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Variation in soil water content in the delta plain has its own particularity and is significant for agricultural improvement, the utilization of water resources and flood risk mitigation. In this study, experimental data collected from a plot of farmland located in the Taihu Basin were used to investigate the temporal and vertical variation of soil water content, as well as the effects of individual rainfall on soil water and shallow groundwater and their interaction. The results showed that the variation of soil water content is dependent on the comprehensive influence of soil hydraulic properties, meteorological factors and shallow groundwater and the correlation to the groundwater table is the strongest due to the significant capillary action in the delta plain. A saturated-unsaturated three-dimensional soil water numerical model was developed for the study area in response to rainfall and evapotranspiration. Scenario simulations were performed with different soil depths for soil water content and the error source was analyzed to improve the model. The average RMSE, RE and R2 values of the soil water content at the five depths between the measured and simulated results were 0.0192 cm3·cm−3, 2.09% and 0.8119, respectively. The results indicated that the developed model could estimate vertical soil water content and its dynamics over time at the study site at an acceptable level. Moreover, further research and application to other sites in delta plains are necessary to verify and improve the model.
Wenjuan Hua; Chuanhai Wang; Gang Chen; Hai Yang; Yue Zhai. Measurement and Simulation of Soil Water Contents in an Experimental Field in Delta Plain. Water 2017, 9, 947 .
AMA StyleWenjuan Hua, Chuanhai Wang, Gang Chen, Hai Yang, Yue Zhai. Measurement and Simulation of Soil Water Contents in an Experimental Field in Delta Plain. Water. 2017; 9 (12):947.
Chicago/Turabian StyleWenjuan Hua; Chuanhai Wang; Gang Chen; Hai Yang; Yue Zhai. 2017. "Measurement and Simulation of Soil Water Contents in an Experimental Field in Delta Plain." Water 9, no. 12: 947.
The theoretical variance-scale relation has been widely used in detecting scale phenomena in ecology. Mathematical derivation and verification in mathematical functions have been demonstrated in this paper that the inherent law, e.g., variance of an independent variable, decreases while scale (resolution) increases. Based on this variance-scale relation and the attribute of grid DEM, an accuracy assessment approach for interpolation methods applied to generating grid DEMs was developed. A numerical test and two real-world examples were employed as a means of examining the feasibility of this accuracy assessment approach by comparing four interpolation methods, i.e., HASM, Spline, Kriging, and IDW. A scale-based error model of DEM was obtained in the numerical test and interpolation accuracy could be compared based on the matching scales. Both the regular sampling case and the random sampling case showed that all of the calculated variance-scale relations of all four methods broke the theoretical law because of synthetic effect of sampling density, terrain characteristics, scale and smoothing effect of interpolators in the real-world test. The overall level of variance at most scales was thus used as an accuracy assessment criterion. After perfecting the second assumption, we established the final assessment criteria. Based on the new accuracy assessment framework, all the results indicated that HASM and Spline were more accurate than Kriging and IDW. The new accuracy assessment approach provides an alternative framework for comparing different interpolation methods in grid DEMs.
Hai Yang; Chuanhai Wang; Tengfei Ma; Weijian Guo. Accuracy assessment of interpolation methods in grid DEMs based on a variance-scale relation. Environmental Earth Sciences 2015, 74, 6525 -6539.
AMA StyleHai Yang, Chuanhai Wang, Tengfei Ma, Weijian Guo. Accuracy assessment of interpolation methods in grid DEMs based on a variance-scale relation. Environmental Earth Sciences. 2015; 74 (8):6525-6539.
Chicago/Turabian StyleHai Yang; Chuanhai Wang; Tengfei Ma; Weijian Guo. 2015. "Accuracy assessment of interpolation methods in grid DEMs based on a variance-scale relation." Environmental Earth Sciences 74, no. 8: 6525-6539.