Current Constraints and Future Directions for Risk Adapted Land-Use Planning Practices in the High-Density Asian Setting of Ho Chi Minh City

Figures & data

Figure 1 The development of the built-up extent of HCMC for the period from 1989 to 2007. Source: Author's own.

Table 1 Estimated urban population as a percentage of total population (2010)

Country/region and urban population as a percentage of total population in 2010
China	46	Laos	32	Vietnam	30
Japan	66	Malaysia	71	Bangladesh	27
Mongolia	62	Myanmar	22	India	30
Cambodia	20	Philippines	49	Pakistan	36
Indonesia	44	Thailand	33	Sri Lanka	14
World					51
Developed countries					75
Asia					42

Source: Population Division United Nations (2009).

Figure 2 Spatial distribution of changes in population between 2000 and 2011 in HCMC. Source: Author's own.

Table 2 Urban structural changes in HCMC from 2005 to 2010—core indicators for changes in dominant building types

	Coverage (ha)			Floor space (ha)			Height (flr)
Building type	2005 (ha)	2010 (ha)	Change (%)	2005 (ha)	2010 (ha)	Change (%)	2005 (flr)	2010 (flr)	Change (%)
Apartment	113	166	48	569	890	57	5.0	5.3	6
High-rise	19	28	51	120	223	86	6.4	7.9	23
Detached	2,149	2,872	34	2,824	5,893	109	1.3	2.1	56
Semi detached	317	458	45	334	724	117	1.1	1.6	50
Temp. and other	37	17	− 54	41	21	− 50	1.1	1.2	8
Terraced	3,496	7,154	105	7,001	18,001	157	2.0	2.5	26
Villas	893	897	0	1,504	1,777	18	1.7	2.0	18
Wood-framed	54	52	− 5	56	53	− 6	1.0	1.0	− 1
Markets	8	17	108	29	66	126	3.5	3.8	9
Hotels	39	45	16	160	226	41	4.1	5.0	22
Office building	113	131	16	593	777	31	5.3	5.9	13

Source: Author's own.

Figure 3 Changes in floor space between the years 2005 and 2010 mapped on land-use planning blocks. Source: Author's own.

Table 3 Structural and non-structural land-use planning options and measures in response to increased flood risk

Land-use planning options	Description	Specific structural and non-structural land-use measure
Density control	Applying occupancy and density ceilings for permitted land uses	Limit occupancy load ground coverage and floor area ratios in high population density exposed to floodingDesealing of impervious surfaces or change surface coatings
Site selection and development	Maintaining inappropriate land uses and development out of hazard areas	Avoid areas where development will increase the likelihood of risk or level of impact, including resettlementMaintain development out of risk and extreme-risk zonesFlood proofing in medium to high risk zones
Design and building regulations	Application of appropriate building controls	Building controls in terms of elevation, high foundation walls, stilts, setbacks, minimum lot size, sealing degree, depending on risk levelsSustainable drainage systems, detention/ retention ponds rainwater collecting and reusing, green roofs, facades, tree planting
Protection of critical infrastructure	Critical facilities are ensured of their functionality during disasters	Construct overhead service linesProtect water and sewer lines, extension and optimization of runoff and sewer systemHard protection measure (i.e. dyke systems)
Open space preservation	Specific areas used for low intensity and low density use to minimize damage	Flood plains used only for urban agricultural use, avoid the development of additional settlement areas at risk of floodingDesignation and maintenance of riparian vegetation, conserve and protect the existing natural or near-nature water balance, including aforestationWetlands created as a means to absorb peak flows from floods: Establishment of suitable retention and detention areas

Source: Author's own.

Figure 4 HCMC's non-built-up and built-up areas in flood-risk areas (areas below the current high-tide level of 1.5 m AMSL) mapped on land-use planning blocks. Source:Author's own.

Figure 5 Photograph of a localized flash flood event following heavy rainfall in Nguyen Duy Trinh Street, District 2 of HCMC on 1 October 2012. The cause of the serious flooding was two separate rainfall events of 60.6 mm and 76 mm coinciding with a high tide event of up to 1.5 m. Source: Author's own.

Figure 6 Photograph of the new residential area of Thao Dien Ward in district 2. Recent luxury villa and apartment extensions of the city into low-lying riparian areas of the city. Source: Author's own.

Figure 7 Number of flooding locations in the central and periphery districts of HCMC between 2003 and 2011. Source: SCFC HCMC (2011).