Wetland Water Budgets Research Articles

Plant transpiration in constructed treatment wetland: Effects on water budget and management consequences

Plant transpiration is an important feature of wetlands with biological and hydraulic impacts. The global objective of this study was to question the influence of transpirational water losses on constructed treatment wetland water budget for a variety of wetland design and time of the year. Biomass and transpiration field measurements were carried out in constructed treatment wetlands (CTWs) submitted to oceanic climate and used for waste- or stormwater management. Measurements were carried out during spring, summer and fall. Biomass and transpiration rate were both significantly affected by season and site configuration, although the effect appears more sharply for season than for site. Transpiration can reach 26% of the incoming flow during the warmest part of the year for wastewater management CTW, when the effect on adjacent water courses is likely to be the most significant. The impact on multi-monthly water budget plummets to 2% of the incoming water volume. For stormwater CTW, transpiration can lead to strong water scarcity, virtually emptying all available water in these stochastically fed systems. As transpiration also plays a significant role in biogeochemical processes in wetlands, it seems important to design this type of ecological infrastructure in close relation with the pursued objectives, be it either the quality of outlet water (emphasis on treatment efficiency) or the quantity of outlet water (emphasis on flow regulation).

Small gradients in salinity have large effects on stand water use in freshwater wetland forests

Salinity intrusion is responsible for changes to freshwater wetland watersheds globally, but little is known about how wetland water budgets might be influenced by small increments in salinity. We studied a forested wetland in South Carolina, USA, and installed sap flow probes on 72 trees/shrubs along a salinity gradient. Species investigated included the trees baldcypress (Taxodium distichum [L.] Rich.), water tupelo (Nyssa aquatica L.), swamp tupelo (Nyssa biflora Walt.), and the shrub waxmyrtle (Morella cerifera (L.) Small). This study improves upon past reliance on greenhouse seedling studies by adding measurements of trees/shrubs along a salinity gradient, and better describes the role of low salinity on water use in freshwater wetland forests. We measured patterns of water use related to salinity, atmospheric conditions and season, and hypothesized that salinity would influence wetland forest water use through two mechanisms: salinity disturbances would yield stands with species and size classes that transpire less and individual trees with less conductive xylem tissue (i.e., sapwood). Both hypotheses held. At salinity concentrations ranging from fresh to 3 psu, forest structural changes alone resulted in stand water use reductions from 494 mm year-1 in freshwater stands to 316 mm year-1 in stands of slightly higher salinity. Tree sapwood function (inferred from radial sap flux profiles) also changed along this gradient and reduced sap flow rates by an additional 13.3% per unit increase in salinity (psu). Thus, stand water use was further reduced to 190 mm year-1 on saline sites. We found that forest structure is not the only change that affects water use in salinized watersheds; individual tree eco-physiological responses to salinity, manifesting in different radial sap flow profiles, are important as well.

Synergistic Interaction of Climate and Land-Use Drivers Alter the Function of North American, Prairie-Pothole Wetlands

Prairie-pothole wetlands provide the critical habitat necessary for supporting North American migratory waterfowl populations. However, climate and land-use change threaten the sustainability of these wetland ecosystems. Very few experiments and analyses have been designed to investigate the relative impacts of climate and land-use change drivers, as well as the antagonistic or synergistic interactions among these drivers on ecosystem processes. Prairie-pothole wetland water budgets are highly dependent on atmospheric inputs and especially surface runoff, which makes them especially susceptible to changes in climate and land use. Here, we present the history of prairie-pothole climate and land-use change research and address the following research questions: 1) What are the relative effects of climate and land-use change on the sustainability of prairie-pothole wetlands? and 2) Do the effects of climate and land-use change interact differently under different climatic conditions? To address these research questions, we modeled 25 wetland basins (1949–2018) and measured the response of the lowest wetland in the watershed to wetland drainage and climate variability. We found that during an extremely wet period (1993–2000) wetland drainage decreased the time at which the lowest wetland reached its spill point by four years, resulting in 10 times the amount of water spilling out of the watershed towards local stream networks. By quantifying the relative effects of both climate and land-use drivers on wetland ecosystems our findings can help managers cope with uncertainties about flooding risks and provide insight into how to manage wetlands to restore functionality.

Wetbud – A Free Water Budget Modeling Tool for Created Wetland Design

A common result of Environmental Impact Assessments associated with mining projects is the construction of new wetlands in areas disturbed by mining operations. Where appropriate, this mitigation may be considered an integral part of the mine reclamation process under the principles of sustainable development in the minerals industry. Wetbud is a new tool for estimating wetland water budgets using available weather data and site-specific topographic, soil and geohydrologic data, coupled with mass balance mathematics. Wetbud is primarily intended as a planning tool for use in the design of created wetlands, but it can also be applied to native wetlands or wetland restoration sites where the required input parameters can be specified. Wetbud can be run in its basic form where wetland topography, soil parameters and groundwater flux are simplified, or in the advanced form, where these parameters are included in a more complex approach via integration of the MODFLOW package, a free 3D program that was developed by the United States Geological Survey. Both versions can also include overbank flow hydrology sources and the advanced form can also model sloping and irregular topography. The program downloads weather data from the nearest applicable station and selects appropriate wet-normal-dry (W-N-D) years following a modest user data clean-up step. Wetbud also has the ability to utilize existing short-term (e.g. 6 to 9 months) groundwater data from an up-gradient well to simulate longer-term groundwater level inputs for the selected W-N-D years. In addition, Wetbud features a “Wizard” version that comes pre-loaded with 14 pre-selected weather data sets for all areas of Virginia that can develop a simple monthly water budget in less than 15 minutes – a feature that could be expanded anywhere geographically with historic weather data.

Evapotranspiration Partitioning and Response to Abnormally Low Water Levels in a Floodplain Wetland in China

Evapotranspiration (ET) is an important component of the wetland water budget. Water level declines in Poyang Lake, the largest freshwater lake in China, have caused concerns, especially during low water levels. However, how wetland ET and its partitioning respond to abnormally low water levels is unclear. In this study, wetland ET was estimated with MODIS data and meteorological data. The wetland ET partitioning and its relationship with abnormally low water levels were analyzed for 2000–2013. The results showed that the water evaporation rate (Ewater) was larger than the land ET rate (ETland); theETland/Ewaterranged from 0.77 to 0.99. When the water level was below 12.8 m, the ET partition ratio was larger than 1, which indicates that wetland ET comes from land surface ET more than water evaporation. The negative standardized water level index (SWI) was used to represent an abnormally low water level in the wetland. Although the monthly wetland ET decreased as the negative SWI decreased,ETlandwas higher than the average under negative SWI conditions from September to December, when the water level decreased. The abnormally low water level induced more water loss from the land surface, especially when the water level decreased, which reduced the available water resources along the wetland shore.

Impacts of climate change on land-use and wetland productivity in the Prairie Pothole Region of North America

Wetland productivity in the Prairie Pothole Region (PPR) of North America is closely linked to climate. A warmer and drier climate, as predicted, will negatively affect the productivity of PPR wetlands and the services they provide. The effect of climate change on wetland productivity, however, will not only depend on natural processes (e.g., evapotranspiration), but also on human responses. Agricultural land use, the predominant use in the PPR, is unlikely to remain static as climate change affects crop yields and prices. Land use in uplands surrounding wetlands will further affect wetland water budgets and hence wetland productivity. The net impact of climate change on wetland productivity will therefore depend on both the direct effects of climate change on wetlands and the indirect effects on upland land use. We examine the effect of climate change and land-use response on semipermanent wetland productivity by combining an economic model of agricultural land-use change with an ecological model of wetland dynamics. Our results suggest that the climate change scenarios evaluated are likely to have profound effects on land use in the North and South Dakota PPR, with wheat displacing other crops and pasture. The combined pressure of land-use and climate change significantly reduces wetland productivity. In a climate scenario with a +4 °C increase in temperature, our model predicts that almost the entire region may lack the wetland productivity necessary to support wetland-dependent species.

基于水文平衡的湿地退化驱动因子定量研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于水文平衡的湿地退化驱动因子定量研究 DOI: 10.5846/stxb201305291219 作者: 作者单位: 环境保护部卫星环境应用中心 国家环境保护卫星遥感重点实验室,环境保护部卫星环境应用中心 国家环境保护卫星遥感重点实验室,北京师范大学 民政部/教育部应急与减灾研究院,北京师范大学资源学院,北京师范大学 民政部/教育部应急与减灾研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项资助项目（201204201）；国家自然科学基金资助项目（40801138） Quantitative analysis of driving factors for wetland degradation based on hydrology balance Author: Affiliation: State Environmental Protection Key Laboratory of Satellite Remote Sensing,Satellite Environment Center,MEP Beijing,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:作为地球上最为重要的生态系统类型之一，湿地与森林、海洋并称为地球三大生态系统。但是，近年来湿地生态系统退化速度远大于其他类型生态系统，开展湿地退化的定量评估分析研究对于湿地生态系统的保护和恢复具有重要意义。选择北京城市湿地为研究对象，利用卫星遥感数据分别提取得到1991年和2007年的湿地面积，基于湿地水量平衡理论和湿地水文方程方法，定量评估分析了导致湿地退化的原因和不同驱动因子的贡献率。结果表明：（1）与1991年相比，2007年北京湿地减少约6275.31 hm2，约占1991年北京湿地总面积的24.46%。显著退化区域主要发生在野鸭湖湿地和密云水库湿地，分别减少了约1377.69 hm2和4654.50 hm2。（2）引起湿地退化的自然驱动因子中，以降水减少、入境地表水减少和蒸发量增加为主，驱动湿地退化的贡献率分别为39.22%、14.05%和11.85%。引起湿地退化的人为驱动因子中，以城市扩展为主，驱动湿地退化的贡献率为3.42%，而技术进步所采取的节水措施等有利于湿地保护，贡献率为25.55%。 Abstract:Wetlands are among the most important ecosystems on Earth, which provide plenty of ecological services, and supporting the sustained development of the human being. However, with the development of our society and the change of natural conditions, lots of wetlands is degrading and disappearing. According to the conclusion from Millennium Ecosystem Assessment, the degradation speed of wetlands is faster than any other ecosystems. In order to protect wetlands, it is very important to monitoring degradation of wetland and analysis the driving factors resulting in degrading, then recognize the contribution of these factors by turns. Firstly, extracting exactly wetlands from satellite images is the key in this paper. In the hill region, with the help of spatial analyses function in geographical information system software and DEM simulation method, the simulated images of hill shade is gained according to the solar radiation conditions of remote sensing image, then the mixture of hill shade and wetlands in satellite images can be recognized, and influence of hill shade on wetland can be removed successfully. In the flat urban region, because there is the similar digital number scope of old residential areas and wetlands in urban region, the digital number is replaced with surface reflectance to extract urban wetland information, and old residential area influences on the wetland is wiped off. Urban wetland is exactly extracted with normalized difference water index and its change is accurately detected with Landsat TM images acquired at 1991 and 2007. According to the wetland water budget theory, taking hydrology factors in wetland water budget equation as the main index, together with the society, hydrology and meteorology statistic data, this research quantitatively analyzes the contribution of natural and human driving factors to wetland change. Natural factors are the main reasons for wetland change, the decrease of precipitation, surface water inflows and the increase of evaporation are negative contribution to wetland maintenance, about 39.22%, 14.05% and 11.85% respectively, the decrease of surface water outflows is positive contribution, about 12.75%. To the human factors, urban sprawl is negative contribution, about 3.42%, however, technology progress is positive contribution, about 25.55%, and helpful to protect wetland and reduce the negative contribution of urban sprawl. 参考文献 相似文献 引证文献

Modeling water management scenarios for the Cienega de Santa Clara, an anthropogenic coastal desert wetland system, based on inflow volumes and salinities

The Cienega de Santa Clara in the Colorado River Delta, Mexico is a self-designed wetland system fed since 1977 by brackish groundwater diverted from the U.S. to Mexico. The vegetated upper portion of the Cienega provides habitat for endangered Yuma-Clappers rails and other marsh birds and fulfills other ecological functions. Outflow water pools in the Santa Clara Slough south of the Cienega and provides habitat for migratory shorebirds. Conditions in the Cienega and Santa Clara Slough could be altered by operation of the Yuma Desalting Plant (YDP), which will divert water from the Cienega and replace it with brine water resulting from the desalting process. Our objective was to integrate water budget components into models predicting the extent of the dominant vegetation (southern cattail, Typha domingensis Pers.) in the marsh and the area of the outflow pool below the marsh in response to different operating scenarios for the YDP. The models are intended to serve as tools for resource managers charged with maintaining this wetland complex. Unlike many wetland water budget models, this one explicitly takes into account salinity as a factor in the water budget. We modeled inflow rates ranging from 1 to 6m3s−1 and inflow salinities ranging from 0 to 6gL−1 Total Dissolved Solids. The model indicates that if the inflow rate is reduced below the current 4–5m3s−1 the vegetated area of the Cienega would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of T. domingensis. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration, and on an annual basis 70% of inflows exit into the Santa Clara Slough. These flushing flows maintain the salt balance in the Cienega. The Santa Clara Slough is periodically flushed by spring tides, making this a sustainable, open wetland system in its present state.

Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns

This study examined the end-of-winter snow storage, its distribution and the spatial and temporal melt patterns of a large, low gradient wetland at Polar Bear Pass, Bathurst Island, Nunavut, Canada. The project utilized a combination of field observations and a physically-based snowmelt model. Topography and wind were the major controls on snow distribution in the region, and snow was routinely scoured from the hilltop regions and deposited into hillslopes and valleys. Timing and duration of snowmelt at Polar Bear Pass were similar in 2008 and 2009. The snowmelt was initiated by an increase in air temperature and net radiation receipt. Inter-annual variability in spatial snowmelt patterns was evident at Polar Bear Pass and was attributed to a non-uniform snow cover distribution and local microclimate conditions. In situ field studies and modelling remain important in High Arctic regions for assessing wetland water budgets and runoff, in addition to model parameterization and validation of satellite imagery. Editor Z.W. Kundzewicz Citation Assini, J. and Young, K.L., 2012. Snow cover and snowmelt of an extensive High Arctic wetland: spatial and temporal seasonal patterns. Hydrological Sciences Journal, 57 (4), 738–755.

Cumulative Effects of Impoundments on the Hydrology of Riparian Wetlands along the Marmaton River, West-Central Missouri, USA

The effects of proposed impoundments and resulting streamflow regulation on riparian wetlands in the Marmaton River Basin, Missouri, USA were determined using measurements and numerical simulations of wetland water budgets. Calibrated and validated Soil-Plant-Air-Water (SPAW) models were used to simulate daily water depths of four riparian wetlands for Current (model scenario of existing impoundments) and Proposed (model scenario of existing and proposed impoundments) impoundment conditions. The simulated frequency of flooding decreased 19–65% at the wetlands following the additions of proposed impoundments. The reduced flooding resulted in decreases in wetland water depths at all sites during the 10 simulated growing seasons under Proposed conditions with an average duration of continuous water-depth declines of 289 days at the upstream (most regulated) site. Downstream wetlands within the zone of least regulation had an average duration of water level decreases of about 20 days. Decreased water levels under Proposed conditions resulted in a range of 65–365 additional dry days at the study wetlands during the simulated 10-year period of Proposed conditions. The areas of the four wetlands meeting the hydrologic criteria of a formal jurisdictional wetland definition decreased ranging from zero to 31% under Proposed impoundment conditions.

Water and nutrient inputs, outputs, and storage in Canadian boreal forest wetlands: a review

Boreal wetlands, primarily peatlands, are important global carbon (C) reservoirs and integral components of regional hydrological networks. This paper summarizes our current state of knowledge regarding components of water and nutrient budgets in northern wetlands, with a focus on Canada. Boreal wetland water budgets are strongly influenced by the following: seasonal weather patterns as they relate to the timing of precipitation and meltwater inputs and evapotranspiration (ET) losses;; vegetation cover in the wetland and surrounding uplands as it relates to rain and snow interception and evapotranspiration;; and connectivity of the wetland to the regional hydrological network. Key factors that influence boreal wetland phosphorus (P) budgets are: spatial and temporal variability in the water table as they relate to reduction–oxidation conditions and rewetting of highly decomposed peat;; concentrations of metals and ions involved in P complexation and release;; vegetation age and type (herbaceous versus woody);; and seasonal weather patterns as they relate to water retention time. As with other components of the boreal forest, wetlands are often limited in bioavailable nitrogen (N), therefore bulk deposition and symbiotic fixation are key N sources. Within many wetlands, N is rapidly cycled through vegetation and microbial communities, and converted to gaseous N or exported as organic N in outflows. In terms of C budgets, boreal wetlands are important reservoirs, converting inorganic and organic C inputs to peat. Climate change and anthropogenic N loading threaten the water and C balance in boreal wetlands.

Sensitivity of wetland saturated hydraulic heads and water budgets to evapotranspiration

The sensitivity of wetland saturated hydraulic heads and water budgets to evapotranspiration (ET) was examined using a simplified hydrologic model and eight representations of ET. Estimates of ET that created the most reliable wetland saturated hydraulic heads and water budgets employed vegetation coefficients to correct potential ET, calculated by the Priestley-Taylor equation, to actual ET. The accuracy of simulated hydraulic heads generally improved by , 1 cm, however, when using the most reliable ET estimates based on vegetation coefficients. An ET estimate that used a regression-defined extinction depth created substantial errors in simulated water budgets. Specifically, the extinction-depth ET overestimated the annual actual ET by about 40% (400 mm). An ET approximation that overestimates actual ET by 400 mm annually applied in a regional hydrologic model over the 5400 km 2 area of Everglades National Park would underestimate the annual volume of water available for ground-water recharge and surface- water runoff to coastal estuaries by 2.3 billion m 3 . For comparison, this underestimation is about two thirds of the mean volume of water in Lake Okeechobee (3.8 billion m 3 ), the largest lake in Florida, and clearly demonstrates unbiased estimates of ET are necessary for reliably simulating wetland water budgets.

MODEL ESTIMATION OF LAND-USE EFFECTS ON WATER LEVELS OF NORTHERN PRAIRIE WETLANDS

Wetlands of the Prairie Pothole Region exist in a matrix of grassland dominated by intensive pastoral and cultivation agriculture. Recent conservation management has emphasized the conversion of cultivated farmland and degraded pastures to intact grassland to improve upland nesting habitat. The consequences of changes in land-use cover that alter watershed processes have not been evaluated relative to their effect on the water budgets and vegetation dynamics of associated wetlands. We simulated the effect of upland agricultural practices on the water budget and vegetation of a semipermanent prairie wetland by modifying a previously published mathematical model (WETSIM). Watershed cover/land-use practices were categorized as unmanaged grassland (native grass, smooth brome), managed grassland (moderately heavily grazed, prescribed burned), cultivated crops (row crop, small grain), and alfalfa hayland. Model simulations showed that differing rates of evapotranspiration and runoff associated with different upland plant-cover categories in the surrounding catchment produced differences in wetland water budgets and linked ecological dynamics. Wetland water levels were highest and vegetation the most dynamic under the managed-grassland simulations, while water levels were the lowest and vegetation the least dynamic under the unmanaged-grassland simulations. The modeling results suggest that unmanaged grassland, often planted for waterfowl nesting, may produce the least favorable wetland conditions for birds, especially in drier regions of the Prairie Pothole Region. These results stand as hypotheses that urgently need to be verified with empirical data.

Determination of first order rate constants for wetlands treating livestock wastewater in cold climates

Four years of performance data from a free-water surface constructed wetland receiving dairy wastewater in Nova Scotia was used to compute first order reaction rate constants (Ka) for several parameters including BOD5, TP, TKN, NH4+-N, FC, and TSS. Flow rates at the inlet and outlet of the 5 m wide × 20 m long wetland were continuously measured to assess how external hydrologic influences affected the water budget of the wetland and the system treatment performance. The Ka values were calculated using inlet and outlet concentrations and an assumption of plug flow hydraulics. Adjusted rate constants (Kac) were also computed, in which the effects of dilution and concentration on pollutant concentrations were considered. Precipitation, runoff, and evapotranspiration had a large influence on the wetland water budget. Values of Ka were higher than Kac for all wastewater parameters, illustrating the effects of dilution on outlet pollutant concentrations and the importance of accurately characterizing wetland hydrology when determining or using rate constants. The Kac values did not appear to be influenced by temperature or solar radiation, but were positively correlated with the hydraulic loading rate for most parameters. Rate constants were lower than those reported in the literature for livestock wastewater treatment wetlands operating in warmer climates. This could be due to differences in climate, but could also be attributed to the relatively high strength wastewater and low hydraulic loading rate (0.1 m month–1) used in this study. Key words: treatment wetlands, cold climate, agricultural wastewater, design, rate constants.

Simulating nutrient cycling and removal through treatment wetlands in arid/semiarid environments

The Constructed Wetlands Algorithm for Nutrient Transformations (CWANT) computer program was designed to mathematically simulate the fate, transformation, and transport of nutrients as they move through ammonium-rich treated secondary wastewater in constructed surface-flow wetland systems. CWANT employs empirically derived mathematical functions to represent a wetland water budget, water temperature, emergent vegetation, and algae dynamics, reactions involving important elements (N, P, CBOD 5, and O), and ultimately the water quality of wetland outflow over time. Sensitivity analysis was used to calibrate model parameters. The model was verified with weekly data from the Hemet/San Jacinto Multipurpose Demonstration Wetland, owned and operated by the Eastern Municipal Water District (EMWD), in Riverside County, California, USA. Graphical illustrations showed that, on average, predicted values corresponded to seasonal trends exhibited by the measured data. Overall, the model was determined to slightly overpredict outflow concentrations for most nutrients (mean percent error (MPE) = 1.22% for organic N, 2.1% for NO 3 −, 8.69% for NH 4 +, 9.96% for CBOD, and 20.2% for total P). In its current state, CWANT serves as a screening tool to increase understanding of the nutrient transforming mechanisms dominating constructed treatment wetlands.

Simulation of the annual water table dynamics of a floodplain wetland, Narborough Bog, UK

This paper describes the simulation of a succession of annual hydro-periods describing water table variations in a British floodplain wetland, Narborough Bog. This is achieved through the application of a model, developed using MODFLOW, which requires inputs of weekly precipitation, evapotranspiration and river stage. The model reproduces the observed temporal variation in the wetland water tables illustrating the range in water table conditions experienced by the wetland, their relationship to hydrometeorological conditions, and the seasonal and annual variability in the wetland water budget. The model also estimates defuse water fluxes such as seepage flows to and from the adjacent river. The model simulations demonstrate the importance of successful representation of the stratigraphy of alluvial and organic deposits within the wetland. Model performance is evaluated for 2 years: 1991 and 1992 during a period of field instrumentation. The model is then used to reproduce the wetland hydroperiod for further 6 years: 1979, 1980, 1982, 1983, 1987 and 1988 when local data for precipitation, evapotranspiration and river stage are available. The results indicate how the wetland responds to a combination of hydrological events and emphasise the importance of precipitation—both weekly totals and its annual distribution. The model simulations reveal the importance of the water storage function of the wetland and indicate the varying relationship of the wetland to the lowland river: at low flows the river represents a base level to which the wetland water table grades. Conversely, for small periods of time wetland water tables are elevated by the effects of a marginal silt–clay levee adjacent to the riverbank. Conditions of influent seepage from river to wetland were experienced only on isolated occasions. Such results demonstrate the benefits of floodplain wetlands in moderating extremes of river flow and demonstrating the need for rivers and floodplain wetlands to remain closely integrated.

Transient modelling of water-table variation in a floodplain wetland, Narborough Bog, Leicestershire

This paper describes the application of a transient three-dimensional groundwater model to simulate water flux through a floodplain wetland, Narborough Bog, in Central England. The results of a programme of water-table monitoring are summarised to indicate the extent of water-table fluctuation, and experiments to determine hydraulic flow parameters are detailed. Hydraulic conductivities of deposits are highly variable; observations were in the range 1.16 × 10 −3–4.63 × 10 −2 cm s −1 for herbaceous peat, 1.16 10 −4 cm s −1 for wood peat, and 9.14 × 10 −6–3.36 × 10 −8 cm s −1 for silty clay. A three-layer groundwater model of the wetland is developed using MODFLOW from these initial values, and with stratigraphic data obtained by hand augering. The model is calibrated using data for two periods of recharge from precipitation by adjusting specific yield and vertical hydraulic conductivity within prescribed limits. The accuracy of the model is then assessed by comparing daily model predictions of water-table response to potential evapotranspiration at specific monitoring points. Model, results demonstrate the importance of variation in hydraulic characteristics with depth in wetlands, thus emphasizing the dependence of water-table response upon water-table position, and preceding moisture conditions. The resulting water-table configuration reflects the balance between horizontal and lateral water flow through the wetland, and its relationship to river stage. The success of the stratigraphic representation is considered and its general applicability evaluated. Finally, the use of the calibrated model for local hydrological management is considered, and the effects on the wetland water budget of varying river stage by specified amounts are examined.