Abstract:
Water is at the core of sustainable development and is critical for socio-economic
development, healthy ecosystems and for human survival. This research
study has been carried out in Nakuru County, a tropical region in the
Rift Valley of Kenya, bounded between latitude 0.28˚N and 1.16˚S, and longitude
36.27˚E and 36.55˚E. The objective of the study has been to use GIS and
remote sensing in assessment of water scarcity using Land use Land cover area
changes, standard precipitation index and crop yields. Lands at satellite images
for the year 1985, 1995, 2005 and 2015 were used. Classification was done
using maximum likelihood algorithm while classification accuracy assessment
entailed the use of confusion matrix method and ground truth data. Post classification
change detection results gave percentage cropland areas as 21% in
1985, 29% in 1995, 53% in 2005 and also 53% in 2015. Eleven (11) ground
rainfall stations and TRMM satellite rainfall data from 1985 to 2015 has been
used to show meteorological drought. Validation of rainfall data done using
correlation coefficient (R2) and root mean square (RMS) methods showed that
ground rainfall data and TRMM data correlate. Modelling of 3 months SPI for
each of the three seasons (MAM, JJA and OND) has been done using interpolation
distance weighted method (IDW). 3 months SPI time scales curves gave
October 1984 May 1993, and July 2004 as water scarce and dry seasons and
were categorized as either Normal, moderately dry, severely dry and extremely
dry. Crop yield trends curves showed crop yield decrease in this identified
water scarce and dry years. Conclusion reached is that crop yields is not dependent
on size of land ploughed only but mostly on rainfall quantities.
Therefore, the findings of this research can be used as drought monitoring
tools.
