scholarly journals Characterising phosphorus transfers in rural catchments using a continuous bank-side analyser

2007 ◽  
Vol 11 (1) ◽  
pp. 372-381 ◽  
Author(s):  
P. Jordan ◽  
A. Arnscheidt ◽  
H. McGrogan ◽  
S. McCormick
Keyword(s):  
Point Sources ◽  
Mitigation Measures ◽  
Data Series ◽  
Storm Events ◽  
Catchment Scale ◽  
Concentration Data ◽  
Monitoring Technology ◽  
Transfer Event ◽  
Discharge Data ◽  
Total Period

Abstract. A six-month series of high-resolution synchronous stream discharge and total phosphorus (TP) concentration data is presented from a 5 km2 agricultural catchment in the Lough Neagh basin, Northern Ireland. The data are hourly averages of 10-minute measurements using a new bankside, automatic, continuous monitoring technology. Three TP transfer "event-types" occur in this catchment: (1) chronic, storm independent transfers; (2) acute, storm dependent transfers; (3) acute, storm independent transfers. Event-type 2 transferred over 90% of the total 279 kg TP load in 39% of the total period; it corresponded to diffuse transfers from agricultural soils. Event-types 1 and 3, however, maintained the river in a highly eutrophic state between storm events and were characteristic of point source pollution, despite there being no major industrial or municipal point sources. Managing P transfers at the catchment scale requires a robust monitoring technology to differentiate between dynamic, multiple sources and associated event types and so enable a reliable assessment of the performance of mitigation measures, monitored at catchment outlets. The synchronous and continuous TP and discharge data series generated in this study demonstrate how this is possible.

scholarly journals High-resolution phosphorus transfers at the catchment scale: the hidden importance of non-storm transfers

2005 ◽  
Vol 9 (6) ◽  
pp. 685-691 ◽  
Author(s):  
P. Jordan ◽  
J. Arnscheidt ◽  
H. McGrogan ◽  
S. McCormick
Keyword(s):  
High Resolution ◽  
Northern Ireland ◽  
Total Phosphorus ◽  
Continuous Flow ◽  
Storm Events ◽  
Catchment Scale ◽  
Discharge Data ◽  
Lough Neagh ◽  
Stream Discharge ◽  
Sampling Regime

Abstract. High-resolution measurements of total phosphorus (TP) concentrations in a stream draining a 5 km2 agricultural catchment (a sub-catchment of Lough Neagh in Northern Ireland) were made every 10 min by continuous flow instrumentation using new homogenisation, digestion and colorimetric phases. Concurrently, rainfall and stream discharge data were collected at 5 and 15 min intervals. Major P flushing episodes during storm events peaked on the rising limbs of storm hydrographs. A period of baseflow also indicated the importance of other sources that maintain the stream in a eutrophic state between storm events. These data provide insights into catchment processes that conform to definite patterns that, in a coarser sampling regime, might ordinarily be attributed to sampling and analytical "noise".

Successful reduction of diffuse nitrogen emissions at catchment scale: example from the pilot River Odense, Denmark

2016 ◽  
Vol 73 (11) ◽  
pp. 2583-2589 ◽  
Author(s):  
J. Windolf ◽  
H. Tornbjerg ◽  
C. C. Hoffmann ◽  
J. R. Poulsen ◽  
G. Blicher-Mathiesen ◽  
...  
Keyword(s):  
Wetland Restoration ◽  
Coastal Waters ◽  
Point Sources ◽  
Downward Trend ◽  
Mitigation Measures ◽  
N Leaching ◽  
Catchment Scale ◽  
Nitrogen Emissions ◽  
Successful Reduction ◽  
Gauging Station

Land-based total nitrogen (N) loadings to Danish coastal waters have been markedly reduced since 2000. This has been achieved by general measures reducing discharges from all point sources and N leaching from farmed land supplemented with more local and targeted mitigation measures such as restoration of wetlands to increase the catchment-specific N retention. In the catchment of River Odense, restoration of wetlands has been extensive. Thus, in the major gauged catchment (485 km2) eleven wetlands (860 ha) have been restored since 2000. A comparison of data on N concentrations and loss from a gauging station in the River Odense with data from a control catchment (772 km2), in which a significantly less intensive wetland restoration programme has been undertaken, showed an excess downward trend in N, amounting to 124 t N yr−1, which can be ascribed to the intensive wetland restoration programme carried out in the River Odense catchment. In total, the N load in the River Odense has been reduced by 377 t N yr−1 (39%) since 2000. The observed downward trend is supported by monitoring data from two wetlands restored in 2001 and 2004 in the River Odense catchment.

Nitrogen and phosphorus in the Vistula River, Poland -- changes from source to mouth

1994 ◽  
Vol 30 (5) ◽  
pp. 177-186 ◽  
Author(s):  
Karin Sundblad ◽  
Andrzej Tonderski ◽  
Jacek Rulewski
Keyword(s):  
Central Region ◽  
Northern Region ◽  
Point Sources ◽  
Nutrient Loss ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
Concentration Data ◽  
Diffuse Sources ◽  
Vistula River ◽  
South Central

Nitrogen and phosphorus concentration data representing samples collected once a month for nine months at 13 locations along the Vistula River are considered in a preliminary discussion of the sources of the nutrients transported to the Baltic Sea. Concentrations in relation to flow data indicated substantial differences between subbasins. Based on those differences, on the area-specific nutrient loss for a six-month period and on the wastewater discharge in each subbasin, four regions could be recognized in the river basin: i) the southern region with a large impact of point sources, ii) the south central region, where diffuse sources seemed to be of major importance, iii) the north central region with a combined effect of point and diffuse sources, and retention in two reservoirs, iv) the northern region where point sources seemed to be the dominating source, at least for phosphorus. Our results illustrate the importance of differences in phosphorus retention between the basins. Long-term retention along the course of the river, particularly in the two reservoirs, must be estimated to allow proper source apportionment in the Vistula basin. Concentration decreases in the Wloclawek Reservoir varied between 44 and 68% for P, and 11 to 37% for N, in the months with significant retention. In some months, however, concentrations increased, indicating a release of nutrients.

scholarly journals The Rise of Climate-Driven Sediment Discharge in the Amazonian River Basin

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 208 ◽  
Author(s):  
Nazzareno Diodato ◽  
Naziano Filizola ◽  
Pasquale Borrelli ◽  
Panos Panagos ◽  
Gianni Bellocchi
Keyword(s):  
River Basin ◽  
Amazon Basin ◽  
Global Climate ◽  
Climate Extremes ◽  
Temporal Variations ◽  
Sediment Discharge ◽  
Storm Events ◽  
Discharge Data ◽  
Magdalena River ◽  
Sediment Export

The occurrence of hydrological extremes in the Amazon region and the associated sediment loss during rainfall events are key features in the global climate system. Climate extremes alter the sediment and carbon balance but the ecological consequences of such changes are poorly understood in this region. With the aim of examining the interactions between precipitation and landscape-scale controls of sediment export from the Amazon basin, we developed a parsimonious hydro-climatological model on a multi-year series (1997–2014) of sediment discharge data taken at the outlet of Óbidos (Brazil) watershed (the narrowest and swiftest part of the Amazon River). The calibrated model (correlation coefficient equal to 0.84) captured the sediment load variability of an independent dataset from a different watershed (the Magdalena River basin), and performed better than three alternative approaches. Our model captured the interdecadal variability and the long-term patterns of sediment export. In our reconstruction of yearly sediment discharge over 1859–2014, we observed that landscape erosion changes are mostly induced by single storm events, and result from coupled effects of droughts and storms over long time scales. By quantifying temporal variations in the sediment produced by weathering, this analysis enables a new understanding of the linkage between climate forcing and river response, which drives sediment dynamics in the Amazon basin.

scholarly journals A cost-effectiveness analysis of water security and water quality: impacts of climate and land-use change on the River Thames system

2013 ◽  
Vol 371 (2002) ◽  
pp. 20120413 ◽  
Author(s):  
P. G. Whitehead ◽  
J. Crossman ◽  
B. B. Balana ◽  
M. N. Futter ◽  
S. Comber ◽  
...  
Keyword(s):  
Water Quality ◽  
Land Use ◽  
Cost Effectiveness ◽  
Land Use Change ◽  
Algal Blooms ◽  
Economic Benefits ◽  
Point Sources ◽  
Mitigation Measures ◽  
Mitigation And Adaptation ◽  
River Thames

The catchment of the River Thames, the principal river system in southern England, provides the main water supply for London but is highly vulnerable to changes in climate, land use and population. The river is eutrophic with significant algal blooms with phosphorus assumed to be the primary chemical indicator of ecosystem health. In the Thames Basin, phosphorus is available from point sources such as wastewater treatment plants and from diffuse sources such as agriculture. In order to predict vulnerability to future change, the integrated catchments model for phosphorus (INCA-P) has been applied to the river basin and used to assess the cost-effectiveness of a range of mitigation and adaptation strategies. It is shown that scenarios of future climate and land-use change will exacerbate the water quality problems, but a range of mitigation measures can improve the situation. A cost-effectiveness study has been undertaken to compare the economic benefits of each mitigation measure and to assess the phosphorus reductions achieved. The most effective strategy is to reduce fertilizer use by 20% together with the treatment of effluent to a high standard. Such measures will reduce the instream phosphorus concentrations to close to the EU Water Framework Directive target for the Thames.

scholarly journals Mobilisation or dilution? Nitrate response of karst springs to high rainfall events

2014 ◽  
Vol 18 (11) ◽  
pp. 4423-4435 ◽  
Author(s):  
M. Huebsch ◽  
O. Fenton ◽  
B. Horan ◽  
D. Hennessy ◽  
K. G. Richards ◽  
...  
Keyword(s):  
High Resolution ◽  
Nitrate Contamination ◽  
Karst Aquifers ◽  
The European Union ◽  
Storm Events ◽  
Discharge Data ◽  
Rainfall Events ◽  
Nitrate Concentrations ◽  
Nitrate Response ◽  
Karst Systems

Abstract. Nitrate (NO3−) contamination of groundwater associated with agronomic activity is of major concern in many countries. Where agriculture, thin free draining soils and karst aquifers coincide, groundwater is highly vulnerable to nitrate contamination. As residence times and denitrification potential in such systems are typically low, nitrate can discharge to surface waters unabated. However, such systems also react quickest to agricultural management changes that aim to improve water quality. In response to storm events, nitrate concentrations can alter significantly, i.e. rapidly decreasing or increasing concentrations. The current study examines the response of a specific karst spring situated on a grassland farm in South Ireland to rainfall events utilising high-resolution nitrate and discharge data together with on-farm borehole groundwater fluctuation data. Specifically, the objectives of the study are to formulate a scientific hypothesis of possible scenarios relating to nitrate responses during storm events, and to verify this hypothesis using additional case studies from the literature. This elucidates the controlling key factors that lead to mobilisation and/or dilution of nitrate concentrations during storm events. These were land use, hydrological condition and karstification, which in combination can lead to differential responses of mobilised and/or diluted nitrate concentrations. Furthermore, the results indicate that nitrate response in karst is strongly dependent on nutrient source, whether mobilisation and/or dilution occur and on the pathway taken. This will have consequences for the delivery of nitrate to a surface water receptor. The current study improves our understanding of nitrate responses in karst systems and therefore can guide environmental modellers, policy makers and drinking water managers with respect to the regulations of the European Union (EU) Water Framework Directive (WFD). In future, more research should focus on the high-resolution monitoring of karst aquifers to capture the high variability of hydrochemical processes, which occur at time intervals of hours to days.

scholarly journals Bayesian trend analysis of extreme wind using observed and hindcast series off the Catalan coast, NW Mediterranean Sea

2014 ◽  
Vol 14 (9) ◽  
pp. 2387-2397 ◽  
Author(s):  
M. I. Ortego ◽  
J. J. Egozcue ◽  
R. Tolosana-Delgado
Keyword(s):  
Generalized Pareto Distribution ◽  
Western Mediterranean ◽  
Quality Data ◽  
Occurrence Rate ◽  
Data Series ◽  
Model Parameters ◽  
Storm Events ◽  
Average Wind Speed ◽  
Magnitude Distribution ◽  
Catalan Coast

Abstract. It has been suggested that climate change might modify the occurrence rate and magnitude of large ocean-wave and wind storms. The hypothesised reason is the increase of available energy in the atmosphere–ocean system. Forecasting models are commonly used to assess these effects, given that good-quality data series are often too short. However, forecasting systems are often tuned to reproduce the average behaviour, and there are concerns on their relevance for extremal regimes. We present a methodology of simultaneous analysis of observed and hindcast data with the aim of extracting potential time drifts as well as systematic regime discrepancies between the two data sources. The method is based on the peak-over-threshold (POT) approach and the generalized Pareto distribution (GPD) within a Bayesian estimation framework. In this context, storm events are considered points in time, and modelled as a Poisson process. Storm magnitude over a reference threshold is modelled with a GPD, a flexible model that captures the tail behaviour of the magnitude distribution. All model parameters, i.e. shape and location of the magnitude GPD and the Poisson occurrence rate, are affected by a trend in time. Moreover, a systematic difference between parameters of hindcast and observed series is considered. Finally, the posterior joint distribution of all these trend parameters is studied using a conventional Gibbs sampler. This method is applied to compare hindcast and observed series of average wind speed at a deep buoy location off the Catalan coast (NE Spain, western Mediterranean; buoy data from 2001; REMO wind hindcasting from 1958 on). Appropriate scale and domain of attraction are discussed, and the reliability of trends in time is addressed.

scholarly journals Assessment of catchment response and calibration of a hydrological model using high-frequency discharge–nitrate concentration data

2013 ◽  
Vol 44 (6) ◽  
pp. 995-1012 ◽  
Author(s):  
Rajesh R. Shrestha ◽  
Karsten Osenbrück ◽  
Michael Rode
Keyword(s):  
Surface Runoff ◽  
High Frequency ◽  
Hydrological Model ◽  
Nitrate Concentration ◽  
Subsurface Flow ◽  
Nitrate Transport ◽  
Response Analysis ◽  
Catchment Scale ◽  
Concentration Data ◽  
High Frequency Discharge

This study uses a high-frequency discharge and nitrate concentration dataset from the Weida catchment in Germany for the catchment scale hydrologic response analysis. Nitrate transport in the catchment is mostly conservative as indicated by the nitrate stable isotope (δ15N and δ18O) analysis. Discharge–nitrate concentration data from the catchment show distinctive patterns, suggesting flushing and dilution response. A self-organizing feature map-based methodology was employed to identify such patterns or cluster in the datasets. Based on knowledge of the catchment conditions and prevailing understanding of discharge–nitrate concentration relationship, the clusters were characterized into five qualitative flow responses: (1) baseflow; (2) subsurface flow increase; (3) surface runoff increase; (4) surface runoff recession; and (5) subsurface flow decrease. Such qualitative flowpaths were used as soft data for a multi-objective calibration of a hydrological model (WaSiM-ETH). The calibration led to a reasonable simulation of overall discharge (Nash–Sutcliffe coefficient: 0.84) and qualitative flowpaths (76% agreement). A prerequisite for using such methodology is limited biogeochemical transformation of nitrate (such as denitrification).

Combining  concentration-discharge hysteresis and reach-scale lateral flow modelling to characterize flood water origin and processes: application to karst catchments

2021 ◽  
Author(s):  
Martin Le Mesnil ◽  
Jean-Baptiste Charlier ◽  
Roger Moussa ◽  
Yvan Caballero
Keyword(s):  
Surface Runoff ◽  
Hysteresis Loops ◽  
Hydrological Processes ◽  
Storm Events ◽  
New Classification ◽  
Catchment Scale ◽  
Saturation State ◽  
Relationship Analysis ◽  
Water Origin

<p>We propose a data-driven approach of concentration-discharge (C-Q) relationship analysis, including a new classification of C-Q hysteresis loop at the catchment scale, combined to a simulation of lateral Q and C at the reach scale. We analyse high-frequency, multiple-site records of Q and electrical conductivity (EC) in karst catchment outlets, in which EC informs on water residence time. At the catchment scale, contributions of pre-event water (PEW) and event water (EW) during storm events are investigated through hysteresis loops analysis, which allows inferring hydrological processes. Our new classification of hysteresis loops is based on loop mean slope and hysteresis index. At the reach scale, lateral Q and EC are simulated using a diffusive wave equation model, providing a more spatialized picture of PEW and EW contributions to streamflow during storm events. The methodology is applied to two catchments (Loue river and Cèze river) in France, including 8 gauging stations with hourly Q and EC time series covering 66 storm events.</p><p>For both catchments, a conceptual model of water origin and hydrological-processes seasonal and spatial variability is drawn. Regarding Loue catchment, summer and fall storm-events are characterized by contribution of PEW through piston-type flows, whereas decreasing EC values in winter and spring storm-events indicate the major contribution of EW through surface runoff and following fast infiltration in karst. EW contribution is increasing towards downstream. Regarding Cèze catchment, higher contributions of EW are observed, indicating that fast infiltration and surface runoff are the dominant processes, associated to a PEW signature in summer and fall. PEW contribution also increases in karstified areas. Intra-site water origin seasonality is mostly related to karst aquifer saturation state, whereas inter-site variability is linked to karst areas extension. These results are encouraging to extend this approach to a variety of sites, notably influenced by important surface water/groundwater interactions, and groundwater flooding.</p>

Nutrient pollution at the lower reaches of Mediterranean coastal rivers in Israel

2000 ◽  
Vol 42 (1-2) ◽  
pp. 147-152 ◽  
Author(s):  
B. Herut ◽  
N. Kress ◽  
H. Hornung
Keyword(s):  
Inorganic Nitrogen ◽  
Agricultural Runoff ◽  
Point Sources ◽  
Industrial Wastes ◽  
Nutrient Concentrations ◽  
Contamination Level ◽  
Nutrient Load ◽  
Nutrient Loads ◽  
Discharge Data ◽  
Coastal Rivers

This study represents the first attempt to evaluate the nutrient load introduced into the coastal waters by the rivers along the Mediterranean coast of Israel. Measurements of nutrient concentrations (phosphate, ammonium, nitrate, nitrite, silicic acid) at two or three stations along the lower river reaches (11 rivers) were carried out annually from 1990 up to 1998. Combining the nutrient concentrations with the monthly riverine discharges we assessed the nutrient load. In general, most of the coastal rivers contain high nutrient contamination level, compared to the criteria adopted by NOAA (USA) for coastal river estuaries. The high degree of contamination is attributed to extreme low natural flow combined with the discharge of domestic and industrial wastes, and with agriculture runoff. In terms of nutrient concentrations, the Kishon River is the most polluted, followed by the Soreq, Poleg and Alexander Rivers. The preliminary estimate is that the coastal rivers transport between ~2000 to 6000 tons of dissolved inorganic nitrogen (DIN) and between ~250–800 tons of dissolved inorganic phosphorus (DIP) to the sea. An additional 3500 and 3000 tons of DIN and DIP, respectively, are supplied through the Kishon River. The load of the Poleg River is unknown (no discharge data) but expected to be significant based on nutrient concentration measured. The total load of the coastal rivers constitutes a major component among the other land-base point sources such as the Gush Dan outfall. Our estimate probably represents minimal values, as it does not include diffused input of agricultural runoff nor the riverine particulate and dissolved organic nutrient loads (which are unknown).

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