Evaluation of Three Geostatistical Interpolation Methods for the Estimation of Average Daily Rainfall | Chapter 03 | Current Perspectives to Environment and Climate Change Vol. 3
This study focuses on evaluating the
results from three geostatistical interpolation methods used for the estimation
of average daily rainfall in ILWIS 3.7. Rainfall data from nine (9) gauging
points over the Upper Deep River Basin, North Central Nigeria were used. The
total catchment area is 6076 km2. The moving average method,
ordinary kriging technique and nearest point or Thiessen method were used for
the interpolation. The rainfall values used were for five (5) days in the same
month where rainfall data for at least six (6) of the nine (9) gauging points
were recorded, since rain did not fall on the whole the catchment on the same
day. The results obtained from the different geostatistical methods used were
different but closely similar with the moving average method recording the
highest rainfall values for all interpolations. The techniques behind the
methods were evaluated and discussed based on the results obtained. From the
results it was observed that the moving average method calculated half of the
maximum rainfall within the catchment and assigned that value for the average
rainfall while in the Thiessen polygon method, the results obtained were
similar to the arithmetic average of the rainfall values with all zero points
counted as one point. The work demonstrated that remote sensing and GIS
techniques are fast in the estimation of average rainfall over a catchment area
and the estimated rainfall data for any point within the catchment can be
obtained from the output raster maps. It is recommended for GIS users to choose
the geostatistical method that best suits their purpose.
Author(s) Details
R. E. Daffi
Department of Civil
Engineering, University of Jos, Jos, Nigeria.
F. B. Wamyil
Department of Civil
Engineering, University of Jos, Jos, Nigeria.
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