Effectiveness of measures aiming to stabilize urban gullies in tropical cities:Results from field surveys across D.R.Congo

Urban gullies are a rapidly growing concern in many tropical cities of the Global South.Various measures are already implemented for their stabilization.However,an overview of these measures and their overall effectivenesss is currently lacking.We aim at addressing this gap by documenting existing ini-tiatives to stabilize urban gullies in D.R.Congo and assessing their overall effectiveness.To this end we conducted extensive field campaigns in Kinshasa,Kikwit and Bukavu and combined our terrain obser-vations with data on gully expansion rates(derived from series of satellite imagery).In total,we char-acterized present and past stabilization initiatives for 398 urban gullies.For 69 of these gullies,the effect of a specific measure on gully expansion rates could be estimated.Results show that for the large ma-jority of gullies,various measures have been implemented.Yet,these are mainly ad-hoc measures installed by the affected population.More structural measures based on larger engineering works were observed for only 20-30%of gullies.The huge efforts invested in the installation of measures strongly contrast with their overall low impact Among all strategies,only the deviation of runoff resulted in significantly lower expansion rates after installation.The numerous initiatives that rely on the sparse means available seem to have limited effects.This does not imply,however,that they are completely ineffective and should be abandoned.Based on our findings,we formulate recommendations for further research on how to effectively prevent and stabilize urban gullies,taking into account the difficult environmental and socio-economic context.

Does Tenure Security Reduce Disaster Risk? A Comparative Study of the Nairobi Settlements of Kibera and Kawangware

While scholarship suggests that improving tenure security and housing significantly reduces disaster risk at the household level within urban settings,this assertion has not been adequately tested.Tenure security can be conceived as being composed of three interrelated and overlapping forms:tenure security as determined by legal systems;de facto tenure security;and tenure security as perceived by residents.This article traces the relationship between tenure security,the quality of housing,and disaster risk on the basis of a mixed methods comparative case study of the settlements of Kawangware and Kibera in Nairobi.Although the findings suggest that owner-occupancy is associated with the structural integrity of dwellings to a greater extent than tenantship,no association was found between the length of occupancy by households and the structural integrity of the dwelling.Moreover,tenantship is not found to be closely associated with fires and flooding affecting the dwelling as extant scholarship would suggest.Formal ownership is linked with greater investment and upgrading of property with significant implications for disaster risk.Our findings highlight the complex relationship between tenure security and disaster risk in urban informal settlements and provide impetus for further investigation.