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| DOI：10.13522/j.cnki.ggps.2021110 |
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| Evolutionary Change in Groundwater Table in Qingtongxia Irrigation District and Its Determinants |
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ZHAI Jiaqi , CAO Jipeng LIU Kuan ZHAO Yong , DONG Yiyang , ZHAO Jifang
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(1. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China; 2. School of Water Conservancy Engineering, Zhengzhou University,
Zhengzhou 450001, China; 3. Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China;
4. Urban and Rural Construction College, Hebei Agricultural University, Baoding 071001, China)
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| Abstract: |
| 【Objective】Understanding evolutionary change in groundwater table depth and its underlying driving forces in a region can help improve its water management. Taking an irrigation district in Qingtongxia of China as an example, this paper analyzes the temporal variation in its groundwater table, as well as the factors that drive this change.【Method】The analysis was based on regional water balance calculated using the data measured from 1998 to 2017 in an irrigation district in Qingtongxia. The factors we envisaged to have impacted the groundwater dynamics in this region included irrigation areas, canal leakage, infiltration of rainfall and irrigation water.【Result】The groundwater table in the studied region had been dropping at an average rate of 0.038 m/a from 1998 to 2017. Annually, the groundwater level showed two alternate rising-fall cycles. Spatially, the groundwater table in the region around Yinchuan dropped more significantly, forming a depressed zone in the urban of Yinchuan and Dawukou in Yinbei irrigation district. The factors modulating inter-annual groundwater table change and their contribution (numbers in the bracket) were ranked in the order of recharge from canal leakage (39.71%) > lateral groundwater flow (28.24%) > groundwater evaporation (14.16%) > field infiltration (7.46%). The recharge of canal leakage from April to August as well as in November contributed most to the rise in the groundwater table (45.33%), while the lateral groundwater flow from September to October and December was the first driving force (45.6%) of the fall in the groundwater table. Spatially, the change in groundwater table was mainly driven by leakage of the canals, with the impact of other factors varying with region. In areas around Yinchuan, Yinnan and Hedong, the lateral groundwater flow impacted the groundwater table change the most, while in areas around Yinbei, groundwater evaporation played the dominant role.【Conclusion】The continued reduction in water allowed to divert from the Yellow River to the irrigation district is the driving force affecting the dropping in groundwater table in Qingtongxia, and keeping the groundwater table at an optimal depth is essential to maintaining ecological functions while in the meantime preventing salt accumulation on the soil surface in this region. |
| Key words: groundwater depth; spatiotemporal change; irrigation district; Qingtongxia |
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