Water storage and evaporation as constituents of rainfall interception

• Published in: Journal of hydrology (Amsterdam) 1998-12, Vol.212 (1-4), p.36-50
• Main Authors: Klaassen, Wim, Bosveld, Fred, de Water, E.
• Format: Article
• Language: English
• Subjects: Evaporation; forest soils; mixed forests; rain; Rainfall interception; Water storage
• ISSN: 0022-1694; 1879-2707
• DOI: 10.1016/S0022-1694(98)00200-5

Intercepted rainfall may be evaporated during or after the rain event. Intercepted rain is generally determined as the difference between rainfall measurements outside and inside the forest. Such measurements are often used to discriminate between water storage and evaporation during rain as well. Two well-accepted methods underestimate water storage by a factor two as compared to direct observations. The underestimation of storage is compensated by an overestimation of evaporation during rain by a factor of three. The direct observations of water storage and evaporation appear to agree with previous direct observations. Thus, it is concluded that these observations are representative. Also, our results based on methods using only rainfall measurements inside and outside the forest appear to agree with previous results. This would result in the conclusion that the common methods systematically underestimate water storage and overestimate evaporation during rain. Indeed, the systematic errors can be explained by the neglect of drainage before saturation. Water storage is better simulated assuming an exponential saturation of a larger storage capacity. A smaller evaporation can be simulated using an appropriate resistance to vapour transport. The observations in dense coniferous forest showed water storage to be the dominant process in rainfall interception, but this conclusion should not be generalized to other forests and climates. Direct observations of water storage and evaporation are recommended to build a realistic set of parameters for rainfall interception studies of the main vegetation types.