hydrol Earth Syst Sci. 2014;18(1):193–

doi: 10.5194/hess-18-193-2014.

Edokpa DO, Nwagbara MO. Atmospheric stability pattern over Port Harcourt, Nigeria. J Atmos

Pollut. 2017;5(1):9–17.

Greater Port Harcourt City Development. The greater Port Harcourt City Development Master Plan.

Stormwater Master Plan, Volume 3. Nigeria: Government of Rivers State. 2009.

Chinago AB. Analysis of rainfall trend, fluctuation and pattern over Port Harcourt, Niger Delta

coastal environment of Nigeria. Biodivers Int J. 2020;4(1):1–8. doi: 10.15406/bij.2020.04.00158.

Augustine C, Nnabuchi MN. Relationship between global solar radiation and sunshine hours for

Calabar, Port Harcourt and Enugu, Nigeria. Int J Phys Sci. 2009;4(4):182–8.

Umoh MD, Udo SO, Udoakan YN. Estimating global solar radiation on horizontal surface from

sunshine hours over Port Harcourt, Nigeria. J Electr Electron Eng Research. 2014;6(1):1–5.

Edokpa OD. Atmospheric stability conditions of the lower atmosphere in selected cities in Nigeria

[Ph.D. thesis]. Nigeria: Department of Geography and Environmental Management, University of

Port Harcourt; 2018.

Nigeria Hydrological Services Agency. (2021). Monthly flood and drought monitor; 2021 [Online].

Available from: https://nihsa.gov.ng/publications/.

Uko ED, Tamunobereton-Ari I. Variability of climatic parameters in Port Harcourt, Nigeria. J

Emerg Trends Eng Appl Sci. 2013;4(5):727–30.

Karamage F, Liu Y, Fan X, Justine MF, Wu G, Liu Y et al. Spatial relationship between

precipitation and runoff in Africa. Hydrol Earth Syst Sci Discuss. 2018:1–27.

Riou C. Experimental study of potential evapotranspiration (PET) in Central Africa. J Hydrol.

;72(3-4):275-88. doi: 10.1016/0022-1694(84)90085-4

Dunning CM, Black E, Allan RP. Later Wet Seasons with More Intense Rainfall over Africa under

Future Climate Change. J Climate. 2018;31(23):9719–38. doi: 10.1175/JCLI-D-18-0102.1.

Thecla A. Determinants of flooding in Port Harcourt Metropolis, Nigeria. IOSR J Humanit Soc Sci.

;19(11):64–72. doi: 10.9790/0837-191186472.

West I, Wodike OO. Environmental degradation effects and urban flooding in Port Harcourt. J Am

Sci. 2019;15(9):1–7.


Refbacks

  • There are currently no refbacks.