The influence of bedrock hydrogeology on catchment-scale nitrate fate and transport in fractured aquifers

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.

Download Full-text

River Quality Models for Consent Setting in England and Wales

Water Science & Technology ◽

10.2166/wst.1989.0303 ◽

1989 ◽

Vol 21 (8-9) ◽

pp. 1015-1024 ◽

Cited By ~ 4

Author(s):

C. P. Crockett ◽

R. W. Crabtree ◽

I. D. Cluckie

Keyword(s):

River System ◽

Quality Model ◽

Catchment Scale ◽

Quality Models ◽

England And Wales ◽

Future Developments ◽

Statistical Framework ◽

River Quality ◽

National Approach

In England and Wales the placing of effluent discharge consents within a statistical framework has led to the development of a new hybrid type of river quality model. Such catchment scale consent models have a stochastic component for the generation of model inputs and a deterministic component to route them through the river system. This paper reviews and compares the existing approaches for consent modelling used by various Water Authorities. A number of possible future developments are suggested including the potential need for a national approach to the review and setting of long term consents.

Download Full-text

Coliform transport in a pristine reservoir: modeling and field studies

Water Science & Technology ◽

10.2166/wst.1998.0124 ◽

1998 ◽

Vol 37 (2) ◽

pp. 137-144 ◽

Cited By ~ 11

Author(s):

Elisa Garvey ◽

John E. Tobiason ◽

Michael Hayes ◽

Evelyn Wolfram ◽

David A. Reckhow ◽

...

Keyword(s):

Model Development ◽

Fate And Transport ◽

Field Studies ◽

Meteorological Conditions ◽

Reservoir Modeling ◽

Vertical Circulation ◽

Quality Model ◽

Circulation Patterns ◽

In Situ Experiments

This paper reports on field studies and model development aimed at understanding coliform fate and transport in the Quabbin Reservoir, an oligotrophic drinking water supply reservoir. An investigation of reservoir currents suggested the importance of wind driven phenomena, and that both lateral and vertical circulation patterns exist. In-situ experiments of coliform decay suggested dependence on light intensity and yielded an appropriate decay coefficient to be used in CE-QUAL-W2, a two-dimensional hydrodynamic and water quality model. Modeling confirmed the sensitivity of reservoir outlet concentration to vertical variability within the reservoir, meteorological conditions, and location of coliform source.

Download Full-text