Uncertainty of Deardorff’s soil moisture model based on continuous TDR measurements for sandy loam soil

Abstract

Knowledge on soil moisture is indispensable for a range of hydrological models, since it exerts a considerable influence on runoff conditions. Proper tools are nowadays applied in order to gain in-sight into soil moisture status, especially of uppermost soil layers, which are prone to weather changes and land use practices. In order to establish relationships between meteorological conditions and topsoil moisture, a simple model would be required, characterized by low computational effort, simple structure and low number of identified and calibrated parameters. We demonstrated, that existing model for shallow soils, considering mass exchange between two layers ( the upper and the lower), as well as with the atmosphere and subsoil, worked well for sandy loam with deep ground water table in Warsaw conurbation. GLUE (Generalized Likelihood Uncertainty Estimation) linked with GSA (Global Sensitivity Analysis) provided for final determination of parameter values and model confidence ranges. Including the uncertainty in a model structure, caused that the median soil moisture solution of the GLUE was shifted from the one optimal in deterministic sense. From the point of view of practical model application, the main shortcoming were the underestimated water exchange rates between the lower soil layer (ranging from the depth of 0.1 to 0.2 m below ground level) and subsoil. General model quality was found to be satisfactory and promising for its utilization for establishing measures to regain retention in urbanized conditions.

Impact of Uncertainty of Floodplain Digital Terrain Model on 1D Hydrodynamic Flow Calculation

“…the expectation operator. With the noise e ∼ N(0, Σ) or e ∼ N 0, σ 2 (Equation (1)) the expected cross section elevations are the same as their nominal values:E[Z] =Ẑ.For nonlinear models Equation (2) does not necessarily hold true, this was demonstrated in a case of an uncertainty introduced to a flow model with roughness parameters[37,38,[55][56][57].…”

Ground Water Modelling for the Restoration of Carex Communities on a Sandy River Terrace

“…Materials observed in 20 soil borings of a depth up to 7 m, taken across the site, proved the presence of sandy deposits. Laboratory tests proved that they were very homogenous and contained from 88% to 94% sand fraction, from 0% to 3% loam, and 1% to 6% of silt, and the hydraulic conductivity derived from granular data reaching from 24 to 30 m/day [10,13]. Ground water levels were observed at six double-piezometer locations, with one tube screened to the depth of 2 m and the deeper one at 7.5 m below ground, finding no head difference between them.…”

“…The decision-making ought to be based on hydrological criteria that can be incorporated into modelling studies and enables one to compare different management scenarios. One of the biggest uncertainties in the restoration of wetland hydrology is the form of the criteria, and the environmental variables that can be easily attributed to target habitat quality-i.e., water levels or flooding frequency [6,10]. Since the relevance of criteria is still subject to discussion, we considered the adoption of threshold values of ground water levels for sandy soils on the basis of Polish experience, summarized by Szuniewicz [11] as: minimum allowable depth (upper limit): 0.35 m, mean depth: 0.40 m, and maximum allowable depth: 0.45 m. Those values are extensively used over the area of Poland, being justified by research on a wide range of soils.…”

“…Precipitation totals were achieved by linear interpolation over a wider area on the basis of the records from three stations: Warszawa (37 km), Siedlce (about 40 km), and Kozienice (about 37 km). However, only meteorological data from Kozienice were used to calculate potential evapotranspiration according to Penman-Monteith method [10], since that station largely reflects the conditions outside the city area. It should be stressed that those values are not fully representative for the Całowanie Peatland, and should also undergo calibration.…”

“…The achieved values (0.6-0.79) do not indicate good or very good quality, but rather suggest a satisfactory (or acceptable) one. according to Penman-Monteith method [10], since that station largely reflects the conditions outside the city area. It should be stressed that those values are not fully representative for the Całowanie Peatland, and should also undergo calibration.…”