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Použití programu Rosetta k odhadu retenčních čar půdní vlhkosti z experimentální plochy Bohaté Málkovice / Using program Rosetta to estimate of soil moisture retention curves from experimental size Bohaté MálkoviceČermák, Petr January 2015 (has links)
Hydraulic characteristics are the most important properties of soil, i.e. retention curve of soil moisture and hydraulic conductivity. Hydraulic conductivity of soil characterizes the ability of the soil to conduct water. Retention curve expresses the relationship between moisture and moisture potential of soil. The running of retention curve is influenced by many factors, eg. grain size and mineralogical composition, content of humus, reduce bulk density and structure of soil. Measurement of retention curves takes a lot of time and money in laboratory conditions therefore pedotransfer functions seem to be an alternative solution. The thesis aims to estimate moisture retention curves of soil in a selected area of interest in South Moravia using program Rosetta (Schaap, 2003). Data of granularity (% content of clay, sand and dust), bulk density of soil and hydrolimits field water capacity and wilting point were used as predictors in individual models of program Rosetta. Data of grain were matched by FAO / USDA system. Retention curves of soil moisture were measured on a sand tank and overpressure devices. The measured retention curves were parameterized by RETC program. Estimated retention curves were graphically compared with measured to determine the quality of the estimate. The accuracy of the estimate was assessed by correlation coefficient R of determination coefficient R2 and standard error SMRE. Usability own derivatives pedotransfer functions is hard to say due to the size of the input data file. I would recommend further verification of data at the other localities in south Moravia.
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Funções de pedotransferência e estrutura de variabilidade espacial da retenção de água em solos de várzea do Rio Grande do Sul / Pedotransfer functions and spatial variability of water retention in lowland soils of Rio Grande do Sul stateNebel, Álvaro Luiz Carvalho 24 April 2009 (has links)
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Previous issue date: 2009-04-24 / The understanding of the dynamics of the water in the soil-plant-atmosphere system,
including the water availability to the crops, soil water infiltration, drainage and soil
solute movement, depends on the knowledge of the relation between the soil water
content and the matric potential, represented by the soil water retention curve
(SWRC). However, the establishment of SWRCs is laborious and time consuming,
besides being costly. A alternative is its estimate through statistical equations called
Pedotransfer Functions (PTFs). The aim of this study was to evaluate the ability of
some existing PTFs, in predicting the soil water retention and to capture its spatial
variability structure, using geostatistical tools, when applied in a lowland soil of the
south region of Brazil. For this, an experimental 10 x 10 m grid was established and
soil disturbed and undisturbed samples were collected in the 0-0.20 m soil depth,
totaling 100 experimental points. The following soil attributes were determined in
each point: soil texture, soil organic carbon, pH, cation exchange capacity, soil bulk
density, and the soil water retention curve. Eight developed PTFs for estimating
gravimetric soil water content, eight for estimating volumetric water content and five
for estimating the van Genuchten model parameters were evaluated using the
statistical measures mean error (ME), and the root mean square error (RMSE).
Results indicated that the Oliveira et al. (2002) PTF presented the best performance
for estimating the gravimetric soil water content at the tension of 33kPa, with mean
error (ME) value of 0.0136g.g-1, while for the gravimetric water content at tension of
1500kPa the Pidgeon (1972) FPT was the best, with ME value of -0,0054g.g-1.
Concerning to the potential of describing the spatial variability structure the Bell &
van Keulen (1995 and 1996) and of Urach (2007) PTFs presented the best
performance based on the results from the cross validation technique. For estimating
the soil water volumetric content at the tension of 10kPa the Tomasela et al. (2002)
was the best (ME of 0.019cm3.cm-3), while Rawls et al. (1982) and van den Berg et
al. (1997) PTFs were the best for estimating soil water content at the tension of
33kPa (ME of 0.001cm3.cm-3) and 1500kPa (ME of -0.008cm3.cm-3), respectively.
The range and sill geostatistical parameters for the tension of 33kPa were
reasonable estimated, while for the tension of 1500kPa they were underestimated by
the evaluated PTFs. The Parametric Pedotransfer Function constructed by
Vereecken et al.(1989) presented the lowest value of ME (0.0247cm3.cm-3), while the
Hodnett and Tomasella (2002) PTF presented the lowest value of RMSE (0.0367
cm3.cm-3). Both PTFs well described the experimental semivariograms of the soil
water content at the tensions of 10kPa and 33kPa, however their performance was
not good for the tension of 1500kPa. / Estudos que envolvem a dinâmica da água no sistema solo-planta-atmosfera tais
como disponibilidade de água no solo para as culturas, infiltração, drenagem e
movimento de solutos no solo necessitam do conhecimento da relação entre o
conteúdo de água no solo e o potencial matricial, representada pela curva de
retenção de água no solo. No entanto, sua execução é laboriosa, demanda
considerável tempo e custos. Uma alternativa é sua estimativa através de equações
estatísticas denominadas Funções de Pedotransferência (FPTs). O objetivo deste
estudo foi avaliar o desempenho de funções de pedotransferência em estimar a
retenção de água no solo e capturar a sua estrutura de variabilidade espacial,
usando ferramentas geoestatísticas, quando aplicadas em um solo de várzea da
região sul do Brasil. Para isto, uma malha experimental de 10m x 10m foi
estabelecido e amostras deformadas e indeformadas do solo foram coletadas
representativas da camada de 0 0,20m, totalizando 100 pontos amostrais. Os
seguintes atributos do solo foram determinados em cada ponto: textura, carbono
orgânico, pH, capacidade de troca de cátions, densidade do solo e a curva de
retenção de água no solo. Oito FPTs desenvolvidas para estimar o conteúdo
gravimétrico de água no solo, oito para estimar o conteúdo volumétrico e cinco para
estimar os parâmetros do modelo de van Genuchten foram avaliadas, usando as
medidas estatísticas erro médio (ME) e raiz quadrada do erro médio ao quadrado
(RMSE). Os resultados obtidos para a estimativa do conteúdo de água gravimétrico
mostram que a FPT de Oliveira et al. (2002) apresentou o melhor desempenho para
a tensão de 33kPa, com erro médio (ME) de 0,0136g.g-1, enquanto para a tensão de
1500kPa a FPT de Pidgeon (1972) foi melhor, com ME de -0,0054g.g-1. Com relação
ao potencial de descrever a estrutura de variabilidade espacial do conjunto de dados
medidos, as FPTs desenvolvidas por Bell & van Keulen (1995 e 1996) e Urach
(2007) foram as que apresentaram melhor desempenho baseado nos resultados da
validação cruzada. Para o conteúdo volumétrico de água retida no solo, os melhores
desempenhos foram obtidos pela FPT de Tomasela et al.(2003) para a tensão de
10kPa, Rawls et al. (1982) para 33kPa e van den Berg et al.(1997) para 1500kPa,
com ME iguais a 0,019cm3.cm-3, 0,001cm3.cm-3 e -0,008cm3.cm-3, respectivamente.
Os parâmetros da estrutura de dependência espacial, alcance e patamar, para a
tensão de 33kPa foram razoavelmente estimados, enquanto para a tensão de
1500kPa foram subestimados pelas FPTs avaliadas. A FPT paramétrica
desenvolvida por Vereecken et al. (1989) apresentou o menor valor de ME
(0,0247cm3.cm-3), enquanto a FPT de Hodnett e Tomasella (2002) apresentou o
menor valor de RMSE (0,0367 cm3.cm-3). Ambas FPTs descreveram bem os
semivariogramas experimentais do conteúdo de água retido no solo a 10kPa e
33kPa, entretanto para a tensão de 1500kPa nenhuma das FPTs testadas
apresentou bom desempenho.
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Stanovení hydraulických charakteristik půdy ve vybraném zájmovém území / Determination of hydraulic characteristics of soil in a selected areaSalač, Jan January 2018 (has links)
The diploma thesis is focused on issues of measurement and evaluation of hydraulic characteristics of soil. In the literary research, the definitions of hydraulic conductivity and retention curve of soil moisture, their measurements in laboratory and field conditions and the prediction of these characteristics by using of pedotransfer functions. In the practical part of the diploma thesis, an evaluation of the hydraulic conductivity of soil from the experimental areas near the village Bohaté Málkovice. Two-cylindrical and mini-disc infiltration meters were used for field measurements, and a constant-gradient permeameter was used in the laboratory. Physical and empirical equations were used to evaluate the hydraulic conductivity. The results were processed numerically, tabulated and then compared.
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Pedotransferové funkce pro odhad vlhkostních retenčních křivek středně těžkých půd jižní Moravy / Pedotransfer functions for estimation of moisture retention curves of medium-heavy soils of South MoraviaGavlasová, Iva January 2014 (has links)
The most important characteristics of each soil is its hydro-physical properties, which include retention curve. Retention curve expresses the relationship between humidity and pressure head. It is course affected by many factors such as grain size and mineralogical composition, humus content, structure and bulk density of dry soil. This thesis deals with direct and indirect determination of one of the basic hydraulic characteristics of the soil, soil moisture retention curve. For laboratory determination of moisture retention curves were used for sand tank and pressure instruments. Measured body retention curves were optimized RETC program.For indirect determination of retention curves were used Pedotransfer function by Wösten et . al .(1998 ) , derived from the European soils and under HYPRES Šútora and Štekauerová (2000). As in the project Wösten et al . (1998), PTF were processed for arable land in the area. The accuracy of both models PTF was assessed by the correlation coefficient R and standard error RMSE. Simple models PTF provide estimates of retention curves with sufficient accuracy for practical use in the locality.
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