Groundwater Management in Asian Coastal Cities: A proposal for climate change impact and adaptation study

Transcription

1 Groundwater Management in Asian Coastal Cities: A proposal for climate change impact and adaptation study Asian Science and Technology Seminar (ASTS) in Thailand March 11, 2008, Swisshotel Nai Lert Park, Bangkok Dr. Water Engineering and Management, AIT

2 Presentation Outline Introduction Coastal aquifer issues Research studies at AIT Other studies in Asia Potential impacts of climate change on coastal aquifers Proposed research Next steps

3 Introduction Globally, groundwater provides about 50% of current potable water supplies (serving nearly 2 billion people) 40% of self-supplied industries 20% of water use in irrigation Asia and the Pacific: groundwater provides drinking water to nearly 32% of population Coastal aquifers: important source of water in coastal zones Indian coast (7,000km): 2 nd richest GW reservoir Coastal water supplies dependent on interaction between fresh and saltwater

4 Introduction Urbanization, increase in population and water demand due to economic development put immense pressure on groundwater resources leading to undesirable consequences Groundwater use trends in Asia Philippines: industrial and domestic use increase annually by 14% and 11.5%, resp. ( ) HCMC, Vietnam: GW use steadily increases, 34% of total demand (2005) Tianjin, China: exploitation ( ) has exceeded available in most districts

5 Introduction Asian Cities (selected) Role of Groundwater Groundwater Problems Dhaka, Bangladesh Sole source Falling groundwater levels Tianjin, China Major source Land subsidence Nagpur, India Major source Pollution from urban area Jakarta, Indonesia Minor source Salinity intrusion Cebu City, Philippines Major source Sal. Intrusion, Pollution (urban) Jaffna, Sri Lanka Sole source Sal. Intrusion, Pollution (urban) Bangkok, Thailand Major source Sal. Int., Poll. (urb), subsidence Hat Yai, Thailand Minor source Sal. Intrusion, Pollution (urban) Hanoi, Vietnam Major source Pollution from urban area Source: World Bank (1998). Groundwater in urban development.

6 Coastal Aquifer Issues Major groundwater management issues in coastal aquifers Decline of piezometric level Land subsidence Groundwater contamination (more especially salinity intrusion)

7 AIT Research in Bangkok Aquifer Past studies (selected) : Investigation of Land Subsidence : Groundwater Resources Development and Management Study : Simulation Study of the Bangkok Aquifer System Most recent studies (selected) : Sustainable Groundwater Management in Bangkok (IGES) : Estimation of Safe Yield for the Bangkok Aquifer System Current studies : Groundwater Quality Management Policy Research in Bangkok and Vicinity (IGES)

8 AIT Research in Bangkok Aquifer 10,300 km 2 total area 10.6 million people (2003)

9 AIT Research in Bangkok Aquifer 8 aquifer layers Most of extraction from 3 aquifers at depths m (PD, NL, and NB Aquifers) Aquifer 1 Bangkok Aquifer 2 Phra Pradaeng Aquifer 3 Nakhon Luang Aquifer 4 Nonthaburi Aquifer 5 Sam Khok Aquifer 6 Phaya Thai Aquifer 7 Thonburi Aquifer 8 Pak Nam Aquifer Code BK PD NL NB SK PT TB PN Zone 50-m zone 100-m zone 150-m zone 200-m zone 300-m zone 350-m zone 450-m zone 550-m zone Nonthaburi (NB) Aquifer: one of the most productive, yielding up to 200 m 3 /hr of excellent quality water Deeper aquifers seldom used by domestic wells

10 AIT Research in Bangkok Aquifer Pumpage (m 3 /d) 2,500,000 2,000,000 1,500,000 1,000, ,000 0 Groundwater Pumpage in Bangkok and Surrounding Areas Total Pumpage MWA Pumpage (Various Studies) MWA Pumpage (collected from MWA in 2004) MWA Pumpage (DMR, 1998) Estimated Private Pumpage (Various Studies) Estimated Private Pumpage (DMR, 1998) Estimated Private Pumpage (Kasetsart Univ., 2004) Estimated Public Pumpage (Kasetsart Univ., 2004) Total Pumpage (Kasetsart Univ., 2004) Year Mid-1950 s: extensive use of GW started Continuous increase in GW use until 1997 According to DGR, in 2004: Total GW use = 2.2 MCM/d Private Pumpage = 1.8 MCM/d Private Users: largest groundwater users

11 AIT Research in Bangkok Aquifer Decline of piezometric level Water Level (m below G.L.) Phra Pradaeng Aquifer Apr-78 Jan-81 Oct-83 Jul-86 Apr-89 Dec-91 Sep-94 Jun-97 Mar-00 Dec-02 PD0055 Bang Bauthong, Nonthaburi PD0002 Muang, Samut Prakan PD0040 Minburi, Bangkok PD0068 Bang Sai, Ayutthaya PD0059 Lat Lumkaew, Pathm Thani PD0053 Nakhon Chaisiri, Nakhon Pathom PD0018 Kra Thumbaen, Samut Sakhon 35

12 AIT Research in Bangkok Aquifer Decline of piezometric level 0 10 Nakhon Luang Aquifer Apr-78 Jan-81 Oct-83 Jul-86 Apr-89 Dec-91 Sep-94 Jun-97 Mar-00 Dec-02 Water Level (m below G.L.) NL0005 Bang Bauthong, Nonthaburi NL0055 Muang, Samut Prakan NL0016 Minburi, Bangkok NL0012 Bang Sai, Ayutthaya NL0071 Lat Lumkaew, Pathum Thani NL0068 Nakhon Chaisiri, Nakhon Pathom NL0032 Kra Thumbaen, Samut Sakhon

13 AIT Research in Bangkok Aquifer Decline of piezometric level 0 10 Nonthaburi Aquifer Apr-78 Jan-81 Oct-83 Jul-86 Apr-89 Dec-91 Sep-94 Jun-97 Mar-00 Dec-02 Water Level (m below G.L.) NB0004 Bang Bauthong, Nonthaburi NB0049 Muang, Samut Prakan NB0046 Minburi, Bangkok NB0069 Bang Sai, Ayutthaya NB0015 Lat Lumkaew, Pathum Thani NB0020 Nakhon Chaisiri, Nakhon Pathom NB0025 Kra Thumbaen, Samut Sakhon Bangkok Samut Sakhon

14 AIT Research in Bangkok Aquifer Land subsidence Land Subsidence in 2003 (Source: DGR) Land subsidence still occurring (~1.0 cm/yr in most parts) Since 1978: Max. subsidence= ~1.0 m observed : Reached 5-10 cm/yr in some areas Subsiding areas coincide with GW depression zones Surrounding areas at risk

15 AIT Research in Bangkok Aquifer Land subsidence

16 AIT Research in Bangkok Aquifer Groundwater contamination N W E S Kilometers Chloride levels (mg/l) N D Chloride levels (mg/l) in PD aquifer, 1990

17 AIT Research in Bangkok Aquifer Groundwater contamination N Kilometers Chloride levels (mg/l) in PD aquifer, 1995 W S E Chloride levels (mg/l) N D

18 AIT Research in Bangkok Aquifer Groundwater contamination N Kilometers Chloride levels (mg/l) in PD aquifer, 2005 W S E Chloride levels (mg/l) N D

19 AIT Research in Bangkok Aquifer Measures undertaken by the Government 1969: Land subsidence given public attention 1978: Enforced Groundwater Act, B.E (1977); Start licensing for groundwater activities 1983: Critical Zone identified (4 provinces) 1984: Groundwater tariff of 1 Bt/m 3 imposed (6 provinces) 1992: Groundwater Act amended 1994: Tariff increased to 3.5 Bt/m 3 (6 provinces) 1995: All provinces must pay groundwater charge; Critical Zone expanded (7 provinces) : Tariff increased from 3.5 to 8.25 Bt/m 3 (in Critical Zone) 2003: Groundwater Act amended 2004: Tariff increased to 8.5 Bt/m 3 (Critical Zone); Groundwater Preservation Charge imposed in Critical Zone

20 AIT Research in Bangkok Aquifer Total Groundwater Charge THB Groundwater Preservation Charge Groundwater Use Charge TOTAL CHARGE THB 8.50 THB 8.50 THB 3.50 THB 1.00 Jan-84 Jan-85 Jan-86 Jan-87 Jan-88 Jan-89 Jan-90 Jan-91 Jan-92 Jan-93 Jan-94 Jan-95 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04 Jan-05 Jan-06 Date Charge (Bt/m 3 )

21 AIT Research in Bangkok Aquifer Major Deficiencies Identified ( study) 1. Lack of institutional thrust (Resulting in ineffective laws and regulations) Illegal wells still exist; Not all wells metered despite regulations 2. Inadequate inspection and budgetary constraints 3. Groundwater Database and Monitoring System not updated and maintained Monitoring well system does not cover all aquifers 4. Lack of alternative sources of water Limits control of groundwater use and effectiveness of charges 5. Groundwater Development Fund Difficult to use Fund by other stakeholders especially by academic institutions, and even by DGR 6. Groundwater Preservation Charge Imposed at a flat rate

22 AIT Research in Bangkok Aquifer Proposed Policy Options/Improvements ( study) Regulatory or Direct Control Controlling illegal users of groundwater Controlling the use of water in industries Relocation of large groundwater users (ex. Industries) Allow some authority (existing or new) to extract groundwater and supply to customers Economic Measures Also charge agro-wells for groundwater use Modification of Groundwater Preservation Charge rates Further increase of groundwater use charges

23 AIT Research in Bangkok Aquifer Proposed Policy Options / Improvements Technical Measures Conduct artificial recharge (ASR) Provision of alternative water sources Supporting Measures Updating/redefining the Critical Zones Improved monitoring of groundwater activities Demand-side management in domestic and industrial sectors, such as leakage management in pipe networks Amendment of the Groundwater Act or relevant regulations regarding the procedural changes in the use of the Groundwater Development Fund (GDF) Promote the sustainable use of groundwater instead of complete stoppage as well as the conjunctive use of groundwater and surface water Promotion of knowledge and public awareness on groundwater Establish regulations at national and local levels Build local capacities in managing groundwater

24 AIT Research in Bangkok Aquifer Objectives of the current study on GW quality ( ) Collect background data and assess the extent of groundwater pollution (more particularly chloride contamination) in Bangkok aquifer system focusing on the three aquifers: PD, NL, NB; Collect and analyze the existing policies on groundwater quality management to determine their effectiveness and identifying gaps with respect to the current situation; Suggest options and/or policy measures to address the flaws in existing groundwater quality management

25 Other Studies in Asia Decline of piezometric level Manila, Philippines: groundwater abstraction has lowered the piezometric level by 2.4m per year HCMC, Vietnam: groundwater table declines down to 1.95m annually ( ) Tianjin, China: water level has continually dropped in saltwater regions Difference between deep groundwater levels in 1958 and 1998 in the Hai Basin Plains in northern China Source: Agenda for Water Sector Strategy for North China. Ministry of Water Resources, World Bank and AUSAID, 2001

26 Land subsidence Other Studies in Asia Metro Manila, Philippines: subsidence ranges from 0.12 to 1.20 cm Tianjin, China: 7,300 km 2 is affected, max subsidence at 3m ( )

27 Other Studies in Asia Salinity intrusion Andhra Pradesh, India: brackish groundwater have been observed Manila, Philippines: intrusion in aquifers reaching 5km inland, upconing of saline connate water; Cl levels in some parts exceeded 17,000mg/L HCMC, Vietnam: 2,359 damaged wells due to saltwater intrusion S. Korea (west): 5% of wells within 10km from coast with Chloride levels above standards

28 SEVERITY OF ISSUES WERE MAINLY DUE TO INCREASE IN GROUNDWATER EXTRACTION. WHAT ABOUT THE IMPACTS OF CLIMATE CHANGE???

29 Climate Change Impacts 1. Potential impacts by changes in temperature and precipitation Changes in precipitation and evaporation will influence recharge, including temporal changes Increased evapotranspiration in semi-arid and arid regions may lead to salinization of shallow aquifers Droughts result to declining water levels, while increased rainfall intensity may lead to more runoff and less recharge Reduced groundwater head caused by lower rainfall will exacerbate the impacts of sea level rise

30 Climate Change Impacts 1. Potential impacts by changes in temperature and precipitation Coastal aquifers in Peninsular India is expected to lose % of fresh groundwater per year from due to increased salinity Increased extraction of groundwater (more particularly in deep aquifers) as surface water becomes more unreliable BUT, overexploitation of the deep aquifers will cause arsenic contamination in deep aquifers, e.g. in western Bangladesh

31 Climate Change Impacts 2. Potential impacts due to sea level rise (globally, 2 to 3 mm/yr in the early 21 st century) Sea level rise leads to intrusion of saltwater into fresh groundwater in coastal aquifers (India, China and Bangladesh are especially susceptible) In two small, flat coral islands off the coast of India, the thickness of freshwater lens was computed to decrease from 25m to 10m and from 36m to 28m for a sea level rise of only 0.1m In Ho Chi Minh City, saltwater intrusion has been observed and is escalating Tidal inflow into the Pasig River (Philippines) contributes to high salinity of groundwater

32 Climate Change Impacts Adaptation issues Increasing knowledge and awareness of vulnerability of coastal aquifers to climate change Increasing storage capacity: groundwater recharge, rainwater harvesting and conservation Enabling environment for groundwater governance more inclusive management of groundwater resources Capacity of institutions and suitability of institutional arrangements to cope with the impacts of climate change capacity building Financial resources to support adaptation measures

33 WHAT HAS BEEN DONE??? At present, there has been only very little research on the impact of climate change on groundwater resources

34 OUR PROPOSAL.

35 Proposed Research Assessing the impacts of climate change on coastal aquifers Groundwater quantity Groundwater quality Recommendation of policy options/measures based on technical findings for adaptation

36 Proposed Research Assessing the impacts of climate change on coastal aquifers (some ideas) Groundwater quantity Groundwater quality Natural ecosystems Society and economy Etc.

37 Proposed Research Groundwater Quantity (some ideas) Identification of recharge areas of deep aquifers Effects of changes in precipitation, temperature and land use on recharge amount in these areas Estimation of safe yield Identification of appropriate measures for sustainability of deep aquifers in coastal areas

38 Proposed Research Groundwater Quality (some ideas) Understanding the mechanism of salinity intrusion in coastal aquifers Assessment of sea level rise in selected coastal areas Characterization of salinity intrusion in selected coastal aquifers in Asia under climate change scenarios

39 Proposed Research Recommendation of policy options/measures for adaptation (some ideas) Adaptive measures grouped according to the following categories Regulatory or Direct Control Measures Economic Measures Technical Measures Informative Measures Supporting Measures

40 Next Steps Development of research partnership Development of concept paper and full proposal to be initiated by AIT (with inputs from this forum) Funding by donor agencies?? Research implementation (3-5 years)

41 Thank you