UNSODA 2.0: Unsaturated Soil Hydraulic Database. Database and program for indirect methods of estimating unsaturated hydraulic properties

This database contains measured soil water retention, hydraulic conductivity, and water diffusivity data, as well as pedological information of some 790 soil samples from around the world.

Quantifying water flow and chemical transport in the vadose zone typically requires knowledge of the unsaturated soil hydraulic properties. The UNsaturated SOil hydraulic DAtabase (UNSODA) was developed to provide a source of unsaturated hydraulic data and some other soil properties for practitioners and researchers. A first MS-DOS version of the database was released in 1996. It has been applied in numerous studies. In this paper, we describe the second version (UNSODA V2.0) for use with Microsoft Access-97®1. The format and structure of the new database have been modified to provide additional and more convenient options for data searches, to provide compatibility with other programs for easy loading and downloading of data, and to allow users to customise the contents and look of graphical output. This paper reviews the structure and contents of the database as well as the operations that can be performed on the different data types in UNSODA V2.0. The use and application of the new database are illustrated with two examples. The retrieval of data is briefly illustrated, followed by a more detailed example regarding the interpolation of soil particle-size distribution data obtained according to different national definitions of particle-size classes. The interpolation procedure, which is based on finding similar particle-size distribution curves from a large European data set, also performed well for soils that originate from other geographical areas.

本数据库收录了全球约790份土壤样品的实测土壤持水特性、导水率及水分扩散率数据，同时附带相关土壤学信息。

量化包气带内的水流与化学运移过程，通常需要掌握非饱和土壤水力特性相关知识。非饱和土壤水力数据库（UNsaturated SOil hydraulic DAtabase，缩写为UNSODA）旨在为从业者与研究者提供非饱和水力数据及其他部分土壤属性的数据源。该数据库的首个MS-DOS版本于1996年发布，已被大量研究应用。

本文介绍适配Microsoft Access-97®的第二版数据库（UNSODA V2.0）。新版数据库的格式与结构已完成优化，可为数据检索提供更多且更便捷的选项，实现与其他程序的兼容性以方便数据的导入与导出，同时支持用户自定义图形输出的内容与外观。

本文综述了UNSODA V2.0的数据库结构与内容，以及可对不同数据类型执行的各类操作。通过两个示例对新版数据库的使用方法与应用场景进行演示：首先简要展示数据检索流程，随后详细讲解一则基于不同国家粒径分级标准获取的土壤粒径分布数据的插值案例。该插值流程基于从大型欧洲数据集内匹配相似粒径分布曲线的方法，对源自其他地理区域的土壤样本同样适用。