VOL. 10, NO. 18, OCTOBER 2015 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences ©2006-2015 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 8192 STATISTICAL EVALUATION OF HYDRO-METEOROLOGICAL DATA: A CASE STUDY OF ISHIAGU IN SOUTH-EAST ZONE NIGERIA B. U. Ngene 1 , I. T. Tenebe 1 , P. C. Emenike 1 and R.I. Airiofolo 2 1 Department of Civil Engineering, Covenant University, Ota, Ogun State, Nigeria 2 Department of Civil Engineering, Ambrose Alli University, Ekpoma, Edo State, Nigeria E-Mail: uchengene26@yahoo.com ABSTRACT For any Engineering project to be efficient, it must be based on consistent and reliable data with good analysis. Reliability, especially for hydro-meteorological data depends on the method of collection, analysis and storage. Ishiagu weather data has been collected since the inception of the school of agriculture in the town in 1997 to date. Statistical analysis of the randomly varying data to check for their consistency and reliability is necessary before use. In this regard, the monthly data set is analysed for annual mean, trends and seasonal distribution pattern. A significant finding of this analysis is that the monthly rainfall has bimodal distribution with peaks in July and September. For the temperature of the area, it showed a sinusoidal pattern due to the seasons and this also reflects on the relative humidity of the area. A regression analysis of the three data of rainfall, temperature and relative humidity indicates a coefficient of correlation of r = 0.3, t = -0.40 and rh = -0.67. Because of the low state of the coefficient of correlation of the three parameters it may be necessary to recheck with either power, exponential or polynomial functions. From the determination of frequency of extreme events using Gumbel distribution, the highest annual rainfall value is determined to have a return period of less than 20years and the 17years records also was adjudged adequate. Keywords: hydrology, weather, hydro-meteorological, rainfall. INTRODUCTION Hydro-meteorological data are important to Engineers interested in water resources management. Hydrology is the study of the presence and distribution of waters on earth (Biswas, 1970), while Meteorology looks at the Physics of evaporation of the water and the transformation to rainfall (Shaw et al., 2011). Hydro- meteorological data study will help in understanding how variations in rainfall in different regions of the earth will affect water resources management. As observed by Sharon (1972), rainfall varies even within short distances which are particularly the case for tropical regions of the earth due to the nature of rain formation. Studies on South Eastern Nigeria Hydro-meteorological characteristics are very scarce in literature, hence the need for this analysis. Water resources management projects includes: water supply for domestic and industrial use, drought and flood control, irrigation, hydro-electricity, watershed management, navigation, fisheries and wildlife habitat, recreation, drainage, groundwater recharge and abstraction, sediment and salinity control (Lee, 2005). Global warming and climate change effect has made the study of weather data to enhance the knowledge of the variability of such data and how they affect water resources projects very necessary (Ngongodo et al., 2011; Odekunle, 2004). In this regard, trend analysis overtime, variability of extreme events and frequency of occurrence of extreme rainfall, will aid Engineering design and economic appraisal of structures required in water resources management. The hydro-meteorological data of interest for the Ishiagu study include the rainfall, temperature and relative humidity. A correlation among the data set is established while the seasonal variability as it affects water resources management is determined. Mean annual temperature affects rainfall since it is a critical factor affecting the process of evaporation and wind direction (Mutreja, 1990). Also it is noted that rainfall amount and frequency are greater in wind ward direction of air mass lift. Air mass lifting is the cause of most precipitation, hence, high elevation tend to have greater rainfall. Flood is a meteorological hazard produced by persistent extreme rainfall event over an area (Obasi, 1991). The amount and consistency of available meteorological data contribute to the reliability of flood forecasting. Drought, on the other hand is a period of persistent below average availability of water either in form of precipitation, surface water runoff or ground water. Agriculture consumes the largest amount of water at 80% of total water controlled by man (FAO, 1972; Orkuma, 2002). This notwithstanding efficiency of allocation and use is also important to humanity as scarcity of water possess economic danger. Heavy Engineering projects such as dams require information on extreme weather events to avoid failure risk and associated damages to downstream users. With the proposal for a dam at locations shown in figure-1 below, it is necessary to ensure constant availability and adequacy of the Ivo River to sustain such a dam. Since rain at Ishiagu and environment contributes to the recharge, it is important to understand the rainfall and other hydro-meteorological pattern of the area, hence this study. MATERIALS AND METHODS The study area is Ishiagu, Ivo Local Government Area, Ebonyi State; Nigeria. It is located on the plains of the south-eastern savannah belt in Nigeria. Ishiagu is located 5°56ƍ55ƎN 7°34ƍ00ƎE with a height above sea level