Seasonal Trend Analysis of Climatic Indices on Gauge Rivers in N/E Nigeria

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.