Assessing the Performance of Thermal Inertia and Hydrus Models to Estimate Surface Soil Water Content

Abstract

Abstract:The knowledge of soil water content (SWC) dynamics in the upper soil layer is important for several hydrological processes. Due to the difficulty of assessing the spatial and temporal SWC dynamics in the field, some model-based approaches have been proposed during the last decade. The main objective of this work was to assess the performance of two approaches to estimate SWC in the upper soil layer under field conditions: the physically-based thermal inertia and the Hydrus model. Their validity was firstly assessed under controlled laboratory conditions. Thermal inertia was firstly validated in laboratory conditions using the transient line heat source (TLHS) method. Then, it was applied in situ to analyze the dynamics of soil thermal properties under two extreme conditions of soil-water status (well-watered and air-dry), using proximity remote-sensed data. The model performance was assessed using sensor-based measurements of soil water content acquired through frequency (FDR) and time domain reflectometry (TDR). During the laboratory experiment, the Root Mean Square Error (RMSE) was 0.02 m 3 m −3 for the Hydrus model and 0.05 m 3 m −3 for the TLHS model approach. On the other hand, during the in situ experiment, the temporal variability of SWCs simulated by the Hydrus model and the corresponding values measured by the TDR method evidenced good agreement (RMSE ranging between 0.01 and 0.005 m 3 m −3 ). Similarly, the average of the SWCs derived from the thermal diffusion model was fairly close to those estimated by Hydrus (spatially averaged RMSE ranging between 0.03 and 0.02 m 3 m −3 ).

HYDRUS-1D Simulation of Soil Water Dynamics for Sweet Corn under Tropical Rainfed Condition

“…The average values of the goodness of fit indicators: R 2 , EF, and RMSE for depths of 20, 40, 60, and 80 cm were 0.72, 0.68, and 0.017, and 0.86, 0.73, and 0.014 for the first and second seasons, respectively. The goodness of fit indicators was within the range of values reported by different researchers [22,[30][31][32][33][34]. The statistical analysis shows that HYDRUS-1D captured the change in water content at all depths except at 140 cm depth.…”

“…As compared to other models, HYDRUS-1D has the flexibility of accommodating different boundary conditions and the capability to consider the root uptake of water and nutrient simultaneously. The model is capable of simulating soil water and solute dynamics under different management practices [13][14][15][16][17][18][19][20][21][22]. All these researchers validated HYDRUS-1D as a reliable tool for such investigations.…”

Effects of Saline and Deficit Irrigation on Soil-Plant Water Status and Potato Crop Yield under the Semiarid Climate of Tunisia

“…Based on the field observation, the lengths of crop development stages for potato crop were adapted from those proposed in Table 11 of FAO-56 manual for semiarid regions, whereas the values for single crop coefficient (Kc) and basal crop coefficient (Kcb) where assumed equal to those published in Tables 12 and 17 of the same manual [22]. On the other hand, evaporation coefficient (K e ) was estimated as differences between values of single crop coefficient, K c , and basal crop coefficient, K cb [23][24][25].…”

Water Status and Yield Response to Deficit Irrigation and Fertilization of Three Olive Oil Cultivars under the Semi-Arid Conditions of Tunisia

“…The applied dose per week varied during the olive tree phenological stages. The applied concentration was equal to 3.0 Kg/ha per week in the period from bud break to fruit set (weeks 1-14), 3.6 Kg/ha per week from the fruit set to pit hardening, when seeds become hard (weeks [15][16][17][18][19][20][21][22] and, finally, 2.9 Kg/ha per week from pit hardening to harvesting (weeks 22-32).…”