Spatial-temporal changes of landcover types in response to anthropogenic dynamics in Yala Swamp, Siaya County, Kenya
Ondere, Lavendah Alwaka
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Research in wetlands has made great progress and it is widely recognized globally that they are under threat of disappearing and degradation due to overexploitation of their products and services. The study was undertaken in Yala wetland that covers an area of 17,500 ha in an area with one of the highest population density and growth rate in Kenya. The wetland is mainly cleared for crop cultivation and settlement and about 2,800ha (Figure 4.14) have been drained for commercial agriculture. It is therefore important to characterize the composition of land cover before any conservation and management programs are put in place. The main aim of this study was to analyse, identify, characterize and examine associated spatia-temporal land use changes linked to anthropogenic activities in the wetlands and its environs from satellite imagery, the information will be used to develop and come up with land use/cover maps to aid in sustainable management and utilization of the Yala wetland resource. Geographic Information systems (GIS) and Remote Sensing were employed to achieve this objective, LANDSAT ETM for 1990, 2000, 2010 and 2014 satellite images were used. Image analysis was done in Arc GIS 10.1 and ERDAS 9.3 software packages. Based on GIS and RS analysis, it was evident that the study area has undergone major changes. The size of the wetland had reduced by 33 % over the 25 year period, and agricultural land had increased by over 65%, lake area reduced by 7%, shallow waters reduced by 7 %, settled area increased by 50%, rice paddies increased by 21 % open grasslands with shrubs on the other had reduced by 83%. This could be attributed to increase in population at 65% 1989 and 2009 census of Kenya. Field studies indicated that burning of the wetland at 41%, uprooting of wetland vegetation 14% and cutting of the wetland vegetation at 32% are the main methods used to clear the wetland for farmland and settlements. Though the residents engage in other economic activities the most preferred one is mat making at 29% mainly dependant on papyrus reeds. Land ownership is also contributing to low sustainable measures being undertaken; the field survey indicates that 42% of the respondents are managing family land while 40% have inherited making it hard to easily implement conservation measures in the wetland. SPSS T-test was run for both null hypothesis HAO1; there are significant spatial and temporal changes in land cover types due to land use changes in the Yala wetland over the study period was 0.9223 and HAO2; spatiotemporal characteristics of population growth in the study area have direct linkages on land use land cover changes in the Yala wetland was 0.9126, the results were accepted. In conclusion, it was realized that the Yala swamp wetland has increasingly been faced with serious problems especially human interference leading to degradation and overexploitation of its resources thus the continuous reduction of the wetland size. Sustainable measures such as development of the tourism and papyrus industry, aquaculture practice and better policy implementation should therefore be undertaken to ensure its resources are used sustainably and promote coexistence with the growing human population.