Prof. Dr Wolfgang Kinzelbach, Dr. Yu Li, Dr. Lu Wang, Dr. Ning Li, P. Burlando
ETH Zurich
Dr. Haijing Wang, Dr. Beatrice Marti, Dr. Silvan Ragettli
Hydrosolutions, Zurich
(a) Purpose or objectives and status of study or research hypothesis
The North China Plain is a global hotspot of groundwater overuse. It is caused by the double cropping of winter wheat and summer maize, which requires more water than the annual rainfall can provide. The gap is mainly covered by groundwater abstraction. Consequences include falling dry of streams and wetlands, land subsidence and seawater intrusion. Declining groundwater levels impair an aquifer’s ability to act as a reservoir, buffering agricultural production against expected climate extremes. The project chooses Guantao County in Hebei Province to identify a strategy for sustainable groundwater use.
(b) Key issue(s) or problem(s) addressed
Groundwater management comprises three components: monitoring of water levels and pumping rates, interpretation of monitoring data with models advising policy and implementation of policy measures in the field.
(c) Methodology or approach used
Groundwater levels are recorded in real time. Land use is monitored by satellite remote sensing. Water abstraction is monitored using pumping electricity as a proxy. A groundwater model based on these data concludes that presently abstractions are still about 20% above the sustainability requirement. A quota system is in an experimental stage. It is proposed to implement it via a water fee proportional to and collected together with the electricity fee, rewarding farmers who stay below the quota.
(d) Results and conclusions derived from the project
The project concludes that over-pumping cannot be stopped by water saving irrigation alone. It requires a change in cropping system. A reduction in winter wheat production by about 30% can fill the supply-demand gap. In view of national grain supply security, the reduction can be less if a corresponding quantity of surface water is provided through South-North Water Transfer. Up-to-date technology for monitoring, modeling and decision support implemented in Guantao County promises to be effective in reaching the sustainability goal.
Implications of the project relevant to selected conference theme, theory and/or practice The return to a sustainable use of groundwater involves a reduction in agricultural production. With less production on average, abstraction can be brought into hydrologic equilibrium in the long term while allowed overdraft in drought periods makes production robust. Inter-institutional cooperation is essential to reach a compromise between grain security and sustainability. The Agricultural Department has to contribute subsidies for fallowing while the Water Resources Department has to increase surface water transfers from the South. The Electric Power Department can contribute to discipline in pumping by an easily implemented fee system involving electricity as a proxy.