Spatiotemporal analysis of encroachment on wetlands : hazards, vulnerability and adaptations in Kampala City, Uganda

Thesis (PhD)--Stellenbosch University, 2016.ENGLISH ABSTRACT: Wetlands provide vital ecosystem services including water purification, flood control and climate moderation, which enhance environmental quality, promote public health and contribute to risk reduction. The biggest threat to wetlands is posed by human activities that transform wetlands, often for short-term consumptive uses. Population pressure, urbanization and industrial developments, among other factors, have resulted in severe degradation of wetlands. In the face of increased climate variability, several hazards continue to emerge, affecting the vulnerable sectors of society, especially the poor. This study sought to quantify and map the extents and spatiotemporal dynamics of human activities in wetlands, taking a case of Nakivubo wetland that drains Kampala city’s wastewater to Lake Victoria; assess the range of hazards, perceived vulnerabilities and associated factors among wetland communities, and assess the benefits and opportunities informal wetland communities in Kampala Uganda derive from their location in the wetland and how they adapt to minimise vulnerability to hazards such as floods and disease vectors. In order to achieve the study objectives, a mix of methods were used. These included GIS and Remote sensing techniques for analysis of very high resolution aerial photos and satellite imagery (captured in 2002, 2010 and 2014), a survey of 551 households, four focus group discussions among wetland communities and five key informant interviews with stakeholders. Analysis of land cover in Nakivubo wetland showed a 62% loss of wetland vegetation between 2002 and 2014, which is mostly attributed to crop cultivation. Results from the survey showed floods and waterlogging as the principal hazards; however, secondary effects of floods and waterlogging such as disease vectors and diseases affect more people than the floods. Tenants were more likely to be exposed to floods, but less likely to prefer to adapt, and to perceive themselves able to afford adaptation than landlords/homeowners, and households that spend more than US$ 80 per month were less likely than households that spend less to be exposed to floods. Households that had been exposed to floods before were more likely to perceive themselves as vulnerable. Free water from spring wells and cheaper rental units topped the benefits associated with location while the main benefit associated with the wetland itself is that it supports crop farming. However, cultivation in the buffer wetland vegetation makes it unstable to anchor to the substrate, implying that it will likely be calved away by receding lake waves as evidenced by the 2014 data. With barely no wetland vegetation buffer around the lake, the heavily polluted wastewater streams will further deteriorate the quality of lake water. Furthermore, with increased human activities in the wetland, exposure to flooding and pollution will likely have more impact on the health and livelihoods of vulnerable communities. There is a need for coordinated adaptation strategies that involve all stakeholders, and a multi-faceted approach such as ecosystem-based adaptation needs to be implemented; possibly through zoning out the wetland and restricting certain activities to specific zones so as to enhance equitable utilisation of wetland resources without compromising their ecosystem services and benefits.AFRIKAANSE OPSOMMING: Vleilande bied belangrike ekosisteemdienste soos watersuiwering, vloedbeheer en klimaat moderering, wat die omgewingsgehalte verbeter, openbare gesondheid bevorder en bydra tot risiko vermindering. Die grootste bedreiging vir vleilande is die transformasie daarvan as gevolg van kort termyn menslike aktiwiteite en hul verbruikende doeleindes. Bevolkingsdruk, verstedeliking en industriële ontwikkelings, onder andere, het gelei tot ernstige agteruitgang van vleilande. In die aangesig van die verhoogde klimaat variasie, kom sekere gevare steeds na vore wat die kwesbare sektore van die samelewing, veral die armes, affekteer. Hierdie studie poog om die mate en tyd-ruimtelike dinamika van menslike aktiwiteite in vleilande te kwantifiseer en te karteer, en neem 'n gevallestudie van Nakivubo vleiland wat Kampalastad se afvalwater na Lake Victoria dreineer; evalueer die omvang van gevare, waarneming van kwesbaarhede en verwante faktore onder vleiland gemeenskappe, en om die voordele en geleenthede wat informele vleiland gemeenskappe in Kampala, Uganda put uit hul nedersetting in die vleiland, te bepaal, asook hoe hulle aanpas om kwesbaarheid vir gevare soos vloede en siektes te verminder. Om die studie se doelwitte te bereik, is verskeie metodes gebruik. Dit sluit in GIS en afstandswaarnemings tegnieke vir die ontleding van baie hoë resolusie lugfoto's en satellietbeelde (vasgevang in 2002, 2010 en 2014), 'n opname van 551 huishoudings, vier fokusgroepbesprekings onder vleiland gemeenskappe en vyf belangrike informant onderhoude met belanghebbendes. Ontleding van gronddekking in die Nakivubo vleiland het gewys dat 'n verlies van 62% van die vleiland plantegroei tussen 2002 en 2014 plaas gevind het, wat meestal toegeskryf word aan gewasverbouing. Resultate van die opname het getoon dat vloede en water deurtrokkenheid die hoof gevare is; daar is egter sekondêre gevolge van vloede en water deurtrokkenheid, byvoorbeeld siekte vektore en siektes, wat mense meer affekteer as die vloede. Huurders was meer geneig om blootgestel te word aan vloede, maar minder geneig om te verkies om aan te pas, en om hulself te sien bekostig om aan te pas as verhuurders/huiseienaars, en huishoudings wat meer as US$ 80 per maand spandeer was minder geneig as huishoudings wat minder spandeer om blootgestel te word aan vloede. Huishoudings wat blootgestel was aan vloede voorheen was meer geneig om hulself as kwesbaar te beskou. Gratis water vanaf die lente putte en goedkoper huureenhede het die voordele verbonde aan die omgewing oorskry, terwyl die grootste voordeel wat verband hou met die vleiland is die ondersteuning van gewasverbouing. Egter, verbouing in die buffer vleiland plantegroei maak dit onstabiel om te anker, wat impliseer dat dit waarskynlik weg gekalf sal word deur die afname van meergolwe soos blyk uit die data van 2014. Met skaars geen vleiland plantegroei buffer rondom die meer, sal die hoogs besoedelde afvalwaterstrome verder die meer se waterkwaliteit verswak. Verder, met verhoogde menslike aktiwiteite in die vleiland, sal blootstelling aan vloede en besoedeling waarskynlik ‘n groter impak op die gesondheid en lewensbestaan van kwesbare gemeenskappe hê. Daar is 'n behoefte aan gekoördineerde aanpassingsstrategieë wat alle belanghebbendes betrek, en 'n veelvuldige benadering, soos byvoorbeeld ekosisteem gebaseerde aanpassing moet geïmplementeer word; moontlik deur die sonering uit die vleiland en die beperking van sekere aktiwiteite tot spesifieke gebiede sodat die billike benutting van vleiland hulpbronne kan verbeter sonder om hul ekosisteem dienste en voordele te kompromiseer