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Fig.1. Desert and plains under desertification.
Three-Dimensional Modeling of Groundwater Ages and Implications for
Sustainable Groundwater Management in the Ordos Basin, Northwest China Cheng Yu1 ([email protected]), Guoliang Cao2, Yingying Yao1, Fusheng Hu3, Chunmiao Zheng1,2
1: Center for Water Research, Peking University, China. 2: Department of Geological Sciences, University of Alabama, USA. 3:China University of Geosciences (Beijing), China
Introduction
Basin scale groundwater flow models are
often required in sustainable groundwater
management. But scarcity and unreliability of
data would produce significant uncertainties.
Direct simulation of groundwater ages has
made great contribution to basin scale ground
water modeling and management, because
A. Comparison between computed age
distribution and age data from isotopic dating
could constrain the flow model calibration and
reduce uncertainties in model prediction.
B. Groundwater age is an indicator of
groundwater renewable capacity and could
help in sustainable groundwater management
and industrial planning.
Ordos Basin
Age Modeling
Acknowledgements
Ordos Basin has 38% of coal, 50% of gas
and 6% of oil of the national reservations. But
economy is hampered by severe water scarcity.
Deserts and plains along Yellow River used
to be significant pasturing area but is now
subject to desertification (Fig .1).
Sustainable management of limited ground
water resources is of major concern.
Hydrogeological Conditions
Fig. 4. Conductivity distributions.
Fig. 5. Spatial discretization, horizontal: 180 x
330(2km x 2km); vertical: 4 layers.
Fig. 6. Boundary conditions.
Flow Modeling
We acknowledge the financial and technical support from National Natural Science Foundation of China and Xi’an Regional Center of China Geological Survey.
Layer 1. Layer 2. Layer 3. Layer 4.
Cretaceous aquifer was separated into four
layers (Fig. 4).
Fig 7. Head Calibration. Conductivities were adjusted using PEST. Head was well calibrated to fit 53 observed heads.
Fig. 2. Geography.
Conclusions
Ordos Basin consists of deserts and Leoss
Plateau with Baiyu Mountain as watershed
(Fig .2). There are four aquifer types (Fig. 3) .
Only Cretaceous aquifer was simulated.
A. Age simulation provided strong support for
flow model for the well matched ages. Age
calibration helped flow model improvement
as another constraint in head calibration.
B. Age simulation could present not only the
flow path and also the interaction between
ground water mass or between ground
water and surface water.
C. Age indicates refresh speed. Much of deep
aquifer groundwater may be nonrenewable
within a practical time frame. Mining in old
ground water might be unsustainable.
Fig. 8. Age simulation (using MT3DMS) and comparison with C14 sampling age data at 46 points.
Fig. 3.
Four aquifer types.
Only Cretaceous
aquifer of the four
was simulated.
