Transient flow between aquifers and surface water: analytically derived field-scale hydraulic heads and fluxes

Abstract. The increasing importance of catchment-scale and basin-scale models of the hydrological cycle makes it desirable to have a simple, yet physically realistic model for lateral subsurface water flow. As a first building block towards such a model, analytical solutions are presented for horizontal groundwater flow to surface waters held at prescribed water levels for aquifers with parallel and radial flow. The solutions are valid for a wide array of initial and boundary conditions and additions or withdrawals of water, and can handle discharge into as well as lateral infiltration from the surface water. Expressions for the average hydraulic head, the flux to or from the surface water, and the aquifer-scale hydraulic conductivity are developed to provide output at the scale of the modelled system rather then just point-scale values. The upscaled conductivity is time-variant. It does not depend on the magnitude of the flux but is determined by medium properties as well as the external forcings that drive the flow. For the systems studied, with lateral travel distances not exceeding 10 m, the circular aquifers respond very differently from the infinite-strip aquifers. The modelled fluxes are sensitive to the magnitude of the storage coefficient. For phreatic aquifers a value of 0.2 is argued to be representative, but considerable variations are likely. The effect of varying distributions over the day of recharge damps out rapidly; a soil water model that can provide accurate daily totals is preferable over a less accurate model hat correctly estimates the timing of recharge peaks.

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Hydrological Characteristics of the Te Hapua Wetland Complex:The Potential Influence of Groundwater Level, Bore Abstraction and Climate Change on Wetland Surface Water Levels

10.26686/wgtn.16973461.v1 ◽

2021 ◽

Author(s):

◽

Craig Wayne Allen

Keyword(s):

Climate Change ◽

Surface Water ◽

Groundwater Level ◽

Hydrological Cycle ◽

Shallow Groundwater ◽

Water Levels ◽

Groundwater Abstraction ◽

Potential Threat ◽

Through Flow ◽

Future Viability

<p>Te Hapua is a complex of small, privately owned wetlands approximately 60 km northwest of Wellington. The wetlands represent a large portion of the region's remaining palustrine swamps, which have been reduced to just 1% of the pre-1900 expanse. Whilst many land owners have opted to protect wetlands on their land with covenants, questions have been raised regarding potential threats stemming from the wider region. Firstly, some regional groundwater level records have shown significant decline in the 10 to 25 years they have been monitored. The reason for this is unclear. Wetlands are commonly associated with groundwater discharge, so a decline in groundwater level could adversely affect wetland water input. Secondly, estimated groundwater resources are currently just 8% allocated, so there is potential for a 92% increase in groundwater abstraction from aquifers that underlie the wetlands. Finally, predictions of future climate change indicate changes in rainfall quantity and intensity. This would likely alter the hydrological cycle, impacting on rainfall dependant ecosystems such as wetlands as well as groundwater recharge. Whilst previous ecological surveys at Te Hapua provide valuable information on biodiversity and ecological threat, there has been no detailed study of the hydrology of the wetlands. An understanding of the relationship between the surface water of the wetlands and the aquifers that underlie the area is important when considering the future viability of the wetlands. This study aims to define the local hydrology and assess the potential threat of 'long term' groundwater level decline, increased groundwater abstraction and predicted climate change. Eleven months of water level data was supplied by Wellington Regional Council for three newly constructed Te Hapua wetland surface water and adjacent shallow groundwater monitoring sites. The data were analysed in terms of their relative water levels and response to rainfall. A basic water balance was calculated using the data from the monitoring sites and a GIS analysis of elevation data mapped the wetlands and their watersheds. A survey of 21 individual wetlands was carried out to gather water quality and water regime data to enable an assessment of wetland class. Historical groundwater level trends and geological records were analysed in the context of potential threat to the wetlands posed by a decline in groundwater level. Climate change predictions for the Kapiti Coast were reviewed and discussed in the context of possible changes to the hydrological cycle and to wetlands. Results from the wetland survey indicated that there are two distinct bands of wetlands at Te Hapua. Fens are found mostly in the eastern band and are more likely to be discharge wetlands, some of which are ephemeral. Swamps are found mostly in the western band and are more likely to be recharge wetlands. Dominant water input to fens is via local rainfall and local through-flow of shallow groundwater, especially from surrounding dunes. The eastern band of wetlands is typified by higher dunes and hence has greater input from shallow groundwater than wetlands in the western band. Dominant water input to swamps is via local rainfall, runoff, and through-flow from the immediate watershed and adjacent wetlands. Overall, the future viability of the Te Hapua wetland complex appears promising. Historical groundwater declines appear to be minimal and show signs of reversing. Abstraction from deep aquifers is not likely to impact on wetland water levels. Climate change is likely to have an impact on the hydrological cycle and may increase pressure on some areas, especially ephemeral wetlands. The effect of climate change on groundwater level is more difficult to forecast, but may lower water level in the long term.</p>

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An Integrated Modeling Approach to Study the Surface Water-Groundwater Interactions and Influence of Temporal Damping Effects on the Hydrological Cycle in the Miho Catchment in South Korea

Water ◽

10.3390/w10111529 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1529 ◽

Cited By ~ 3

Author(s):

Jaewon Joo ◽

Yong Tian ◽

Chunmiao Zheng ◽

Yi Zheng ◽

Zan Sun ◽

...

Keyword(s):

Surface Water ◽

Temporal Variability ◽

Hydrological Cycle ◽

Spatial Scales ◽

Dominant Role ◽

Integrated Modeling ◽

Energy Conditions ◽

Catchment Scale ◽

Hydrological System ◽

Damping Effects

Integrated surface water–groundwater (SW–GW) models could be used to assess the impacts of climate change or variability on the hydrological cycle. However, the damping effects of the hydrological system have rarely been explored via integrated SW–GW modeling. This paper presents an integrated modeling study in a typical humid area, the Miho catchment in Korea, using an integrated model called Groundwater and Surface-water FLOW (GSFLOW). The major findings of this study are as follows: (1) The simulated results from 2005 to 2014 indicate that the temporal variability in the streamflow, stream-groundwater interactions and groundwater recharge are dominated by the precipitation, while the temporal variability in the evapotranspiration (ET) is controlled by the energy conditions; (2) Damping effects can affect the hydrological cycle across different temporal and spatial scales. At the catchment scale, the soil zone and aquifer play a dominant role in damping the precipitation on monthly and annual time scales, respectively; (3) Variability in the capacity to buffer earlier precipitation is found at small spatial scales, such as streams, and larger spatial scales, such as the whole catchment. This variability could affect the water balance at larger spatial scales and affect the hydrography recession at smaller spatial scales.

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Hydrological Characteristics of the Te Hapua Wetland Complex:The Potential Influence of Groundwater Level, Bore Abstraction and Climate Change on Wetland Surface Water Levels

10.26686/wgtn.16973461 ◽

2021 ◽

Author(s):

◽

Craig Wayne Allen

Keyword(s):

Climate Change ◽

Surface Water ◽

Groundwater Level ◽

Hydrological Cycle ◽

Shallow Groundwater ◽

Water Levels ◽

Groundwater Abstraction ◽

Potential Threat ◽

Through Flow ◽

Future Viability

<p>Te Hapua is a complex of small, privately owned wetlands approximately 60 km northwest of Wellington. The wetlands represent a large portion of the region's remaining palustrine swamps, which have been reduced to just 1% of the pre-1900 expanse. Whilst many land owners have opted to protect wetlands on their land with covenants, questions have been raised regarding potential threats stemming from the wider region. Firstly, some regional groundwater level records have shown significant decline in the 10 to 25 years they have been monitored. The reason for this is unclear. Wetlands are commonly associated with groundwater discharge, so a decline in groundwater level could adversely affect wetland water input. Secondly, estimated groundwater resources are currently just 8% allocated, so there is potential for a 92% increase in groundwater abstraction from aquifers that underlie the wetlands. Finally, predictions of future climate change indicate changes in rainfall quantity and intensity. This would likely alter the hydrological cycle, impacting on rainfall dependant ecosystems such as wetlands as well as groundwater recharge. Whilst previous ecological surveys at Te Hapua provide valuable information on biodiversity and ecological threat, there has been no detailed study of the hydrology of the wetlands. An understanding of the relationship between the surface water of the wetlands and the aquifers that underlie the area is important when considering the future viability of the wetlands. This study aims to define the local hydrology and assess the potential threat of 'long term' groundwater level decline, increased groundwater abstraction and predicted climate change. Eleven months of water level data was supplied by Wellington Regional Council for three newly constructed Te Hapua wetland surface water and adjacent shallow groundwater monitoring sites. The data were analysed in terms of their relative water levels and response to rainfall. A basic water balance was calculated using the data from the monitoring sites and a GIS analysis of elevation data mapped the wetlands and their watersheds. A survey of 21 individual wetlands was carried out to gather water quality and water regime data to enable an assessment of wetland class. Historical groundwater level trends and geological records were analysed in the context of potential threat to the wetlands posed by a decline in groundwater level. Climate change predictions for the Kapiti Coast were reviewed and discussed in the context of possible changes to the hydrological cycle and to wetlands. Results from the wetland survey indicated that there are two distinct bands of wetlands at Te Hapua. Fens are found mostly in the eastern band and are more likely to be discharge wetlands, some of which are ephemeral. Swamps are found mostly in the western band and are more likely to be recharge wetlands. Dominant water input to fens is via local rainfall and local through-flow of shallow groundwater, especially from surrounding dunes. The eastern band of wetlands is typified by higher dunes and hence has greater input from shallow groundwater than wetlands in the western band. Dominant water input to swamps is via local rainfall, runoff, and through-flow from the immediate watershed and adjacent wetlands. Overall, the future viability of the Te Hapua wetland complex appears promising. Historical groundwater declines appear to be minimal and show signs of reversing. Abstraction from deep aquifers is not likely to impact on wetland water levels. Climate change is likely to have an impact on the hydrological cycle and may increase pressure on some areas, especially ephemeral wetlands. The effect of climate change on groundwater level is more difficult to forecast, but may lower water level in the long term.</p>

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A Distributed Groundwater/Surface Water Model for the Suså-Catchment

Hydrology Research ◽

10.2166/nh.1982.0026 ◽

1982 ◽

Vol 13 (5) ◽

pp. 311-322 ◽

Cited By ~ 7

Author(s):

Jens Chr Refsgaard ◽

Eggert Hansen

Keyword(s):

Surface Water ◽

Hydrological Cycle ◽

Water Model ◽

Confined Aquifer ◽

Groundwater Abstraction ◽

Physically Based Model ◽

Physical Mechanisms ◽

Physically Based ◽

Streamflow Data ◽

Streamflow Depletion

A distributed physically based model of the entire land phase of the hydrological cycle has been developed for the Suså-area, covering about 1,000 km2 of Zealand, Denmark. The model is described in part I of the paper, also presented in this volume. The model's ability to simulate the streamflow depletion caused by a groundwater abstraction from a confined aquifer, overlaid by Quaternary drift deposits, has been tested on historical streamflow data from the catchment of Køge Å. This catchment has been heavily influenced by a major groundwater abstraction started in 1964. The physical mechanisms of streamflow depletion are discussed, and the effects of a groundwater abstraction on the recharge to the confined aquifer and on the streamflow are illustrated. General conclusions regarding streamflow depletion due to groundwater abstraction are made.

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Groundwater protection and diffuse nitrogen emissions to surface waters – which catchment areas have to be considered?

Water Science & Technology Water Supply ◽

10.2166/ws.2007.072 ◽

2007 ◽

Vol 7 (3) ◽

pp. 103-110

Author(s):

C. Schilling ◽

M. Zessner ◽

A.P. Blaschke ◽

D. Gutknecht ◽

H. Kroiss

Keyword(s):

Surface Water ◽

Total Nitrogen ◽

Surface Waters ◽

Flow Path ◽

Emission Model ◽

Catchment Scale ◽

Danube Basin ◽

Nitrogen Emissions ◽

Nitrogen Levels ◽

Catchment Areas

Two Austrian case study regions within the Danube basin have been selected for detailed investigations of groundwater and surface water quality at the catchment scale. Water balance calculations have been performed using the conceptual continuous time SWAT 2000 model to characterise catchment hydrology and to identify individual runoff components contributing to river discharge. Nitrogen emission calculations have been performed using the empirical emission model MONERIS to relate individual runoff components to specific nitrogen emissions and for the quantification of total nitrogen emissions to surface waters. Calculated total nitrogen emissions to surface waters using the MONERIS model were significantly influenced by hydrological conditions. For both catchments the groundwater could be identified as major emission pathway of nitrogen emissions to the surface waters. Since most of the nitrogen is emitted by groundwater to the surface water, denitrification in groundwater is of considerable importance reducing nitrogen levels in groundwater along the flow path towards the surface water. An approach was adopted for the grid-oriented estimation of diffuse nitrogen emissions based on calculated groundwater residence time distributions. Denitrification in groundwater was considered using a half life time approach. It could be shown that more than 90% of the total diffuse nitrogen emissions were contributed by areas with low groundwater residence times and short distances to the surface water. Thus, managing diffuse nitrogen emissions the location of catchment areas has to be considered as well as hydrological and hydrogeological conditions, which significantly influence denitrification in the groundwater and reduce nitrogen levels in groundwater on the flow path towards the surface water.

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Analyses of freshwater stress with a couple ground and surface water model in the Pra Basin, Ghana

Applied Water Science ◽

10.1007/s13201-015-0279-x ◽

2015 ◽

Vol 7 (1) ◽

pp. 137-153 ◽

Cited By ~ 2

Author(s):

George Owusu ◽

Alex B. Owusu ◽

Ebenezer Forkuo Amankwaa ◽

Fatima Eshun

Keyword(s):

Surface Water ◽

Water Model

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Review on Applications of 17O in Hydrological Cycle

Molecules ◽

10.3390/molecules26154468 ◽

2021 ◽

Vol 26 (15) ◽

pp. 4468

Author(s):

Yalalt Nyamgerel ◽

Yeongcheol Han ◽

Minji Kim ◽

Dongchan Koh ◽

Jeonghoon Lee

Keyword(s):

Water Vapor ◽

General Circulation ◽

Hydrological Cycle ◽

General Circulation Models ◽

Convective Precipitation ◽

Subsurface Water ◽

Polar Regions ◽

Sea Ice Concentration ◽

Moisture Source ◽

Depositional Processes

The triple oxygen isotopes (16O, 17O, and 18O) are very useful in hydrological and climatological studies because of their sensitivity to environmental conditions. This review presents an overview of the published literature on the potential applications of 17O in hydrological studies. Dual-inlet isotope ratio mass spectrometry and laser absorption spectroscopy have been used to measure 17O, which provides information on atmospheric conditions at the moisture source and isotopic fractionations during transport and deposition processes. The variations of δ17O from the developed global meteoric water line, with a slope of 0.528, indicate the importance of regional or local effects on the 17O distribution. In polar regions, factors such as the supersaturation effect, intrusion of stratospheric vapor, post-depositional processes (local moisture recycling through sublimation), regional circulation patterns, sea ice concentration and local meteorological conditions determine the distribution of 17O-excess. Numerous studies have used these isotopes to detect the changes in the moisture source, mixing of different water vapor, evaporative loss in dry regions, re-evaporation of rain drops during warm precipitation and convective storms in low and mid-latitude waters. Owing to the large variation of the spatial scale of hydrological processes with their extent (i.e., whether the processes are local or regional), more studies based on isotopic composition of surface and subsurface water, convective precipitation, and water vapor, are required. In particular, in situ measurements are important for accurate simulations of atmospheric hydrological cycles by isotope-enabled general circulation models.

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