Impacts Of Climate Change On Groundwater Irrigation Supply And Adaptive Response Of Irrigation Management

The growing shortage of water resources has affected the agricultural production and caused a threat to food security. More important is that climate change has intensified the shortage of water resources, and thus indirectly affect agricultural production. In the face of the risk of climate change on water supply, how to adapt to climate change is highly concerned by policy makers and scholars. Because irrigation plays an important role in agricultural production, it is particularly important to adapt to climate change for irrigation management.Agricultural production in the North China Plain (NCP) relies heavily on groundwater irrigation and results in rapid groundwater depletion and adverse environmental effects. Moreover, such situation is also threatened by the climate change. However, few studies have quantitatively analyzed how climate change affects the reliability of groundwater supply for irrigation, especially at micro-level. Although adaptive water management has been paid high attention by policy makers and researchers to mitigate the negative effects of climate change, existing quantitative studies on groundwater irrigation management don’t consider the effects of climate change. Therefore, the role of current irrigation management in mitigating potential negative effects of climate change on the reliability of groundwater supply for irrigation has not been understood well.The aim of this study is to identify how climate change influence groundwater irrigation supply in the NCP through constructing empirical models based on literature review and relevant theory analysis, and analyze the adaptive response of groundwater irrigation management to climate change and the effectiveness in mitigating potential negative effects of climate change. Finally, some policy implications will be provided based on the results to deal with climate change and carry out sustainable groundwater management. This study will provide evidence at micro level for the theory of the impacts of climate change and adaptation, and has important practical significance to promote the sustainable utilization of water resources and ensure food security in the North China Plain. In addition, the results of this study will help policy makers to design effective groundwater irrigation management strategies to adapt to climate change.In order to achieve the above objectives, the dataset used for this study is constructed based on four-rounds survey data covering 1036 plots and 518 farm households in 88 villages in three provinces (autonomous regions) and national meteorological observation data. The survey data were collected by the Center for Chinese Agricultural Policy, Chinese Academy of Sciences in four rounds in 2001,2004,2008 and 2012. Using the dataset, firstly, this study describes the characteristics of the long-term climate change and the trend of the change of groundwater irrigation supply in the North China Plain. Secondly, according to the survey data and relevant studies, three variables are selected to represent groundwater irrigation supply and the marginal effect of climate change on them is quantitatively assessed by constructing econometric models. Then, the evolution of groundwater irrigation management in the North China Plain over the past 20 years is described based on the survey data, including the evolution of tubewells ownership and the development of groundwater markets. Finally, the determinants of groundwater irrigation management in response to climate change is identified and the effectiveness in dealing with climate risks, improving water use efficiency and ensuring the food security is analyzed by the establishment of a series of empirical econometric models.The main results of this study are as follows:(1) The annual mean temperature displayed a clear warming trend and the annual total precipitation fluctuated from year to year without any clear trend in the sample area and in the North China Plain over the past 30 years. (2) The reliability of the groundwater irrigation supply decreased both at village level and at plot level, and the groundwater level also showed a significant downward trend in the sample area. (3) The temperature and precipitation in the long-term and short-term and the droughts are likely to have a significant influence on groundwater irrigation supply, especially for the villages which are dependent on shallow tubewells, the marginal effects of climate factors are larger. (4) In the face of the potential threat of climate change to the irrigation supply of groundwater, the groundwater irrigation management in the North China Plain has made an adaptive response. In the past 20 years, tubewell ownership has continuely shifted from collective to private tubewells, which makes the tubewell management has changed. The village collective direct management or contract management has shown a downward trend, and non-collective management has increased significantly, which causes the rapid development of groundwater markets. By 2011, the proportion of villages having groundwater market has increased to 68.1%, and the proportion of tubewells selling water has also increased to 47.3%, covering 40.6% of irrigated area. (5) Both the average climatic conditions and the long-term climate fluctuations are related to the adaptive response of groundwater irrigation management, and the response is effective in improving agricultural water use efficiency and ensuring crop yields. Estimation results show that farmers who buy water from groundwater markets apply less irrigation on wheat plots than farmers who have their own tubewells or use collective tubewells. However, wheat yields are not negatively affected. Partly this is because groundwater market offers the flexibility of adjusting the quantity as well as timing of irrigation application. Therefore, groundwater markets are farmers’adaptive response to the negative effects of climate change on groundwater supply.Our findings have important implications as follows for the NCP where climate change and water management are arguably two of the most important policy challenges:(1) when designing local and state level policies governing groundwater use management, policy makers should take into account climate change and integrate adaptive management into the design. (2) Estimation of the impact of climate change in groundwater management decisions should consider the characteristics of the aquifer. (3) For adapting to the inevitable climate change and water shortage in the NCP, policy supports are still needed to be provided considering the local characteristics. (4) Policy makers should help shape the development of groundwater markets to responde to climate risks.