About the Project

In arid and semi-arid regions, reliable agricultural production is only feasible with irrigation. Groundwater as the only water resource, which is available all year round, has become more and more attractive to agricultural water users to guarantee high yield. Severe over-pumping of aquifers has become common. It is estimated that about a quarter of the 1000 km3 pumped annually from aquifers worldwide is not renewed by recharge and thus leads to depletion of aquifers.
Aquifers can store water over years and are therefore particularly suited for mitigation of drought periods, which are expected to occur more frequently under climate change. To serve this purpose they must however be allowed to recover in times of above-average rainfall. Only under strict management, aquifers will be able to relieve droughts reliably. The main purpose of the project is to preserve or restore an aquifer’s capability of drought mitigation and provide insurance against expected climate extremes. It thus constitutes an adaptation measure with respect to climate variability.

China is the ideal laboratory to investigate control systems for groundwater, which in future can be transferred to other arid and semi-arid countries in the developing and transitioning world. China offers the problem in a severe form, the climatic conditions of interest in the context of many developing countries, the infrastructure and personnel for a relatively fast implementation of the system and a still greater closeness to conditions in developing countries than Switzerland. It is therefore an excellent test bed for technologies and rural institutional development aiming at sustainable groundwater allocation and drought mitigation also in developing countries.

In the Heihe Basin component of the project, a system of control was successfully implemented, in which all pumping wells can only be operated by a swipe card (IC) card carrying the quota allowed for each well. The pumped amounts are recorded and transmitted to a server in 8-hour intervals in order to provide fast servicing in case a system malfunctions. Quota are determined centrally using a surface water-groundwater model of the Heihe mid-reach, which can in real time assimilate all observation data on groundwater levels, pumping rates of wells, surface water imports and meteorology. Quota can be set higher in times of drought to mitigate drought conditions and low in times of good availability of surface water flows to allow recovery. With a sufficiently high water table even several consecutive drought years can be overcome.

The system can, however, not be copied to the North China Plain (NCP). In the NCP, the cropland per farmer is considerably smaller than in the Heihe Basin and so are the wells, which moreover only supply supplementary irrigation. As all wells are operated by electricity, the monitoring of water abstraction can be based on the electricity used. With pumping tests, the conversion rate from kWh to cubic meters is readily determined. Monitoring abstraction via the electric energy used has meanwhile been adopted in the whole of Hebei province. For the pilot county Guantao, tools such as a numerical model of the aquifer system, an irrigation calculator and remote sensing information have been combined into a decision support system to allow the annual planning of water saving measures and to keep the groundwater level above the “red line”. They include fallowing of winter wheat, planting of water saving crops, replacing flood irrigation by water saving irrigation, and low till management of soils for water conservation. In the implementation of measures, water prizing, subsidies and awareness building are employed. A serious game has been developed to test farmers’ acceptance of different policies. By now it is clear that the growing of winter wheat, the most water consuming crop, has to be reduced. Subsidized fallowing of winter wheat has been the most efficient way of water saving so far.

The overall goal of the present project is to develop and apply a system for improving groundwater management on the basis of monitoring, modelling and controlling groundwater abstractions in an effort to restore the aquifers’ capability of mitigating climate variability.