|Hopmans, Jan - UC DAVIS, CA|
|DE Rooij, Gerrit - WAGENINGEN, NETHERLANDS|
Submitted to: Vadose Zone Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 11, 2006
Publication Date: March 8, 2006
Citation: Corwin, D.L., Hopmans, J.W., De Rooij, G.H. 2006. From field- to landscape-scale vadose zone processes: Scale issues, modeling, and monitoring. Vadose Zone Journal. 5:129-139. Interpretive Summary: Because of the extensive variation in soil properties from one point to the next, the spatial scale or extent of an area is a primary consideration when trying to model or monitor processes that occur from the soil surface to the groundwater, i.e., the vadose zone. Environmental and natural resource problems such as non-point source pollution, watershed management, and nutrient management, to mention a few, are greatly influenced by scale. Processes that dominate at one scale may be less significant at another scale. A special issue of Vadose Zone Journal was organized with the objective of presenting a collection of research papers that reflect the current trends in modeling and monitoring processes that occur in in the vadose zone over multiple scales ranging from the size of a field to an entire landscape. It is the objective of this paper to run a common thread through this research to show the interrelationship of the work, to identify the significant contribution of each paper, and to discuss the current direction and trend of research, as well as remaining challenges and needs. The complexity of this issue is a consequence of the complex heterogeneity of soil and the complexity that occurs at multiple scales. Future research will focus on computational techniques and measurement tools that can measure or characterize these complex spatial variations for modeling and monitoring applications.
Technical Abstract: Modeling and monitoring vadose zone processes over multiple scales is a fundamental component of many environmental and natural resource issues including non-point source (NPS) pollution, watershed management, and nutrient management, to mention just a few. It is the objective of this special issue to of Vadose Zone Journal to present a collection of papers reflecting current trends in modeling and monitoring vadose zone processes from field to landscape scales. The objective of this introductory paper is to run a thread through the papers to show their interrelationship and to identify the significant contribution of each paper. The spectrum of topics covered includes (i) issues of scale, (ii) spatial analysis of model error; (iii) modeling of NPS pollutants and hillslope stability; (iv) the use of estimation and conditioning tools such as upscaling, pedotransfer functions, and generalized likelihood uncertainty estimation; (v) data assimilation with flow modeling and passive microwave remote sensing to estimate moisture distribution; (vi) effective hydraulic parameters across spatial scales; (vii) spatio-temporal stability of soil properties (e.g., Cl- transport, salinity, B, NO3-N, and soil physical and hydraulic properties); and (viii) nested sampling to determine spatial patterns. The common thread running through each paper, whether for modeling or monitoring vadose zone processes, is how to address the complex issue of spatial and/or temporal variability at the scale of interest. Future research will likely involve inverse modeling; combinations of multiple sensors to monitor at various scales; and continued application of pedotransfer functions, of upscaling and downscaling, and of the concept of the hierarchy of scales.