Trend and Frequency Analyses of Rainfall in North West Geopolitical Zone of Nigeria

Abstract

The major occupation of people in the North-west geopolitical zone of Nigeria is farming, which depends on rainfall and other factors. It is well known that climate change has been contributing to change in amount of rainfall worldwide. In this paper the existence of trend and rainfall frequency analyses were conducted on rainfall data in North-west geopolitical zone of Nigeria with a particular attention to yearly total rainfalls using Mann- Kendall and Sen’s slope techniques as well as Pearson log type III distribution. Rainfall data from 1905 – 2008 were collected from ve locations in the region and the test were conducted using standard methods stated in literature. The study revealed that there are trends in the rainfall in the region and Sen’s test revealed that the trends are signi cant at 99 % con dence level. Sen’s slopes revealed that there are downward trends in the rainfall for the last 30 years in all the ve locations. The slopes are -0.94, -6.91; -0.94; -0.84 and -5.66 mm/year for Sokoto, Kano, Kebbi, Kaduna and Katsina respectively. Rainfall frequency analyses for 2 years return period for these locations (Sokoto, Kano, Kebbi, Kaduna and Katsina) are 651.08 mm; 844.42 mm 735.68 mm, 1168.47 mm and 669.52 mm respectively. It was concluded that there are downward trends in the rainfall in last 3 decades for all the locations. 

Keywords

• Hydrological data,Rainfall,Sen’s estimator,Trend analysis,Non-parametric tests

Nijerya’nın Kuzeybatı Jeopolitik Bölgesine Düşen Yağış Miktarlarının Eğilim ve Frekans Analizi

Abstract

Nijerya’nın kuzeybatı jeopolitik bölgesinde yaşayan insanların büyük çoğunluğu yağış miktarı ve diğer faktörlere bağlı olarak tarımla iştigal ederler. İklim değişikliğinin dünya çapında yağıştaki miktar değişimine katkı sağladığı bilinmektedir. Bu çalışmada mevcut olan yağış frekans ve eğilim analizlerinde Pearson log tip III dağılımı hem de Mann-Kendall ve Sen’in eğim teknikleri kullanılarak yıllık yağış miktarlarının toplamlarına dikkatle Nilerya’nın kuzeybatı jeopolitik bölgesindeki yağışlar üzerine odaklanılmıştır. 1905-2008 yılları arasındaki yağış bilgileri bölgedeki beş yerden toplanmış ve literatürde verilen standart metotlarla test edilmiştir. Çalışma, bölgedeki yağışlarda eğilimler olduğu, bu eğilimlerin Sen’in testlerine göre % 99 oranında önemli seviyeye sahip olduğunu ortaya çıkarmıştır. Sen’in eğimleri tüm yerleşim yerlerinde son 30 yılda aşağı doğru eğilimlerin var olduğunu açığa çıkarmıştır. Eğimler Sokoto, Kano, Kebbi, Kaduna ve Katsina için sırasıyla -0.94, -6.91; -0.94; -0.84 ve -5.66 mm/ yıl şeklindedir. Yağış frekans analizi bu yerleşim yerlerinde 2 yıllık geriye dönük periyotlar için 651.08 mm; 844.42 mm 735.68 mm, 1168.47 mm ve 669.52 mm (Sokoto, Kano, Kebbi, Kaduna ve Katsina) sırasıyla ölçülmüştür. Tüm yerleşim birimlerinde son 30 yılda yağışta azalma eğilimi olduğu tespit edilmiştir. 

Keywords

• Hydrolik veriler,yağış,trend analizi,parametrik olmayan testler

References

1. Abaje, I.B.; Ishaya, S. and Usman S.U. 2010 , An Analysis of Rainfall Trends in Kafanchan, Kaduna State, Nigeria. Research Journal of Environmental and Earth Sciences 2(2): 89-96. A debayo A.A, and Umar A.S 2005. “Climate”, in Tukur A. L, Adebayo A. A and Galtima M. Eds, The land and people of the Mambilla Plateau, Heinemann, Ibadan. pp. 25-32.
2. Adefolalu D.O, Pam, J.L, and Habbi H.M 2007. “Climate change and safety of air transportation – A Nigerian perspective”. Proceedings of the International Conference on the impacts of extreme weather and climate on socio-economic development in Africa held at the Federal University of Technology, Akure, Nigeria, 11-15 Nov. 2007. pp. 1-15.
3. A esimama E.A, Ojo S.O, and Gbuyiuro S.O 1999. “The diagnosis of climatic trends over Nigeria in the last half century of this millennium”, A paper presented at the Annual Conf. Meteorol. Organization, Lagos.
4. Akintola, J.O 1986 .: Rainfall Distribution in Nigeria 1892– 1983, 1st edn. Impact Publishers Nigeria Ltd, Ibadan.
5. Antonopoulos, V. Z.; D. M. Papamichail and K. A. Mitsiou 2001. Statistical and trend analysis of water quality and quantity data for the Strymon River in Greece. Hydrology and Earth System Sciences, 5(4), 679–691
6. Ayuba H.K, Maryah U.M, and Gwary D.M 2007. “Climate change impact on plant species composition in six semi- arid rangelands of Northern Nigeria”, Nig. Geogr. J., 5(1):35-42.
7. Burn D.H, and Hag Elnur M.A. 2002. Detection of hydrological trends and variability. Journal of Hydrology 255: 107– 122.
8. Cengiz T, Kahya E, Karaca M. 2003. Trends and annual cycles in Turkish lake levels. International Association of Hydraulic Engineering

9. Drápela , K and I. Drápelová 2011. Application of Mann-Kendall test and the Sen’s slope estimates for trend detection in deposition data from Bílý Kříž (Beskydy Mts., the Czech Republic) 1997–2010. Beskydy, 4 (2): 133–146
10. Hirsch R.M, and Slack J.R. 1984. A non-parametric trend test for seasonal data with serial dependence. Water Resources Research 20: 727–732.
11. Hirsch R.M, Slack J.R, and Smith R.A. 1982. Techniques of trend analysing for monthly water quality data. Water Resources Research 18:107–121.
12. Izinyon, O.C;. Ihimekpen, M.D and G.E. Igbinoba 2011 Flood Frequency Analysis of Ikpoba River Catchment at Benin City Using Log Pearson Type III Distribution Journal of Emerging Trends in Engineering and Applied Sciences (JETEAS) 2 (1): 50-55
13. Kadıŏglu M. 1997. Trends surface air temperature data over Turkey. International Journal of Climatology 17: 511- 520.
14. Kahya E, and Kalayci S. 2004. Trend analysis of stream ow in Turkey. Journal of Hydrology 289: 128–144.
15. Kahya E, Kalayci S, and Burdurlu Y. 1998. Analysis of trends in the water quality parameters of Gediz basin. In Proceedings of 1st International
16. Karaca M, Antepliogˇlu U ̈ , Karsan H. 1995. Detection of urban heat island in PIstanbul, Turkey. Il Nuovo Cimento 18: 49–56.
17. Lettenmaier D.P, Wood E.F, and Wallis J.R. 1994. Hydro- climatological trends in the continental United States, (1948–88). Journal of Climate 7: 586–607.
18. Lins H, and Slack J.R. 1999. Stream ow trends in United States. Geophysicsal Research Letters 26: 227–230.
19. Loveday, R. 1980. Statistics, A second course in statistics, 2nd edn, University Press Cambridge
20. Nkomo J.C, Nyong A.O, and Kulindwa K 2006. The Impacts of Climate Change in Africa. Final Draft submitted to the Stern Review on The Economics of Climate Change.
21. Nwafor J.C 2007. Global climate change: The driver of multiple causes of ood intensity in sub-Saharan Africa. Paper presented at the International Conference on Climate Change and Economic Sustainability held at Nnamdi Azikiwe University, Awka, Nigeria. 12-14 June 2007.
22. Obot; N.I.M; Chendo; A.C; Udo,S.O and Ewona. I.O 2010. Evaluation of rainfall trends in Nigeria for 30 years (1978-2007). International Journal of the Physical Sciences. 5(14), 2217-2222.
23. Odjugo P.A.O 2005. “An analysis of rainfall pattern in Nigeria”, Global J. Environ. Sci., 4(2): 139-145.
24. Oke, I. A 2008 Utilization of Weibull Techniques For Short Term Data In Environmental Engineering. Environmental Engineering and Sciences. 25 (7),1099- 1107
25. Partal, T and Kahya,E 2006. Trend analysis in Turkish precipitation data. Hydrol. Process. 20, 2011–2026.
26. Sen P.K. 1968. Estimates of the regression coef cient based on Kendall’s tau. Journal of the American Statistical Association 39: 1379–1389.
27. Toros H. 1993. Trend analysis of climatologic series in Turkey. MSc thesis, Institute of Science Technology, Istanbul Technical University.
28. Türkeş, M. 1996. Spatial and temporal analysis of annual rainfall variations in Turkey. International Journal of Climatology 16: 1057–1076.
29. Türkeş, M, Ŝumer U.M, and Kılı ̧c G. 1995. Variations and trends in annual mean air temperatures in Turkey with respect to climatic variability.
30. Umoh E 2007 , “Flooding problems in Rivers state”, J. Environ. Sci. 4(2): 44-60.
31. Van Belle G, and Hughes J.P. 1984. Nonparametric tests for trend in water quality. Water Resources Research 20: 127–136.
32. Von Storch H, and Navarra A. 1995. Analysis of Climate Variability—Applications of Statistical Techniques. Springer-Verlag: New York.
33. Yue S, and Hashino M. 2003. Long term trends of annual and monthly precipitation in Japan. Journal of the AmericanWater Resources Association39: 587–596.
34. Zhang X, Harvey K.D, Hogg W.D, and Yuzyk T.R. 2001. Trends in Canada stream ow. Water Resources Research 37: 987–998.
35. Zhang X, Vincent L.A, Hogg W.D, and Niitsoo A. 2000. Temperature and precipitation trends in Canada during the 20th century. Atmospheric Ocean 38: 395–429.