Soil measurements during HAPEX-Sahel intensive observation period

This article describes measurements made at each site and for each vegetation cover as part of the soils program for the HAPEX-Sahel regional scale experiment. The measurements were based on an initial sampling scheme and included profile soil water content, surface soil water content, soil water potential, infiltration rates, additional measurements on core samples, and grain size analysis. The measurements were used to categorize the state of the surface and profile soil water regimes during the experiment and to derive functional relationships for the soil water characteristic curve, unsaturated hydraulic conductivity function, and infiltration function. Sample results for different supersites and different vegetation covers are presented showing soil water profiles and total soil water storage on days corresponding to the experimental ‘Golden Days’. Sample results are also presented for spatial and temporal distribution of surface moisture content and infiltration tests. The results demonstrate that the major experimental objective of monitoring the supersites during the most rapid vegetative growth stage with the largest change of the surface energy balance following the rainy season was very nearly achieved. Separation of the effects of probable root activity and drainage of the soil profile is possible. The potential for localized advection between the bare soil and vegetation strips of the tiger bush sites is demonstrated

[1]  J.-P. Goutorbe,et al.  HAPEX-Sahel: a large-scale study of land-atmosphere interactions in the semi-arid tropics , 1994 .

[2]  R. Schulin,et al.  Calibration of time domain reflectometry for water content measurement using a composite dielectric approach , 1990 .

[3]  G. Vachaud,et al.  Temporal Stability of Spatially Measured Soil Water Probability Density Function , 1985 .

[4]  C. Valentin,et al.  Morphology, genesis and classification of surface crusts in loamy and sandy soils , 1992 .

[5]  Thomas J. Schmugge,et al.  Land surface evaporation : measurement and parameterization , 1991 .

[6]  Bilan hydrique dans le Sud-Tunisien: II. Modélisation numérique et prévision des transferts hydriques en sol stratifié , 1981 .

[7]  Thomas J. Schmugge,et al.  Pushbroom microwave radiometer results from HAPEX-MOBILHY , 1993 .

[8]  N. Jarvis,et al.  The use of tension infiltrometers to assess routes and rates of infiltration in a clay soil , 1987 .

[9]  D. Elrick,et al.  IN SITU MEASUREMENT OF FIELD‐SATURATED HYDRAULIC CONDUCTIVITY, SORPTIVITY, AND THE α‐PARAMETER USING THE GUELPH PERMEAMETER , 1985 .

[10]  K. Jon Ranson,et al.  The Boreal Ecosystem-Atmosphere Study (BOREAS) : an overview and early results from the 1994 field year , 1995 .

[11]  Willem Bouten,et al.  A Computer-Controlled 36-Channel Time Domain Reflectometry System for Monitoring Soil Water Contents , 1990 .

[12]  Brent Clothier,et al.  Field measurement of the hydraulic properties of soil , 1991 .

[13]  T. J. Dean,et al.  SOIL MOISTURE MEASUREMENT BY AN IMPROVED CAPACITANCE TECHNIQUE, PART I. SENSOR DESIGN AND PERFORMANCE , 1987 .

[14]  Thomas J. Schmugge,et al.  Remote Sensing Observations for the Monitoring of Land-Surface Fluxes and Water Budgets , 1991 .

[15]  P. Nye,et al.  Predicting the rate of dissolution of lime in soil , 1987 .

[16]  Alain Casenave,et al.  Les états de surface de la zone sahélienne : influence sur l'infiltration , 1989 .

[17]  H. DeBruin,et al.  EFEDA - European field experiment in a desertification-threatened area , 1993 .

[18]  C. Carré,et al.  The measurement of thermal neutron constants of the soil; application to the calibration of neutron moisture gauges and to the pedological study of soil , 1975 .

[19]  A. P. Annan,et al.  Electromagnetic determination of soil water content: Measurements in coaxial transmission lines , 1980 .

[20]  R. Haverkamp,et al.  Error analysis in estimating soil water balance of irrigated fields during the EFEDA experiment: 1. Local standpoint , 1994 .

[21]  Daniel Hillel,et al.  Introduction to soil physics , 1982 .

[22]  J. W. Biggar,et al.  Scaling of field-measured soil-water properties: I. Methodology , 1979 .

[23]  Piers J. Sellers,et al.  The first International Satellite Land Surface Climatology Project (ISLSCP) Field Experiment - FIFE , 1992 .

[24]  J. Bouma,et al.  Measurement of surface redistribution of rainfall and modelling its effect on water balance calculations for a millet field on sandy soil in Niger , 1997 .

[25]  Richard H. Cuenca,et al.  Hydrologic Balance Model Using Neutron Probe Data , 1988 .

[26]  David E. Elrick,et al.  Scaling in soil physics : principles and applications , 1990 .

[27]  Jan W. Hopmans,et al.  Stochastic analysis of soil water regime in a watershed , 1989 .

[28]  J. Taupin,et al.  EPSAT-Niger : campagne 1992 , 1991 .

[29]  Randel Haverkamp,et al.  ERROR ANALYSIS IN ESTIMATING SOIL WATER CONTENT FROM NEUTRON PROBE MEASUREMENTS: 1. LOCAL STANDPOINT , 1984 .

[30]  T. J. Dean,et al.  Measurement of near surface soil water content using a capacitance probe , 1993 .

[31]  Yunheng Ji.  MORPHOLOGY , 1937, A Grammar of Italian Sign Language (LIS).

[32]  D. R. Nielsen,et al.  Spatial variability of field-measured soil-water properties , 1973 .

[33]  Keith A. Smith,et al.  Soil analysis: physical methods. , 1991 .

[34]  Patrick Bertuzzi,et al.  CALIBRATION, FIELD‐TESTING, AND ERROR ANALYSIS OF A GAMMA‐RAY PROBE FOR IN SITU MEASUREMENT OF DRY BULK DENSITY , 1987 .

[35]  D. Grant.  MEASUREMENT OF SOIL MOISTURE NEAR THE SURFACE USING A NEUTRON MOISTURE METER , 1975 .

[36]  D. Elrick,et al.  Determination of Hydraulic Conductivity Using a Tension Infiltrometer , 1991 .

[37]  Application of scaling to the characterization of spatial variability in soils. , 1990 .

[38]  D. R. Nielsen,et al.  Simultaneous scaling of soil water retention and hydraulic conductivity curves , 1992 .

[39]  Mushtaque Ahmed,et al.  Simple field method for determining unsaturated hydraulic conductivity , 1991 .

[40]  Error associated with measurement of soil moisture change by neutron probe , 1979 .

[41]  T. Lebel,et al.  Estimating hydraulic conductivity of crusted soils using disc infiltrometers and minitensiometers , 1997 .

[42]  Pierre Bessemoulin,et al.  Evaporation over land surfaces - First results from HAPEX-MOBILHY Special Observing Period , 1988 .

[43]  I. White,et al.  Designs for disc permeameters , 1988 .

[44]  Richard H. Cuenca,et al.  Use of Soil Moisture Measurements in Hydrologic Balance Studies , 1991 .

[45]  Richard H. Cuenca,et al.  Irrigation System Design: An Engineering Approach , 1989 .