Calculation of the steady flow of ground water in vertical cross sections.

Ernst, L.F.

doi:10.18174/njas.v4i1.17793

Cited by 25 publications

(9 citation statements)

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“…Lateral runoff occurs in saturated soil layers and at the surface, if infiltration capacity is exceeded. Additional drainage is calculated by the Ernst equation to account for rapid lateral drainage in steep terrain [ Ernst , ]. In the model, we assume that downslope lateral runoff will occur on the permafrost table.…”

Section: Data and Modelsmentioning

confidence: 99%

Modeled sensitivity of two alpine permafrost sites to RCM‐based climate scenarios

et al. 2013

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[1] Climate change as projected by contemporary general circulation models (GCMs) and regional climate models (RCMs) will have a great impact on high latitude and high mountain permafrost. A process-based one-dimensional permafrost model is used to evaluate the sensitivity of two characteristic alpine permafrost sites to changes in climate for a 110 year time period starting 1991 and ending 2100 using output time series of six different GCM-RCM model chains. Statistical analysis of the RCM climate variables and output of the impact model has been conducted to gain insight into the sensitivity of the active layer to changes in climatic conditions. Strong sensitivity to climate change was found for the active layer thickness (ALT) at Schilthorn, which increased by up to 100% before most of the models pointed to a degradation of the permafrost around the year 2020. The sensitivity of the ALT at the rock glacier site Murtèl is less pronounced; permafrost degradation is slower and sets in only around 2070. At both sites, the thermal evolution is linked to an increase in unfrozen water content within the permafrost body. Multiple linear regression analysis shows a strong model dependency of ALT on ice content and summer soil surface temperatures and to a less significant degree on snow cover timing and duration. The ALT at Schilthorn is influenced by the ALT of the preceding year, while at Murtèl, the ALT is influenced by the ALT of up to 15 preceding years.

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Section: Data and Modelsmentioning

confidence: 99%

Modeled sensitivity of two alpine permafrost sites to RCM‐based climate scenarios

et al. 2013

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“…The bottom boundary conditions can also be described through various options: groundwater level as a function of time, flux to/from the semi‐confined aquifer, flux to/from open surface drains, an exponential relationship between bottom flux and groundwater table or zero flux, free drainage or free outflow at the bottom of the profile. SWAP allows evaluation of the drainage system by using the equations of Hooghoudt () and Ernst (, ). Five‐field drainage situations are considered in SWAP.…”

Section: Methodsmentioning

confidence: 99%

Application of Soil–water–atmosphere–plant Model to Assess Performance of Subsurface Drainage System Under Semi‐arid Monsoon Climate

Verma

Gupta

Isaac

2013

Irrigation and Drainage

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The Soil–Water–Atmosphere–Plant (SWAP) model was evaluated for its capability to predict groundwater table behaviour under drained conditions for a semi‐arid monsoon climate in the state of Haryana (India). SWAP simulated and observed values ranging within absolute deviation of 0.17–0.18 m for groundwater table, 0.87–1.07 mm day‐1 for drainage discharge rate and 7.8–39.4 mm for cumulative drain discharge. The calibrated and validated model was used to predict excess water stress utilizing the SEW30 index, which is the sum of daily exceedances (cm) of the groundwater table depth above the depth of 30 cm below the soil surface for different spacing under varying rainfall situations. The maximum annual SEW30 of 5 years having all the combinations of rainfall was 297.0 cm day with drains spaced at 75 m, 92.7 cm day with drains spaced at 50 m and 15.1 cm day for drains spaced at 25 m. These results reveal that there would be no aeration problem with drains spaced at 25 m in all the years and in years with below normal rainfall in all of the test spacing. Long‐term simulations revealed that there is no residual effect of a year's rainfall pattern on the groundwater table during the next year under drained conditions. Copyright © 2013 John Wiley & Sons, Ltd.

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“…Such events are known to contribute significantly to phosphorus loadings into ditches and streams (van der Salm et al, 2012). The optimal spacing of these drains or ditches under steady state and transient conditions is one of the classical problems in agricultural hydrology (de Zeeuw & Hellinga, 1958;Ernst, 1956;Glover & Dumm, 1960;Hooghoudt, 1940;Kraijenhoff van de Leur, 1958). The role of the unsaturated zone is typically ignored in the solutions for spacing optimization.…”

Section: Introductionmentioning

confidence: 99%

Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields

Appels

Bogaart

Zee

2017

Water Resources Research

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In winter, saturation excess (SE) ponding is observed regularly in temperate lowland regions. Surface runoff dynamics are controlled by small topographical features that are unaccounted for in hydrological models. To better understand storage and routing effects of small‐scale topography and their interaction with shallow groundwater under SE conditions, we developed a model of reduced complexity to investigate SE runoff generation, emphasizing feedbacks between shallow groundwater dynamics and mesotopography. The dynamic specific yield affected unsaturated zone water storage, causing rapid switches between negative and positive head and a flatter groundwater mound than predicted by analytical agrohydrological models. Accordingly, saturated areas were larger and local groundwater fluxes smaller than predicted, leading to surface runoff generation. Mesotopographic features routed water over larger distances, providing a feedback mechanism that amplified changes to the shape of the groundwater mound. This in turn enhanced runoff generation, but whether it also resulted in runoff events depended on the geometry and location of the depressions. Whereas conditions favorable to runoff generation may abound during winter, these feedbacks profoundly reduce the predictability of SE runoff: statistically identical rainfall series may result in completely different runoff generation. The model results indicate that waterlogged areas in any given rainfall event are larger than those predicted by current analytical groundwater models used for drainage design. This change in the groundwater mound extent has implications for crop growth and damage assessments.

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Calculation of the steady flow of ground water in vertical cross sections.

Cited by 25 publications

References 0 publications

Modeled sensitivity of two alpine permafrost sites to RCM‐based climate scenarios

Modeled sensitivity of two alpine permafrost sites to RCM‐based climate scenarios

Application of Soil–water–atmosphere–plant Model to Assess Performance of Subsurface Drainage System Under Semi‐arid Monsoon Climate

Feedbacks Between Shallow Groundwater Dynamics and Surface Topography on Runoff Generation in Flat Fields

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