Best practise of groundwater monitoring in Thailand

Transcription

1 Regional Technical Workshop on Groundwater Information in the Lower Mekong Basin Best practise of groundwater monitoring in Thailand Tussanee Nettasana, PhD Department of Groundwater Resources February 17,

2 Groundwater is: an extensive, concealed and relatively inaccessible resource. invisible..! 2

3 How to make groundwater visible... by MONITORING it, e.g: Monitoring groundwater level shows a decreasing water level which allows water managers to obtain the status of gw resource. Q1 Q2 Q3 3

4 Effective groundwater management will Protect the quantity of GW and ensure a reliable and affordable supply of groundwater Protect the GW quality to ensure that gw remains suitable for various uses Prevent land subsidence that can damage expensive public and private infrastructures

5 Groundwater Monitoring Systems by Function System Basic Function Well Locations Reference Monitoring evaluation of groundwater behaviour, e.g.: trends resulting from land-use change + climatic variation processes such as recharge, flow and diffuse contamination in areas with uniform hydrogeology and land use. Protection Monitoring Pollution containment Monitoring protection against potential impacts to: strategic groundwater resource well-fields/springheads for public WS urban infrastructure from land subsidence groundwater-dependent ecosystems early warning of groundwater impacts from: intensive agricultural land use industrial sites solid waste landfills around facilities/areas/ features requiring protection. immediately down + up-gradient from hazard

6 Types of data for Groundwater Management Data Type Groundwater Occurrence & Aquifer Properties Baseline Data hydrogeologic logs, groundwater levels, quality, etc. well & aquifer pumping tests Time-Variant Data (from field stations) groundwater level monitoring groundwater quality monitoring Groundwater use Supporting Information water well pump installations Water use inventories Population registers & forecasts Irrigation energy consumption climatic data land-use inventories geologic maps/sections water well abstraction monitoring (direct/indirect) grdwater level variations riverflow gauging meteorologic observations satellite land-use surveys

7 Monitoring objectives, e.g. trends & changes, impacts & risks, etc. The Monitoring Cycle Management of info. & actions needs of Define actual information needed, what for, where from..? etc. static & dynamic water levels, water quality

8 Effectiveness of groundwater monitoring...is improved by careful attention to: network design system implementation data interpretation data storage from past monitoring activities accessibility of monitoring stations... participatory monitoring amongst water users interpretation and use of data to formulate management actions

9 Measuring GW Use & Aquifer Behaviour monitoring groundwater abstraction + changes in aquifer water levels can provide key information for management of groundwater resources. combined with management actions reduction of pumping can contribute to more stable development of groundwater resources

10 Detecting Groundwater Quality changes Groundwater monitoring requires special sampling procedures as: well pumping + sample handling may cause major sample modification; it needs appropriate sampling procedures.

11 Summary of sampling procedures and precautions for specific groups of groundwater quality parameters

12 Early warning of potential threats to Aquifer + Groundwater supply quality Many cities have experienced rapid growth of urban & industrial waste disposal to the ground... a critical requirement for detecting any threats to groundwater quality Municipal water well Ocean Fresh water Saline water Confining unit Septic tank Accidental spill Water table Municipal landfill Contaminated shallow well Leaking petroleum tank From Fetter (1994) Aquifer (saline water) And that impacts From contamination can be remediated

13 Early warning of potential threats to Aquifer + Groundwater supply quality (contd.)...thus, necessitating a focused groundwater quality management monitoring, using sampling piezometers.

14 Basic rules for a successful groundwater monitoring programme - summary Network Design System implementation objectives must be defined and program adapted accordingly groundwater flow system must be understood sampling locations and monitoring parameters must be selected according to objectivess locations and monitoring parameters must be selected by objectives appropriately-constructed observation + abstraction wells must be used field equipment + laboratory facilities must be appropriate to the objectives a complete operational protocol + data handling system must be established groundwater + surface water monitoring should be integrated where applicable Data Interpretation data quality must be regularly checked through internal and external controls decision makers should be provided with interpreted managementrelevant datasets program should be periodically evaluated and reviewed UC2008 Pre- 14

15 Effective groundwater management will Protect the quantity of GW and ensure a reliable and affordable supply of groundwater Protect the GW quality to ensure that gw remains suitable for domestic, industrial, agricultural, and environmental uses Prevent land subsidence that can damage expensive public and private infrastructure 15

16 Groundwater Monitoring To implement 3 monitoring all at once is expensive Due to financial resources are limited, groundwater level monitoring is the first priority Groundwater level monitoring is a direct indicator of the groundwater supply 16

17 Benefits of Monitoring Groundwater Levels: Determine annual and long-term changes of groundwater in storage Determine direction and gradient of groundwater flow Understand how aquifer systems work Gain insight for well construction and where to set pump bowls for efficient extraction 17

18 Technical Aspects of s of Monitoring Groundwater Levels: Determine the elevation of the ground surface at each monitoring location Types of well to be used in measuring groundwater levels Which levels of monitoring wells are perforated or screened and whether they represent typical extraction wells in the area Area to be monitored and number and the locations of monitoring wells Monitoring frequency and time of year 18

19 Important Groundwater Records: Name of well Location of wellels Ground surface elevation Date of measurement Depth to Groundwater Elevation of Groundwater surface Document reference point from which to consistency measure depth of groundwater Note of well status (pumping or non pumping) and any surrounding conditions that might affect groundwater levels 19

20 How do we Measure the Observation? Head measurements Piezometers, observation wells Pumping wells Flow Rates Seepage measurements Baseflow recession analysis Pumping tests Concentration Monitoring wells Pumping wells hydropunch 20

21 Groundwater Monitoring in Thailand 21

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23 Groundwater Availability Groundwater in Porous media 1-30 m 3 /hr m 3 /hr m 3 /hr Groundwater in Sedimentary rock 1-20 m 3 /hr m 3 /hr Groundwater in Igneous/ metamorphic rock 5 m 3 /hr 5-20 m 3 /hr 20 m 3 /hr

24 GW well distribution DGR 340,500 wells Registered private well 32,500 wells Provincial Agency 21,527 wells Dug well and shallow well 439,200 wells

25 Groundwater Development in Thailand ๐ Consumption ๐ Agriculture ๐ Industry Consumption 80 % Agriculture 5 % Industry 15 % Estimated Total Groundwater Utilization is 8,000 M.CU.M./YR Department of Groundwater Resources, Royal Thai Government

26 Number of Wells Developed by Government Agencies and Private Sectors 29% Government agencies 71% other agencies & Private sector Implementing Agency DMR ARD PWD DOH NSC Other Agency & Private Sectors No of Well Drilled 90,132 50,102 52,790 39,867 9,475 98,592 Hand Pump 37,771 42,257 40,621 27,362 5,914 No.of Pump Installed Submersible Pump 40,019 2, Engine Pump 28,592 70,000 Rural Piped Water Supply System 12,342 5,324 11,359 12,505 3,561 - total 340, , ,942 70,000 45,091 Department of Groundwater Resources, Royal Thai Government

27 No Groundwater Basin No. station No.well Aquifer 1 Khorat-Ubon Porous/fractured 2 Udon-Sakhon Nakhon 2 2 fractured 3 Loei 4 6 Porous/fractured 4 Phetchabun 2 2 Porous/fractured 5 Phrae 3 4 Porous/fractured 6 Nan Porous/fractured 7 Mae Hong Son 2 4 Porous/fractured 8 Lampang 7 10 Porous/fractured 9 Fang 4 7 Porous/fractured 10 Chiang Rai-Phayoa 6 6 Porous 11 Chiang Mai*Lamphun Porous 12 Upper Chao Phraya Porous 13 Tak 2 4 Porous/fractured 14 Kanchanaburi 2 3 fractured 15 Lower Chao Phraya Porous 16 Phetchaburi-Prachuap 4 5 fractured 17 Prachin Buri-Srakaeo Porous/fractured 18 Chantaburi-Trat 1 1 Porous/fractured 19 Rayong Porous/fractured 20 Chon Buri Porous/fractured 21 Surat Thani 9 10 Porous/fractured 22 Nakhon Si Thammarat-Phattalung Porous 23 Ranong-Satun Porous/fractured 24 Hat Yai Porous 25 Pattani 26 Chana 27 Narathiwat

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30 Lithological & Geophysical Logging

31 Well Design data

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33 Pumping Test Analysis 33

34 figures of the existing monitoring network GW-in Porous media Karst-GW and GW in fractured rock Water Quality Sampling as a rule 2x a year (Analyse Physical and Chemical properties and heavy metal) Costs of selection, establishing sampling sites, analyses and data transfer are met by Bureau of Groundwater Conservation and Restoration, DGR Costs per year throughout the whole country : 10 to 20 million baht 34

35 Existing groundwater quality monitoring network 35

36 Existing groundwater quality monitoring network 36

37 TDS Concentration

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39 Geology Alluvium Formation Phu Thok Formation Maha Sarakham Formation 39

40 Mahasarakham Formation 391 m Well TP1 Regional Office of Agricultural Extension

41 GW Flow

42 Ban Nong Kranuan Ban Nong Waeng Ban Nong Bua Deemee Ban Tha Phra Chi River Elevation (m.amsl) Distance (km)

43 B. Nong Khrai Nun B. Huai Toei Regional Agri. Office Wat Pa Hin Kaeng B. Nong Kranuan Khon Kaen Brewery B. Nong waeng Elevation (m.amsl) Distance (km)

44 Groundwater Flow in Confined Aquifers (Phu thok Formation) 44

45 Groundwater Flow in Confined Aquifers (Sand and Gravel aquifer) 45

46 Groundwater Flow in Confined Aquifers Flowing well Spring seepage 46

47 Flowing Artesian well Ban Non Sombun, Amphoe Ban Haet, Khon Kaen Well Depth 120 m Flow 6 m abgs found fracture at m and m, free flow rate > 170 m 3 /hr UC2008 Pre- 47

48 Thank you for you attention Department of Groundwater Resources, Royal Thai Government