Natural Hazards

, Volume 77, Issue 2, pp 1205–1221 | Cite as

Rainfall and river flow trends using Mann–Kendall and Sen’s slope estimator statistical tests in the Cobres River basin

  • Richarde Marques da Silva
  • Celso A. G. SantosEmail author
  • Madalena Moreira
  • João Corte-Real
  • Valeriano C. L. Silva
  • Isabella C. Medeiros
Original Paper


The main objective of this study is to obtain a better understanding of the spatial and temporal variability and trends of rainfall and river flow in the Cobres River basin, southern Portugal, using statistical tools. The present study is focused on the analysis of the trends in annual precipitations and river flow at a regional scale over 40 years (1960–2000). Datasets of daily precipitation recorded in eight rainfall stations and three river flow stations were analyzed. The nonparametric Mann–Kendall and Sen’s methods were used to determine whether there was a positive or negative trend in rainfall data with their statistical significance. A detailed statistical analysis applied to the river flow and rainfall time series of all gauges indicates that rainfall is highly temporally variable and there is a decrease in the annual rainfall amount for the period studied (1960–2000). Thus, there are signs of significant rainfall reduction in the basin, and in fact, some rain gauges show a small rainfall increase during the recent decades. The annual river flow variation has a cyclic behavior with a period length of approximately 10 years. The results seem integrated to the global and European continental scale findings: Decreasing trends are dominant for almost all indices; most of the calculated slopes are statistically insignificant; the distribution of positive and negative slopes in the area is extremely irregular; and the changes in basin are more significant compared to other studies.


Tendencies Portugal Hydrometeorology 



The authors thank Brazil’s National Council for Scientific and Technological Development.


  1. Abghari H, Tabari H, Talaee PH (2013) River flow trends in the west of Iran during the past 40 years: impact of precipitation variability. Glob Planet Change 101:52–60. doi: 10.1016/j.gloplacha.2012.12.003 CrossRefGoogle Scholar
  2. Bathurst JC, Kilsby C, White S (1996) Modelling the impacts of climate and land-use change on basin hydrology and soil erosion in Mediterranean Europe. In: Brandt CJ, Thornes JB (eds) Mediterranean desertification and land use. Wiley, Chichester, p 355–387Google Scholar
  3. Batisani N, Yarnal B (2010) Rainfall variability and trends in semi-arid Botswana: implications for climate change adaptation policy. Appl Geogr 30:483–489. doi: 10.1016/j.apgeog.2009.10.007 CrossRefGoogle Scholar
  4. Brandão C, Rodrigues R (2000) Hydrological simulation of the international catchments of Guadiana River. Phys Chem Earth (B) 25(3):329–339. doi: 10.1016/S1464-1909(00)00023-X
  5. Celleri R, Willems P, Buytaert W, Feyen J (2007) Space–time rainfall variability in the Paute Basin, Ecuadorian Andes. Hydrol Processes 21:3316–3327. doi: 10.1002/hyp.6575 CrossRefGoogle Scholar
  6. Comas-Bru L, McDermott F (2014) Impacts of the EA and SCA patterns on the European twentieth century NAO–winter climate relationship. Q J R Meteorol Soc 140(679):354–363. doi: 10.1002/qj.2158 CrossRefGoogle Scholar
  7. Costa AC, Soares A (2009) Trends in extreme precipitation indices derived from a daily rainfall database for the South of Portugal. Int J Climatol 9:1956–1975. doi: 10.1002/joc.1834 CrossRefGoogle Scholar
  8. Croitoru A-E, Chiotoroiu B-C, Todorova VI, Torică V (2013) Changes in precipitation extremes on the Black Sea Western Coast. Glob Planet Change 102:10–19. doi: 10.1016/j.gloplacha.2013.01.004 CrossRefGoogle Scholar
  9. de Lima MIP, Carvalho SCP, de Lima JLMP (2010) Investigating annual and monthly trends in precipitation structure: an overview across Portugal. Nat Hazards Earth Syst Sci 10:2429–2440. doi: 10.5194/nhess-10-2429-2010 CrossRefGoogle Scholar
  10. de Lima MIP, Santo FE, Ramos AM, de Lima JLMP (2013) Recent changes in daily precipitation and surface air temperature extremes in mainland Portugal, in the period 1941–2007. Atmos Res 27:195–209. doi: 10.1016/j.atmosres.2012.10.001 CrossRefGoogle Scholar
  11. Duhan D, Pandey A (2013) Statistical analysis of long term spatial and temporal trends of precipitation during 1901–2002 at Madhya Pradesh, India. Atmos Res 122:136–149. doi: 10.1016/j.atmosres.2012.10.010 CrossRefGoogle Scholar
  12. El Nesr MN, Abu-Zreig MM, Alazba AA (2010) Temperature trends and distribution in the Arabian Peninsula. Am J Environ Sci 6:191–203. doi: 10.3844/ajessp.2010.191.203 CrossRefGoogle Scholar
  13. Fragoso M, Gomes TP (2008) Classification of daily abundant rainfall patterns and associated large-scale atmospheric circulation types in Southern Portugal. Int J Climatol 28:537–544. doi: 10.1002/joc.1564 CrossRefGoogle Scholar
  14. Gallego MC, Trigo RM, Vaquero JM, Brunet M, García JA, Sigró J, Valente MA (2011) Trends in frequency indices of daily precipitation over the Iberian Peninsula during the last century. J Geophys Res 116:D02109. doi: 10.1029/2010JD014255 Google Scholar
  15. Gilbert RO (1987) Statistical Methods for Environmental Pollution Monitoring. Wiley, New YorkGoogle Scholar
  16. Gocic M, Trajkovic S (2013) Analysis of changes in meteorological variables using Mann–Kendall and Sen’s slope estimator statistical tests in Serbia. Glob Planet Change 100:172–182. doi: 10.1016/j.gloplacha.2012.10.014 CrossRefGoogle Scholar
  17. Hamlaoui-Moulai L, Mesbah M, Souag-Gamane D, Medjerab A (2013) Detecting hydro-climatic change using spatiotemporal analysis of rainfall time series in Western Algeria. Nat Hazards 65(3):1293–1311. doi: 10.1007/s11069-012-0411-2 CrossRefGoogle Scholar
  18. Hu Y, Maskey S, Uhlenbrook S, Zhao H (2011) Runoff trends and climate linkages in the source region of the Yellow River, China. Hydrol Processes 25(22):3399–3411. doi: 10.1002/hyp.8069 CrossRefGoogle Scholar
  19. Hurrell JW, van Loon H (1997) Decadal variations associated with the North Atlantic Oscillation. Clim Change 36(3–4):301–326. doi: 10.1023/A:1005314315270 CrossRefGoogle Scholar
  20. Junker NW, Grumm RH, Hart R, Bosart LF, Bell KM, Pereira FJ (2007) Use of normalized anomaly fields to anticipate extreme rainfall in the mountains of Northern California. Weather Forecast 23(3):336–356. doi: 10.1175/2007WAF2007013.1 CrossRefGoogle Scholar
  21. Kahya E, Kalayci S (2004) Trend analysis of stream flow in Turkey. J Hydrol 289(2):128–144. doi: 10.1016/j.jhydrol.2003.11.006 CrossRefGoogle Scholar
  22. Kendall MG (1975) Rank correlation methods. Griffin, LondonGoogle Scholar
  23. Kisi O, Ay M (2014) Comparison of Mann–Kendall and innovative trend method for water quality parameters of the Kizilirmak River, Turkey. J Hydrol 513(26):362–375. doi: 10.1016/j.jhydrol.2014.03.005 CrossRefGoogle Scholar
  24. Kutiel H, Trigo RM (2014) The rainfall regime in Lisbon in the last 150 years. Theoret Appl Climatol. doi: 10.1007/s00704-013-1066-y Google Scholar
  25. Lazaro R, Rodrigo FS, Gutierrez L, Domingo F, Puigdefabregas J (2001) Analysis of a 30 year rainfall record (1967–1997) in semi-arid SE Spain for implications on vegetation. J Arid Environ 48:373–395. doi: 10.1006/jare.2000.0755 CrossRefGoogle Scholar
  26. Mann HB (1945) Nonparametric tests against trend. Econometrica 13:245–259CrossRefGoogle Scholar
  27. Milly PCD, Dunne KA, Vecchia AV (2005) Global pattern of trends in stream flow and water availability in a changing climate. Nature 438:347–350. doi: 10.10138/nature04312 CrossRefGoogle Scholar
  28. Mourato S, Moreira M, Corte-Real J (2010) Interannual variability of precipitation distribution patterns in Southern Portugal. Int J Climatol 30:1784–1794. doi: 10.1002/joc.2021 Google Scholar
  29. Nalley D, Adamowski J, Khalil B, Ozga-Zielinski B (2013) Trend detection in surface air temperature in Ontario and Quebec, Canada during 1967–2006 using the discrete wavelet transform. Atmos Res 132–133:375–398. doi: 10.1016/j.atmosres.2013.06.011 CrossRefGoogle Scholar
  30. Pingale SM, Khare D, Jat MK, Adamowski J (2014) Spatial and temporal trends of mean and extreme rainfall and temperature for the 33 urban centers of the arid and semi-arid state of Rajasthan, India. Atmos Res 138(1):73–90. doi: 10.1016/j.atmosres.2013.10.024 CrossRefGoogle Scholar
  31. Ramos, C. (1994) Condições geomorfológicas e climáticas das cheias da Ribeira de Tera e do Rio Maior (Bacia Hidrográfica do Tejo), Ph.D. Dissertation, Departamento de Geografia, Lisboa, F.L. Universidade de Lisboa, 520Google Scholar
  32. Ramos MC, Durán B (2014) Assessment of rainfall erosivity and its spatial and temporal variabilities: case study of the Penedès area (NE Spain). Catena 123:135–147. doi: 10.1016/j.catena.2014.07.015 CrossRefGoogle Scholar
  33. Ramos C, Reis E (2002) Floods in Southern Portugal: their physical and human causes, impacts and human response. Mitig Adapt Strateg Glob Change 7(3):267–284. doi: 10.1023/A:1024475529524 CrossRefGoogle Scholar
  34. Rose S (2009) Rainfall–runoff trends in the south-eastern USA: 1938–2005. Hydrol Processes 23(8):1105–1118. doi: 10.1002/hyp.7177 CrossRefGoogle Scholar
  35. Santo FE, Ramos AM, de Lima MIP, Trigo RM (2013) Seasonal changes in daily precipitation extremes in mainland Portugal from 1941 to 2007. Regional Environ Change. doi: 10.1007/s10113-013-0515-6 Google Scholar
  36. Santos CAG, Morais BS (2013) Identification of precipitation zones within São Francisco River basin (Brazil) by global wavelet power spectra. Hydrol Sci J 58(4):789–796. doi: 10.1080/02626667.2013.778412 CrossRefGoogle Scholar
  37. Sen PK (1968) Estimates of the regression coefficient based on Kendall’s tau. J Am Stat As 63:1379–1389. doi: 10.1080/01621459.1968.10480934 CrossRefGoogle Scholar
  38. Silva RM, Santos CAG, Macedo MLA, Silva L, Freire PKMM (2013) Space–time variability of rainfall and hydrological trends in the Alto São Francisco River basin. IAHS-AISH Publ 359:48–54Google Scholar
  39. Subash N, Singh SS, Priya N (2011) Variability of rainfall and effective onset and length of the monsoon season over a sub-humid climatic environment. Atmos Res 99:479–487. doi: 10.1016/j.atmosres.2010.11.020 CrossRefGoogle Scholar
  40. Tabari H, Marofi S (2011) Changes of pan evaporation in the west of Iran. Water Resour Manage 25:97–111. doi: 10.1007/s11269-010-9689-6 CrossRefGoogle Scholar
  41. Tramblay Y, Badi W, Driouech F, El Adlouni S, Neppel L, Servat E (2012) Climate change impacts on extreme precipitation in Morocco. Glob Planet Change 82(2):104–114. doi: 10.1016/j.gloplacha.2011.12.002 CrossRefGoogle Scholar
  42. Trigo RM, DaCamara CC (2000) Circulation weather types and their influence on the precipitation regime in Portugal. Int J Climatol 20:1559–1581. doi: 10.1002/1097-0088(20001115)20:13<1559::AID-JOC555>3.0.CO;2-5 CrossRefGoogle Scholar
  43. Trigo RM, Osborn TJ, Corte-Real JM (2002) The North Atlantic Oscillation influence on Europe: climate impacts and associated physical mechanisms. Clim Res 20:9–17. doi: 10.3354/cr020009 CrossRefGoogle Scholar
  44. Trigo RM, Pozo-Vazquez D, Osborn TJ, Castro-Diez Y, Gámis-Fortis S, Esteban-Parra MJ (2004) North Atlantic Oscillation influence on precipitation, river flow and water resources in the Iberian peninsula. Int J Climatol 24:925–944. doi: 10.1002/joc.1048 CrossRefGoogle Scholar
  45. Vicente-Serrano SM, López-Moreno JI (2008) The nonstationary influence of the North Atlantic Oscillation on European precipitation. J Geophys Res Atmos 113:D20120. doi: 10.1029/2008JD010382 CrossRefGoogle Scholar
  46. WMO (2007) The role of climatological normal in a changing climate. WCDMP-No. 61, WMO-TD No. 1377, GenevaGoogle Scholar
  47. Yang K, Wu H, Qin J, Lin C, Tang W, Chen Y (2014) Recent climate changes over the Tibetan Plateau and their impacts on energy and water cycle: a review. Glob Planet Change 112(1):79–91. doi: 10.1016/j.gloplacha.2013.12.001 CrossRefGoogle Scholar
  48. Yue S, Pilon P, Phinney B, Cavadias G (2002) The influence of autocorrelation on the ability to detect trend in hydrological series. Hydrol Processes 16:1807–1829. doi: 10.1002/hyp.1095 CrossRefGoogle Scholar
  49. Yunling H, Yiping Z (2005) Climate change from 1960 to 2000 in the Lancang River Valley China. Mt Res Dev 25(4):341–348. doi: 10.1659/0276-4741(2005)025[0341:CCFTIT]2.0.CO;2 CrossRefGoogle Scholar
  50. Zarghami M, Abdi A, Babaeian I, Hassanzadeh Y, Kanani R (2011) Impacts of climate change on runoffs in East Azerbaijan Iran. Glob Planet Change 78(3–4):137–146. doi: 10.1016/j.gloplacha.2011.06.003 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Richarde Marques da Silva
    • 1
  • Celso A. G. Santos
    • 2
    Email author
  • Madalena Moreira
    • 3
  • João Corte-Real
    • 3
    • 4
  • Valeriano C. L. Silva
    • 2
  • Isabella C. Medeiros
    • 2
  1. 1.Department of GeosciencesFederal University of ParaíbaJoão PessoaBrazil
  2. 2.Department of Civil and Environmental EngineeringFederal University of ParaíbaJoão PessoaBrazil
  3. 3.Institute of Mediterranean Agrarian and Environmental Sciences (ICAAM), Group Water, Soil and ClimateUniversity of Évora, Núcleo da MitraÉvoraPortugal
  4. 4.Research Unit Dreams, Department of Aeronautics and TransportsUniversity Lusófona of Humanities and TechnologiesLisbonPortugal

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