Subjects: Biology >> Ecology submitted time 2017-11-29 Cooperative journals: 《中国生态农业学报》
Abstract： The Loess Plateau suffers serious soil and water loss; resulting in a fragile ecological and environment and an intense deficit on available water resources. The groundwater is crucial to guarantee the regional social and economic development and maintain the ecosystem balance; however; the mechanism of groundwater transformation and recharge on the Loess Plateau is still not clear. The objective of this study was to investigate the water movement in deep soil profile and test the possibilities of rainfall in recharging the shallow groundwater in the water-wind erosion crisscross region on the Loess Plateau. Considering the restrictions of current equipment and techniques for deep soil profile moisture observation; HYDRUS-1D model was applied to calculate solute the soil hydraulic parameters and simulate deep profile 0~15 m soil water movement; by using of the data sets of meteorological factors and soil water contents in soil depth 0~600 cm in a Chinese willow field plot with aeolian sandy soil from 2013 to 2016. Upper boundary condition was set as atmosphere boundary conditions with inputs of rainfall and potential transpiration (Tp) and potential evaporation (Ep) which were partitioned from crops evapotranspiration (ET0); ET0 derived from Penman-Monteith method and the partition into Tp and Ep had used the measured leaf area index (LAI) in different growing periods; and lower boundary condition was set free drainage. The optimized hydraulic parameters were derived from repeatedly inverse solution process; and then these parameters were used to simulate soil water movement in 0~1 500 cm; and the depth of soil water infiltration and the possibility of recharging shallow underground water were analyzed. Results showed that soil water contents at the end and the beginning of the growth season in 0~600 cm had a slight deficit in 2014 (439 mm; normal precipitation year) and 2015 (371 mm; dry year). However; there had a surplus of soil water at the end of the growth season as compared with the beginning of the growth season in 2013 and 2016 (669 mm and 704 mm respectively; wet years); and the rainfall infiltration had exceeded the observing depth 600 cm. From the simulating results; soil water contents in deep soil profile had not change significantly in 2014 and 2015; and the water moves slowly into deeper soil layers; but rainfall could infiltrate to soil depths 11 m and 12 m; respectively; exceeding rooting zone at the end of the 2013 and 2016; which indicated the possibilities of rainfall in recharging the shallow groundwater. During the simulated period of 4 years; the mean value of water infiltration rate on aeolian sandy soil is 606.28 cm穌-1; average soil evaporation in 4 years is 14.87 cm; and average plant transpiration in 4 years is 33.71 cm; soil water contents were mainly lossed in the form of transpiration. Thanks to the high infiltration rate in coarse-textured soil in wet years; a large proportion of rainfall may transform into shallow underground water. Dry and wet years alternate on the Loess Plateau with intensive rainfall variations; the rainfall infiltration in wet years may be one way of shallow groundwater recharge.
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