Ponded infiltration experiment is a simple test used for in-situ determination of soil hydraulic properties, particularly saturated hydraulic conductivity and sorptivity. It is known that infiltration process in natural soils is strongly affected by presence of macropores, soil layering, initial and experimental conditions etc. As a result, infiltration record encompasses a complex of mutually compensating effects that are difficult to separate from each other. Determination of sorptivity and saturated hydraulic conductivity from such infiltration data is complicated. In the present study we use numerical simulation to examine the impact of selected experimental conditions and soil profile properties on the ponded infiltration experiment results, specifically in terms of the hydraulic conductivity and sorptivity evaluation. The effect of following factors was considered: depth of ponding, ring insertion depth, initial soil water content, presence of preferential pathways, hydraulic conductivity anisotropy, soil layering, surface layer retention capacity and hydraulic conductivity, and presence of soil pipes or stones under the infiltration ring. Results were compared with a large database of infiltration curves measured at the experimental site Liz (Bohemian Forest, Czech Republic). Reasonably good agreement between simulated and observed infiltration curves was achieved by combining several of factors tested. Moreover, the ring insertion effect was recognized as one of the major causes of uncertainty in the determination of soil hydraulic parameters.
Global climate change is projected to continue and result in prolonged and more intense droughts, which can
increase soil water repellency (SWR). To be able to estimate the consequences of SWR on vadose zone hydrology, it is
important to determine soil hydraulic properties (SHP). Sequential modeling using HYDRUS (2D/3D) was performed on
an experimental field site with artificially imposed drought scenarios (moderately M and severely S stressed) and a control
plot. First, inverse modeling was performed for SHP estimation based on water and ethanol infiltration experimental data, followed by model validation on one selected irrigation event. Finally, hillslope modeling was performed to assess water balance for 2014. Results suggest that prolonged dry periods can increase soil water repellency. Inverse modeling was successfully performed for infiltrating liquids, water and ethanol, with R2 and model efficiency (E) values both > 0.9. SHP derived from the ethanol measurements showed large differences in van Genuchten-Mualem (VGM) parameters for the M and S plots compared to water infiltration experiments. SWR resulted in large saturated hydraulic conductivity (Ks) decrease on the M and S scenarios. After validation of SHP on water content measurements during a selected irrigation event, one year simulations (2014) showed that water repellency increases surface runoff in non-structured soils at hillslopes.
An accurate representation of reality in numerical variably-saturated flow models requires reliable estimates of necessary model parameters. Inverse modeling seeks to estimate parameters such as the saturated and residual water contents, the saturated hydraulic conductivity, the shape parameters of the soil hydraulic functions, using easily attainable observations of actual or cumulative water fluxes, pressure heads, water contents, and concentrations. The inverse procedure usually combines the nonlinear leastsquares-based (SSQ) parameter optimization method with a numerical solution of the variably-saturated flow and transport equations. The SSQ-based inverse method is however sensitive to outliers. A novel Squared ε-Insensitive Loss Function (SILF) approach is introduced in this study. The SILF approach is inspired by the ε-insensitive loss function proposed by Vapnik (1995). The objective function used in the SILF approach is similar to the least-squares objective function, except that it penalizes only for errors greater than a certain predefined acceptable error term ε. The SILF approach shows an improved performance over the SSQ approach in estimating the soil hydraulic parameters. Apart from providing robust estimates of the soil hydraulic parameters, the SILF approach also gives an approximation of the relative measurement error during sampling. and Presná reprezentácia skutočností v numerických modeloch prúdenia vo vodou nenasýtenej pôde vyžaduje spoľahlivé určenie potrebných parametrov modelu. Inverzným modelovaním sa snažíme o určenie takých parametrov, ako sú reziduálna vlhkosť pôdy, nasýtená hydraulická vodivosť, tvarové parametre hydraulických funkcií pôdy, využijúc ľahko realizovateľné pozorovania momentálnych alebo kumulatívnych tokov vody, tlakových výšok, vlhkostí pôdy a koncentrácií rozpustených látok. Inverzná procedúra obyčajne kombinuje nelineárnu optimalizáciu parametrov založenú na metóde najmenších štvorcov (SSQ) s numerickým riešením transportných rovníc vo vodou nenasýtenej pôde. Táto metóda (SSQ) je však citlivá na náhodné chyby. Nová, necitlivostná stratová funkcia s necitlivosťou ε(SILF), použitá v tejto štúdii, bola inšpirovaná návrhom publikovaným Vapnikom (1995). Optimalizovaná funkcia použitá v prístupe SILF je podobná tej, ktorá sa používa v metóde najmenších štvorcov s tou výnimkou, že táto penalizuje len chyby väčšie ako je určitá preddefinovaná akceptovateľná chyba ε. Pri určovaní hydraulických parametrov pôdy táto metóda SILF preukázala svoje prednosti pred prístupom SSQ. Okrem toho, že metóda SILF dáva robustné odhady hydraulických parametrov pôdy, umožňuje tiež aproximáciu relatívnych chýb merania počas odberu vzoriek.
This paper investigates the impact of surface soil moisture assimilation on the estimation of both parameters and states in the Soil and Water Assessment Tool (SWAT) model using the ensemble Kalman filter (EnKF) method in upper Huai River basin. The investigation is carried out through a series of synthetic experiments and real world tests using a merged soil moisture product (ESA CCI SM) developed by the European Space Agency, and considers both the joint state-parameter updating and only state updating schemes. The synthetic experiments show that with joint stateparameter update, the estimation of model parameter SOL_AWC (the available soil water capacity) and model states (the soil moisture in different depths) can be significantly improved by assimilating the surface soil moisture. Meanwhile, the runoff modeling for the whole catchment is also improved. With only state update, the improvement on runoff modeling shows less significance and robustness. Consistent with the synthetic experiments, the assimilation of the ESA CCI SM with joint state-parameter update shows considerable capability in the estimation of SOL_AWC. Both the joint stateparameter update and the only state update scheme could improve the streamflow modeling although the optimal model and observation error parameters for them are quite different. However, due to the high vegetation coverage of the study basin, and the strong spatial mismatch between the satellite and the model simulated soil moisture, it is still challenging to significantly benefit the runoff estimates by assimilating the ESA CCI SM.
Land use change is a phenomenon appearing in many part of world, not only in a local scale, but also at global level. This phenomenon can be resulting from climatic variation or from human activities on the land surface. It is rightfully assumed that the vegetation cover has a key impact on the rainfall-runoff process. For instance induced deforestation may cause disastrous flood; (after the flood in the Odra River and the Morava River basin in 1997 this phenomenon has been frequently disscussed). Among the appropriate tools to study the rainfall-runoff process changes are hydrological models. In the present work, three lumped conceptual models have been used, each emphasizing more or less processes which contribute to the water cycle on the landscape and in deeper zones. The model SAC-SMA, the BROOK´90 and the TOP-model have been used for the investigation in the hilly basin of Vltava River at Lenora. A daily time step has been used for all the models. Although the models have different structures, their results indicate similar tendency in runoff differences. and Změny ve využívání krajiny jsou procesem, objevujícím se v různých místech na Zemi, nejen na lokální úrovni, ale i v globálním měřítku. Proměnlivost odtoku je jednak důsledkem klimatické variability a jednak lidské činnosti v povodí. Všeobecně je uznáván klíčový význam vegetační pokrývky pro vývoj srážko-odtokového procesu. Zejména nucené odlesňování může způsobovat ničivé povodně; to bylo námětem častých diskusí i o povodni na Moravě a Odře v roce 1997. Mezi vhodné nástroje pro zkoumání jeho různých aspektů lze bezpochyby zařadit hydrologické modely. V předkládané práci byly pro daný účel užity tři různé modely srážko-odtokového procesu, zvýrazňující více či méně různé části hydrologického cyklu na povrchu území, či v podpovrchových zónách. V experimentech pro horskou část povodí Vltavy po Lenoru byly pro hodnocení odtokových změn užity modely SAC-SMA, BROOK´90 a TOPmodel. Pro simulace byly k dispozici denní časové řady srážek, odtoků a teplot vzduchu z období 40 roků. I když struktura užitých modelů je odlišná, výsledky indikují jasné a podobné tendence ve změnách odtokových diferencí.
Investigations indicate that correct estimation of seasonal thermal stratification in a dam reservoir is very important for the dam reservoir water quality modeling and water management problems. The main aim of this study is to develop a hydrodynamics model of an actual dam reservoir in three dimensions for simulating a real dam reservoir flows for different seasons. The model is developed using nonlinear and unsteady continuity, momentum, energy and k-ε turbulence model equations. In order to include the Coriolis force effect on the flow in a dam reservoir, Coriolis force parameter is also added the model equations. Those equations are constructed using actual dimensions, shape, boundary and initial conditions of the dam and reservoir. Temperature profiles and flow visualizations are used to evaluate flow conditions in the reservoir. Reservoir flow’s process and parameters are determined all over the reservoir. The mathematical model developed is capable of simulating the flow and thermal characteristics of the reservoir system for seasonal heat exchanges. Model simulations results obtained are compared with field measurements obtained from gauging stations for flows in different seasons. The results show a good agreement with the field measurements.
Editors of several journals in the field of hydrology met during the General Assembly of the European Geosciences Union–EGU in Vienna in April 2017. This event was a follow-up of similar meetings held in 2013 and 2015. These meetings enable the group of editors to review the current status of the journals and the publication process, and to share thoughts on future strategies. Journals were represented at the 2017 meeting by their editors, as shown in the list of authors. The main points on invigorating hydrological research through journal publications are communicated in this joint editorial published in the above journals.
John McDowell argues that ethical behavior cannot be grounded in an external set of normative rules. Instead, he proposes to ground ethical behavior in being a virtuous person. A fully virtuous person is able to identify unambiguously any moral fact she is confronted with. McDowell’s strategy seems to be, prima facie, an attractive one as it escapes some of the most serious problems that beset normative ethics. The concept of a virtuous person runs, however, into its own difficulties. It does not seem to be easily compatible with what we know about human psychology, namely about the normal perception and cognition. The aim of the paper is to expose the core of the incompatibility., John McDowell tvrdí, že etické chování nemůže být založeno na externím souboru normativních pravidel. Místo toho navrhuje, aby etické chování bylo uznáno za ctnostného člověka. Plně ctnostná osoba je schopna jednoznačně identifikovat jakýkoli morální fakt, se kterým je konfrontována. McDowellova strategie se zdá být na první pohled atraktivní, protože uniká některým z nejzávažnějších problémů, které sužují normativní etiku. Koncept ctnostného člověka však běží do vlastních potíží. Nezdá se, že by bylo snadno kompatibilní s tím, co víme o lidské psychologii, konkrétně o normálním vnímání a poznání. Cílem příspěvku je odhalit jádro neslučitelnosti., and Ivo Dragoun