An integrated approach for estimation of van genuchten model parameters in undisturbed and unsaturated soils

IF 0.7 4区 农林科学 Q3 AGRICULTURE, MULTIDISCIPLINARY
Muhammad Aslam
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引用次数: 3

Abstract

The hydraulic properties of soil are very important to determine the soil relationship with water. The Soil Hydraulic Properties (SHP) are used to determine the soil water relationship as it is very crucial for estimation of water holding capacity of soil. In real field conditions, most widely used model for soil moisture retention curves is van Genuchten model. The soil samples were taken randomly from five different depths with three replications of each depth. Moreover, two samples at the depth of 5-35cm and 35-155cm were selected for evaluation of integrated approach to find soil characteristic curves. Soil moisture characteristic curves calculated by integral approach were compared with, soil moisture curves measured by pressure plate apparatus, and Soil Plant Air Water (SPAW) hydrology a computer based Model. The accuracy of results were evaluated by determination of Root Mean Square Error (RMSE), Normalize Root Mean Square Error (NRMSE) and Willmott’s index of agreement (£). A good agreement was observed between integrated approach, high-pressure technique and SPAW model results. In case of integrated method versus high-pressure technique the RMSE was 9.51×10-3 for 5-30cm depth and 8.32×10- 3 for 30-155cm depth. The NRMSEs was 6.52 ×10-2 for 5-30cm depth and 6.1×10-2 for 30-155cm depth, similarly £ was 0.881 and 0.893 for both depths 5-30cm and 30-155cm respectively. Regression coefficient (R2 ) for 5-35cm depth for sorptivity (s) and wetting distance (d) were 0.991 and 0.988 respectively and at depth of 35-155cm, R2 for (s) was 0.990 and for wetting distance (d) was 0.994. In case of integrated method versus SPAW hydrology the RMSEs was 1.3×10-2 for 5-30cm depth and 1.15×10-2 for 30-155cm depth. The NRMSEs for was 9.33 ×10-2 for 5-30cm depth and 7.15×10-2 for 30-155cm depth and similarly £ was 0.852 and 0.863 for both depths respectively. Results indicated a good relationship between high-pressure technique, SPAW hydrology results and integral method. However, integrated approach is best approach to determine the soil moisture characteristics curves of undisturbed and unsaturated soils
非饱和土和未扰动土中van genuchten模型参数的综合估计方法
土的水力特性对于确定土与水的关系是非常重要的。土壤水力特性(SHP)是确定土壤水分关系的重要参数,对土壤持水能力的估计至关重要。在实际的田间条件下,应用最广泛的土壤保水曲线模型是van Genuchten模型。土壤样本随机取自5个不同深度,每个深度重复3次。选取深度为5-35cm和35-155cm的2个样品,对综合方法寻找土壤特征曲线进行评价。将积分法计算的土壤水分特征曲线与压力板仪测量的土壤水分曲线和基于计算机模型的土壤植物空气水(SPAW)水文学进行了比较。通过确定均方根误差(RMSE)、归一化均方根误差(NRMSE)和Willmott一致指数(£)来评估结果的准确性。综合方法、高压技术与SPAW模型结果吻合较好。在综合方法与高压技术的情况下,5-30cm深度的RMSE为9.51×10-3, 30-155cm深度的RMSE为8.32×10- 3。5-30cm和30-155cm的nrmse分别为6.52 ×10-2和6.1×10-2, 5-30cm和30-155cm的nrmse分别为0.881和0.893。5 ~ 35cm深度吸附率(s)和润湿距离(d)的回归系数R2分别为0.991和0.988,35 ~ 155cm深度吸附率(s)和润湿距离(d)的回归系数R2分别为0.990和0.994。对于SPAW水文综合方法,5-30cm深度的均方根误差为1.3×10-2, 30-155cm深度的均方根误差为1.15×10-2。5-30cm深度的nrmse为9.33 ×10-2, 30-155cm深度的nrmse为7.15×10-2,同样,两种深度的£分别为0.852和0.863。结果表明,高压技术、SPAW水文结果与积分法之间关系良好。综合方法是确定原状土和非饱和土土壤水分特征曲线的最佳方法
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来源期刊
Pakistan Journal of Agricultural Sciences
Pakistan Journal of Agricultural Sciences AGRICULTURE, MULTIDISCIPLINARY-
CiteScore
1.80
自引率
25.00%
发文量
18
审稿时长
6-12 weeks
期刊介绍: Pakistan Journal of Agricultural Sciences is published in English four times a year. The journal publishes original articles on all aspects of agriculture and allied fields.
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