Modelling and Simulation of Rainfall-Runoff
Relations for Sustainable Water Resources
Management in Ethiope Watershed using SCS-CN,
ARC-GIS, ARC-HYDRO, HEC-GEOHMS and HEC-HMS
Volume 2 - Issue 3
Ihimekpen NI, Ilaboya IR* and Onyeacholem OF
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- Department of Civil Engineering, University of Benin, Nigeria
*Corresponding author:
Ilaboya IR, Department of Civil Engineering, Faculty of Engineering, University of Benin, P.M.B 1154, Benin City, Edo
State, Nigeria
Received: August 07, 2018; Published: August 13, 2018
DOI: 10.32474/TCEIA.2018.02.000136
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Abstract
Rainfall-runoff modelling is an integral part of water resources planning and management. Runoff is one of the most important
hydrologic variables used in most of the water resources applications and accurate information on the quantity and rate of runoff
from land surface into streams and rivers is vital for integrated water resource management since information on runoff is required
to deal with many watershed development and management problems.
The aim of the research was to develop a conceptual rainfall-runoff model using River Ethiope as a case study. The input data
for the model were annual rainfall data, annual temperature data, daily rainfall data and the digital elevation model (DEM) of the
study area. The annual rainfall and temperature data were first analyzed for outliers, homogeneity and normality before used while
the HEC-HMS model was calibrated using one month daily rainfall data. The runoff simulation was done by integrating ARC-HYDRO,
HEC-GEOHMS, HEC-HMS and ARCGIS.
To develop the runoff model and compute the daily runoff, information on the watershed characteristics were first determined.
The initial base flow was assumed to be 0.00, Soil conservation systems (SCS) curve number (CN) for direct runoff value was
determined from existing standard tables based on the catchment characteristics, initial abstraction was assumed to be 0.00,
Muskingum K (Hr), was calculated using the routing equation, Muskingum X lies between 0.1 to 0.3 for reach while impervious
surface (%) was taking as 0.00.
Results obtained shows that the climatic data used for the analysis are homogeneous, devoid of possible outliers, characterized
with seasonal variability and do not follow a normal distribution which is expected owing to the stochastic nature of climatic
variables. The computed Muskingum k value was 2.2hrs. In addition, results of the runoff simulation shows that the peak discharge
from subbasin one was 10.3m3/s, the total precipitation was observed to be 1738.60mm, total precipitation loss was 124.14mm
while the total excess precipitation was calculated as 1614.46mm. For subbasin two, the peak discharge was observed to be 9.3m3/s,
the total precipitation was observed to be 1738.60mm, total precipitation loss was 113.17mm while the total excess precipitation
was calculated as 1625.43mm. For the reach (River), the peak inflow was computed to be 10.3m3/s, the peak outflow was 9.8m3/s
while the total inflow was 1609.92m3/s. The time for peak inflow was 17th September, 2016 and the time for peak outflow was
observed to be 14th September, 2016.
Keywords: SCS curve number; Base flow, Muskingum K and X; HEC-GEOHMS; HEC-HMS
Abbreviations: SCS: Soil Conservation Systems; DEM: Digital Elevation Model; CN: Curve Number; ANN: Artificial Neural Network;
DRO: Direct Runoff
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