DPSIR model framework Dupuit Ecopath model History of engineering & technology Lianshi Lake MODFLOW Songnen Plain Technology: general issues Thiem Yangtze River Yongding River alga control artificial ecological water supplement brackish water distribution drinking suitability ecological restoration environmental management factor analysis fluorine formation fuzzy comprehensive evaluation model general algebraic modeling system groundwater groundwater flow system groundwater hydrochemistry groundwater numerical simulation groundwater quality groundwater recharge resources amount evaluation health risk assessment