Journal
JOURNAL OF HYDROLOGY
Volume 426, Issue -, Pages 79-92Publisher
ELSEVIER
DOI: 10.1016/j.jhydrol.2012.01.015
Keywords
Infiltration; Land use; Temporal variability; Spatial variability; Spatially variable infiltration model; Soil crusting
Funding
- DRV (Departement des Ressources Vivantes) of IRD
- CNRS/INSU
- GIS Climat-Environnement-Societe through the PASTEK
- DRV (Departement des Ressources Vivantes) of IRD
- CNRS/INSU
- GIS Climat-Environnement-Societe through the PASTEK
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In northern Laos, small agricultural catchments are under high pressure because of the past decades of land management policies. Although the land degradation is well documented, no clear relationships have been established between land use and event scale runoff and erosion. In this study, we use a simple yet realistic model to obtain a per land use characterisation of small plot runoff production at the event scale. Runoff produced during 7 years (2003-2009) from 1 m(2) plots under different land uses is analyzed with the spatially variable infiltration (SVI) model. This model has been recently used by different authors to study infiltration at the plot scale under monsoon climate. It depends on rainfall intensity and a parameter to be calibrated that we called infiltrability. This parameter is an average infiltration rate during a rainfall event for given soil characteristics and a given land use. The analysis and calibration of runoff production with the SVI model led to a data set of almost 3000 infiltrability values. The statistical analysis of this data set with soil parameters, like surface features and slope, land use and the antecedent precipitation index (API), which is an indicator of soil moisture content, shows that infiltrability is strongly correlated with the percentage of crust and land use type. Except for certain land use like rice, the correlation with API is not well established and it is clear that minima of infiltration are reached in the rainy season after a close sequence of rainfall events and infiltrability is generally highest at the end of the dry season. Since we could not establish clear relationships between infiltrability, soil and meteorological parameters, we propose to consider infiltrability as a random function in space and time described, for each land use, by a log normal probability density function. (C) 2012 Elsevier B.V. All rights reserved.
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