Groundwater Management in Urban Area N.Dörfliger of Changsha, May 2014 ASEM Seminar on Sustainable Management of Water resources in the context of urbanization
Urban water cycle - facts > Outline Urban water cycle framework Role of the groundwater and of reclaimed water Urbanization and water supply in the world and with a focus in Asia Groundwater abstraction for water supply in India and in China Groundwater management In terms of quantity with contribution of groundwater modeling to face water demand In terms of early warning system for flooding In terms of groundwater protection and vulnerability In terms of reclaimed water Conclusions and Perspectives > 2
Urban water cycle - facts Groundwater River Reservoir/Lake Alternative source (reuse, desalinization) Water supply Storm water Wastewater Water quality Potential resource Flooding control and mitigation Reduce leaking of pipes Protection scheme - vulnerability Sewer capacities Water treatment standards Potential resource Reuse of water Reclaimed water > 3
The increase of urban density More than one habitant of the world/two leaves in town. Acceleration of the trend Population of the 30 largest urban centers In millions More than Evolution of worldwide population In billions In 2015, > 50% of all people on earth, about 4 billions of people are expected to live in urban areas Asia is strongly concerned for large urban centers > 4
Groundwater abstraction in India i.e. : Today, 89% of groundwater abstraction are for irrigation needs (70% of irrigation needs) and 9% of groundwater abstraction are for water supply, covering 80% of domestic water supplies; 251 km 3 /year in 2010, Groundwater abstraction in total Groundwater abstraction in China : 20 % of groundwater = urban water supply ; overexploitation with geological hazards and environmental issues; 112km 3 /year in 2010 of Groundwater abstraction in total Source: Margat, J., and J. van der Gun. 2013. Groundwater around the World, CRC Press/Balkema > 5
Groundwater management issues in urban areas variety of groundwater types Local and shallow aquifers Groundwater basins Complex hydrogeological structures (karst, hard rock, ) > 6
Groundwater management issues in urban areas - In terms of quantity with conjunctive use with surface water and alternative water such as reclaimed water - Needs of monitoring Groundwater level through appropriated network, as well as abstraction volumes and of modeling various demand scenarios in order to avoid overexploitation and linked problems : subsidence, quality problems. Modified from Foster et al 1998 > 7
Groundwater management issues in urban areas Overexploitation due to increase of water demand => cone of depression in groundwater of several decades of m depth Needs to set up various scenarios for remediation, and to carry out modeling Here example of Shanghai Illustration with similar situations in 1970 s in Bordeaux urban area in South West France Y. Zhou et al Physics and Chemistry of the Earth 47 48 (2012) 99 113 > 8
Groundwater management issues in urban area Bordeaux (SW France) Consequences of an intense development In Eocene: depression of GW level in Bordeaux area In Oligocene: dewater of sectors A threatened Gw ressource 65% of GW used for Water supply In quantity: - Eocene: renewal compromise - Oligocene: decrease of spring discharges In quality: - Eocene: possible salt water intrusion - Oligocene: increased vulnerability to surface pollutions > 9
Groundwater management issues in urban areas Example of MONA model in Bordeaux area (South West France) - 15 layers from Plio Quaternary to Bajocian - 66953 meshes of calculation (2km x 2Km) - Pseudo 3D model (no explicit scheme for impervious layers) - Year time step from 1972 2013-3248 capture works - 400 groundwater level time series > 10
Groundwater management issues in urban areas Simulation of scenarios and also recently concerning Climate changes MONA model = a decision support tool, running every year and update of the model > 11
Groundwater management mitigation of flooding where groundwater contributes to floods, i.e. in karst aquifers area, through determining the proof of GW contribution, and groundwater level and saturation index of soil and sub-soil within warning systems Example Of catchment Of La fontaine de Nîmes Spring (Nîmes town South France) > 12
Water level of index (gw saturation) m a.s.l Urbanization and Wsupply Groundwater management mitigation of flooding where groundwater contributes to floods, i.e. in karst aquifers area, through determining the proof of GW contribution, and groundwater level and saturation index of soil and sub-soil within warning systems Level 3 historical Level 2 overflow Level 1 vigilance Taking into consideration initial water saturation of soil and of aquifer within a real time warning system Valorisation of groundwater level => Reservoirs modeling Warning chart for forecasting Rainfall cumul (mm) > 13
Groundwater management groundwater protection scheme (protection zones) and vulnerability mapping - Example of Montpellier (South France ) and urban area > 14
Groundwater management groundwater protection scheme (protection zones) and vulnerability mapping - Example of Montpellier (South France ) and urban area Global vulnerability PaPRIKa method Very high vulnerability High vulnerability Moderate vulnerability Low vulnerability Risk index A support to cross with occupation of soil, activities, in order to define risk sectors and as well protection measures such as protection perimeters of capture work => A decision tool for planning > 15
Groundwater management and reclaimed water Management aquifer and soil treatment concept under a variety of environmental conditions (hard rock and granular aquifers, ephemeral streams, ) Gajuel catchment peri urban area of Hyderabad, India Influence of infiltration pond To the recharge of the aquifer Water budget, using isotopic analyses of rainfall and gw Electrical conductivity of Gw > 16
Groundwater management and reclaimed water Management aquifer and soil treatment concept under a variety of environmental conditions (hard rock and granular aquifers, ephemeral streams, ) Importance of maintenance of ponds in order to optimize infiltration Survey of quality impact (chemistry, microbiology) > 17
Groundwater management and reclaimed water Management aquifer and soil treatment concept under a variety of environmental conditions (hard rock and granular aquifers, ephemeral streams, ) Optimization of waste water treatments through combined geomaterials and natural soil filter, reactive geobarriers Optimizing treatment of wastewater using natural soil system for infiltration ponds Mechanical filtration of organics and heavy metals Oxidative degradation of Dissolved Organic Matter and ammonium From pilot column to geo barriers ponds From experimental data to transport reactive modeling (MARTHE brgm + MIN3P (Mayer et al. 2002)) Monitoring of water level Porous cups Secondary effluent of Waste water Fixed hydraulic Head Geochemical monitoring of outlet solution Non saturated biogeochemical transfert reactive model > 18
NO 3 - mol/l NH 4 + mol/l Urbanization and Wsupply Groundwater management and reclaimed water MAR Optimization of waste water treatments through combined geomaterials and natural soil filter, reactive geobarriers Waste water Column outlet Slight overestimation of nitrification processes: All NH 4 + transformed in NO 3 - NO 3 - matches with N tot Production of N 2 = denitrification with CH 2 O degradation and pyrite oxidation N tot initial=3.15 x10-3 mol/l N tot final=1.44 x10-3 mol/l Consumption of CH 2 O reproduced at the column outlet after 30 numerical tests N tot Column outlet NO 3 - Column outlet Pettenati et al. 2011 WaterReuse Barcelona NO 3 - Waste water Modelling artifact Adjustment of kinetic redox processes coefficients > 19
- Groundwater = high potential resource for urban area - Strong development with potential problems of susbidence, quality problems - Importance of adequate managing in terms of quantity and quality, with conjuncture use of surface water and reclaimed water, of integrated management approach - MAR important concept through infiltration ponds to improve infiltration, or geomaterials barrier in order to strengthen purification process Thank you for your attention! > 20