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In most studies on flood risk in Nigeria, priority is given to urban flood risk than rural flood risk. Smallholder farmers who mostly inhabit rural areas and flood plains are known to be at great risk of flooding, but to date, there have been no studies on the impacts they experience and how they cope with these impacts.
To establish the existence of significant change in precipitation in the study area, statistical analysis of precipitation data was conducted using linear regression and non-parametric Mann Kendall test. Landsat satellite images for 1986, 2003 and 2016 were obtained from the United States Geological Survey’s (USGS) website and used to collect and analyze data related to land use.
To determine flood risk in the context of land use change, the HEC-HMS model version 3.5 was used. Land use maps corresponding to 1986, 2003, and 2016 LULC conditions were analysed and prepared for the calculation of CN values using Soil Conservation Service (SCS-CN) method. CN map was prepared by integrating the maps of hydrologic soil groups and land use in ArcGIS software.
Based on selected morphological parameters, a flood risk map was developed for the study area. The morphologic flood risk showed that most parts of the basin face moderate flood risk. Higher runoff values were observed under 2016 LULC conditions mainly due to intense deforestation relative to those of 1986 and 2003. The results indicated that runoff and peak discharge are significantly affected by deforestation instead of changes in the rainfall pattern. Flood inundation maps of the study area were prepared for the flood events of 2012 and 2015. Maximum depth for the 2012 and 2015 flood events was calculated as 10.58m and 7.39m, respectively.
The socioeconomic aspects of the research were conducted using household survey method. Using snowball sampling techniques, 400 flood-affected households were selected. The results show that the adaptive capacity of smallholder farmers in the study area remains very low and hampered by several factors such as poverty and weakened social networks. The synopsis of the examined variables leads to the following conclusion: Instead of climatic factors – as one indicator of vulnerability – it is social inequality and poverty in the region as well as the structural economic differences between various groups that mainly drives vulnerability in the study area.
Urban adaptation is a critical issue for many of the developing countries of Southeast Asia. Vietnam is likely to be among the countries most adversely affected by climate change. Moreover, its largest city, Ho Chi Minh City is considered worldwide as one of most vulnerable to a multitude of climate-related hazards, including flooding, sea-level rise and extreme heat events. Similar to other rapidly developing megacities in Southeast Asia, Ho Chi Minh City has undergone enormous changes in recent decades and has rapidly developed into an emerging megacity shaped by global processes and local settlement patterns. Recently, the need to adapt to the multiple stressors of rapid urbanisation and climate change has become increasingly evident. Adaptation to climate change in urban areas depends on decision-makers’ understanding of the current and future impacts of climate change. Land-use planning as a place-based and problem-solving strategy has been recognised as a key tool in this respect, to mainstream climate change adaptation and disaster risk reduction into urban development. Yet a key challenge is a lack of relevant information on exposed populations and assets at risk to planners and policymakers. The dissertation outlines the development of an integrated framework predominantly based on an urban structure type approach. This approach was used to manually interpret high resolution, remotely sensed imagery in order to portray and understand patterns of settlement and urban structure layout of the current and emerging landscapes of Ho Chi Minh City. The approach is able to capture the highly dynamic spatiotemporal, social and structural changes associated with rapid urbanisation. The overall findings show the applicability of the developed framework to produce important input indicators for risk adapted land-use planning. These are ultimately useful to determine hotspots for administrative interventions and to assist prioritising in spatial and urban planning decision-making.
Urbanisation is an extreme case of land-use change. The geographical patterns of urban expansion of a city have a direct relationship with its environmental quality, particularly water flows, flooding and urban thermal stress. A key question for urban policy and planning is how to direct these changes in ways that minimise environmental impacts and risks. Since many of the main impacts of climate change in Ho Chi Minh City additionally exhibit a land use dimension, such as the increased frequency of urban flooding events or the intensification of the already existing urban heat island effect, land-use planning and land-use controls can be seen as the most appropriate adaptation management strategy.
These recommendations have been developed under the German Ministry for Education and Research Funded research project ‘‘Integrative Urban and Environmental Planning for Adaptation of Ho Chi Minh City to Climate Change” which is funded as part of the research programme ‘‘Sustainable Development of the Megacities of Tomorrow’’ by the German Federal Ministry of Education and Research (BMBF) in close cooperation with the Department of Nature Resources and Environment, Ho Chi Minh City.
The main objective was to respond to the needs of the Department of Nature Resource and Environment, Ho Chi Minh City by providing guidance and recommendations that can be used by land-use planners and policy makers to reduce the potential adverse effects of both urbanisation and the current and future effects of climate change. The recommendations have been compiled as a stand-alone document that can be read and understood on their own, however they also contain references to the additional document entitled “Land-use Planning Recommendations - Adaptation Strategies to a Changing Climate in Ho Chi Minh City” referenced within this document as LUPR.Eleven specific focus areas were selected (labelledfrom A to K) in combination with the Department of Natural Resources and Environment. For each area the current situation is described and detailed planning recommendations are provided.
Urban morphology is used in many developed countries to classify and manage the dis-tribution of urban functions. In urban planning, it helps to identify the emerging prob-lems and solve the disorder of urban functions. The megacity Ho Chi Minh City has faced many problems with uncontrollable urbanization, urban management and plan-ning. It has received increasing tropical storms and cyclones which caused more heavy rains in recent decades. Rapid urbanization has caused the increase of built-up coverage with disordered typologies, incomplete infrastructure and urban-peripheral instability. In the flooding context, these problems have increased more seriously with flooding impacts and caused uncontrollable planning and management in the city. This study applies the urban morphology method to measure flood impacts on urban functions and develop the adaptive solutions for flooding adaptation for Ho Chi Minh City. The methods in this study are based on applying fractal geometry, GIS and Remote Sensing on large-scale maps for measuring the urban morphology. The land-use map and the building footprints map of 2010 were founded to analyze the distribution of urban areas by high resolution of satellite images and large scale GIS data. The fractal geometry was a setting based on Avenue program of Arcview GIS to measure the urban morphology. This formed a key input for the multi-criteria analysis (MCA) method that investigated the cause of flood impacts and suggested the solution for flooding adapta-tion. In addition, alterations of lakes, ponds and watercourse from 1995 to 2009 were explored. The study showed HCMC had problems on irrational development in residential densi-ties areas and urban functions, and the uneven development of population and residen-tial density between the urban areas: too much in the urban districts (about 300 to 500 persons per hectare per block and coverage ratio 0.7 - 0.9). This pushed the increasing demand on built-up area and filled-up rivers and canals (About 80 percent of original ponds and lakes in inner-center were filled-up in the past; and 63 percent of ponds and lakes have been filled-up in Sub-Districts and new-urban-development areas). It made the imbalance between the permeability of land surface and the run-off water flows; then leads the inundation to increase. This is the main reason for reducing the water-storage capacity in rainy season. Flooding in urban residential area was more im-pacted than in rural residential area, higher level and longer flood time; while flooding in the rainy season due to high tides, heavy rains or both was the emerging and uncon-trollable problems. For flooding adaptation, urban morphology analysis helped to figure out the potential areas in the city could be used for reducing flooding impacts in urban areas. There are many low-density residential areas in above 1.5 meter AMSL areas in the North, Northwest and Northeast areas of the city which could be developed with complete infrastructure and urban services to attract people from high-density residential areas impacted deeply by floods in the center. These potential areas could be the long-term strategic solution to flooding adaptation for HCMC. The results also suggested that some current flooded areas would be re-planned or returned to be the water-storage and permeable areas (such as green parks, ponds and lakes). This re-planning would improve the city landscape and increase the permeable surface, green spaces and open spaces to HCMC. More green spaces, lakes and ponds will also help to reduce the temperature of urban center in the dry season. This adaptation solution would reduce at least 25 percent of current flooded areas in urban center. The protection and constructed restriction of current agricultural areas in peri-urban Districts would maintain the infil-tration and green-tree areas. Furthermore, the complete drainage system would help to reduce better flood for these areas. Finally, fully dredging river and canal system of the city would reduce about 25 to 30 percent of current flooded areas.
Strategic Environmental Assessment in regional land use planning (here: SEA-REP) is a systematic process in Germany, which aims at an optimisation of the integration of environmental policies into decision-making at regional scale. It therefore plays an essential role for the comparison of site alternatives, and the implementation of mitigation and adaptation measures of negative effects of both regional development and climate change. Significant findings and personal experiences gained in an INTERREG project (‛transSEA’) created a fundamental basis for this doctoral research. The main objective was to develop the ‛LUCCA’ indicator system, which is a result of an analysis of land use types, that are increasingly important for effects of global climate change, and should therefore adapt to future conditions with regional land use planning. This system was developed from current German practice of the methodological application of SEA-REP in the core assessment of site-specific impacts on the affected area and impact zone. Main objectives were to integrate spatial effects of climate change into SEA-REP, and to develop a method to make particularly the tendency of physical degradation of natural resources in a region transparent. The research was based on a comprehensive analysis of best practice of SEA and assessment methods applied in German case studies of regional land use planning. Proposed was a a two-tiered environmental baseline- and objective-led approach of impact assessment. Its first tier is a site-specific assessment of significant impacts of regional plan designations and their alternatives. An environmental conflict analysis has the aim to apply assessment thresholds of conflict intensity for each impact factor affecting the importance of assessed components of LUCCA. Results are three classes of conflict intensity, which were determined and can be measured with the help of state indicators, impact indicators and assessment thresholds. 12 LUCCA indicators were defined in connection to regional environmental orientation objectives, environmental components, land uses and further criteria for indicator selection. The second tier is represented by an overall strategic assessment of the regional plan and its designation criteria. This assessment additionally considers positive and cumulative impacts, as well as structural alternatives. The result of the research is a standard concept for environmental orientation objectives, guidance indicators and assessment ranges for the LUCCA indicator system. Regional environmental orientation objectives, which represent outcome values of the future state of environment, were derived from existent environmental quality objectives and environmental quality standards. For each LUCCA indicator mitigation and adaptation measures of regional planning and requirements for tiering to SEA of lower land use planning were proposed. Recommendations for vital and critical action are addressed to competent national and regional authorities of spatial and sector planning. These involve the direct integration of concerns of climate change into SEA-REP, the regional operationalisation of environmental objectives for adaptation to climate change, an improved cooperation between spatial and sector planners concerned with the future use of land and resources, and, last but not least, an involvement of the public in the setting of regional objectives for the future state of a region’s environment. Recommendations for the competent national and federal ministries are the integration of substantial standards into legislation, the setting of binding standards for a stricter reduction of land consumption, the determination of clear responsibilities and activities at all planning levels, and the release of guidance for effective regional land use planning practice that enhances adaptation to climate change. The main recommendations for European regional planning bodies are to establish regional environmental objective concepts for SEA-REP, update regional environmental data profiles, apply the SEA-REP+LUCCA indicator system, develop a tiered decision-support system, challenge conventional regional planning, improve cooperation with sector planning and involve the public in the development of adaptation strategies. A recommended adaptation task at regional planning level is the designation of strictly safeguarded priority areas with specific functions of land uses for the mitigation of negative effects of climate change. Such priority areas, which should be area-specifically defined in a regional land use map, should be linked to the implementation of binding adaptation measures in lower land use planning and at project level. An operationalisation of proposed assessment steps will be necessary for the regional-specific geographic and bio-physical conditions of the EU regions. The thesis concludes with future research needs and an outlook on the potential future role of SEA-REP. A clear responsibility of the future tasks of SEA-REP and LUCCA was recognised as a formal driving force for adaptation of land use to effects of climate change. Improved knowledge on spatial effects of climate change and vulnerability assessments will be required for an effective revision and application of SEA-REP and LUCCA. SEA should gain further importance in a transparent and participative decision-making. Environmental concerns and the protection of LUCCA will have to gain more weight, if the significance of danger and harm, caused by effects of climate change and anthropogenic land degradation, shall be mitigated now and in the future.