ANALYSIS OF LAKE NAKURU SURFACE WATER AREA VARIATIONS USING GEOSPATIAL TECHNOLOGIES

Abstract

The research intended to analyse the trend of Lake Nakuru water surface variation between 1984 and 2013 with the aim of identifying probable causes. Landsat images including Tropical Rainfall measuring mission (TRMM) were used  to  determine  the  lake  surface  level  variations  within  the  period.  Supervised  classification  was  used  in generating Land Use/Land Cover changes between 1984 and 2013. The results show that changes in the lake level variations may not  entirely be attributed the amount  of rainfall during the period under consideration.  There is consistent trend in reduction of forest cover and increase of farm or agricultural land. Forest cover increased from 30.99%  to  33.73%  between  1984  and  2013  while  agricultural  land  increased  from  59.12%  to  68.61%  during  the same period. The lake water surface area had a steady increase of between 30.46 km2 in November 2009 to 57.55
km2 in January 2014 an increase of 27.09 km2 which is 88.94%.  In 2006 the water surface area was 35.38 km2 , it also witnessed the highest amount of rainfall but the lake water surface area did not reflect that. The rainfall data from TRMM 2009  - 2010 the difference was 36.3%, 2010-  2011 reduced to 29.8%, 2011 –  2012 increased to 32.4% and  2012  –  2013  finally  increased  to  36.6%.  The  rain  gauge  rainfall  amounts  2009  -  2010   had  a  difference  of 24.4%, 2010-  2011 reduced to 19.3%, 2011  –  2012 reduced further to 13.1% then 2012  –  2013 increased to 49%. The  lake  surface  area  2009  -  2010  difference  of  44.6%,  2010-  2011  increased  to  46.7%,  2011  –  2012  increased
further to 70.1% and 2012  –  2013 finally increased to 86.6%. This showed when rainfall amounts were falling the lake surface areas were still increasing indicating no direct correlation between the rain and the lake surface area.

Key  words:  Geospatial  information  Systems,  tropical  rain  measuring  mission,  land  use,  land  cover,  supervised
classification, landsat images, lake water surface area.