Severe drought has affected Kenya in the past decades reducing crop yields leaving millions of people in dire need of food. Drought cycle in Kenya has reduced increasing drought frequency in the recent decades. This study assessed drought characteristics in Laikipia West sub-County which lies in a region classified as arid and semi arid. The specific objective of the study was to analyze seasonal and annual drought characteristics in Laikipia West sub-County between 1984 and 2014. The study adopted documentary review design in the data collection. Standard Precipitation Index was used during the data analysis process. The drought years identified in Laikipia West sub-County were: 1984, 1985, 1987, 1991, 1995, 1999, 2000, 2005, 2008 and 2009. The seasonal drought events shows that for the period under study Laikipia West sub-County has never experience drought during the MAM and OND seasons in the same year. This explains the importance of seasonal climate forecast to crop farmers. The study also established that the average drought cycle in the study area is 3 years. The study recommends construction of mega water reservoirs which could collect water during the wet season to be utilized during the dry seasons. The study also recommends channeling of drought information through the government agencies at the beginning of every season.
Drought is a form of environmental stress that originates from a deficiency in precipitation over an extended period of time long enough to cause moisture deficiency, biotic loss, crop failure, loss of lives both human and bovine and general hardships [
El Niño events are associated with many global climatic anomalies such as flooding and drought [
Between the early 1970s and the mid 1990s the African Sahel experienced one of the most dramatic long-term changes in climate observed anywhere in the world in the twentieth century, with rainfall declining on average by more than twenty percent [
The study area was Laikipia West sub-County in Laikipia County, Kenya. The choice of Laikipia West sub-County was based on variation in livelihood options. Drought impacts and adaptations strategies are determined by economic activities of the households and their variations leads to adoption of different adaptation strategies. Laikipiameans treeless plain in Maasai language [
The study area is located in the rain shadow of Mount Kenya making the area dry. The sub-County has humid, semi humid and semi-arid agro-ecological zones. The agro ecological zone of Rumuruti ward the sampled ward is LH 4, LH 5 and UM 5 [
Rainfall amount data for a period of 31 years (1984 to 2014) was utilized. Thirty one year’s period was chosen because it is within the minimum period which climate change is believed to take place. In 1984 Kenya experienced among the worst droughts in history while 2014 severe drought predicted. This necessitated the study on drought characteristics and trends between the two inter drought periods in Laikipia West sub-County. Rainfall data was collected from Rumuruti and Ndaragwa WRMA stations. The selection of the stations was informed by the fact that they are the only reliable stations in the study area. Although there are other weather stations such Mukogondo forest and Nyahururu rainfall stations in Laikipia West sub-County, the data collected from these stations was not considered for the analysis because more than 34% of the data was missing and failed the reliability of climatological test.
Standardized precipitation index (SPI) was used in the analysis of drought characteristics. Standardized Precipitation Index (SPI) expresses the actual rainfall as a standardized departure with respect to rainfall probability distribution function and hence the index has gained importance in recent years as a potential drought indicator permitting comparisons across space and time [
2.0+ | Extremely wet |
---|---|
1.5 to 1.99 | Very wet |
1.0 to 1.49 | Moderately wet |
−0.99 to 0.99 | Near normal |
−1.0 to −1.49 | Moderate dry |
−1.5 to −1.99 | Severely dry |
−2 and less | Extremely dry |
Source: WMO (2012).
Rainfall trend is the graphical representation of the observed drought years from 1984 to 2014 in Laikipia West sub-County. Results in
The lowest average rainfall experienced in 1999 and 2000 coincides with the La Niña phenomena that followed the El Niño rains of 1997 and 1998. In a related study, it was established that in South Africa drought disasters tend to occur in the year following the onset of El Niño and are less frequent at other times [
When compared to the mean rainfall, 47% of the study period in Ndaragwa station received below the mean rainfall while 37% received rainfall above the mean. This shows that during the study period more years recorded below normal rainfall as compared to the years that received above normal rainfall. During the study period only 16% of the years received normal rainfall in Ndaragwa. The mean rainfall in Ndaragwa station is higher compared to Rumuruti station and this could mean that Mutara location which is in proximity to Ndaragwa could have favourable conditions to support maize (other crop) farming or growth of pasture than the other Locations in Rumuruti Ward.
Rainfall amount data was used to identify, quantify and classify seasonal drought years, both long and short rain seasons in Laikipia West sub-County from 1984 to 2014. Drought characteristics have been analyzed on seasonal and annual bases. Drought analysis during the wet months has been necessitated by the importance of the seasons to crop growers in the study site who entirely depend on rain fed agriculture. The wet months in Laikipia West sub-County are March, April and May (MAM) which is a long rain season and October, November and December (OND) which is a short rain season. The dry months are January, February, June, July, August and September. In this study, drought was categorized as moderate, severe and extreme. Moderate drought refers to the drought with the SPI value of −1.0 to −1.49. Severe drought refers to drought with SPI value of −1.5 to −1.99 and extreme drought refers to drought with SPI value of −2.
Results in
drought during MAM was in 2009 in Ndaragwa and Rumuruti stations. The SPI results in
The seasonal drought events shows that for the period under study Laikipia West sub-County has never experience drought during the MAM and OND seasons in the same year. This shows that in case there is drought in one season the following season is a non drought season. This explains the importance of seasonal climate forecast to crop farmers on placing the best bet in maximizing production in favourable seasons and to caution them during unfavorable seasons either by planting drought resistant seeds or opting not to cultivate crops. The findings supports the earlier argument by [
The annual drought analysis is important because of the livestock farmers who depend entirely on natural pasture for their livestock throughout the year. The standard precipitation index annual results in
The results highlight the significance of localized factors such vegetation cover and topography in influencing rainfall amount. Notable too is establishment that Rumuruti station has experienced more droughts in the past than Ndaragwa station.
The results presented in
These results concur with earlier studies that the drought cycle has changed in the recent time and become more frequent, 2 - 3 years, giving no time to recover from the effects [
There has been an increasing trend on average rainfall amount in Laikipia West sub-County. The years that received below normal rainfall (drought years) (−0.99 to 0.99) were: 1984, 1985, 1987, 1991, 1995, 1999, 2000, 2005, 2008, 2009 and 2014. The recent extreme drought event in Laikipia West sub-County was experienced in 2009. The near normal rainfall (−0.99 to 0.99) years were: 1986, 1988, 1989, 1992, 1993, 1994, 1996, 2001, 2002, 2004, 2006 and 2012. The above normal rainfall (Wet years) were: 1990, 1997, 1998, 2003, 2007, 2010, 2011 and 2013. The highest amount of Laikipia West sub-County was experienced in 1997 and 1998 and this was during the El Nino phenomena where Kenya as Country received rainfall above normal. The seasonal drought events shows that for the period under study Laikipia West sub-County has never experience drought during the MAM and OND seasons in the same year. This explains the importance of seasonal climate forecast to crop farmers. The study recommends construction of mega water reservoirs that will collects water during the rainy seasons and this water could be utilized during the dry periods for both domestic and irrigation use. Since the demand for horticulture product is high during dry periods the collected water can be utilized during drought as an opportunity to make wealth in Laikipia West sub-County. The study also recommends channeling of drought information through the government agencies at the beginning of every season.
The authors of this article acknowledge the Egerton University, Division of Research and Extension for availing funds to support in publication of the article from the on-going research on effects drought on household livelihoods and adaptation strategies in Laikipia West sub-County, Kenya. The authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors, editors and publishers of journals and books from where the literature of this article has been referred.
Karanja, A., On- dimu, K. and Recha, C. (2017) Analysis of Temporal Drought Characteristic Using SPI Drought Index Based on Rainfall Data in Laikipia West Sub-County, Kenya. Open Access Library Journal, 4: e3765. https://doi.org/10.4236/oalib.1103765