Seasonal Trend Analysis of Climatic Indices on Gauge Rivers in N/E Nigeria
M. N. Dammo *
Department of Civil Engineering, Ramat Polytechnic Maiduguri, Nigeria
A. O. Yakeen
Department of Civil Engineering, Ramat Polytechnic Maiduguri, Nigeria
M. J. Deborah
Department of Civil Engineering, Ramat Polytechnic Maiduguri, Nigeria
S. G. Yadima
Department of Civil and Water Resources Engineering, University of Maiduguri, Nigeria
A. Y. Sangodoyin
Department of Agricultural and Environmental Engineering, University of Ibadan, Nigeria
*Author to whom correspondence should be addressed.
Abstract
The surface water of river basins in particular the Sahel region of north – east Nigeria show very sensitive inter-annual fluctuations due to climate changes. Seasonal changes of climatic indices on water level of six rivers: Dadin-kowa, Jimeta, Donga, Geidam, Alau and Jamaare of north-east Nigeria were examined by modeling the changes of mean monthly rainfall, temperature, relative humidity and evaporation. Trends in seasonal climatic indices were analyzed using Mann-Kendall test to determine their effect on gauge water level of rivers in north-east Nigeria. The result indicated significant effects of climate indices on gauge water level with decadal mean temperature and evaporation ranging between 24.1 – 31.4°C and 3 – 7.5 mm respectively across the region. Similarly, the positive impacts of climatic indices from rainfall and relative humidity ranged between 8 – 2127 mm and 28.6 – 71.4% respectively. Pathway effects among climatic variables quantitatively revealed that the highest impact on water level was evaporation (89.8%) then temperature (82.1%) relative humidity (78.3%) and rainfall (71.2%), respectively. Although the effects of climatic indices varied within different locations, they generally impacted significantly on the water levels within the sub-region.
Keywords: Seasonal trend, climatic indices, Gauge Rivers, north-east