Adaptation of land use and houses in the upper mekong deltas deep flooding area 2

Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Chapter 4 Current Adaptation to Floods This chapter studies current flood adaptation strategies in land use planning and housing practices in the studied area This is obtained through literature review on adaptation of land use and houses, site visits, sketches, and interviews of 47 households in the Mekong Delta Figure 43 and Figure 44 present the location of the studied area and houses in the administrative and flood maps Section 4.1 studies infrastructure development and its impact on floods while Section 4.2 examines the community in the studied area Then, Section 4.3 explores adaptation of houses by analyzing houses from different aspects that have impacts on adaptation Based on these analyses and evaluation criteria of safe shelter, ensuring connectivity, and supporting livelihoods, Section 4.4 discusses the limitations of current adaptation strategies Figure 43. Location of the studied area and houses   Source: NAGECCO (1998)  69 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 44. Location of studied area and houses studied in the flood map for year 2000   Source: Author (based on maps of SIWRP)  4.1 Adaptation of land use: Infrastructure development dealing with floods This section studies the flood control planning and infrastructure in the studied area and its impacts on floods, socio-economic development and the environment 4.1.1 Flood control infrastructure development Infrastructure in the Mekong Delta has been developed for flood control and agriculture intensification, especially since 1990s In the studied area, year-round flood protection is provided in the urban areas, for main transportation systems, and the fruit tree areas This is achieved by constructing full dykes9, main roads or landfills higher than flood peak levels in 1996 and 2000 (Figure 45, Figure 46 and Figure 47) Full dykes protect the farms from floods completely, with the control of sluice gates and pumps, enabling three rice crops per year Outside the above areas, Full dykes (high dykes) are dykes constructed higher than peak flood levels, protecting the areas from floods all year round They are usually combined with roads and residential dykes 70 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area partial flood control solution, which protects the rice crops from early floods in August and late floods in November-December, is possible with semi-dyke systems (Figure 48) At the end of July and beginning of August, rice crops are ready for harvest, if floods happened early and there are no dykes, crops would be damaged Therefore, semi-dykes are constructed around the level of floods in this time, protecting the areas from early floods After harvesting, floods overflow semi-dykes into the fields The semi-dykes also protect the farms from late floods in November – December, so that farmers can start cultivating the next crop Semi-dyke systems help decrease the flood duration for agricultural production, ensuring two crops of rice (SIWRP 1998b; To 1998) In the studied area, 67% of the dykes are semi-dykes with an average level of about 2.5 m.a.s.l, and the rest are full dykes with an average level of about 4.5 m.a.s.l Moreover, there are more than 1000 man-made canals in the Mekong Delta, which have been used for flood drainage, irrigation, and transportation (Le et al 2008)   Figure 45. Preliminary design of dykes in Tam Nong District   Source: MRC (2009)  Figure 46. A main road  combined with dyke in Tam  Nong District   Source: Author (Tam Nong  District, November 11, 2009)  71 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 47. Local road combined with semi‐dyke, canal system, and high elevated area in the  studied area   Source: Author (Tam Nong District, December 01, 2009)   Figure 48. Flood control infrastructure of the studied area in 2004  Source: SIWRP (2010)  In the studied area, during 1996-2000, early flood prevention embankments were constructed, and the Tan Thanh – Lo Gach canal was dredged (Figure 49) After 2000, major changes in infrastructure include further dredging of canals, and the expansion and raising of Road No 30 to exceed the peak flood levels in 2000 (5.23 meters amsl at Tan Chau) (Figure 50) Soil obtained from dredging canals is used to elevate the roads, and to build embankments along canals and along residential areas (Le et al 2008) 72 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 49. Infrastructural change in the Mekong Delta: (a) during 1996 – 2000  Source: Le et al. (2008)  Figure 50. Infrastructural change in the Mekong Delta: (b) after 2000  Source: Le et al. (2008)  73 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area 4.1.2 Impacts of flood control infrastructure on floods Figure 51, Figure 52, Figure 53, and Figure 54 illustrate average elevations of dykes in Tam Nong and Tan Hong districts, with simulated water levels in the historical 97 years under current infrastructure in the Mekong Delta The average elevations of dykes in Tam Nong and Tan Hong are about 2.4 meters and meters, respectively These dykes can protect the area from the early floods in August, for roughly 90 percent of flood water levels simulated This also implies that semidykes account for the majority of dykes in the studied area Figure 51. Average elevations of dykes in Tam Nong District and simulated max water levels in the  historical 97 years under current infrastructure situation   Source: MRC (2009)  Figure 52. Average elevations of dykes in Tam Nong District and simulated water levels in August  in the historical 97 years under current infrastructure situation  Source: MRC (2009)  74 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure  53.  Average  elevations  of  dykes  in  Tan  Hong  District  and  simulated  max  Figure 54. Average elevations of dykes in Tan Hong District and simulated water  levels in August in the historical 97 years under current infrastructure situation  water levels in the historical 97 years under current infrastructure situation  Source: MRC (2009)  Source: MRC (2009)  Figure 55. Flood control infrastructure in a nice flood10 in the studied area  Source: Author  10 Nice floods have peak flood levels from 3.5 to 4.5 m, which bring fertile sediments, fishery resources, and renew the water and soil quality of the farmland (Please refer to Section 2.3.1.1 for more details) 75 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 55 illustrates the flood control infrastructure in a nice flood11 in transsections12 of the studied area It shows high elevated roads, elevated residential or urban areas, and areas protected by full dykes, which are higher than flood peak levels in 1996 or 2000, hence they are not affected by floods It also shows that areas protected by semi dykes areas with low elevation of the roads and ground, and areas not protected are inundated by peak levels of a nice flood Section 4.3.2.1 further discusses how houses in these areas are affected by floods Le et al (2008) examined the impacts of infrastructure on floods in the Mekong Delta based on the analysis of flood variation from 1961 to 2004 and effects of infrastructure changes from 1996 to 2001 using hydraulic model HydroGIS It is suggested that these engineering structures make the flood duration approximately 5–10 days longer and water level 0.2–0.3 m deeper in some areas near or between the high embankment systems Floods are reduced in areas protected by embankments and increased in water level and duration in other areas such as downstream of Dong Thap Muoi towards the Vam Co River, because the engineering structures make changes to the flow and obstruct drainage Another impact is overbank inflow to Vietnam is decreased and water flow in the canals is increased, resulting in a trend of increase with progression in flood peaks downstream (Le et al 2008) 11 Based on Tan Chau station’s flood level, floods can be classified into four categories, including dreadful floods, damaging floods, nice floods and light floods when flood level is more than m, 4.5 to m, 3.5 to 4.5 m, and less than 3.5 m, respectively The “nice” floods bring fertile sediments, fishery resources, and renew the water and soil quality of the farmland while the “damaging” floods or “serious” damage properties and infrastructure The “dreadful” floods cause heavy human casualties and severe damage to infrastructure In the “light” floods, fishery production decreases, the soil is less fertile, and salinity increases (Please refer to Section 2.3.1.1 for more details) 12 The trans-section is combined from typical sections of houses in the studied area 76 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area 4.1.3 Impacts of flood control infrastructure in the studied area Positive impacts Changes in infrastructure mentioned above have significant impacts on agricultural practices and flooding in the Mekong Delta Flood control infrastructure in the studied area has benefited socio-economic development, protected people, infrastructure and houses, and supplied fresh water Thanks to dyke systems and hydraulic constructions, rice production has almost quadrupled from 1974 to 2005 (Nguyen 2007a), and damages caused by floods have reduced substantially Elevated roads ensure convenient transportation and connections of inhabitants to public services in the flooding season Negative impacts Although the current strategy dealing with flood in the Mekong Delta is a combination of “Living with floods” and flood control, the numerous measures of flood control and underestimation of the complexity of the Mekong Delta’s ecology have resulted in numerous drawbacks and challenges to the area’s environment and flood regime These measures have brought about a decrease in fishery resources and sediments in the flood control area (To 1998), as well as soil acidification, water pollution, and increase in insects and vermin in the rice fields Recently, yields have decreased, in some cases to 25-50 kg per 1000 m2 Due to decrease in sedimentation, more chemical fertilizers and insecticides were used, leading to higher production cost and harm to the environment In addition, full dyke protection may constrain water transportation (Le and Chu et al 2007) In conclusion, the main strategies for coping with flood in the studied area are building semi-dyke systems to control early floods, and using canals for quick 77 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area flood water drainage These may be good adaptive measures to deal with floods in the studied area as they have benefited agriculture development and reduced damages and loss of human lives, and damage to infrastructure and properties Development of semi-dykes in the studied area is a better solution compared to fulldykes because it can both reduce damages and receive benefits from floods, which is critical to people’s livelihoods While drawbacks of full-dykes such as degradation of soil and water quality and fishery resources depletion result in difficulties for agriculture activities in the long term, semi-dykes cause these drawbacks to a lesser extent Therefore, even with more pressure on agricultural production, full-dykes may not be an efficient solution for this specific area and any proposal to build full dykes should be carefully examined 4.2 Adaptation of community 4.2.1 Characteristics Unlike villages in the Red River Delta in Northern Vietnam which are closed by bamboos and walls, villages in the Mekong Delta are open Villages are along the roads or the rivers, usually with one layer of houses and about – kilometers long, but the density is not high Historically, when the farm land was not enough for the population, a part of the population moved to fresh land for cultivating and formed new villages (Figure 56 and Figure 57) (Phan 2004) 78 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 113. Plan of a house in Hung Thanh Village, Thap Muoi District in dry season   Source: Author    Figure 114. Section of a house in Hung Thanh Village, Thap Muoi District in dry season   Source: Author  119 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 115. Plan of a house in Hung Thanh Village, Thap Muoi District in a nice flood   Source: Author    Figure 116. Section of a house in Hung Thanh Village, Thap Muoi District in a nice flood  Source: Author  120 Addaptation of land l use andd houses in th he upper Mek kong Delta’ss deep flooding area 4.3.2.3 Th he issue off durabilityy – Choice of materia als and con nstruction n technolog gy a The isssue of durrability In terms t of durrability, houuses in the studied areea can be cllassified intto four groups Thee first group p includes hhouses with h concrete frame f (founndations, columns, and beams)) and brick k wall, whicch last over 20 years The seconnd group in ncludes houses withh brick and d timber fraame and briick wall, which w last leess than 20 years The third group g includ des houses with frame of high qu uality timberr, with a lo ong life span The fourth f group p, which is the least du urable grou up of housess, includes houses h with framee of low quality q woood such as bamboo, Melaleuca M and cajupu ut, and temporary materials m fo or the walls such as thaatch and mettal panel (D DTPDC 2004) In the t studied area, housees in the fou urth group share the laargest prop portion Figure 1177 shows thaat 70 percennt of housess in Tam Nong N Districct have fram mes in poor qualitty timber and a walls inn temporary y materials (DTPDC 22004) Theerefore, houses in the t studied area are vuulnerable to o storm surg ges and stroong winds, which usually happpen in the flooding f seaason Figure 117. Duraability of housses in Tam No ong District  Sourcce: Author; Data a from DTPDC ((Dong Thap Pro ovince’s Department of Constrruction) (2004)  Thee majority of o houses inn the studied d area are built with tem mporary strructure and materiaals Figure 118 illustrattes that, in Tam T Nong District, D a ggreat proporrtion of 121 Addaptation of land l use andd houses in th he upper Mek kong Delta’ss deep flooding area 70 percent of houses have framees built of low quality y wood, 766 percent of floor material is wooden plaank, 91 perrcent of roof material is thatch andd other tem mporary materials, 88 percentt of claddinng materiall is metal, thatch, annd wooden plank (DTPDC 2004) Figurre 119 show ws houses with low quality q timbber frame, wall w of metal panells and thatch in the studdied area (a) Structture (b) Floorr (c) Roo of (d) Claddinng Figure 118. Matterials of housses in Tam No ong District  Source: A Author; Data fro om DTPDC (200 04)  Figure 1119. Houses in the studied a area  Source: Authorr (Binh Thanh V Village, Hong Nggu District, December 04, 2009 9 (left) and Phuu Tho Village, Ta am Nong  Districct, December 01, 2009 (right)) 122 Addaptation of land l use andd houses in th he upper Mek kong Delta’ss deep flooding area For houses on n stilts, althhough most of building materialss are not du urable, majority off stilts are built b using ddurable matterials such as concretee, stone, brick and high qualityy wood (Fig gure 120) T This shows the people’’s prioritizinng of their limited l resources for fo critical components in the housses Figure 120. Materials of  stilts of housses on stilts in n Tam Nong D District  Source: A Author; Data fro om DTPDC (200 04)  b Adapta ation meassures: Cho oosing matterials and d constructtion techn nology A Available materials and constrruction tecchnology For housing construction c n, the mateerials used are in readdy supply in the Melaleuca, ccajuput, bam mboo), settlementss These incclude clay roof tiles, timbers (M and thatch, as well as materials w which are afffordable an nd easy to ffind such ass metal panels andd plastic fabrics f Thhe houses are also built b usingg availablee local construction technolog gy Lightweigght constru uction Lighhtweight materials m suuch as wo ood, thatch, bamboo, steel, sheeets of plywood, etc e are useed The lighhtness of construction c n is an advaantage becaause it reduces thee cost of foundation f aand structu ure, especiaally for houuses on stillts and floating houuses, and itss low therm mal mass allo ows effectiv ve cooling iin tropical heat h 123 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Optimization of limited resources Due to limited resources, durable materials are used for priority elements such as for load bearing structures, especially for the stilts of houses, to ensure durability (Figure 121) Cables may also be used to tie the houses to the ground, making houses more stable to cope with strong winds and storm surges However, houses with improvised construction have limited durability Figure 121 shows photos of a house which was built with the available construction technology and light, natural and available materials The material of the columns and beams of the main house’s ground level is concrete, while that of the columns of the back house is bamboo In this house, the materials used for cladding comprise wood for the front cladding, steel for the side cladding, thatch for the back house, and cloth for the bathroom The roof of the main house is clad in metal decking supported by timbers while the back house has a roof made of Nypa fruticans (dừa nước) thatch The floor construction of the main house is in Melaleuca wood and in bamboo for the back house The boundary fence is constructed by bamboo along live Ceiba pentandra trees (bơng gịn) This presents the people’s flexibility and utilization of limited resources in using materials of houses in the studied area          Flexibity and utilization of available materials                    The fence: live Ceiba pentandra trees and bamboo    124 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area   Cladding: metal panels,  thatch and plastic;  Columns: concrete and  bamboo     Cladding of the bathroom:  cloth  The back house: thatch and metal panels for roof  and cladding, and bamboo for floor  Figure 121. Flexibility and utilization of available construction technology and light, natural and  available materials in a house in Tan Hong District  Source: Author (Tan Cong Chi Village, Tan Hong District, November 28, 2009)  4.3.2.4 Flexibility  Several houses built of high quality wood can be disassembled and raised to a higher level or moved to other places (Figure 122)  Houses in the studied area support livelihood activities such as cultivating cash crops (rice and vegetables); growing Melaleuca trees; poultry and livestock farming and fish farming; running small businesses (selling fertilizers, drink, cakes, and farm produce, etc.); and producing incense, cakes, etc.) People flexibly create spaces of their houses for these activities For example, the ground floor of houses on stilts is used for storing farming and fishing tools, seeds, and fertilizers (Figure 126), part of the side house or back house may be used to store rice harvest, the foreground or side ground to dry husk, some small structures outside the house to raise livestock, a small store to sell things, and a part of the verandah can be used for activities relevant to livelihoods such as cake making (Figure 123)  In case these houses are damaged by flood, they can be repaired or rebuilt fast, using local construction methods and available materials 125 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 122. Flexibility of houses   Source: Author (An Phong Village, Thanh Binh District, December 02, 2009 (left) and Chau Doc District,  December 08, 2009 (right))  The whole house on the left of Figure 122 was moved to adjacent ground, and the floor level was raised about 1.5 meters higher than the previous level The house on the right of Figure 122 was uninstalled, moved to another place and reinstalled Figure 123. Flexibility of space: the verandah is used for livelihood activities (left); the pigsty  (right)  Source: Author (Long Khanh Village, Hong Ngu District, December 04, 2009 (left) and Phu Tho Village, Tam  Nong District, December 01, 2009(right)) 4.3.2.5 Landscape  Melaleuca trees14 and bamboos are grown surrounding the houses to protect them from strong winds and erosion They can also be used as construction materials (Figure 126) 14 The Melaleuca forest once covered most of the seasonally inundated area in the Mekong Delta, as it adapts well to the acid sulphate soils in the area However, there has been destruction of Melaleuca 126 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area  The houses, especially houses in the vast area of fields, are usually built low to avoid strong wind (Figure 126)  Small jetty (bến ghe) Each house which is settled along a canal or river may have a small jetty (Figure 124 and Figure 126) For houses without direct access to waterway, many houses may share a jetty (Figure 125) People may travel by boats frequently, especially in the flooding season and when transporting heavy things such as farming harvest and fertilizer Small jetties connect people and the canals Here they may also use river water for washing Figure 124. A small jetty of a house  Figure 125. A jetty shared by many houses   Source: Author (Phu Cuong Village, Tam Nong District,  November 29, 2009)  Source: Author (Phu Cuong Village, Tam Nong District,  November 29, 2009) Figure 126 shows a house along a local soil path and surrounded by farm, illustrating the adaptation measures mentioned above in the war and recently for agriculture development The existing area of Melaleuca forest, both natural and planted, is 100,000 in the Mekong Delta (Truong, 2002) Melaleuca trees provide wood for construction and fuel, prevents acidification of soil and water, stores and renovates fresh water, provides habitat for fish and other aquatic species, maintains biodiversity, mitigates erosion, and provides oil, honey, medicinal plants and handicraft materials (German Development Cooperation, 2011) 127 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Melaleuca trees are planted densely    The house is built low  The small jetty (Bến ghe)  The ground floor is used as storage space    Figure 126. Photos of a house in Phu Tho Village, Tam Nong District  Source: Author (Phu Tho Village, Tam Nong District, December 01, 2009)  Figure 127 to Figure 130 illustrate changes in landscape, use of spaces and people’s activities in dry and flooding seasons of the house pictured in Figure 126 To deal with floods, the people change their livelihood activities from farming in the dry season to fishing in the flooding season The sides of the soil path are utilized as storage space in the flooding season and for drying husks in the dry season 128 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 127. House in Phu Tho Village, Tam Nong District – House plan in dry season  Source: Author   Figure 128. A house in Phu Tho Village, Tam Nong District – House section in dry season  Source: Author  129 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 129. A house in Phu Tho Village, Tam Nong District – House plan in flooding season  Source: Author    Figure 130. A house in Phu Tho Village, Tam Nong District – House section in a nice flood  Source: Author  130 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area In conclusion, the adaptation strategies of houses in the studied area are straight-forward and practical, aiming to satisfy people’s basic needs with the least resources In terms of settlement, people have managed to build shelters protecting them from floods and storms with least resources In terms of livelihoods, houses support livelihood activities, from farming, fishing to small commercial businesses In terms of connections, houses are connected to infrastructure and services by elevated ground, bridge or water transportation In the studied area, there were houses well adapted to floods and storms in current conditions The main challenge for implementing these strategies effectively is poverty and lack of resources 4.3.2.6 Other criteria: land ownership, main source of income, and wealth Besides these criteria concerning the built environment, other criteria such as land ownership, main source of income, and wealth also affect houses’ adaptation to floods in the Mekong Delta However, these measures are not within the scope of this research, so they are just mentioned to provide a larger picture of the problem People possessing large areas of land are involved mainly in on-farm practice (agriculture production) Meanwhile, people who not own land and those possessing less land are involved more in non-farm and off-farm activities (hired labour, trading, fishing, or migrating) Floods have different impacts on different occupational groups People possessing large areas of land and involved in on-farm practice earn their main income in the dry season, hence they are just slightly affected by floods In the meantime, it is difficult for people involved in off-farm activities to find jobs in the flooding season, hence they are significantly affected by floods (Vo 2010) In addition, wealth affects the access to livelihood assets and patterns to deal with floods (Vo 2010) Wealth directly affects the types and stability 131 Addaptation of land l use andd houses in th he upper Mek kong Delta’ss deep flooding area of houses In short, land posssession, maain source of incomee, and weaalth of householdss have a cllose relatioonship, and together the t availabiility of ressources affects the capability c of o householdds to adapt to floods Figure 131. Main incom me source of households in Tam Nong Diistrict  Source: A Author; Data fro om DTPDC (200 04)  4.4 Limiitations o of curren nt adapta ation of houses in the studied area in ccurrent context Lim mitations of current adaaptation in current ntexts are exxamined baased on the criteria of safe sheelter, ensuriing connecttivity to inffrastructure and servicees, and supporting livelihoodss First, in teerms of sheelter, althoug gh majorityy of houses visited in the studiied area are safe from tthe flood leevel, housess are now m more vulneraable to storm surgges and stro ong winds in the flooding seaso on than the he floods This T is because moost houses are a built outt of inadequ uate construcction materiials Second, in term ms of conneectivity to infrastructurre and serviices, some houses h in the infieeld area hav ve difficult access to roads and/o or canals H Houses alon ng low elevation rooads are alsso affected when the flood f level is i higher thhan the road d level, causing intterruption in connectioons to infraastructure and a servicess In these cases, people mayy travel by boat and tthen transfeer to the maain road buut this causes discontinuity in i connectiv vity Thirrd, in term ms of livelihhoods, whiile houses built b by thhe people support s livelihood activities quite q well, houses in resettlemen nt residentiial clusters cause 132 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area difficulties for people to sustain their livelihoods The reasons include longer distances to farms, inconvenient access to water transportation, and constraints of land for raising husbandry and cultivating activities In addition, in terms of sanitation and comfort, sanitary conditions and spaces for private activities such as sleeping and studying may need improving for higher standards of living and more privacy In summary, although people living in the upper Mekong Delta’s deep flooding area are still vulnerable to floods, especially the poor, generally they have developed adaptation strategies to deal with floods Achieving the objectives of adaptation including sheltering, ensuring connectivity, and supporting livelihoods is a challenge for houses in the upper Mekong Delta’s deep flooding area, especially when there are changes of hydrology and climate The next chapters will examine the future context and limitations of adaptation of houses in the future context 133 ... Source: Author (Thuong Phuoc Village, Hong Ngu District, December 03,? ?20 09)  1 02 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Figure 91. Plan? ?of? ?a house? ?in? ?the? ?farm? ?in? ?dry season  Figure  92.  Plan? ?of? ?a house? ?in? ?the? ?farm? ?in? ?flooding? ?season ... loss of sediments, increase of vermin, and reduction of fishery resources   97 Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area Houses in flooded areas For houses. .. Adaptation of land use and houses in the upper Mekong Delta’s deep flooding area choice of houses? ?? locations and cropping patterns in the studied area, which then affect the houses and settlement