Effects of capillarity and microtopography on wetland specific yield

Sumner, David M.

doi:10.1672/0277-5212(2007)27[693:eocamo]2.0.co;2

Cited by 30 publications

(33 citation statements)

References 19 publications

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“…A specific yield increasing within the top 25 cm of the soil profile is in contrast to the VSC function shown in Figure 8 but could be caused by a cracked and heterogeneous peat surface at the site. Such an effect in similar soils has been observed by Bohne and Bohne (2007) or Summer (2007).…”

supporting

confidence: 85%

Evaluating the use of diurnal groundwater fluctuations for estimating evapotranspiration in wetland environments: case studies in southeast England and northeast Germany

et al. 2010

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Wetlands are characterized by frequent saturated conditions, dense vegetation growth and thus high evapotranspiration (ET) rates. Understanding wetland processes and water resource implications of wetland management and restoration requires estimates of ET rates. The analysis of diurnal groundwater fluctuations (DGFs) for estimating ET has been established for nearly 80 years, yet the method is not yet well utilized in practice due to inherent limitations. This paper assesses contemporary updates to the method to define a consistent tool and applies this to two contrasting riparian zones, in southeast England and northeast Germany. The method's accuracy is compared to reference ET evaluation methods and its utility for wetland hydrological management is assessed. Finally, practical guidance on how to apply the tool is provided, with a view to providing robust estimation of ET loss at wetland sites.

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supporting

confidence: 85%

Evaluating the use of diurnal groundwater fluctuations for estimating evapotranspiration in wetland environments: case studies in southeast England and northeast Germany

et al. 2010

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“…This conceptualization assumes that the effective specific yield of the ponds was unity. This is generally true where stages are well-above land surface (Sumner 2007), which was generally the case for these ponds throughout the period of record. Net groundwater inflow was computed on daily time steps to determine the net groundwater recharge from the ponds to the underlying aquifers during June-September.…”

Section: Physical Hydrologymentioning

confidence: 65%

Water Sources and Hydrodynamics of Closed-Basin Depressions, Cook Inlet Region, Alaska

Rains

2011

Wetlands

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Among the most prevalent wetland and deepwater habitats in Alaska are ponds, many of which are subarctic ponds occurring as moraine, ice-scour, or dead-ice depressions. Many are closed-basin depressions, where surface-water inflows and outflows are negligible. The objective of this study was to quantify the water sources and hydrodynamics of these subarctic ponds, particularly with respect to the role they play in groundwater recharge. There are two types of ponds on the study site. Perchedprecipitation ponds have inflows by melt water and direct precipitation, outflows by evapotranspiration and groundwater recharge, and are seasonally inundated because surface water is perched above the water table and infiltration through the low-permeability surficial deposits to the water table is slow. Flow-through ponds have inflows by melt water, direct precipitation, and groundwater discharge, outflows by evapotranspiration and groundwater recharge, and are perennially inundated because of groundwater throughflow. Both are groundwater recharge focal points. This is particularly true for perched-precipitation ponds, where net groundwater recharge rates were 215% larger than in flow-through ponds, and 332% larger than in the broader landscape. Most of the additional groundwater recharge occurs immediately following breakup, as aeoliantransported snow trapped in the depressions melts which results in enhanced groundwater recharge rates.

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“…The inefficiency may become a relevant problem when a high number of these calculations are required either for a spatially distributed model or during inverse parameter estimation. Secondly, although Sumner () presented a correct representation of a simultaneous consideration of nonlinear S y ,soil and microrelief effects, the study failed to illustrate and discuss the important implications on S y when water levels are below the soil surface. We believe that this is one reason that this approach has not been adopted in all subsequent publications on this topic.…”

Section: Introductionmentioning

confidence: 99%

One‐dimensional expression to calculate specific yield for shallow groundwater systems with microrelief

Dettmann¹,

Bechtold²

2015

Hydrol. Process.

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Although the importance to account for microrelief in the calculation of specific yields for shallow groundwater systems is well recognized, the microrelief influence is often treated very simplified, which can cause considerable errors. We provide a general onedimensional expression that correctly represents the effect of a microrelief on the total specific yield that is composed of the soil and surface specific yield. The one-dimensional expression can be applied for different soil hydraulic parameterizations and soil surface elevation frequency distributions. Applying different van Genuchten parameters and a simple linear microrelief model, we demonstrate that the specific yield is influenced by the microrelief not only when surface storage directly contributes to specific yield by (partial) inundation but also when water levels are lower than the minimum surface elevation. Compared with a simplified representation of the soil specific yield, in which a mean soil surface is assumed for the calculation of soil specific yield, the correct representation can lead to lower as well as higher soil specific yields depending on the specific interaction of the soil water retention characteristics and the microrelief. The new equation can be used to obtain more accurate evapotranspiration estimates from water level fluctuations and to account for the effect of microtopographic subgrid variability on simulated water levels of spatially distributed hydrological models.

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Effects of capillarity and microtopography on wetland specific yield

Cited by 30 publications

References 19 publications

Evaluating the use of diurnal groundwater fluctuations for estimating evapotranspiration in wetland environments: case studies in southeast England and northeast Germany

Evaluating the use of diurnal groundwater fluctuations for estimating evapotranspiration in wetland environments: case studies in southeast England and northeast Germany

Water Sources and Hydrodynamics of Closed-Basin Depressions, Cook Inlet Region, Alaska

One‐dimensional expression to calculate specific yield for shallow groundwater systems with microrelief

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