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Climate Change and Water Supply in the Mekong Delta. Workshop Results

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This presentation is part of the ProSPER.Net Young Researchers' School 2017 ‘Water Security for Sustainable Development in a Changing Climate’.

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Climate Change and Water Supply in the Mekong Delta. Workshop Results

  1. 1. Climate Change and Water Supply in the Mekong Delta Workshop Results 4 – 7 October 2016 A Regional Water Supply Scheme for the Mekong Delta, Southwest of the Hau River Phased Design of a Transmission-Distribution Network
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  3. 3. Contents Workshop impression 4 Study area 6 Sense of urgency 8 Ground & surface water 9 Urbanization 10 Population prognosis 11 Business as usual 12 Regional water supply planning 13 Workshop objectives 15 Water demand 16 Methodology 16 Assumptions 17 Results 19 Design principles 21 Production 21 Network 22 Rural 26 Phasing 27 Wider perspectives 29 Alternative solutions 29 Equity & sustainability 30 Institutional 31 Financial models 32 Conclusions 35 Colophon 36 3Cover picture: Bao Moi, 2014
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  5. 5. Workshop Impression Background of participants at the workshop Time allocation during the workshop Male and female participants at the workshop 5
  6. 6. Land UseAdministrative Boundaries Study Area Source: Mekong Regional Water Security Project Revised Pre-Feasibility Study Report (2016) Source: Sub-National Institute of Agriculture Planning & Projection (2002) 6
  7. 7. 7 Pictures (incl. top right): VNExpress, 2013 - Nguyễn Vĩnh Hiển Picture: Bao Moi, 2014
  8. 8. Sense of Urgency: Overview Climate change  sea-level rise  gradually increased salinity of groundwater  inland intrusion of sea-water*  longer spells of drought  reduced runoff Mekong  inland intrusion of sea-water*  more intense and unpredictable bouts of rainfall  more erosion of river banks Construction dams  natural pattern of runoff Mekong affected  inland intrusion of sea-water* (e.g. China/Laos)  annual flooding by Mekong uncertain  deposit of fertile sediments uncertain Diverting of water from Mekong to other catchments (e.g. Thailand)  inland intrusion of sea-water*, etc. Over-abstraction of groundwater  induced land subsidence  flooding  gradually increased salinity of groundwater * Especially during the dry season 8
  9. 9. Sense of Urgency: Ground & Surface Water Drawdown Rate (cm/year) Compaction-based Subsidence Rate (cm/year) Salinity Intrusion February 2016 (g/L) Source: Erban et al. (2014) Groundwater extraction, land subsidence, and SLR in the Mekong Delta, Vietnam (2010) Source: Southern Irrigation Science Institute (2016) 9
  10. 10. Water Demand: Urbanization Can Tho (simulated 2005) Can Tho (simulated 2100) Can Tho (observed 1972) Can Tho (observed 2007) 10 km 5 km Modified from: Huong and Pathirana (2013) Urbanization and climate change impacts on future urban flooding in Can Tho city, Vietnam. Modified from: Thy and Pawar (2010) Urban expansion of Can Tho City, Vietnam: A study based on multi-temporal satellite images. The rate of rapid urbanization is assessed on the basis of historical trends As well as on the basis of modeling and projections 10
  11. 11. Sense of Urgency: Population Prognosis The full cost of groundwater is higher than the cost to build the infrastructure and operate groundwater plants alone: Other economic costs and environmental impacts should be taken into account as well. Modified from: Rogers et al. (2002) Water is an economic good: How to use prices to promote equity, efficiency, and sustainability? Demographic projections for the total population of the provinces Southwest of the Hau river indicate a strong rise in urbanization of the study area. Modified from: VIWASE (2016) Final Draft Mekong Regional Water Supply Master Plan. 11
  12. 12. Security of public water supply is not guaranteed, in particular during the dry season Dependence on groundwater abstraction – in particular by the agriculture – continues, in spite of the government policy to reduce abstraction Groundwater abstraction is a primary cause of land subsidence, which is expected to cause extensive flooding in the Mekong Delta in the future Short-sighted approach that lacks vision Conclusion: Groundwater is not a feasible water supply source in the long term Sense of Urgency: Business as Usual 12
  13. 13. Regional Water Supply Planning Accepted Master Plan for Water Supply in the Mekong River Delta (11-2010) Mekong Delta Plan Long-term Vision and Strategy (12-2013) Final Draft Mekong Regional Water Supply Master Plan (07-2016) Mekong Regional Water Security Project Updated Pre-Feasibility Study (06/2016) 13
  14. 14. The proposed transmission pipeline network in the Mekong Regional Water Supply Masterplan to 2030 and vision to 2050 Master Plan 14 Large water transmission mains Source: E.A. Drillcon Regional Water Supply
  15. 15. Workshop Objectives The FOCUS was on: • Water demand projections • Design principles of a transmission-distribution network • Phasing of the design for the regional piped water supply system 15 The focus was NOT on: • Alternative solutions (to secure public water supply in the Mekong Delta) • Institutional arrangements • Financing
  16. 16. NOW 2050 Long-term target 2030 2016 Water Demand: Methodology 16
  17. 17. Water Demand: Overview of Assumptions VIWASE (2025) Workshop (2050)* Population 7,763,000 8,680,000 Coverage piped (safe) water supply 95% – 100% (urban) 30% (rural) 100% (urban) 60% (rural) Liters per capita per day (lcd) 115 – 150 (urban) 90 (rural) 100 – 110 (urban) 80 (rural) Non-domestic demand for water 20% – 30% 22% Physical water losses 18% (urban) 15% (rural) 20% (Can Tho City) 15% (elsewhere) Maximum day factor 1.2 1.1 * The rationale is based on the historical performance of water supply companies (www.vnwd.vn/), provincial master plans, and professional experience. 17
  18. 18. Water Demand: Example Netherlands • Water consumption in the Netherlands (liters/capita/day) dropped by 9% over the past 25 years • Decrease is mainly due to more efficient toilets and washing machines • The water use for personal hygiene has increased over the past 25 years Conclusion: Per capita consumption in liters per day does not necessarily increase over time 18
  19. 19. Water Demand: Workshop Results The long-term vision (2050) can be reached by following a: • Fast track • Gradual approach Conclusion: The brainstorm workshop estimated a lower demand compared to the prefeasibility study 19
  20. 20. Water Demand • The strong urbanization rate increases the water demand in cities, especially Can Tho • Economic centers along the Hau river upstream from Can Tho can secure their own water supply fairly easily • The coastal provinces have the most vulnerable existing water production sites, but are located further away from reliable fresh water sources, such as the upstream reaches of the Hau river • Cross-subsidies will be needed to meet the demand for safe water of all households in the provinces of the Mekong Delta, southwest of the Hau river Conclusion: Provinces upstream the Hau river should share in the costs of safe water supply in the coastal provinces 20 8% 13% 38% 9% 13% 9% 10% The percentages in the circles in the provinces indicate the relative water demand of the population living southwest of the Hau river
  21. 21. Design Principles: Production • The master plan shows four WTPs: o Incorporate ongoing developments (AquaOne) o Construction of WTP Hau 1 has highest priority, but a location more upstream could be preferable o The location of WTP Hau 2 may be reconsidered, but could be combined with WTP Hau 1 o WTP Hau 3 has the lowest priority for government involvement and financing → the private sector can be expected to get involved • Raw water quality risks are to be considered: o Salinity intrusion during the dry season o Industrial and/or shipping accidents • Consider treatment technologies to eliminate a wide range of (micro) pollutants: i.e. pesticides, herbicides, petrochemicals, and medicine residues • Redundancy of water intake and treatment facilities is to be taken into account 21 Salt intrusion Hau 1 Aquaone Hau 1 Hau 2 Hau 3
  22. 22. Design Principles: Network Linear system WTP River CITY Distribution Network Distribution Network Distribution Network Distribution Network CITY CITY CITY Process Intake → Pre-treatment → Transmission → Treatment → Distribution Advantages • More control at provincial level Disadvantages • Higher cost due to more WTPs (no economies-of-scale) • More difficult to connect rural areas Conclusion: System is not preferable for Mekong Delta Pre-treatment WTP CITY Distribution Network Distribution Network Distribution Network Distribution Network CITY CITY CITY WTP WTP WTP Nodular system River 22 Process Intake → Treatment Transmission → Distribution Distribution Advantages • Possibility to connect both rural and urban areas Disadvantages • Higher investment costs due to the need for larger diameter pipes to meet peak hour demand • Higher operational cost as higher pressures are required to meet peak hour demand Conclusion: System is not preferable for Mekong Delta
  23. 23. Design Principles: Network Process Intake → Treatment → Transmission → Reservoirs → Distribution Advantages • Lower investment costs due to smaller dimension transmission pipes (stable operational mode of production and transmission) • Lower operational cost as lower pressure is needed (transmission system operates under stable conditions) Disadvantages • Higher costs as the dedicated transmission mains do not allow use for purpose of water distribution Conclusion: Preferred system for Mekong Delta Linear system with distribution reservoirs Distribution Network WTP CITY CITY CITY CITY River Res. Booster Booster Distribution Network Distribution Network Res. Res.Res. Res.
  24. 24. Design Principles: Network Design of the transmission-distribution system: • Separation of water transmission from water distribution • Redundancy of critical elements • Need for and locations of distribution reservoirs and boosters • Interconnected primary distribution network • District metering areas (DMAs) to control non-revenue water (NRW) • Branched reticulation system • Phasing of implementation provides an important degree of flexibility to the realization of the designed system, but without losing sight of the ultimate goal (i.e. the long-term “complete” network design) • Peak factor can be reduced with increasing economies-of-scale • Prioritization based on urgency 24 Example of an interconnected transmission-distribution network with redundancy of critical elements Bad example of too many pipelines along the same route
  25. 25. Design Principles: Example Netherlands Step 1: Demand foreast per region Step 2: Visualization of end situation Step 3: Phased implementation. Planning is reassessed regularly. Water Company Limburg (WML) • Environmental concerns pushed for a shift from a reliance on groundwater to surface water as main source of water • Provincial government basically dictated the shift • Over-capacity of production enabled the shift • Transmission ring main provides redundancy • Separation of water transmission from water distribution • Phasing of implementation • Phased out production locations kept as strategic reserve
  26. 26. Design Principles: Rural Areas • Mekong Delta is densely populated • Concentrations of population can be found along roads & canals → by installing distribution pipes along roads and canals many households can be connected to a (regional) public piped water supply system • A high rate of rural coverage seems possible • The obvious opportunity a regional piped water supply system offers to technically connect the majority of the rural population in the Mekong Delta needs to be recognized • This has institutional implications: the separation between urban and rural service providers at provincial level is not logical Source: Population Density – Landscan – 2011 ICEM GIS DATABSE 2015 26
  27. 27. Design Principles: Initial phase (green) • Prioritize the most acute areas: Ca Mau, Bac Lieu, Soc Trang & Kien Giang • Start with one WTP • Extend provincial reticulation systems in parallel Follow-up phase (blue) • Create alternative routes for redundancy → connected/looped network • Expand the reach of the system to cover other areas • Increase the production capacity of the existing WTP, or build additional WTPs (and/or link up with private initiatives, such as AquaOne, if possible) • Continue extension of the water reticulation systems at provincial level → increase coverage Final phase (red) • Continually reassess necessity Phasing 27
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  29. 29. Wider Perspectives: Alternative Solutions 1. Raw water transport with localized treatment: • Transport of raw water via open watercourses • Not all parts of the Mekong Delta can be reached • Does not easily allow the connection of the rural population 2. Localized desalination: • May be technically viable in (near) future • Currently high operational cost, but may be financially viable in (near) future • Can become a suitable alternative for public water supply in remote rural communities 3. Localized continued abstraction and use of groundwater: • Inevitable in the short term • Cost-effective for remote rural communities • Better regulation and enforcement is key WTP WTP WTP WTP CITY CITY CITY CITY River Distribution Network Distribution Network Distribution Network Distribution Network Conclusion: There are no apparent options that provide a complete alternative solution 29
  30. 30. Wider Perspectives: Equity & Sustainability Technical sustainability • Aim for long-term useful life: > 50 years • Professional asset management is critical: o Maintenance o Monitoring o Renewal • Who will bear responsibility, who will finance? Equity • Who will benefit, who will not? o Prioritization: households & small-businesses ↔ large (industrial) consumers o Fraction of the rural population to be reached • Ensuring alternative solutions for remote rural areas 30
  31. 31. Wider Perspectives: Institutional • Strong need for institutional cooperation o MARD – MOC – MONRE o Inter-provincial • Top-down guidance to inspire cooperation seems necessary: Directions of the national government Provincial WSCs Inter-provincial Bulk Water Supply Entity • Central Gov’t owned? • Equitized? RawWater Transmission TreatedWater Transmission TreatedWater Distribution River Intake WTP Bulk Meter & Reservoir Distribution Water Purchase Sales Agreements 31
  32. 32. Wider Perspectives: Financial ModelsRawWater Transmission TreatedWater Transmission TreatedWater Distribution River Intake WTP Bulk Meter & Reservoir Distribution Provincial stakes Water Purchase Financier(s) Loan Loan  Subloan Provincial WSCs Interprovincial Bulk Water Supply Entity; Central Gov’t owned Central government Financing Provincial Government(s) Financing Provincial Government(s) Financing Loan  Subloan Prov. and Central Gov’t in Transmission Description • Financier provides loan to the interprovincial body for water production and transmission • Financier provides a sub-loan to the provincial water companies to expand coverage of the water distribution network • Service agreement between interprovincial bulk water supply entity and the provinces Advantages • Promotes interprovincial collaboration • Distribution remains the task of provincial water companies (serving urban as well as rural areas) 32
  33. 33. Wider Perspectives: Financial ModelsRawWater Transmission TreatedWater Transmission TreatedWater Distribution River Intake WTP Bulk Meter & Reservoir Distribution Water Purchase Water Purchase Financier(s) Loan Loan  Subloan Loan  Subloan Provincial WSCs Interprovincial Bulk Water Supply Central govern- ment Financing Private Water Production Provincial Government(s) Financing Provincial stakes Provincial Government(s) Financing Private Financing Private Company Description • Production of water by a private entity • Interprovincial bulk water entity purchases the water and transmits it to the various provinces water companies • Provincial water companies buy the water from the interprovincial entity and distribute it to the consumers Advantages • Mobilization of private capital • Distribution remains the task of provincial water companies (serving urban as well as rural areas) Disadvantage • Cherry picking by the private investor; leaves government entities with the most difficult tasks
  34. 34. Wider Perspectives: Financial ModelsRawWater Transmission TreatedWater Transmission TreatedWater Distribution River Intake WTP Bulk Meter & Reservoir Distribution Financier(s) Loan  Subloan Provincial WSCs Private Production and Transmission Provincial Government(s) Financing Private FinancingPrivate Company Water Purchase Description • Interprovincial water production and transmission by private entity • Provincial water companies buy the water from the interprovincial private entity and distribute it to the consumers Advantages • Suitable for individual provinces near the Hau River (e.g. An Giang province, Can Tho city, Hau Giang province & AquaOne) Disadvantages • Piecemeal approach, does not solve the problem for all • Does not inspire regional solidarity to serve the populations of all provinces in the Mekong Delta, southwest of the Hau river 34
  35. 35.  There is a need for:  An integrated approach: Production + transmission + distribution  Leadership and guidance from an overarching authority  Interprovincial cooperation and solidarity  The demand prognosis as presented in the pre-feasibility study for the Mekong Regional Water Security Project seems too high  The separation of the transmission and distribution systems is strongly advocated  Distribution reservoirs are meant to cover daily demand fluctuations  Phasing provides flexibility  Prioritize piped water supply of the most acute areas  Integrate with the phasing out of existing infrastructure (i.e. groundwater abstraction)  Redundancy is to be a key design principle (to be realized in due course of time)  A regional piped water supply system provides an excellent opportunity to expand coverage to rural areas Conclusions 35
  36. 36. Colophon 36 Project : Climate Change and Water Supply in the Mekong Delta Country : Vietnam Financier : Netherlands Sustainable Water Fund – Ministry of Foreign Affairs Lead Partner : Vitens Evides International B.V. Partners : Soc Trang Water Supply Company, Tra Vinh Water Supply and Drainage Company, Saigon Water Corporation, People’s Committee of Soc Trang, People’s Committee of Tra Vinh, Can Tho University – Dragon Reseach Institute for Climate Change, UNESCO-IHE Institute for Water Education Authors : Rik Dierx, Adriaan Ruijmschoot and Jonne Kleijer Contributions : Fook Chuan Eng, Le Van Tuan, Assela Pathirana, Sytze Jarigsma, Michel Riemersma, et al. Project Manager : Rik Dierx Contact Person : Rik Dierx (rik.dierx@vitens.nl) Date : 31 October 2016

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