Hydrologic indices for nontidal wetlands

Lent, Robert M.; Weiskel, Peter K.; Lyford, Forest P.; Armstrong, David

doi:10.1007/bf03160715

Cited by 20 publications

(18 citation statements)

References 18 publications

(12 reference statements)

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“…For example, Lent et al (1997) summarize water budgets for 19 well-characterized wetlands that show a nearly complete continuum among sources of water. Wetlands resulting from water con L tributed by only precipitation and runoff would not be revealed by the model.…”

Section: Limitations Of the Methodsmentioning

confidence: 99%

Estimating the ground-water contribution in wetlands using modeling and digital terrain analysis

Gerla

1999

Wetlands

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Wetland classification and management often requires information on the contribution of ground water to a wetland's water budget. Direct estimation of this parameter, however, is time-consuming, expensive, and can typically only be accomplished for small areas. Thus, a method to characterize ground-water flow in wetland areas and regions may be useful in many applications. The estimation technique described combines the use of a digital elevation model (DEM) with transient numerical modeling and assumes that the water table reflects the general pattern of surface topography. The DEM grid elevations are used as initial heads in the model. Stepwise ground-water drainage from the flow domain is simulated until a reasonable match is obtained between the observed and model water tables. By knowing or assuming hydraulic conductivity and using the model water-table configuration, an estimate for ground-water flow to and from each discrctizcd grid node can be estimated from Darcy's Law and the Dupuit approximation. The net result, when mapped, shows the simulated distribution of recharge and discharge within and surrounding the wetland, Two examples from the Shingobee River headwaters in central Minnesota indicate how the method may be used. Geologically recent development of glacial landforms has led to numerous lakes, ponds, and wetlands in the region. Using a 30-m, 1:24,000 scale DEM grid in combination with data from the U.S. Fish and Wildlife National Wetlands Inventory, the model predicts the most likely areas of ground-water interaction in and near wetlands and lakes. More quantitative results can be obtained by applying observed water budget and soil/aquifer parameter data.

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Section: Limitations Of the Methodsmentioning

confidence: 99%

Estimating the ground-water contribution in wetlands using modeling and digital terrain analysis

Gerla

1999

Wetlands

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“…DOC fluxes summarized by Jordan et al (1983) were also reviewed in Taylor and Allanson (1995 Implications for pore-water flushing and wetland-estuary exchange-The flux of water governs the exchange of materials in and out of wetlands. Consequently, Lent et al (1997) suggested that the dominance of different components of water balances defines the degree of wetland interaction within the landscape. The Ringfield marsh was thus more hydrologically isolated within the landscape in the late summer (July and August) when precipitation and evapotranspiration were a greater proportion of the sediment water budget.…”

Section: Discussionmentioning

confidence: 99%

Quantifying groundwater discharge through fringing wetlands to estuaries: Seasonal variability, methods comparison, and implications for wetland‐estuary exchange

Tobias

Harvey

Anderson

2001

Limnology & Oceanography

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Because groundwater discharge along coastal shorelines is often concentrated in zones inhabited by fringing wetlands, accurately estimating discharge is essential for understanding its effect on the function and maintenance of these ecosystems. Most previous estimates of groundwater discharge to coastal wetlands have been temporally limited and have used only a single approach to estimate discharge. Furthermore, groundwater input has not been considered as a major mechanism controlling pore-water flushing. We estimated seasonally varying groundwater discharge into a fringing estuarine wetland using three independent methods (Darcy's Law, salt balance, and Br Ϫ tracer). Seasonal patterns of discharge predicted by both Darcy's Law and the salt balance yielded similar seasonal patterns with discharge maxima and minima in spring and early fall, respectively. They differed, however, in the estimated magnitude of discharge by two-to fourfold in spring and by 10-fold in fall. Darcy estimates of mean discharge ranged between Ϫ8.0 and 80 L m Ϫ2 d Ϫ1 , whereas the salt balance predicted groundwater discharge of 0.6 to 22 L m Ϫ2 d Ϫ1 . Results from the Br Ϫ tracer experiment estimated discharge at 16 L m Ϫ2 d Ϫ1 , or nearly equal to the salt balance estimate at that time. Based upon the tracer test, pore-water conductivity profiles, and error estimates for the Darcy and salt balance approaches, we concluded that the salt balance provided a more certain estimate of groundwater discharge at high flow (spring). In contrast, the Darcy method provided a more reliable estimate during low flow (fall). Groundwater flushing of pore water in the spring exported solutes to the estuary at rates similar to tidally driven surface exchange seen in previous studies. Based on pore-water turnover times, the groundwaterdriven flux of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and NH to the estuary was ϩ 4 11.9, 1.6, and 1.3 g C or g N m Ϫ2 wetland for the 90 d encompassing peak spring discharge. Groundwater-induced flushing of the wetland subsurface therefore represents an important mechanism by which narrow fringing marshes may seasonally relieve salt stress and export material to adjacent water masses.Identifying the hydrological factors affecting chemical fluxes within and through wetlands is critical to understanding wetland function and maintenance within the landscape. Intertidal wetlands have been suggested as transformers and potential regulators of nutrient fluxes with nearby coastal

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“…It quantifies what Brinson (1993a) presented as a ternary diagram showing the relative importance only of water inputs. Combining the proportions of both inputs and outputs, Lent et al (1997) derived 9 basic hydrologic types of wetlands. Interestingly, "types" based on vegetation (e.g., marshes, swamps, bogs, fens) did not all group together into single hydrologic "types.…”

Section: A Diversity Of Biological and Functional Templatesmentioning

confidence: 99%

“…These indices provide quantitative indications of the strength and type of water exchanges between a wetland and the larger ground-water and surface-water systems of which it is a part (Lent et al 1997). These indices quantify the hydrologic portion of what Brinson (1993a) presented as conceptual categories (e.g., donor, receptor, conveyor) for classifying wetlands according to exchanges of elements and sediments as these are affected by water exchanges.…”

Section: A Diversity Of Biological and Functional Templatesmentioning

confidence: 99%

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Cumulative effects on wetland landscapes: Links to wetland restoration in the United States and southern Canada

Bedford

1999

Wetlands

122

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The cumulative effects of human actions on wetland ecosystems motivate current efforts at wetland restoration. They also have created in part the context within which restorations are undertaken. Using modern hydrogeological understanding of wetland-landscape linkages, I argue that restorations should begin with a cumulative impact analysis for the entire region in which the restoration is proposed. The analysis, however, should not focus merely on number of hectares of wetlands lost or degraded. It should be based on the concept of templates for wetland development. These templates are the diversity of settings created in specific landscapes by the complex interactions of hydrogeologic factors and climate. They control key hydrologic variables and hydrologically influenced chemical variables that cause specific wetland types to form and to be maintained through time. They also determine in large part the biogeochemical cycling characteristics specific to different types of wetlands. They thus account for both the biological and functional diversity of wetlands. A cumulative impact assessment for restoration purposes should identify the kinds, numbers, relative abundances, and spatial distribution of wetland templates in a region--both past and present. These past and present profiles of the wetland landscape can be used to make decisions regarding the type and location of restorations. Matching type and location to the appropriate hydrogeologic setting will maximize the probability of success for individual projects. Regional wetland diversity can be restored if individual restoration decisions about wetland type and location are made in light of the diversity of templates in past and present regional profiles.

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Hydrologic indices for nontidal wetlands

Cited by 20 publications

References 18 publications

Estimating the ground-water contribution in wetlands using modeling and digital terrain analysis

Estimating the ground-water contribution in wetlands using modeling and digital terrain analysis

Quantifying groundwater discharge through fringing wetlands to estuaries: Seasonal variability, methods comparison, and implications for wetland‐estuary exchange

Cumulative effects on wetland landscapes: Links to wetland restoration in the United States and southern Canada

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