Wolfgang Kinzelbach

Policy selection and implementation rely on monitoring data and technical decision support tools. Monitoring data of Guantao County include groundwater levels at 55 observation wells, pumping rates of 7600 wells, surface water flows, precipitation, and land use in monthly time steps.

The combination of fallowing and substituting groundwater by surface water was effective in reducing aquifer depletion in Guantao. The average annual depletion rate after 2014 was about half the value of the pre-project period 2000–2013 and basically limited to the deep aquifer. The goal of closing all deep aquifer wells has only been reached partially, their use being necessary in locations where the shallow aquifer is too saline.

Starting in the 1990s, China has been issuing regulations and policy rules related to groundwater management and pumping control on both national and provincial levels. These policies include the requirement of permits for well drilling, a well spacing policy, pumping quota management, water resources fee collection, setting of irrigation water prices, a water rights system, water markets, and more.

The depletion of aquifers by excessive pumping is one of the prominent global sustainability issues in the field of water resources. It is mainly caused by the water needs of irrigated agriculture. The North China Plain is a global hotspot of groundwater overexploitation.

Irrigation being the main cause of aquifer depletion, agriculture is the first candidate to contribute to its solution. Options of agricultural planting structure in Beijing-Tianjin-Hebei region are analyzed using various planting scenarios.

Sponsored by the Environmental & Water Resources Institute (EWRI)

The large number of users and the small scale of wells greatly complicate monitoring of groundwater abstraction in areas of intensive pumping by numerous smallholders such as in the North China Plain. This paper presents a study in a typical county in the North China Plain. It discusses the application and challenges of an indirect, energy-based approach to groundwater abstraction monitoring. Intensive field experiments at individual wells were carried out to provide a basis for the conversion from electric energy consumption to groundwater abstraction and to explore the feasibility of direct and indirect abstraction monitoring methods in the study area. The results show that the main challenge of electricity-to-water conversion lies in the large spread of conversion factors between wells. The conversion error at an individual well is found to be less than 20%. The same accuracy is achieved on spatially aggregated levels by testing only a small number of wells. Trade-offs can be made to obtain groundwater abstraction estimates at the required accuracy and with reasonable efforts regarding data collection. The analysis shows that energy-based groundwater abstraction monitoring outperforms direct water metering with respect to cost and robustness. It provides satisfactory data accuracy and equitability in regions where irrigation wells are powered by electricity.

In arid regions, sustainable groundwater management is crucial for the protection of vulnerable local ecosystems but often leads to conflict with the interests of economic development. Management models containing simulation-optimization techniques are widely used to explore sustainable strategies of conjunctive water use, but previous studies often failed to address the system’s complexity as a whole, characterized by many stakeholders, a heterogeneous flow regime, and uncertain driving forces. This article contributes to a many-objective robust decision-making (MORDM) framework that integrates a state-of-the-art multiobjective optimization algorithm (MOEA) with robustness-based decision analysis to advance the field’s knowledge of conjunctive water use. The framework is applied to the trans-regional Heihe River Basin in China, which is facing a number of consequences of unsustainable water management, jeopardizing the downstream ecosystem and agricultural development in the river’s midreach. Results show that the current water management scheme is unsustainable in two respects: It overexploits groundwater resources locally and it cannot fulfill the minimum ecological outflow target. The baseline can be further improved with optimized solutions, but an unresolvable conflict exists between the required environmental outflow and water demand for the irrigated agriculture scheme under the current policy of inflow-proportional water sharing with the downstream. The robustness assessment highlights the key driving forces and how they shape the robustness of the system under different policies and changing conditions. The case study sheds light on the potential of MORDM to solve complex conjunctive water management problems and shows how it can help to improve understanding of the problem itself.