Final Report IGPVN Activities and Achievements Proposal of Recommendations and Measures for Water Resources Management in S6c Träng

Hoang Thi Hanh Roland Bäumle Final Report IGPVN Activities and Achievements Proposal of Recommendations and Measures for Water Resources Management in S6c Träng • n22 m n21 o n13 Technical Report Phase III -1 May 2017 II t -� Q -=-�J � �v;ttP., BG R Bundesanstalt für Geowissenschaften _ , _._ und Rohstoffe GEOZENTRUM HANNOVER � W Ministry of Natural Resources and Environment Federal Ministry for Economic Cooperation and Development, BMZ Final Report IGPVN Activities and Achievements, Proposal of Recommendations and Measures for Water Resources Management in Sóc Trăng Technical report Phase III -1 Authors: Hoang Thi Hanh, Roland Bäumle Date: May 2017 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Authors: Hoang Thi Hanh (IGPVN Project Team Member), Roland Bäumle (BGR) Commissioned by: Federal Ministry for Economic Cooperation and Development (Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung, BMZ) Project: Improvement of Groundwater Protection in Vietnam (IGPVN, 20122015) BMZ-No.: 2013.221.2 BGR-No.: 05-2374 BGR-Archive No.: Date: May 2017 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 II German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Table of Contents Project framework and objectives Investigation Area 3 2.1 Location 2.2 Topography 2.3 Edaphology 2.4 Climate 2.5 Population, socio-economic conditions Overview on water resources 3.1 3.1.1 Surface water 3.1.2 Groundwater 3.2 Current status of groundwater exploitation and use 10 3.2.1 Groundwater abstraction for water supply in urban areas 11 3.2.2 Groundwater abstraction for water supply in rural areas 13 3.2.3 Groundwater abstraction at household scale 13 3.2.4 Groundwater abstraction for industry, agriculture and aquaculture 13 3.3 Main water resources of Sóc Trăng Province Current state of water resources management and protection 14 3.3.1 Advisory to the PPC to issue secondary regulations and implementation of the legal documents in the water resources sector 14 3.3.2 Water resources planning and basic investigation 15 3.3.3 Water resources licensing 16 3.3.4 Water resources financing 16 3.3.5 Inspection, examination and handling of the legislation violations in the water resources sector 17 3.3.6 Communication, dissemination, education on legislation in the water resources sector 17 Approach and Study Methods 18 4.1 Construction of the monitoring wells 18 4.1.1 Site selection, drilling and development 18 4.1.2 Geodetic survey 19 4.1.3 Drill cuttings sampling and analysis 19 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 III German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam 4.2 4.2.1 Sampling for hydrochemical analysis 21 4.2.2 Sampling for groundwater dating and recharge 24 4.3 Groundwater dating methodology 29 4.3.1 Groundwater dating using 3H 29 4.3.2 Groundwater dating using 14C 29 4.4 Groundwater level monitoring 31 4.4.1 Monitoring equipment 31 4.4.2 Periodical check, extraction and processing of the monitoring data 32 4.5 Water sampling and analysis 21 Capacity building for Sóc Trăng DONRE 32 4.5.1 Equipment 32 4.5.2 Training 32 4.5.3 Study tour on water resource management 32 4.5.4 IWRM workshop 33 4.5.5 Guidebook 33 Study results 33 5.1 Grain size analysis 33 5.2 General hydrochemical characteristics of groundwater 38 5.2.1 Data base 38 5.2.2 Water type 38 5.2.3 Major ion composition 41 5.2.4 Major ion ratios and geochemical processes 44 5.2.5 Regional distribution 49 5.3 Hydrochemical characteristics of water samples collected in 2013 by IGPVN 51 5.3.1 Water type 51 5.3.2 Major ion composition 53 5.3.3 Major ion ratios 63 5.3.4 Saturation indices 64 5.4 Water quality 64 5.4.1 Surface water 64 5.4.2 Groundwater 65 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 IV German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam 5.5 Stable isotopes analysis results 66 5.6 Groundwater dating 69 5.6.1 3H 5.6.2 Groundwater dating in Sóc Trăng using 14C 70 activity of water samples in Sóc Trăng Province 69 5.7 Groundwater flow direction and groundwater transit velocity 71 5.8 Groundwater level monitoring results 72 Proposed Recommendations and Solutions for Groundwater Management in Sóc Trăng Province 78 6.1 Review and assessment of the implementation of legal documents and secondary regulations in water resource sector 78 6.2 Water resources planning 78 6.3 Specific tasks regarding to water resources management 79 6.3.1 Groundwater exploitation licensing 79 6.3.2 Investigation for updates of the status of groundwater exploitation and use 79 6.3.3 Water resources allocation 80 6.3.4 Protection of fresh/slightly saline aquifers 80 6.3.5 Management of saline aquifer 81 6.3.6 Artificial recharge 82 6.3.7 Groundwater monitoring 82 6.4 Development of guidebooks 83 6.5 Strengthening the integrated water resources management, networking and information sharing 84 6.6 Awareness raising on water resources 84 Conclusions and suggestions for further investigations 86 References 89 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 V German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam List of Tables Table Groundwater production wells for domestic and service water supply in the urban areas of Sóc Trăng Province (Source: Chân (2010)) 12 Table Groundwater production wells for domestic water supply in rural area in Sóc Trăng Province 13 Table Number of private wells of each aquifer (Source: Chân (2010)) 14 Table Number of groundwater production wells for industry, agriculture and aquaculture use in Sóc Trăng (Source: Chân (2010)) 14 Table IGPVN monitoring wells in qp2-3 aquifer, Sóc Trăng Province 18 Table Information recorded during the IGPVN monitoring well flushing in Sóc Trăng Province 19 Table Coordinates and elevations of the monitoring wells determined by geodetic measurement 19 Table List of the drilling core samples taken for grain size analysis 20 Table Water samples collected in Sóc Trăng Province in April and November 2013 22 Table 10 Water samples collected in Sóc Trăng Province in June, 2013 for 14C and 3H dating 26 Table 11 Grain size analysis results 34 Table 12 Hydraulic conductivities (m/day) calculated for each aquifer using various methods by SizePerm 37 Table 13 Summary of groundwater samples used for the interpretation of groundwater chemistry in Sóc Trăng Province (IGPVN database) 38 Table 14 Field parameters of water samples collected in Sóc Trăng Province 52 Table 15 Chemical analytical results of water samples collected in Sóc Trăng Province in April 2013 54 Table 16 Chemical analytical results of water samples collected in Sóc Trăng Province in November 2013 55 Table 17 Stable isotope composition of water samples collected in Sóc Trăng in 2013 67 Table 18 3H Table 19 13C activity of water samples collected in Sóc Trăng Province in June, 2013 70 concentration, 14C activity and estimated groundwater age in Sóc Trăng Province 70 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 VI German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam List of Figures Figure Administrative map of Sóc Trăng Province (Source: http://bandokholon.com/wp-content/uploads/2016/06/BAN-DO-HANHCHINH-TINH-SOC-TRANG.jpg ) Figure Edaphological groups in Sóc Trăng Province Figure Schematic representation of sedimentary aquifer succession in Sóc Trăng Province 10 Figure Groundwater abstraction in m³/d and % as by user groups in Sóc Trăng Province; Total current abstraction amount are estimated at about 201,500 m³/d 11 Figure Map of the sampling locations in Sóc Trăng Province in April and November, 2013 23 Figure Location map of water sampling for radioactive isotopes (14C and 3H) and stable isotopes (2H, 18O) in Sóc Trăng Province in June, 2013 25 Figure A device used to collect TDIC in groundwater samples 27 Figure Scheme of the device used to trap CO2 evolved from the reaction between BaCO3 and H3PO4 1M (adapted from Feltz & Handshaw (1963)) 28 Figure Piper diagram of groundwater of Holocene and Pleistocene aquifers in Sóc Trăng Province 39 Figure 10 Piper diagram of groundwater of Pliocene and Miocene aquifers in Sóc Trăng Province; selected analysis numbers provided, please refer to text 40 Figure 11 Box charts showing major ion composition of aquifers in Sóc Trăng Province Units are mg/l except for pH 42 Figure 12 Plot of Na/Cl ratio against fraction of seawater fSea of groundwater samples 45 Figure 13 Plot of Na/(Ca+Mg) ratio against fraction of seawater fSea of groundwater samples 46 Figure 14 Binary graphs of major ions that can be regarded a result of geochemical processes other than conventional fresh/saltwater mixing for groundwater samples of qp2-3 and n12: (a) Plot of alkalinity against sodium content; (b) sulfate against alkaline earth metal content 47 Figure 15 Binary graphs of major ions that can be regarded a result of geochemical processes other than conventional fresh/saltwater mixing for brackish or saline groundwater samples (fSEA >0.2): (a) Plot of alkaline earth metal against sodium content; (b) alkaline earth metal against sulfate content 49 Figure 16 Distribution of chloride content expressed as fraction of seawater fSea for Holocene and Pleistocene aquifers in Sóc Trăng Province 50 Figure 17 Distribution of ratio between SO4React and (Ca+Mg)React for Holocene and Pleistocene aquifers of Sóc Trăng Province 50 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 VII German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Figure 18 Piper diagram visualizing hydrochemical facies of water samples in Sóc Trăng Samples in dry season indicated by orange symbols; samples in rainy season indicated by blue symbols 52 Figure 19 Schöller diagrams showing the change of major ion composition of surface water in Sóc Trăng Province between dry and rainy season in 2013 56 Figure 20 Schöller diagrams showing the change of major ion composition of groundwater in Sóc Trăng Province between dry and rainy season in 2013 58 Figure 21 Spatial and temporal variation in the major ion compositions of surface water and groundwater in Sóc Trăng Province 62 Figure 22 Molar ratio of Na/Cl vs Cl concentrations of water samples in Sóc Trăng Province in 2013 63 Figure 23 Concentrations of selected ions in water samples in Sóc Trăng Province during dry and rainy season in 2013: a) phosphate, b) nitrate, c) sulfate 66 Figure 24 Stable isotope compositions (2H, 18O) in water samples taken in the rainy (empty symbols) and dry season (filled symbols) in Soc Trăng Province in 2013 Rainwater samples were collected from July to November 2013 Groundwater samples collected from the IGPVN monitoring wells are indicated by circles and groundwater samples collected from private tube wells are indicated by squares; surface water samples are indicated by upwards triangles 68 Figure 25 Groundwater contour line and flow direction in qp2-3 aquifer in Sóc Trăng Province according to the monitoring data in 2005 provided by DWRPIS 72 Figure 26 Fluctuation of groundwater level at ST1 (Phú Lộc Town, Thạnh Trị District, Sóc Trăng Province) 73 Figure 27 Fluctuation of groundwater level at ST3 (An Thạnh I Commune, Cù Lao Dung District, Sóc Trăng Province) 74 Figure 28 Groundwater levels at ST3 at hourly intervals (orange line) and daily intervals (blue line), change in water level per hour (dark brown line) and different moon phases 75 Figure 29 Stage at Station Đại Ngải, Hậu River (Source: Center for Meteo-hydrology Network and Environment) 75 Figure 30 Fluctuation of groundwater level at ST4 (Trần Đề Town, Trần Đề District, Sóc Trăng Province) 76 Figure 31 Fluctuation of groundwater level at ST7 (Thạnh Phú Commune, Mỹ Xuyên District, Sóc Trăng Province) 76 Figure 32 Fluctuation of groundwater level at ST11 (Vĩnh Tân Commune, Vĩnh Châu District, Sóc Trăng Province) 77 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 VIII German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam List of Abbreviations BGR CTU DONRE DOST DWRPIS IGPVN INST LOD MARD MOH MONRE MWL, GMWL NAWAPI PPC TDS TU WTP Bundesanstalt für Geowissenschaften und Rohstoffe (Federal Institute for Geosciences and Natural Resources) Can Tho University Department of Natural Resources and Environment Department of Sciences and Technology Division for Water Resources Planning and Investigation for the South of Vietnam Improvement of Groundwater Protection in Vietnam Institute for Nuclear Sciences and Technology Limit of Detection Vietnam Ministry of Agriculture and Rural Development Vietnam Ministry of Health Vietnam Ministry of Natural Resources and the Environment Meteoric water line, Global meteoric water line National Center for Water Resources Planning and Investigation Provincial People’s Committee Total dissolved solids Tritium Units Water treatment plant Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 IX German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam -6 200 -7 150 -8 100 -9 50 -10 4/2013 Rainfall (mm) Groundwater level (m, asl) ST11 7/2013 10/2013 1/2014 4/2014 7/2014 10/2014 1/2015 4/2015 7/2015 10/2015 1/2016 Figure 32 Fluctuation of groundwater level at ST11 (Vĩnh Tân Commune, Vĩnh Châu District, Sóc Trăng Province) In summary, the groundwater levels at the monitoring stations in Soc Trăng Province are several meters below sea water level and show all a negative trend The groundwater level at ST3, with the lowest level of about m below sea level, is much higher than those at the other monitoring wells The groundwater level at ST1 and possibly also ST7 is expected to drop below m below sea level in the near future The drop in groundwater levels is either caused by unsustainably high abstraction from the qp2-3 aquifer in Soc Trăng Province, reduced groundwater flow from across the Province’s northern border, or a combination of both Changes of inflow from areas upstream of Sóc Trăng could be assessed by regional and transboundary determination of recharge processes and abstraction and groundwater modeling Only the groundwater level hydrographs of ST3 and ST4 clearly show a tidal influence with an exceptionally large amplitude This is most likely related to the strong influence of the tides on the flow of the Hậu River since both stations are located very close to the Hậu River Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 77 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Proposed Recommendations and Solutions for Groundwater Management in Sóc Trăng Province This chapter outlines some recommendations for the improvement of groundwater management in Sóc Trăng Province, based on the existing legal framework 6.1 Review and assessment of the implementation of legal documents and secondary regulations in water resource sector According to the "Review of the groundwater resources management in Sóc Trăng Province" (Quỳnh et al., 2015) implemented by Can Tho University (CTU) and Sóc Trăng DONRE in 2015, the management apparatus and the legal tools for groundwater resource management are tightly set from the central to local levels The legal documents, secondary regulations in water resources sector in general and groundwater in particular have been issued by the Government, the MONRE and Sóc Trăng PPC; and were implemented by Soc Trăng DONRE (see Section 3.3.1) Therefore, Sóc Trăng DONRE should conduct a review and evaluation of the implementation of those documents in order to detect and overcome any shortcomings; The DONRE furthermore should propose orientation guidelines and an implementation plan 6.2 Water resources planning The project "Planning for groundwater resource exploitation, use and protection in Sóc Trăng Province to 2020" (Chân, 2010) was completed in 2010 and was approved by the Sóc Trăng PPC in the beginning of 2011 To date, the results of this planning is still being applied as a basis for management of groundwater exploitation licensing in Sóc Trăng In the context of seriously increasing drought and salinization in the Mekong Delta, and the provisions of the Water Resources Law dated 21/06/2012, the Circular 42/2015/TT-BTNMT dated 29/9/2015 of the MONRE regulating water resources planning techniques, the Sóc Trăng PPC should carry out a general water resources planning, and submit it to the MONRE for comments before submission to the PPC for approval In detail, surface water resource planning should be newly carried out; groundwater resource planning in 2010 needs to be adjusted and supplemented by 2015 Analysis and evaluation of the implementation of this planning are needed to point out the contents to be adjusted and the factors affecting the planning adjustment The general water resources planning will be the basis for the Sóc Trăng DONRE to perform the tasks of water resources management, exploitation licensing and allocation Currently Sóc Trăng is carrying out the project "Planning for surface water resource exploitation, use and protection in Sóc Trăng Province to 2020, orienting to 2030" which to date includes processing the survey data, collecting new data, running the water quality model and topographical mapping of some major rivers The project is expected to be completed by the end of 2016 and will be sent to MONRE for comments and then, submitted to the PPC for approval Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 78 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam 6.3 Specific tasks regarding to water resources management 6.3.1 Groundwater exploitation licensing While an updated water resources planning is not yet available, the Sóc Trăng DONRE has to make use of the groundwater resource planning 2010 However, the groundwater resource exploitation licensing should be done with the following remark: limit the abstraction rate in the qp2-3 aquifer, especially in Thạnh Trị, Mỹ Xuyên, Vĩnh Châu districts where rapid drawdown of groundwater levels are observed as a monitoring result of the IGPVN project (see Section 5.8) The Sóc Trăng DONRE needs to review and sum up all the licensed abstraction rates for each aquifer The newly granted licensing of new groundwater abstraction works must not exceed the sustainable yield of each aquifer The assessment of sustainable yield remains difficult in view of the complex aquifer structure and poorly understood recharge mechanisms but the fact that actual groundwater levels at current abstraction rates in Sóc Trăng are several meters below mean sea water level poses an imminent risk that the freshwater-saltwater interface will move further inland and contaminate the production water at the WTPs Efforts should therefore be undertaken to stepwise reduce groundwater abstractions in order to reverse the trend of declining groundwater levels Hence, priority should be given to drinking water supply whereas pumping for agricultural purposes should be limited However, there still maybe the case when the actual abstraction rate does not exceed the announced sustainable yield of the aquifer but a drawdown in groundwater level is observed This demonstrates the need to further investigate and monitor the groundwater situation, and to evaluate and calculate the sustainable yield of the corresponding aquifers The Sóc Trăng DONRE should notify the District People Committee on current groundwater dynamics in their district and request for coordinating the management and supervision of the qp2-3 exploitation restrictions 6.3.2 Investigation for updates of the status of groundwater exploitation and use The Sóc Trăng DONRE should conduct an investigation to update groundwater exploitation and utilization in the whole province; assess the implementation of the Decision No 11/2008/QD-UBND dated 14/4/2008 issued by the Sóc Trăng PPC on registration for groundwater exploitation and utilization at household scale The Sóc Trăng DONRE should introduce concrete measures to end the household arbitrary drillings (many households drilled tens of wells, one new well is drilled as soon as the previously drilled well has dried up); for example, the PPC should issue a regulation on administrative penalties for household arbitrary drillings, and on the requirement to fill up any household tube well that is no longer in use before drilling any new well Budget allocation is needed to support local people to fill up abandoned wells, and saline wells that are no longer usable; supervision of well filling-up is needed to assure that it is in Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 79 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam accordance with the relevant regulations and standards (Decision No 14/2007/QD-BTNMT dated 4/9/2007) 6.3.3 Water resources allocation The Sóc Trăng DONRE should allocate water resources according to the following priorities: 1) water for domestic use; 2) water for agricultural production; 3) water for aquaculture; then for other purposes Water for domestic use must be guaranteed by a stable water supply from the centralized water supply plants The Sóc Trăng PPC should develop a plan for construction of water supply plants in the Province which points out how many water supply plants are needed to meet the water demand There should be an appropriate roadmap to completely switch from household tube well water to tap water and rainwater The local people should be encouraged and supported to switch to tap water They also need to be trained on how to collect, store and handle rain water for domestic use and supported with instruments for that It is advisable to develop and promote distillation technologies using solar energy for surface saline water purification to produce domestic water during dry season Fresh aquifers should not be exploited for agriculture and aquaculture uses but should be reserved for domestic use Water from the salty aquifer can be exploited and used for this purpose provided that the wells are registered and licensed and the water is consistent with the salinity tolerance of plants and animals The Sóc Trăng DONRE should control the pumping rate that is allowable for the saline aquifer and make public the water quality data The Sóc Trăng Department of Aquiculture and Rural Development (DARD) and other relevant agencies should advise people on how to use saline water for this purpose (direct use or mix with other water sources), or which plants and animals fit this water source The local people should use surface water for agricultural production and aquaculture only if they comply with the following rules: water should be taken at low tide and not at high tide to minimize the tidal impact For this, people not only need to understand the tidal regime, but also need to actively update the weather forecast and salinity forecast for the river system to accordingly make their own irrigation plan The Sóc Trăng PPC should make policies to develop scientific irrigation technology to help save water and ensure crop yields 6.3.4 Protection of fresh/slightly saline aquifers The fresh deep aquifers need to be conserved as a strategic water reserve for domestic use and for prolonged drought or extreme water scarcity The Soc Trăng DONRE should restrict groundwater exploitation licensing for the deep aquifers (qp1, n22, n13) Additionally, the Sóc Trăng DONRE needs to investigate and make a list of the abandoned wells (broken, saline, not usable any more, etc.) and make a plan how to fill up these wells Appropriate policy is needed to support the local people on filling up those wells and the well filling-up should be supervised to assure the quality Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 80 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam The Sóc Trăng DONRE should properly control the drilling quality Drilling licensing should be done adequately to assure the licensed agency/individual must have sufficient equipment and technical capacity While drilling a well, overlying and underlying aquifers/layers must be tightly sealed off to prevent any leakage that may result in aquifer contamination The well owner should report to the DONRE or the district people committee about unusual problems occurring while using the well so that this information will be put into a factual record of the corresponding drilling company The factual record is open access so that people can refer to any relevant information when selecting a drilling company The drilling license will be revoked or will not be extended for the drilling company if the number of the broken wells in their factual records exceed a certain number 6.3.5 Management of saline aquifer As mentioned above, the saline aquifers (qh, qp3) are suitable to be exploited for agricultural production and aquaculture if, and only if, the salinity is consistent with the salinity tolerance of plants and animals Moreover, the abstraction rate from the saline aquifers for this purpose must be tightly controlled The saline water is not suitable for domestic use as the Ministry of Health (MOH) guideline value for Cl in domestic water is 250 mg/L Therefore, the Sóc Trăng DONRE should disseminate information on saline aquifer to the local people to prevent and stop drilling into the saline aquifers for domestic use The saline aquifers should only be exploited by the WTPs with appropriate treatment technologies, using nanofiltration (NF) membrane in combination with reverse osmosis (RO) or distillation The pumping rate must be tightly controlled to ensure the aquifers’ sustainable yield is not exceeded so as not to lower the groundwater level or enhance the salinisation process The Sóc Trăng DONRE should annually update the groundwater level monitoring data and adjust the licensed pumping rate of the corresponding WTPs The Sóc Trăng DONRE needs to coordinate/consult with the Department of Sciences and Technology (DOST) to learn about saline water/seawater treatment technologies in order to improve its licensing and supervising capacity on the operation of the corresponding WTPs Especially when all the water sources (including surface and groundwater) in Sóc Trăng Province are affected by salt water intrusion, then the only remaining solution is to build up centralized WTPs which use saline water/seawater purification technologies A rational development orientation is to build up centralized WTPs of saline water purification technologies using influent water of alternative surface water/rainwater and saline groundwater sources to ensure stable operation and to increase surface water/rainwater exploitation during the rainy season from May to November It is recommended to facilitate the water supply company to build up rainwater harvesting system and reservoir to reduce required groundwater production during the rainy season; and to develop distillation technology using solar energy for surface water treatment to limit groundwater pumping rate during the dry season The Sóc Trăng PPC should Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 81 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam direct the water supply companies in Sóc Trăng to improve their water treatment technologies and prepare for the qp2-3 WTPs to switch to saline water purification technologies 6.3.6 Artificial recharge In the meantime, while a detailed guideline of the MONRE on artificial recharge is not yet available, the Sóc Trăng DONRE together with the District People Committee and the Communal People Committee should work on a plan for a tight control on this issue in combination with awareness raising for the local people to prevent a practice of "spontaneous recharge": people let rainwater and surface water runoff freely flow into the wells leading to a risk of serious pollution The Sóc Trăng DONRE should cooperate with the DOST, research institutes and universities to research and development on aquifer artificial recharge in accordance with the specific conditions of Sóc Trăng Province The Sóc Trăng PPC should have guidelines and policies to encourage this activity: e.g call for investment from the Sóc Trăng Water Supply Company, industrial zones and water stakeholders The Sóc Trăng PPC and Sóc Trăng DONRE should actively seek for any external resources, either scientific, technical or financial resources to implement this solution However, artificial recharge is currently only recommended as a long-term measure Under the context of the recent severe drought and salinization in the Mekong Delta, this measure does not have high priority as any water source that may be used for artificial recharge should be allocated for domestic use Moreover, artificial recharge requires a recovery step to pump out and treat the previously recharged water and therefore, it is not cost effective and not appropriate for Sóc Trăng at current state 6.3.7 Groundwater monitoring In Phase of the IGPVN project, groundwater monitoring wells of the qp2-3 aquifer have been built in districts of Sóc Trăng Province and groundwater monitoring started since April 2013 (see sections 4.4 and 5.8) After taking over the monitoring wells, the Sóc Trăng DONRE should develop an annual monitoring plan, submit it to the PPC to apply for funding The monitoring equipment (datalogger) should be operated and managed according to the Article Circular 19/2013/TT-BTNMT At least, the monitoring data should be read out regularly every months Simultaneously, a maintenance plan should be developed and submitted for approval The monitoring wells should be inspected during each visit to detect any problem occurring Details on the maintenance of the monitoring wells are outlined in the "Short list for implementation of maintenance for groundwater monitoring works" by the IGPVN Project based on Article 13 Circular 19/2013/TT-BTNMT and handed over to the Sóc Trăng DONRE in July 2016 along with the monitoring wells Details are as follows: - Regularly clean, clear up the surrounding area and the entrance to the monitoring work to ensure a safe and convenient performance of the monitoring task Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 82 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam - Check the protection fence, gate and lock of the monitoring work; lubricate, repaint, repair, replace if necessary - Check if the basement of the monitoring well sinks or is flooded; if this is the case, it should be lifted up to a reasonable extent The well pad and the well protection tube must also be lifted up and the attached benchmark must be leveled again - Check the signboard, the well protection tube, cap and lock The signboard must be kept clean to clearly see the printed text The well head must always be closed tightly The well protection tube, cap and lock must be repaired, replaced promptly if they are rusted or damaged - If, during pumping for water sampling, the water is mixed with mud and/or sand, then the well depth is very likely silted up; if the output flow rate is too low, then the well screening is very likely to be clogged In this case, it is recommended to flush the well to restore its depth and clear up its screening - The depth of the monitoring well should be checked every months to immediately detect sedimentation at the bottom of the well or obstacles that have fallen into the well - The monitoring well should be flushed every 3-5 years - If severe damage of the well casing is detected, then decision on repairing or filling up the well should be made 6.4 Development of guidebooks In 2012, the Sóc Trăng DONRE has compiled a guidebook on management of water resources - minerals (for local authorities) which systemized the legal documents and secondary regulations in order to provide basic knowledge and professional guidance to officials in charge of natural resources and environment management and officials of relevant departments in the province To date, additional legal documents are enacted; therefore, it is necessary to compile a revised guidebook on water resources management based on some of the contents of the previous guidebook to conform to the new regulations in the water resources sector Currently, the guidebook on water resource management (for local authorities) and the guidebook on water resource exploitation, utilization and protection (for enterprises and companies) are being compiled by the Sóc Trăng DONRE with the support of the IGPVN project The guidebook on water resource exploitation, utilization and protection (for enterprises and companies) will be compiled in order to provide necessary knowledge to support enterprises and companies in implementation of the legislation in water resources sector The project IGPVN cooperates with the Sóc Trăng DONRE to compile these two guidebooks (Hạnh, 2017a; b) so that they can be released in 2017 Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 83 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam 6.5 Strengthening the integrated water resources management, networking and information sharing Sóc Trăng is a coastal province located in the most downstream part of the Mekong River The tidal regime of the East Sea and the hydrological regime of the Mekong River have a great influence on groundwater resource of the Province In the context of global climate change and increasing drought and salt intrusion in the whole Mekong Delta, Sóc Trăng Province is one of the most vulnerable areas Three estuaries in Sóc Trăng Province facilitate sea water intrusion further inland causing many difficulties for production and people's lives Located in the coastal estuaries, tidal-enhanced saltwater intrusion has affected large portions of the provincial area In some places, salty water can intrude as far as 60 km inland Meanwhile, drought also affects Sóc Trăng Province more seriously than other provinces As a province with quite low per capita income, and as revenues are mainly from aquaculture and vegetables, Sóc Trăng is facing many challenges especially related to financial resources while implementing the legislation in water resources sector In view of these specific challenges, the Province is in need of integrated water resource management together with a regional coordination mechanism In order to overcome these difficulties and challenges, Sóc Trăng needs to proactively: - connect with the neighboring provinces in the Mekong Delta, especially the upstream provinces to share information on water resources, the right and responsibility to protect inter-provincial river water and related resources (upstream protection forests, riverbed sand, etc.); - connect with the provinces in coastal estuaries of similar natural conditions to share information and learn experiences on water resource management 6.6 Awareness raising on water resources So far, water resource exploitation, utilization and protection has been clearly stipulated in the Water Resources Law 2012 and many other legal documents as well as secondary regulations However, in order to ensure that these regulations will come into life and will be enforced, it is the responsibility of the authorities to carry out communication for dissemination of these regulations and policies to the people Appropriate communication forms for awareness raising are necessary for each object in order to promote efficiency For the local people, the most effective form of communication and information dissemination is evidence-based learning People will learn about the issue and gain deeper understanding when witnessing the consequences of over exploitation, indiscriminate use of water resources caused by their neighbors; from that, people will understand that it is only a matter of time for them to become themselves victims Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 84 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam For school children, it is recommended to integrate relevant content into the school curriculum The development of education materials on water resources for school children is essential This is one of the work packages that is being implemented by the IGPVN project University students who are subjected to formal training, have basic knowledge and independent thinking and problem-solving ability need to be given the opportunity to contribute ideas and solutions for water resources issues in particular and for natural resources and environment issues in general It is necessary to strengthen the connection between the local authorities and the students of Sóc Trăng Province who are studying at various universities across the country to make the students better understand the current state of the local issues, so that they will have better career orientation and can contribute to the improvement of the situation in the Province Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 85 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Conclusions and suggestions for further investigations The hydrogeological investigations in this phase of the IGPVN project concentrated on assessing the situation of groundwater resources in Sóc Trăng Province Thus, the project provided valuable contributions to the assessment of the hydrogeological processes and the groundwater situation of the Mekong Delta This is of particular interest not only for Sóc Trăng Province but also for the population of the whole Mekong Delta as groundwater is one of the main sources of freshwater In summary, the main findings of this study are as follows: • The groundwater level of aquifer qp2-3 has been decreasing continuously since April 2013 The observed average decreasing rate varied between 0.29 – 0.77 m/yr Apart from this negative trend, the groundwater levels vary by seasons and, locally and to a minor extent, are influenced by a tidal regime and/or strong rainfall events Decreasing groundwater levels imply a decrease in hydraulic pressure which may cause and accelerate land subsidence • Groundwater transit velocities in the qp2-3 aquifer have been estimated –depending on the method applied - at 2.3 m/yr and 7.8 m/yr The velocities, however, may overestimate natural flow conditions as hydraulic gradients are affected by pumping • The groundwater quality at the investigated wells in qp2-3 is overall good; no heavy metals or significant amounts of trace elements were observed Therefore, groundwater of the qp2-3 can be extracted for domestic water supply with relevant water treatment technology applied The groundwater quality, however, should be monitored continually due to variations of chemical composition with time • The aquifer system is more complex than presumed: Besides the differences in chemical water composition between the individual aquifer layers of Holocene to Miocene age, the hydrochemical and isotope compositions of groundwater samples in qp2-3 also differ significantly in lateral direction An example is that the stable isotope signatures of groundwater samples ST3, ST4 and GW2 of the qp2-3 near the Hậu River are very distinct from other sampling points in Sóc Trăng Province In fact, individual parts of “the same” aquifer seem not to be hydraulically connected to each other In this regard, some groundwater sampling points are believed to be located in salty areas of the aquifer, whose hydrochemistry may be related to paleo-marine transgressions, experiencing only minor flushing by fresh water Furthermore, observed changing redox reactions within the aquifer between dry/wet season make it probable that some interaction with overlying aquifers exists, e.g by way of hydraulic windows or leakages at poorly designed boreholes • Major ions and stable isotope data of both groundwater and surface water samples in dry season showed no hydraulic connection between the rivers and aquifers in Sóc Trăng Province Salt water from the sea was going upstream to some extent on the Hậu River during the dry season but it did not affect the adjacent aquifers Only ST11 showed some indications of freshening during the rainy season Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 86 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam • The available data including radiocarbon ages does provide no evidence of recent groundwater recharge in the Province It is expected that recharge from surface water to aquifers in Sóc Trăng only occurs outside the vicinity of Sóc Trăng Province Most likely, the recharge area/source is located beyond the borders of Vietnam (i.e in Cambodia) Considering the low GW transit velocities roughly estimated in this study, it takes several ten to hundred thousands of years for recharged water to reach the local aquifer in Sóc Trăng Province Consequently, natural recharge cannot help to reduce groundwater declining in the short- to middle-term • Analysis of isotope data suggests that the pump rate at the two water supply stations (Mỹ Xuyên and Long Phú districts) were exceeding the maximum sustainable yield of the aquifer (overexploitation); therefore, vertical contamination may eventually occur It is necessary to control the pump rate at these WTPs to prevent any possible contamination The observed progressive regional decline of groundwater levels in all major aquifers proves that current groundwater usage in the Province and beyond is unsustainable, i.e that despite large volumes of stored groundwater - the amount of groundwater flux into the Delta cannot keep up with current abstraction Furthermore, groundwater levels in all major aquifers were drawn to over 10 m below mean sea level, a constellation which will inevitably lead to the saltwater-freshwater interface moving further inland It is also understood that overdrafting of aquifers may further enhance land subsidence, especially due to the abundance of silt and clay beds in the sedimentary succession of the Delta The imminent threat of water scarcity, saltwater intrusion and land subsidence requires the development of new water supply strategies that incorporate a stepwise reduction of groundwater abstractions and the provision of alternative water sources It is recommended that the fresh deep aquifers are conserved as a strategic water reserve for domestic use and for prolonged drought or extreme water scarcity A comprehensive monitoring network that records groundwater levels, water quality and abstraction data needs to be established and maintained which can provide the information required to clarify to which extent measures of reduced groundwater usage can contribute to reverse the trend of declining groundwater levels The observed drop in groundwater levels is not restricted to Sóc Trăng Province but is observed all over the Mekong Delta and across all aquifers Making quantitative predictions on the future decline of groundwater levels is difficult, though it is regarded certain that groundwater levels will continue to decline under current hydrological conditions This may be due to i) non-sustainable groundwater abstraction in the Province, ii) groundwater abstraction in the Mekong Delta as a whole, iii) reduced recharge and flow from the headwaters or, most likely, iv) a combinations of these factors Consequently, a reduction of groundwater abstraction in Sóc Trăng Province may not automatically reverse the negative trend Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 87 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Lacking information on groundwater recharge further complicates the evaluation of the sustainable yield of aquifers, and thus, the assessment of future groundwater extraction rates By considering the available estimates of groundwater transit velocities, it even seems questionable whether natural recharge (if occurring) can help to reduce the recent decline of groundwater levels Moreover, the conceptual hydrogeological understanding of the Mekong Delta needs further improvement, which requires additional research There are, for instance, indications for leakage between aquifers and trapped (semi-) fossil groundwater bodies which have not been eventually confirmed yet, nor has their influence on groundwater flow been assessed In order to provide a better understanding of the situation of groundwater resources in the Delta, special emphasis should be put on a reliable estimation of sustainable abstraction rates and the identification of sources of groundwater recharge (if existing), esp for the deepseated and probably semi-fossil Pliocene and Miocene aquifers One way to address these questions is by numerical modelling which should be performed and coordinated on a regional level, preferably for the whole Mekong Delta To the knowledge of the authors, such a numerical model which focuses on the quantitative assessment of groundwater resources, and enables the assessment of groundwater recharge and abstraction, is not yet available A prerequisite for establishing a reliable numerical model for predicting groundwater flow is consistent data, e.g records of groundwater levels, abstraction rates and detailed geologic documentation In this regard, the DONREs can take responsibility in carefully operating and maintaining their groundwater monitoring networks This includes improving their capabilities in documenting geological and hydrogeological investigations The above summary shows that concerted efforts on investigating the groundwater situation are needed, as the described problems affect the whole Mekong Delta and cannot be solved on a provincial level However, addressing these problems also necessitates strengthening the cooperation and support of the DONREs Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 88 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam References Anders, R., Mendez, G.O., Futa, K & Danskin, W.R (2013): A geochemical approach to determine sources and movement of saline groundwater in a coastal aquifer Groundwater, 52(5), 756-768, doi:10.1111/gwat.12108 Chân, N.Đ (2010): Plan for groundwater resources extraction, utilization and protection of Sóc Trăng Province to 2020, 148 pp, Division for Water Resources Planning and Investigation, Ho Chi Minh City Chương, B.V (2013): Establishment of coordinates and elevation grid for the IGPVN monitoring wells in Sóc Trăng Province (in Vietnamese) Geodetic survey report, 30 pp, Ho Chi Minh City Coplen, T.B (1988): Normalization of oxygen and hydrogen isotope data Chemical Geology: Isotope Geosciences Section, 72(4), 293-297 Coplen, T.B (1993): Uses of environmental isotopes, in Regional Groundwater Quality edited by W.M Alley, pp 227-254, Van Nostrand, New York DWRPIS (2010): Report on Assessment of Groundwater Resource in Sóc Trăng Province Feltz, H.R & Handshaw, B.B (1963): Preparation of water sample for Carbon-14 dating 480 pp., Washington Gläser, C (2014): Checking the Diver status and collecting monitoring data in Sóc Trăng Province IGPVN Technical Report 46, pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Hạnh, H.T (2014a): Groundwater dating in Sóc Trăng Province using radioactive isotopes 14C and 3H IGPVN Technical Report 44, 32 pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Hạnh, H.T (2014b): Hydrochemical characteristics of surface water and groundwater in Sóc Trăng Province in 2013 IGPVN Technical Report 45, 27 pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Hạnh, H.T (2017a): Guidebook on application of the legal documents on water resource exploitation, utilization and protection – for enterprises and companies IGPVN Guideline, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Hạnh, H.T (2017b): Guidebook on water resource management – for local authorities IGPVN Guideline, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Hạnh, H.T & Phúc, H.Đ (2013): Water sampling in Sóc Trăng Province and installation of the data loggers 03.04.2013 - 04.04.2013 IGPVN Technical Report 26A, 13 pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Hạnh, H.T., Phúc, H.Đ & Thu, P.T (2013): Water sampling in Sóc Trăng Province and checking the data loggers 27.11.2013 - 30.11.2013 IGPVN Technical Report 26B, pp, National Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 89 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Jenn, F., Hạnh, H.T., Nam, L.H., Pechstein, A & Thư, N.T.A (2017 in prep.): Baseline Study Cà Mau – Review of studies, investigations and assessments of groundwater resources in Ca Mau Province IGPVN Technical Report, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Kaufmann, S & Libby, W.F (1954): The natural distribution of Tritium Physical Review, 93(6), 1337-1344, doi:10.1103/PhysRev.93.1337 Louvat, D & Dũng, H.H (1989): Environmental Isotope Study of Mekong Delta Groundwater (Vietnam), 1989, 40 pp, International Aromic Energy Agency (IAEA), Vienna Mercado, A (1985): The use of hydrogeochemical patterns in carbonate sand and sandstone aquifers to identify intrusion and flushing of saline waters Ground Water, 23(5), 635645 Phúc, H.Đ (2014): Checking the Diver status and collecting monitoring data in Sóc Trăng Province IGPVN Technical Report 38, pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Phúc, H.Đ., Tùng, T.T & Gläser, C (2013): Checking the Diver status, collecting monitoring data and installation of two BaroDivers and one rainfall collector in Sóc Trăng Province IGPVN Technical Report 34A, 15 pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Qureshi, R.M., Aravena, R., Fritz, P & Drimmie, R (1989): The CO2 absorption method as an alternative to benzene synthesis method for 14C dating Applied Geochemistry, 4, 625633 Quỳnh, T.T.T., Hằng, T.T.L., Linh, V.T.P., Diễm, N.T.K & Trí, V.P.Đ (2015): Review on groundwater resources management in Sóc Trăng Province (in Vietnamese) Can Tho University Scientific Journal, Special Issue: Environment and Climate Change, 234-245 Robertson, W.D & Cherry, J.A (1989): Tritium as an indicator of recharge and dispersion in a groundwater system in central Ontario Water Resources Research, 25(6), 1097-1109 Rozanski, K., Araguas-Araguas, L & Gonfiantini, R (Eds.) (1993): Isotopic patterns in modem global precipitation, 36 pp., American Geophysical Union, Washington DC Russak, A & Sivan, O (2010): Hydrogeochemical tool to identify salinization or freshening of coastal aquifers determined from combined field work, experiments, and modeling Environ Sci Technol., 44, 4096-4102 Salem, O., Visser, J.M., Deay, M & Gonfiantini, R (1980): Groundwater flow patterns in the western Lybian Arab Jamahitiya evaluated from isotope data Arid Zone Hydrology: Investigation with Isotope Techniques, IAEA, Vienna, Austria, 165-179 Tùng, T.T (2014a): Instructions on the use of the Diver Office Software and Diver USB Reader IGPVN Guideline, 23 pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 90 German Technical Cooperation with Vietnam Improvement of Groundwater Protection in Vietnam Tùng, T.T (2014b): Results of grain size analysis of IGPVN monitoring wells in Soc Trăng Province IGPVN Technical Report 39, 35 pp, National Center for Water Resources Planning and Investigation (NAWAPI), Vietnam & Federal Institute for Geosciences and Natural Resources (BGR), Germany, Hanoi Vietnam, G.S.O.o (2017) edited, doi:http://www.gso.gov.vn/Default_en.aspx?tabid=491 Wagner, F., Trung, Đ.T., Phúc, H.Đ & Lindenmaier, F (2011): Assessment of Groundwater Resources in Nam Đinh Province Part A Phase Final Technical Report, 98 pp, National Center for Water Resources Planning and Investigation (CWRPI), Ha Noi & Federal Institute for Geosciences and Natural Resources (BGR), Hannover, Hanoi Relevant legislation documents as mentioned in this report Improvement of Groundwater Protection in Mekong Delta provinces 2015-2017 91 ... DONRE in establishing and disseminate and promote practices of integrated water resources management (IWRM), and v) the development of recommendations and measures for improved water resources management. .. documents and development of a consolidated final report on the current state of groundwater exploitation, use and management in Sóc Trăng, and proposal of recommendations and measures for water resources. . .Final Report IGPVN Activities and Achievements, Proposal of Recommendations and Measures for Water Resources Management in Sóc Trăng Technical report Phase III -1 Authors: