Effects of Drought Dynamics On Vegetation Cover and Water Resources in Marigat Sub-County, Baringo County, Kenya

Abstract

Droughtis a natural phenomenon that exists when precipitation is significantly below normal, affecting landresourceproduction systems. In the arid and semi-arid areas, where pastoralism is the main source of livelihood,droughts adversely affect vegetation cover and water resources which are the key resources for pastoralism.The effects posed by every drought episode vary depending on drought intensity and duration. Thus,there is need to a certain drought intensity and duration to enable effective drought preparedness by both the inhabitants and other stakeholders. Studies carried out have put less emphasis on specific dynamicsof drought and their associated impacts. This study examined the effects of dought dynamics on . vegetationcover and water resources in Marigat Sub-County. The Specific objectives of study were to establish drought dynamics between 1980 and 2012; to examine the effects of drought intensity and durationon vegetation cover; and to ecamine the effects of drought intensity and duration on water resources.The study adopted cross sectional descriptive dosiga'riz.ce both quantitative and qualitative data for a period of 33 years was obtained at once The unit of analysis was the households. Proportionate randomsampling was used to select 368 households from a total study population of 9,160 households ThreeFocus Group Discussions (FGDs) were conducted and five Key Informants were selected using purposive sampling. Both primary and secordary data was collected and analyzed. The results were presentedin textual outlines, tables, charts, graphs, percentages and description.The study used Landsat imageswhich was processed using ERDAS IMAGINE Version 2011 and resulting maps were analyzed usingGIS ArcMap Version 10.1 software Hydrological data for 6 years for River Perkerra was analyzed using Pearson's Product Moment Correlation Coefficient (r) The study established that droughts in MarigatSub-Countyvaried in both intensity and durations The intensity ranged from 0.1 to 57.8 percent below the long term mean while durations ranged from 1 to 5 years. The effects of these droughts on vegetationcover and water resources were intensity and duration dependent. Low Normalized Drought VegetationIndex (NDVI) values characterized high intensity and prolonged droughts. NDVI values were higherwhen droughts were of lower intensity and shorter durations. The intense drought of the year 20m recordedan NDVI value of-O.07, an indication that most parts of the study area were bare ground devoid of vegetationcover due to the drought whereas the less intense drought of the year 1994 recorded an NDVI value of 0.08. Vegetation cover during the 1994 drought YJS a,-'lr.quatewith few pockets of bare grounds Similarly,the effects of droughts on water resources were intensity and duration dependent. The effects were more severe with increasing drought intensity and duration. The size of Lake Baringo W"iedfrom 39.9knl to 51.3 km2to 62.2 km2during the 2002, 2000 and 1984 droughts. The intensities ofthe droughts were: 57.8% below the long term mean in 2002, 54.4% in 2000 and 52% in 1984. During the prolonged drought of 2000-2004, all water pans and seasonal rivers dried up. The study established a negative relationshipbetween drought intensity and River Perkerra discharge, correlation coefficient (r) was -0.9. This study is useful to the inhabitants, policy makes and other stakeholders in placing appropriate coping measures in order to minimize losses and forms a basis of drought action and preparedness plans for effectivedrought management and mitigation plans in theArid and Semi-Arids Land (ASALs) of Kenya.