Abstract
Abstract. Groundwater overdraft has caused fast water level decline in the North China Plain (NCP) since the 1980s. Although many hydrological models have been developed for the NCP in the past few decades, most of them deal only with the groundwater component or only at local scales. In the present study, a coupled surface water–groundwater model using the MIKE SHE code has been developed for the entire alluvial plain of the NCP. All the major processes in the land phase of the hydrological cycle are considered in the integrated modeling approach. The most important parameters of the model are first identified by a sensitivity analysis process and then calibrated for the period 2000–2005. The calibrated model is validated for the period 2006–2008 against daily observations of groundwater heads. The simulation results compare well with the observations where acceptable values of root mean square error (RMSE) (most values lie below 4 m) and correlation coefficient (R) (0.36–0.97) are obtained. The simulated evapotranspiration (ET) is then compared with the remote sensing (RS)-based ET data to further validate the model simulation. The comparison result with a R2 value of 0.93 between the monthly averaged values of simulated actual evapotranspiration (AET) and RS AET for the entire NCP shows a good performance of the model. The water balance results indicate that more than 70% of water leaving the flow system is attributed to the ET component, of which about 0.25% is taken from the saturated zone (SZ); about 29% comes from pumping, including irrigation pumping and non-irrigation pumping (net pumping). Sustainable water management analysis of the NCP is conducted using the simulation results obtained from the integrated model. An effective approach to improve water use efficiency in the NCP is by reducing the actual ET, e.g. by introducing water-saving technologies and changes in cropping.
Highlights
The use of groundwater as a resource for water supply to urban areas and for irrigation has increased dramatically during the past decades, while in many areas of the world there is still a large unused potential for increased groundwater exploitation (Zektser and Everett, 2004)
An integrated and distributed hydrological model based on the coupled MIKE SHE/MIKE 11 code has been developed for the entire North China Plain
The hydrological model used in the present study is an integrated model including both surface water and groundwater components, while similar studies carried out in the same area only consider the groundwater component (Cao et al, 2013) or treat the surface water component without considering rivers in the model (Shu et al, 2012)
Summary
The use of groundwater as a resource for water supply to urban areas and for irrigation has increased dramatically during the past decades, while in many areas of the world there is still a large unused potential for increased groundwater exploitation (Zektser and Everett, 2004). In some areas of the world groundwater levels of major aquifers are rapidly declining as an effect of unsustainable pumping and insufficient recharge. This is for instance the case in West Java, Indonesia; Dhaka, Bangladesh; and Beijing, China (Braadbaart and Braadbaart, 1997; Hoque et al, 2007; Zhou et al, 2012). The reliability of the model simulations is in question
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