Articoli di riviste: "Catchment loading"

1

Bärlund, I., K. Rankinen, M. Järvinen, E. Huitu, N. Veijalainen e L. Arvola. "Three approaches to estimate inorganic nitrogen loading under varying climatic conditions from a headwater catchment in Finland". Hydrology Research 40, n. 2-3 (1 aprile 2009): 167–76. http://dx.doi.org/10.2166/nh.2009.058.

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Inorganic nitrogen loading was simulated using two dynamic catchment scale models, Integrated Nutrients in Catchments–Nitrogen (INCA-N) and the Generalized Watershed Loading Functions (GWLF). The simulated N loading was compared to a standard method to calculate annual loading using measured discharge and discharge-weighted concentrations. The main aim of the study was to compare these three estimation approaches with regards to their performance in hydrologically variable years in a small headwater catchment in southern Finland. Inter-annual variability of INCA-N and GWLF was compared with measured inorganic N concentrations at the catchment outlet. In years where snow melt dominates the annual discharge pattern all methods gave concurrent annual loading estimates. However, the loading estimates differ between the studied methods in years where large rainfall events in late summer or autumn dominate the annual discharge pattern, or when the model was not able to reproduce the spring discharge maximum properly. The results suggest that both models can be useful tools in estimating dissolved inorganic nitrogen loading from a catchment under changing climate conditions, providing that the key influencing driver, hydrology, is well captured.

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2

Reader, H. E., C. A. Stedmon e E. S. Kritzberg. "Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments". Biogeosciences 11, n. 12 (27 giugno 2014): 3409–19. http://dx.doi.org/10.5194/bg-11-3409-2014.

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Abstract. To examine the potential influence of terrestrially derived DOM on the Baltic Sea, a year-long study of dissolved organic matter (DOM) was performed in three river catchments in Sweden. One catchment drains into the Bothnian Sea, while two southern catchments drain into the Baltic proper. Dissolved organic carbon (DOC) concentrations were positively correlated with discharge from forested catchments over the year. While the overall concentrations of DOC were several times higher in the southern two catchments, higher discharge in the northern catchment resulted in the annual loadings of DOC being on the same order of magnitude for all three catchments. Biological oxygen demand (BOD) was used as a proxy for the lability of carbon in the system. The range of BOD values was similar for all three catchments, however, the ratio of BOD to DOC (an indication of the labile fraction) in Ume river was four times higher than in the southern two catchments. Total annual BOD loading to the Baltic Sea was twice as high in the northern catchment than in the two southern catchments. Lower winter temperatures and preservation of organic matter in the northern catchment combined with an intense spring flood help to explain the higher concentrations of labile carbon in the northern catchment. Lower lability of DOM as well as higher colour in the southern catchments suggest that wetlands (i.e. peat bogs) may be the dominant source of DOM in these catchments, particularly in periods of low flow. With climate change expected to increase precipitation events and temperatures across the region, the supply and quality of DOM delivered to the Baltic Sea can also be expected to change. Our results indicate that DOM supply to the Baltic Sea from boreal rivers will be more stable throughout the year, and potentially have a lower bioavailability.

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Rankinen, Katri, Eila Turtola, Riitta Lemola, Martyn Futter e José Enrique Cano Bernal. "Nutrient Load Mitigation with Wintertime Cover as Estimated by the INCA Model". Water 13, n. 4 (9 febbraio 2021): 450. http://dx.doi.org/10.3390/w13040450.

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Increased nutrient loading causes deterioration of receiving surface waters in areas of intensive agriculture. While nitrate and particulate phosphorus load can be efficiently controlled by reducing tillage frequency and increasing vegetation cover, many field studies have shown simultaneously increased loading of bioavailable phosphorus. In the latest phase of the Rural Programme of EU agri-environmental measures, the highest potential to reduce the nutrient loading to receiving waters were the maximum limits for fertilization of arable crops and retaining plant cover on fields with, e.g., no-till methods and uncultivated nature management fields. Due to the latter two measures, the area of vegetation cover has increased since 1995, suggesting clear effects on nutrient loading in the catchment scale as well. We modeled the effectiveness of agri-environmental measures to reduce phosphorus and nitrogen loads to waters and additionally tested the performance of the dynamic, process-based INCA-P (Integrated Nutrients in Catchments—Phosphorus) model to simulate P dynamics in an agricultural catchment. We concluded that INCA-P was able to simulate both fast (immediate) and slow (non-immediate) processes that influence P loading from catchments. Based on our model simulations, it was also evident that no-till methods had increased bioavailable P load to receiving waters, even though total P and total N loading were reduced.

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4

Reader, H. E., C. A. Stedmon e E. S. Kritzberg. "Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments". Biogeosciences Discussions 11, n. 1 (22 gennaio 2014): 1355–82. http://dx.doi.org/10.5194/bgd-11-1355-2014.

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Abstract. To examine the potential influence of terrestrially derived DOM on the Baltic Sea, a year-long study of dissolved organic matter (DOM) was performed in three river catchments in Sweden. One catchment drains into the Bothnian Sea, while two southern catchments drain into the Baltic Proper. Dissolved organic carbon (DOC) concentrations were positively correlated with discharge from forested catchments over the year and while the overall concentrations of DOC were several times higher in the southern two catchments, annual loading of DOC was on the same order for all three catchments, due to differences in discharge. Biological oxygen demand (BOD) was used as a proxy for the lability of carbon in the system. The range of BOD values was similar for all three catchments, however, the ratio of BOD to DOC (an indication of the labile fraction) in Ume älv was four times higher than in the southern two catchments. Total annual BOD loading to the Baltic Sea was twice as high in the northern catchment. Lower winter temperatures and preservation of organic matter in the northern catchment combined with an intense spring flood help to explain the higher concentrations of labile carbon in the northern catchment. Lower lability of DOM as well as higher colour in the southern catchments suggest that wetlands (i.e. peat bogs) may be the dominant source of DOM in these catchments, particularly in periods of low flow. With climate change expected to increase precipitation events and temperatures across the region, the supply and quality of DOM delivered to the Baltic Sea can also be expected to change. Our results indicate that DOM supply will be more stable throughout the year, and potentially have a lower bioavailability.

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5

Acharya, Sudip. "Land use and land cover changes in the catchments impact the ecosystem in Phewa, Begnas, and Rupa lakes, Nepal". Journal of Nepal Geological Society 60 (16 settembre 2020): 195–205. http://dx.doi.org/10.3126/jngs.v60i0.31267.

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Lakes are the environmental and socioeconomic assets of Nepal. In the past few decades, land use and land cover (LULC) change has severely altered the lake ecosystems. The sediment and nutrients loading into the lakes have altered lake ecosystem significantly. This study analyzes the spatiotemporal variations of LULC change and examines its impact on lake environment of Phewa, Begnas and Rupa lakes during 1975–2018 by using Landsat satellite images and data from published literatures. Results showed that from 1975 to 2018, forest cover and agriculture land in catchments of all three lakes has decreased, while the built-up area has increased. LULC change in the catchment have bought the significant impact on the lake environment in terms of sedimentation rate, physiochemical parameters and biological environment. From 1975 to 2000 forest cover in lakes catchment has decreased, whereas the agriculture land has increased. At the same time, sediment and agriculture based nutrient loading into lakes has increased indicated by changes in sedimentation rate and alteration of physiochemical properties of the lake. From 2000 to 2018, forest and built-up area has increased while the agriculture land has decreased in lakes catchment. From 2000 to 2018, sedimentation rate of lakes has decreased compared to before 2000. Decreased sedimentation rate was interpreted due to increase in forest cover in the lake catchment. Increased nutrients loading into the lake during 2000 to 2018 has resulted serious eutrophication problem in lakes. Overall, this study suggests that the LULC change in the catchment have significant impact on lake environment.

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Kubiak, Jacek, Sylwia Machula, Dorota Oszkinis e Dominik Rokicki. "Anthropogenic pressure on the largest lakes of the River Tywa catchment". Limnological Review 17, n. 3 (1 settembre 2017): 123–32. http://dx.doi.org/10.1515/limre-2017-0012.

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Abstract The largest lakes of the River Tywa basin i.e. Strzeszowskie, Dołgie, Swobnica and Dłużec (north-west Poland, West Pomeranian Lakeland) were studied in the period 2008–2013, usually in a six week cycle. The aim of the study was to determine the degree of anthropogenic pressure on the lakes. Anthropogenic pressure was assessed against the natural vulnerability of lakes to degradation and the actual rate of eutrophication, with particular consideration of the catchment areas. Catchments of the studied lakes were classified as III class – catchment with moderate possibility of matter supply to lakes. Lakes Swobnica and Dłużec are characterised by low resistance to degradation. Lake Strzeszowskie is categorised as having moderate resistance and Lake Dołgie is non-resistant to degradation and highly susceptible to external pressure. The rate of eutrophication of lakes Strzeszowskie and Dłużec was found to be moderate, whereas lakes Dołgie and Swobnica show a high rate of eutrophication. The analysis of nutrient loading reaching the waters of the aforementioned lakes shows that the main area source is arable land, and the fundamental point source is the inflow of river waters to each of the analysed reservoirs. Nutrient loading supplied by the river is several times higher than area load. Such conditions require protective action to be taken within the catchment area and particularly, intensive implementation of good agricultural practice. In the studied lakes, there is a significant predominance of incoming nutrient loadings over dangerous and admissible loads.

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7

Engstrom, Daniel R. "Influence of Vegetation and Hydrology on the Humus Budgets of Labrador Lakes". Canadian Journal of Fisheries and Aquatic Sciences 44, n. 7 (1 luglio 1987): 1306–14. http://dx.doi.org/10.1139/f87-154.

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A mass-balance approach is used to explore the effect of several hydrologic and geographic variables on humic matter concentrations in surface waters of Labrador–Ungava. Water-color measurements from 67 dilute oligotrophic lakes are used to evaluate model predictions of aquatic humus concentration from basin hydrology, catchment vegetation, and internal loss rates. The major trend in water color in the Labrador region — increasing north to south — results from differences in external humus loading from catchment vegetation and soils. Hydrologic influences on aquatic humus concentrations reside in the dilution of catchment drainage by direct precipitation to the lake — effective only when catchments are small — and in water residence time which controls losses due to mineralization and sedimentation.

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8

Kronvang, B., P. Græsbøll, S. E. Larsen, L. M. Svendsen e H. E. Andersen. "Diffuse nutrient losses in Denmark". Water Science and Technology 33, n. 4-5 (1 febbraio 1996): 81–88. http://dx.doi.org/10.2166/wst.1996.0491.

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Since 1989, nutrient loading of the Danish aquatic environment has been monitored in 270 Danish streams draining catchment areas differing in climate, physico-geographic and land usage. Diffuse nutrient loading from non-point sources (mainly agricultural) is now the main cause of eutrophication of the Danish aquatic environment; thus in 1993, diffuse sources accounted for 94% of riverine nitrogen loading and 52% of riverine phosphorus loading. Annual riverine total nitrogen (total-N) loading from diffuse sources during the period 1989-93 was on average 10 times greater in 66 small agricultural catchments (median 23.4 kg N ha−1) than in 9 natural catchments (median 2.2 kg N ha−1). Correspondingly, annual riverine total phosphorus (total-P) loading from diffuse sources was on average 3.5 times greater in the agricultural catchments (0.29 kg P ha−1) than in the natural catchments (0.07 kg P ha−1). The annual total-N and total-P load was found to increase with the proportion of agricultural land in the catchments. In 1993, intensive measurements of phosphorus load in 8 agricultural catchments showed that normal point sampling (fortnightly) underestimates annual total-P loading by a median of 37% as compared to that estimated by frequent sampling. Moreover, estimates of monthly total-P loading are even more biased, especially in late summer and early autumn (−50% to −65%).

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9

Wang, Kunyang, Shin-ichi Onodera e Mitsuyo Saito. "Evaluation of nitrogen loading in the last 80 years in an urbanized Asian coastal catchment through the reconstruction of severe contamination period". Environmental Research Letters 17, n. 1 (29 dicembre 2021): 014010. http://dx.doi.org/10.1088/1748-9326/ac3ced.

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Abstract Most semi-enclosed seas have experienced severe eutrophication owing to high nutrient loading from rivers during rapid population growth periods. In Japan, the coastal areas of some megacities (e.g. Tokyo and Osaka) experienced considerable economic growth during the 1960s–1970s. Therefore, determining the amount of nutrient loading during this period is essential to undertake measures for the conservation of coastal environments. However, determining the nutrient loading that occurred several decades ago is generally difficult owing to lacking water quality records. In this study, the nitrogen loading in the Yamato River catchment, an urbanized coastal catchment in Asia, for 80 years from the 1940s to the 2010s is reconstructed using the Soil and Water Assessment Tool. We considered factors such as population growth, wastewater treatment plant (WWTP) construction, and changes in land and fertilizer usage in different urbanization stages. Results show that the total nitrogen loading in the catchment peaked in the 1970s at 6616 tons yr−1 owing to untreated wastewater discharge and rapid increase in population growth. By reducing 57% of the nitrogen loading in the 2010s from the catchment, WWTPs have been instrumental in improving the water environment. The decrease in and integration of agricultural land has reduced nitrogen loading attributed to nonpoint sources; however, this reduction was not obvious because of the high fertilizer usage before the 2000s. Overall, the findings of this study provide a comprehensive understanding of the impact of rapid urbanization in an Asian coastal catchment on nitrogen loading during the high economic growth period in the past. This study will be useful for the long-term assessment of nutrient loading in other.

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10

Thomas, Z., B. W. Abbott, O. Troccaz, J. Baudry e G. Pinay. "Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments". Biogeosciences Discussions 12, n. 18 (17 settembre 2015): 15337–67. http://dx.doi.org/10.5194/bgd-12-15337-2015.

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Abstract. Direct and indirect effects from agriculture, urbanization, and resource extraction have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. The capacity of a watershed to remove or retain nutrients is a function of biotic and abiotic conditions across the terrestrial-aquatic gradient including soil, groundwater, riparian zone, and surface water. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments. We analysed a five-year, high frequency water chemistry dataset from 3 catchments ranging from 2.3 to 10.8 km2 in northwestern France. Catchments differed in the relationship between hydrology and solute concentrations, associated with catchment characteristics such as hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness appeared to have greater transient storage and residence time, buffering the catchment to fluctuations in water chemistry, reflected in relatively invariant carbon and nutrient chemistry across hydrologic conditions. Conversely, the catchments with smoother, thinner soils responded to both intra- and inter-annual hydrologic variation with high concentrations of PO43− and NH4+ during low flow conditions and strong increases in DOC, sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land use) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on elemental fluxes is both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent catchment buffering capacity and probability of human disturbance provides a useful perspective for evaluating vulnerability of aquatic ecosystems to human disturbance.

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11

Smedberg, E., C. Humborg, M. Jakobsson e C. M. Mörth. "Landscape elements and river chemistry as affected by river regulation – a 3-D perspective". Hydrology and Earth System Sciences Discussions 5, n. 6 (27 novembre 2008): 3355–82. http://dx.doi.org/10.5194/hessd-5-3355-2008.

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Abstract. We tested the hypothesis whether individual land classes within a river catchment contribute equally to river loading with dissolved constituents or whether some land classes act as "hot spots" to river loading and if so, are these land classes especially affected by hydrological alterations. The amount of land covered by forests and wetlands and the average soil depth of a river catchment explain 58–93% of the variability in total organic carbon (TOC) and dissolved silicate (DSi) concentrations for 22 river catchments in Northern Sweden. Whereas only 3% of the headwater areas of the Luleälven have been inundated by the creation of reservoirs, some 10% of the soils and aggregated forest and wetland areas have been lost due to damming and further hydrological alteration such as bypassing entire sub-catchments by headrace tunnels. However, looking at individual forest classes, our estimates indicate that some 37% of the deciduous forests have been inundated by the four major reservoirs built in the Luleälven headwaters. These deciduous forest and wetlands formerly growing on top of alluvial deposits along the river corridors forming the riparian zone play a vital role in loading river water with dissolved constituents, especially DSi. A digital elevation model draped with land classes and soil depths which highlights that topography of various land classes acting as hot spots is critical in determining water residence time in soils and biogeochemical fluxes. Thus, headwater areas of the Luleälven appear to be most sensitive to hydrological alterations due to the thin soil cover (on average 2.7–4.5 m) and only patchy appearance of forest and wetlands that were significantly perturbed. Moreover, since these headwater areas are characterized often by high specific discharge, this relatively minor change in the landscape when compared to the entire river catchment may indeed explain the significant lower fluxes at the river mouth.

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12

Ferguson, C. M., N. J. Ashbolt e D. A. Deere. "Prioritisation of catchment management in the Sydney catchment - construction of a pathogen budget". Water Supply 4, n. 2 (1 aprile 2004): 35–38. http://dx.doi.org/10.2166/ws.2004.0025.

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A methodology has been developed to apply the materials budget concept, used in sediment and nutrient studies, to construct a pathogen budget for drinking water catchments, taking into consideration pathogen origin, deposition, inactivation and movement within a catchment. These processes can be described in terms of stocks (pathogens) and flows (movement of stocks). In south-eastern Australia, the majority of pathogen loading to major tributaries was predicted to occur during and after high intensity rainfall events where in-stream resuspension was not of great relative importance. In contrast, during dry weather the transit time within the studied catchment was sufficiently long that in-stream processes became relatively important. Total pathogen unit (TPU) budgets were constructed for the parasitic protozoa Cryptosporidium and Giardia. This approach enables water utility managers to identify those catchment segments and processes that are contributing or removing the greatest load of pathogens, and thus where management options will be most effective. With improved knowledge of pathogen ecology this approach can be further refined to provide budgets of infectious pathogen units (IPU), more directed to public health risk endpoints.

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13

Müller-Wohlfeil, Dirk-I., Chong-Yu Xu e Hans Legard Iversen. "Estimation of Monthly River Discharge from Danish Catchments". Hydrology Research 34, n. 4 (1 agosto 2003): 295–320. http://dx.doi.org/10.2166/nh.2003.0009.

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To simulate the nutrient loading of Danish coastal waters, river discharge from unmonitored areas must be assessed. In an attempt to identify the most suitable method, for this purpose eight different versions of the three-parameter monthly water balance model “MWB-3” were tested on data from various Danish catchments for the period 1989-97. The model with the highest R2 and the lowest correlation between the model parameters was chosen for subsequent establishment of regression equations between the model parameters and catchment and climate characteristics. The most important explanatory variables of the regressions are soil properties, potential evapotranspiration, groundwater table depth, percentage of wetland area and catchment slope. Mean R2 was 0.82 for the calibration data subset (62 catchments) and 0.79 for the test data subset (22 catchments). Sensitivity tests indicate that the selected model version is more robust for application in catchments dominated by loamy soils than in catchments dominated by sandy soils. Though the MWB-3 model provides a good basis for determining the water balance of Danish catchments at the regional and national levels, modifications and extensions need to be considered for future studies.

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14

Thomas, Zahra, Benjamin W. Abbott, Olivier Troccaz, Jacques Baudry e Gilles Pinay. "Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments". Biogeosciences 13, n. 6 (30 marzo 2016): 1863–75. http://dx.doi.org/10.5194/bg-13-1863-2016.

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Abstract (sommario):

Abstract. Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43−) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent catchment buffering capacity and the probability of human disturbance provides a useful perspective for evaluating vulnerability of aquatic ecosystems and for managing systems to maintain agricultural production while minimizing leakage of nutrients.

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15

Dabrowski, J. M. "Applying SWAT to predict ortho-phosphate loads and trophic status in four reservoirs in the upper Olifants catchment, South Africa". Hydrology and Earth System Sciences 18, n. 7 (16 luglio 2014): 2629–43. http://dx.doi.org/10.5194/hess-18-2629-2014.

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Abstract. Excessive phosphate loading in the upper Olifants River, South Africa has resulted in widespread eutrophication and associated ecosystem health impacts. The majority of sewage treatment works (STWs) are operating poorly and are likely an important source of bioavailable ortho-phosphate (OP) in the catchment. The Soil Water Assessment Tool (SWAT) was used to identify important sources of OP loading in the catchment and to predict changes in the trophic status of four reservoirs associated with three STW effluent OP standards (the current average of 4 mg L−1 and standards of 1 and 0.1 mg L−1). Nash–Sutcliffe and PBIAS statistics showed good model performance for simulations of flow and OP loading using a multi-site calibration and validation approach. Key sub-catchments responsible for high OP loading were identified. Three of the four reservoirs are heavily impacted by OP loading originating from STWs. Two reservoirs show mean annual OP concentrations indicative of eutrophic conditions and a 1 mg L−1 effluent standard would reduce concentrations to well within the mesotrophic range. There was little difference in OP loads and concentrations associated with the 1 and 0.1 mg L−1 effluent standards, indicating that attention to nonpoint sources would be required to realise any benefit associated with the strictest effluent standard. Regression analyses and associated 95% prediction limits between simulated OP loads and concentrations for all effluent treatment scenarios from 2002 to 2010 allowed for the quantification of OP loading that would ensure a specific trophic status in each reservoir. This study is one of the first to apply SWAT in simulating OP loading and concentrations in large reservoirs, and its application in South Africa provides further support for its utility throughout a wide geographical area.

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Dabrowski, J. M. "Applying SWAT to predict orthophosphate loads and trophic status in four reservoirs in the upper Olifants catchment, South Africa". Hydrology and Earth System Sciences Discussions 10, n. 11 (12 novembre 2013): 13635–70. http://dx.doi.org/10.5194/hessd-10-13635-2013.

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Abstract (sommario):

Abstract. Excessive phosphate loading in the upper Olifants River, South Africa has resulted in widespread eutrophication and associated ecosystem health impacts. The majority of sewage treatment works (STWs) are operating poorly and are likely an important source of bioavailable orthophosphate (OP) in the catchment. The Soil Water Assessment Tool (SWAT), was used to identify important sources of OP loading in the catchment and predict changes in the trophic status of four reservoirs associated with three STWs effluent OP standards; (current average of 4 mg L−1 and standards of 1 and 0.1 mg L−1). Naish-Sutcliffe and PBIAS statistics showed good model performance for simulations of flow and OP loading using a multi-site calibration and validation approach. Key sub-catchments responsible for high OP loading were identified. Three of the four reservoirs are heavily impacted by OP loading originating from STWs. Two reservoirs show mean annual OP concentrations indicative of eutrophic conditions and a 1 mg L−1 effluent standard would reduce concentrations to well within the mesotrophic range. There was little difference in OP loads and concentrations associated with the 1 and 0.1 mg L−1 effluent standard, indicating that attention to nonpoint sources would be required to realise any benefit associated with the strictest effluent standard. Regression analyses and associated 95% prediction limits between simulated OP loads and concentrations for all effluent treatment scenarios from 2002 to 2010 allowed for the quantification of OP loading that would ensure a specific trophic status in each reservoir. This study is one of the first to apply SWAT in simulating OP loading and concentrations in large reservoirs and its application in South Africa provides further support for its utility throughout a wide a geographical area.

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17

Smedberg, E., C. Humborg, M. Jakobsson e C. M. Mörth. "Landscape elements and river chemistry as affected by river regulation – a 3-D perspective". Hydrology and Earth System Sciences 13, n. 9 (9 settembre 2009): 1597–606. http://dx.doi.org/10.5194/hess-13-1597-2009.

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Abstract (sommario):

Abstract. We tested the hypothesis whether individual land classes within a river catchment contribute equally to river loading with dissolved constituents or whether some land classes act as "hot spots" to river loading and if so, are these land classes especially affected by hydrological alterations. The amount of land covered by forests and wetlands and the average soil depth (throughout this paper soil refers to everything overlying bedrock i.e. regolith) of a river catchment explain 58–93% of the variability in total organic carbon (TOC) and dissolved silicate (DSi) concentrations for 22 river catchments in Northern Sweden. For the heavily regulated Luleälven, with 7 studied sub-catchments, only 3% of the headwater areas have been inundated by reservoirs, some 10% of the soils and aggregated forest and wetland areas have been lost due to damming and further hydrological alteration such as bypassing entire sub-catchments by headrace tunnels. However, looking at individual forest classes, our estimates indicate that some 37% of the deciduous forests have been inundated by the four major reservoirs built in the Luleälven headwaters. These deciduous forest and wetlands formerly growing on top of alluvial deposits along the river corridors forming the riparian zone play a vital role in loading river water with dissolved constituents, especially DSi. A digital elevation model draped with land classes and soil depths which highlights that topography of various land classes acting as hot spots is critical in determining water residence time in soils and biogeochemical fluxes. Thus, headwater areas of the Luleälven appear to be most sensitive to hydrological alterations due to the thin soil cover (on average 2.7–4.5 m) and only patchy appearance of forest and wetlands that were significantly perturbed. Hydrological alterations of these relatively small headwater areas significantly impacts downstream flux of dissolved constituents and their delivery to receiving water bodies.

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18

Allan, Craig J. "Hydrochemical response of upland Precambrian Shield catchments to additions off H2SO4 and NH4NO3 during snowmelt". Canadian Journal of Fisheries and Aquatic Sciences 52, n. 10 (1 ottobre 1995): 2213–28. http://dx.doi.org/10.1139/f95-814.

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Abstract (sommario):

Two of three upland Precambrian Shield catchments received additions of H2SO4 and NH4NO3 prior to snowmelt in 1989 and 1990; loading levels were equivalent to 18 kg∙ha−1∙yr−1 as SO42− and 2.62 kg∙ha−1∙yr−1 as N. The third catchment served as a reference. The manipulated catchments retained 96–98% of the added NH4+, 73–94% of the added NO3−, 31–48% of the added SO42−, and 72–92% of the added H+. Proton neutralization was attributed to increased cation export (Ca2+ + Mg2+ + Na+ + K+ + Aln+ + Mn2+ + Fe2+: 26–53%) and SO42− retention (48–67%). The protonation of weak organic acids accounted for a 13–34% decline in organic anions during snowmelt. No significant change in dissolved organic carbon export was observed. In manipulated catchments, inorganic monomeric Al export increased from 30 to 80% over reference levels, and the ratio of inorganic to organic monomeric Al changed from < 1.0 to 2.7. Differences in response of the manipulated catchments were attributed to differences in soil thickness and the extent of forest cover. Interannual differences in responses were attributed to differences in snow accumulations, melt sequences, and hydrologic flushing of catchment soils.

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19

Lassaletta, L., E. Romero, G. Billen, J. Garnier, H. García-Gómez e J. V. Rovira. "Spatialized N budgets in a large agricultural Mediterranean watershed: high loading and low transfer". Biogeosciences 9, n. 1 (4 gennaio 2012): 57–70. http://dx.doi.org/10.5194/bg-9-57-2012.

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Abstract (sommario):

Abstract. Despite the particular management practices and climate characteristics of the Mediterranean regions, the literature dealing with N budgets in large catchments subjected to Mediterranean conditions is scarce. The present study aims to deepen our knowledge on the N cycle within the Ebro River Basin (NE Spain) by means of two different approaches: (1) calculating a global N budget in the Ebro River Basin and (2) calculating a series of detailed regional budgets at higher geographical resolution. N inputs and outputs were spatialized by creating a map based on the most detailed information available. Fluvial and atmospheric N export was estimated together with N retention. The Ebro River Basin annually receives a relatively high amount of new N (5118 kg N km−2 yr−1), mostly in the form of synthetic fertilizers (50%). Although it is a highly productive catchment, the net N input as food and feed import is also high (33%). Only 8% of this N is finally exported to the delta zone. Several territorial units characterized by different predominant uses (rainfed agriculture, irrigated agriculture and pastures) have differentiated N dynamics. However, due to the high density of irrigation channels and reservoirs that characterize Mediterranean catchments, N retention is very high in all of them (median value, 91%). These results indicate that problems of eutrophication due to N delivery in the coastal area may not be too severe but that high N retention values may instead lead to problems within the catchment, such as pollution of aquifers and rivers, as well as high atmospheric emissions. The most promising management measures are those devoted to reducing agricultural surpluses through a better balanced N fertilization.

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20

Hansen, O. B., C. Jacobsen, P. Harremoës e P. Skat Nielsen. "Stormwater Loading of Greater Copenhagen Sewage Treatment Plants". Water Science and Technology 27, n. 5-6 (1 marzo 1993): 49–59. http://dx.doi.org/10.2166/wst.1993.0485.

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The study presented in this paper deals with the computation of the increased hydraulic loading of the treatment plants in the Greater Copenhagen area due to the installation of more storage capacity in the combined sewer system in the future. A mathematical model is set up for the entire sewer catchment and predictions of future increased hydraulic loadings are made for various development scenarios. The computed inflow conditions are presented on a statistical form. The results show a significant increase in the hydraulic loading of the plants due to increased storage volume in the sewer system. The computed inflow statistics are used in the design of the treatment plants to ensure proper plant performance during prolonged periods with full hydraulic loading due to storm water.

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21

Sokolov, Serguei, e Kerry P. Black. "Long-term prediction of water quality for three types of catchment". Marine and Freshwater Research 50, n. 6 (1999): 493. http://dx.doi.org/10.1071/mf98069.

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Abstract (sommario):

A simple dynamic model relating the temporal change of the total mass of chemicals in a catchment to the chemical loading in the river provides high-accuracy predictions of absolute and time- integrated chemical loads. The developed model is able to reproduce effectively and simultaneously for all considered time scales the observed hysteresis in the relationship between chemical concentration in stream water and river discharge. Three types of catchment have been examined for long-term modelling: a local urban streamwater catchment, a transition urban–agricultural catchment and a large catchment with varied land use (urban, agricultural and protected forested areas). The long-period changes in model parameters and in water-quality variables are determined for each catchment.

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22

Yu, M. C. L., I. Cartwright, J. L. Braden e S. T. de Bree. "Examining the spatial and temporal variation of groundwater inflows to a valley-to-floodplain river using <sup>222</sup>Rn, geochemistry and river discharge: the Ovens River, southeast Australia". Hydrology and Earth System Sciences Discussions 10, n. 4 (24 aprile 2013): 5225–67. http://dx.doi.org/10.5194/hessd-10-5225-2013.

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Abstract (sommario):

Abstract. Radon (222Rn) and major ion geochemistry were used to define and quantify the catchment-scale river-aquifer interactions along the Ovens River in the southeast Murray-Darling Basin, Victoria, Australia, between September 2009 and October 2011. The Ovens River is characterized by the transition from a single channel river residing within a mountain valley in the upper catchment to a multi-channel meandering river on flat alluvial plains in the lower catchment. Overall, the river is dominated by gaining reaches, receiving groundwater from both alluvial and basement aquifers. The distribution of gaining and losing reaches is governed by catchment morphology and lithology. In the upper catchment, rapid groundwater recharge through sediments that have high hydraulic conductivities in a narrow valley produces higher baseflow to the river during wet (high flow) periods as a result of hydraulic loading. In the lower catchment, the open and flat alluvial plains, lower rainfall and finer-gained sediments reduce the magnitude and variability of hydraulic gradient between the aquifer and the river, producing lower and constant groundwater inflow. With a small difference between the water table and the river height, small changes in river height or in groundwater level can result fluctuating gaining and losing behaviour along the river. The middle catchment represents a transition in river-aquifer interactions from upper to lower catchment. High baseflow in some parts of the middle and lower catchments is caused by groundwater flow over basement highs. Mass balance calculations based on 222Rn activities indicate that groundwater inflow is 4–22% of total flow with higher baseflow occurring in high flow periods. Uncertainties in gas exchange coefficient and 222Rn activities of groundwater alter the calculated groundwater inflow to 3–35%. Ignoring hyporheic exchange appears not to have a significant impact on the total groundwater estimates. In comparison to 222Rn activities, Cl concentrations yield higher estimates of groundwater influxes by up to 2000% in the upper and middle catchments but lower estimates by 50–100% in the lower catchment. Hydrograph separation yields far higher baseflow fluxes than 222Rn activities and Cl concentrations. The high baseflow estimates using Cl concentrations may be due to the lack of distinct difference between groundwater and surface water Cl concentrations. The other mismatches may indicate the input of other sources of water in additional to regional groundwater.

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23

Nõges, T., R. Laugaste, E. Loigu, I. Nedogarko, B. Skakalski e P. Nõges. "Is the destabilisation of lake Peipsi ecosystem caused by increased phosphorus loading or decreased nitrogen loading?" Water Science and Technology 51, n. 3-4 (1 febbraio 2005): 267–74. http://dx.doi.org/10.2166/wst.2005.0600.

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Abstract (sommario):

Lake Peipsi (3,555 km2, mean depth 7.1 m) located on the border of Estonia and Russia is the largest transboundary lake in Europe. L. Peipsi consists of three parts. The shared largest northern part L. Peipsi s.s. (2,611 km2, 8.3 m) and the southern L. Pihkva (708 km2, 3.8 m) which belongs mainly to Russia are connected by the river-shaped L. Lämmijärv (236 km2, 2.5 m). The catchment area (44,245 km2 without lake area) is shared between Estonia (33.3%), Russia (58.6%) and Latvia (8%). Intensive eutrophication of L. Peipsi started in the 1970s. The biomass of N2-fixing cyanobacteria was low at heavy nutrient loading in the1980s. After the collapse of soviet-type agriculture in the early 1990s, the loading of nitrogen sharply decreased. A certain improvement of L. Peipsi s.s. was noticed at the beginning of the 1990s together with the temporary reduction of phosphorus loading from Estonian catchment while in recent years a destabilisation of the ecosystem has been observed. This deterioration has been expressed mainly as intensive blue-green blooms and fish-kills in summer. Reappearance of blooms has been explained by the decrease in N/P loading ratio due to reduced N discharge while in some periods increased phosphorus loading could have supported this trend.

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24

TATTARI, S., J. KOSKIAHO e I. BÄRLUND. "Testing a river basin model with sensitivity analysis and autocalibration for an agricultural catchment in SW Finland". Agricultural and Food Science 18, n. 3-4 (3 gennaio 2009): 428–39. http://dx.doi.org/10.23986/afsci.5966.

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Abstract (sommario):

Modeling tools are needed to assess (i) the amounts of loading from agricultural sources to water bodies as well as (ii) the alternative management options in varying climatic conditions. These days, the implementation of Water Framework Directive (WFD) has put totally new requirements also for modeling approaches. The physically based models are commonly not operational and thus the usability of these models is restricted for a few selected catchments. But the rewarding feature of these process-based models is an option to study the effect of protection measures on a catchment scale and, up to a certain point, a possibility to upscale the results. In this study, the parameterization of the SWAT model was developed in terms of discharge dynamics and nutrient loads, and a sensitivity analysis regarding discharge and sediment concentration was made. The SWAT modeling exercise was carried out for a 2nd order catchment (Yläneenjoki, 233 km2) of the Eurajoki river basin in southwestern Finland. The Yläneenjoki catchment has been intensively monitored during the last 14 years. Hence, there was enough background information available for both parameter setup and calibration. In addition to load estimates, SWAT also offers possibility to assess the effects of various agricultural management actions like fertilization, tillage practices, choice of cultivated plants, buffer strips, sedimentation ponds and constructed wetlands (CWs) on loading. Moreover, information on local agricultural practices and the implemented and planned protective measures were readily available thanks to aware farmers and active authorities. Here, we studied how CWs can reduce the nutrient load at the outlet of the Yläneenjoki river basin. The results suggested that sensitivity analysis and autocalibration tools incorporated in the model are useful by pointing out the most influential parameters, and that flow dynamics and annual loading values can be modeled with reasonable accuracy with SWAT. Sensitivity analysis thus showed the parameters which should be known better in order to result in more realistic parameter values. Moreover, the scenario runs for CWs made with SWAT revealed the high demand of land area for this protective measure to be substantially effective.;

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25

Etheridge, J. R., F. Birgand, M. R. Burchell II, A. Lepistö, K. Rankinen e K. Granlund. "Technical Note: Alternative in-stream denitrification equation for the INCA-N model". Hydrology and Earth System Sciences Discussions 10, n. 11 (29 novembre 2013): 14557–69. http://dx.doi.org/10.5194/hessd-10-14557-2013.

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Abstract (sommario):

Abstract. The Integrated Catchment model for Nitrogen (INCA-N) is a semi-distributed, process based model that has been used to model the impacts of land use, climate, and land management changes on hydrology and nitrogen loading. An observed problem with the INCA-N model is reproducing low nitrate-nitrogen concentrations during the summer growing season in some catchments. In this study, the current equation used to simulate the rate of in-stream denitrification was replaced with an alternate equation that uses a mass transfer coefficient and the stream bottom area. The results of simulating in-stream denitrification using the two different methods were compared for a 9 month simulation period of the Yläneenjoki catchment in Finland. The alternate equation (Nash–Sutcliffe efficiency = 0.59) simulated concentrations during the growing season that were closer to the observed concentrations than the current equation (Nash–Sutcliffe efficiency = 0.47). The results of this work promote the incorporation of the alternate equation into the model for further testing.

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26

Noh, N. S. M., L. M. Sidek, S. H. Haron, A. H. M. Puad e Z. Selamat. "Pollutant Loading Analysis of Suspended Solid, Nitrogen and Phosphorus at Bertam Catchment, Cameron Highlands using MUSIC". International Journal of Engineering & Technology 7, n. 4.35 (30 novembre 2018): 743. http://dx.doi.org/10.14419/ijet.v7i4.35.23100.

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Abstract (sommario):

This paper aimed to analyze the pollutant loading composition of suspended solids, nitrogen and phosphorus in urban stormwater at Cameron Highlands which known as popular tourism, agriculture and function as reservoir water to generate electricity. Researchers found the urban stormwater quantity modeling has achieved sufficient accuracy benchmark. However, modeling stormwater runoff quality is relatively difficult and largely depends on catchment characteristics/land-uses. Model of Urban Stormwater Improvement Conceptualization (MUSIC) estimates pollutant transport from catchments and stormwater treatment through different application of Best Management Practices (BMPs). Result obtained from the observed and calculated data was compared with MUSIC's estimations under a similar scenario where no applications of BMPs. As a second scenario, series of treatment train is propose for each sub-catchments based on the suitability and verification on site that consists of constructed stormwater treatment BMPs (wetlands, bio-retention, on-site detention, sediment basin and gross pollutant traps). Implementation of BMPs reduce nearly 100% of gross pollutant, 65% - 83% TSS, 40% - 66% TP and 52% - 78% due to effectiveness of BMPs in treating the pollutant within different landuse. As a summary, MUSIC can conceptually determine the effectiveness of BMPs without giving a detailed design.

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27

Yu, M. C. L., I. Cartwright, J. L. Braden e S. T. de Bree. "Examining the spatial and temporal variation of groundwater inflows to a valley-to-floodplain river using <sup>222</sup>Rn, geochemistry and river discharge: the Ovens River, southeast Australia". Hydrology and Earth System Sciences 17, n. 12 (6 dicembre 2013): 4907–24. http://dx.doi.org/10.5194/hess-17-4907-2013.

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Abstract (sommario):

Abstract. Radon (222Rn) and major ion geochemistry were used to define and quantify the catchment-scale groundwater-surface water interactions along the Ovens River in the southeast Murray–Darling Basin, Victoria, Australia, between September 2009 and October 2011. The Ovens River is characterized by the transition from a single channel within a mountain valley in the upper catchment to a multi-channel meandering river on flat alluvial plains in the lower catchment. Overall, the Ovens River is dominated by gaining reaches, receiving groundwater from both alluvial and basement aquifers. The distribution of gaining and losing reaches is governed by catchment morphology and lithology. In the upper catchment, rapid groundwater recharge through the permeable aquifers increases the water table. The rising water table, referred to as hydraulic loading, increases the hydraulic head gradient toward the river and hence causes high baseflow to the river during wet (high flow) periods. In the lower catchment, lower rainfall and finer-gained sediments reduce the magnitude and variability of hydraulic gradient between the aquifer and the river, producing lower but more constant groundwater inflows. The water table in the lower reaches has a shallow gradient, and small changes in river height or groundwater level can result in fluctuating gaining and losing behaviour. The middle catchment represents a transition in river-aquifer interactions from the upper to the lower catchment. High baseflow in some parts of the middle and lower catchments is caused by groundwater flowing over basement highs. Mass balance calculations based on 222Rn activities indicate that groundwater inflows are 2 to 17% of total flow with higher inflows occurring during high flow periods. In comparison to 222Rn activities, estimates of groundwater inflows from Cl concentrations are higher by up to 2000% in the upper and middle catchment but lower by 50 to 100% in the lower catchment. The high baseflow estimates using Cl concentrations may be due to the lack of sufficient difference between groundwater and surface water Cl concentrations. Both hydrograph separation and differential flow gauging yield far higher baseflow fluxes than 222Rn activities and Cl concentrations, probably indicating the input of other sources to the river in additional to regional groundwater, such as bank return flows.

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28

Hossain, Md Motaleb, Kazuhisa A. Chikita e Yoshitaka Sakata. "Sediment-Loading Processes in a Forested Catchment: Modeling and Observations". Open Journal of Modern Hydrology 13, n. 02 (2023): 94–113. http://dx.doi.org/10.4236/ojmh.2023.132005.

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29

Wang, Linhua, Haw Yen, Xinhui E, Liding Chen e Yafeng Wang. "Dissolved organic carbon driven by rainfall events from a semi-arid catchment during concentrated rainfall season in the Loess Plateau, China". Hydrology and Earth System Sciences 23, n. 7 (25 luglio 2019): 3141–53. http://dx.doi.org/10.5194/hess-23-3141-2019.

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Abstract (sommario):

Abstract. Dissolved organic carbon (DOC) transported by runoff has been identified as an important role in the global carbon cycle. Despite there being many studies on DOC concentration and flux, little information is available for the semi-arid catchments of the Loess Plateau region (LPR). The primary goal of this study was to quantify DOC exported and driven by a sequence of rainfall events during the concentrated rainfall season. In addition, factors that affect DOC export from a small headwater catchment will be investigated accordingly. Runoff discharge and DOC concentration were monitored at the outlet of the Yangjuangou catchment in Yanan, Shaanxi Province, China. The results showed that DOC concentration was highly variable, with event-based DOC concentrations ranging from 5.14 to 13.14 mg L−1. Hysteresis analysis showed a nonlinear relationship between DOC concentration and flow rate in the hydrological process. The monthly DOC flux loading from the catchment was varied from 94.73 to 110.17 kg km−2, while the event-based DOC flux ranged from 0.18 to 2.84 kg km−2 in the period of June to September. Variations of event-driven DOC concentration contributed slightly to a difference in DOC flux, whereas intra-events of rainfall amount and runoff discharge led to evident differences in DOC export. In conclusion, our case results highlighted the advantages of high-frequency monitoring for DOC export and indicated that event-driven DOC export is largely influenced by the interaction of catchment hydrology and antecedent condition within a catchment. Engineers and scientists can take advantage of the derived results to better develop advanced field monitoring work. In addition, more studies are needed to investigate the magnitude of terrestrial DOC export in response to projected climate change at larger spatio-temporal scales, which may have implications for the carbon balance and carbon cycle model from an ecologically restored catchment in the LPR.

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30

Granlund, K., K. Rankinen e A. Lepistö. "Testing the INCA model in a small agricultural catchment in southern Finland". Hydrology and Earth System Sciences 8, n. 4 (31 agosto 2004): 717–28. http://dx.doi.org/10.5194/hess-8-717-2004.

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Abstract (sommario):

Abstract. Nutrient leaching from agricultural production is still recognised as a major environmental problem in Finland. To estimate agricultural nitrogen loading under changing land-use and climate conditions, the Integrated Nitrogen Model for Catchments (INCA) was applied in Savijoki, a small (15.4 km2) agricultural catchment, which represents the intensively cultivated areas in south-western Finland. Hydrological calibration and testing of the INCA model was first carried out in Savijoki during 1981–2000. In spite of heterogeneous soil and land-use conditions, INCA was able to reproduce the overall hydrological regime in the stream. The model was calibrated further in respect of nitrogen processes during 1995–2000. The model was able, reasonably well, to simulate the overall annual dynamics of the inorganic N concentrations in the stream water and the annual N export from the catchment. The average simulated NO3-N export was 550 kg N km–2 yr–1 and the observed one (constituting more than half of the annual total N export) was 592 kg N km–2 yr–1. For NH4-N, the simulated export was somewhat higher than that measured but NH4-N was only 4% of the total N export. In spite of some underestimation of flow and N concentration during extreme hydrological conditions, the INCA model proved to be a useful tool for analysing flow pattern and inorganic nitrogen leaching in a small agricultural catchment, characterised by a rapid response to rainfall. Keywords: nitrogen, integrated modelling, hydrology, catchment, agriculture

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31

Befekadu Kebede, Adisu, Fekadu Fufa Feyessa e Wakjira Takala Dibaba. "Modeling of Phosphorous Load and Transport Pathways in Dhidhessa Catchment, Oromiya, Ethiopia". International Journal of Environment 8, n. 3 (9 dicembre 2019): 22–33. http://dx.doi.org/10.3126/ije.v8i3.26614.

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Abstract (sommario):

Pollution of surface water with harmful chemicals and eutrophication with excess nutrients are recent serious environmental concerns. This lends the need of knowing the nutrient loading and transport mechanism that will occur with different spatial and temporal extent. Thus, effective information regarding the nutrients load and transport mechanisms are important to hydrologists, water use planners, watershed managers and decision makers for water resource projects and planet ecosystem. Our study aimed for modeling of phosphorous loading and its transport pathways and to identify the most vulnerable sub basin responsible for a significant phosphorus load in Dhidhessa catchment using Soil and Water Assessment Tool (SWAT) model. The pathways of phosphorus were identified and found that the organic phosphorus was dominant exporting mechanism accounted for 58.89% of the total path in the study area. For all forms of phosphorus, surface run off was the most dominant means of transport agent. The average annual loading of total phosphorus was identified as 20 kg ha-1. The sub basins 17, 23, and 3 were identified as the highest loading area of total phosphorous in the study catchment. Best management plan which is simple, economical and adaptable over the study catchment for managing severe impact of surface run off on water resources should be adopted. It is better to undergo detail re-examination over the physical and chemical properties of P in fertilizers and manures to propose the minimizing, neutralizing, replacing strategies to reduce at the source.

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32

Ellis, J. B., e D. M. Revitt. "Defining urban diffuse pollution loadings and receiving water hazard". Water Science and Technology 57, n. 11 (1 giugno 2008): 1817–23. http://dx.doi.org/10.2166/wst.2008.278.

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Abstract (sommario):

The use of unit area loading approaches to address the requirements of the US Clean Water Act (CWA) and the EU Water Framework Directive (WFD) to identify and manage diffuse urban pollution sources is outlined. Issues relating to traditional volume-concentration probabilistic modelling are highlighted and the robustness of total maximum daily load (TMDL) approaches is discussed. A hazard assessment methodology for catchment scale identification of source area pollutant loadings and receiving water ecological impacts is developed based on urban land use activities.

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33

Lassaletta, L., E. Romero, G. Billen, J. Garnier, H. García-Gómez e J. V. Rovira. "Spatialized N budgets in a large agricultural Mediterranean watershed: high loading and low transfer". Biogeosciences Discussions 8, n. 4 (29 agosto 2011): 8723–59. http://dx.doi.org/10.5194/bgd-8-8723-2011.

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Abstract (sommario):

Abstract. Despite the particular management practices and climate characteristics of the Mediterranean regions, the literature dealing with N budgets in large catchments subjected to Mediterranean conditions is scarce. The present study aims to deepen our knowledge on the N cycle within the Ebro River Basin (NE Spain) by means of two different approaches: (1) calculating a global N budget in the Ebro River Basin and (2) calculating a series of detailed regional budgets at higher geographical resolution. N inputs and outputs were spatialized by creating a map based on the most detailed information available. Fluvial and atmospheric N export was estimated together with N retention. The Ebro River Basin annually receives a relatively high amount of new N (5118 kg N km−2 yr−1), mostly in the form of synthetic fertilizers (50 %). Although it is a highly productive catchment, the net N input as food and feed import is also high (33 %). Only 8 % of this N is finally exported to the delta zone. Several territorial units characterized by different predominant uses (rainfed agriculture, irrigated agriculture and pastures) have differentiated N dynamics. However, due to the high density of irrigation channels and reservoirs that characterize Mediterranean basins, N retention is very high in all of them (median value, 92 %). These results indicate that problems of eutrophication due to N delivery in the coastal area may not be too severe but that high N retention values may instead lead to problems within the catchment, such as pollution of aquifers and rivers, as well as high atmospheric emissions. The most promising management measures are those devoted to reducing agricultural surpluses such as balanced N fertilization and low N livestock feeding.

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34

Kondratyev, Sergey, e Nathaniel Trumbull. "Nutrient Loading on the Eastern Gulf of Finland (Baltic Sea) from the Russian Catchment Area". Journal of Hydrology and Hydromechanics 60, n. 3 (1 settembre 2012): 145–51. http://dx.doi.org/10.2478/v10098-012-0012-5.

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Abstract (sommario):

Nutrient Loading on the Eastern Gulf of Finland (Baltic Sea) from the Russian Catchment Area The identification and examination of sources of external loading are important pressure indicators for studying the nutrient balance and eutrophication of water bodies. Focusing on the eastern Gulf of Finland, this paper investigates and decomposes the sources of phosphorus, a limiting factor of eutrophication of the Gulf and its accompanying Neva Bay, and of nitrogen as pressure indicators. The eastern Gulf of Finland's catchment basin represents Europe's largest freshwater basin. Both point and non-point sources of pollution, as well as their current and possible withdrawals from the watershed's nutrient loading, are considered. The investigation identifies poultry plants and animal husbandry enterprises in the coastal watershed as critical contributing sources to eutrophication in the eastern Gulf of Finland. Analyses based on such pressure indicators can help to contribute directly to future policy-making as concerns environmental protection measures and water resources planning in the eastern Gulf of Finland and other regions.

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35

Marttila, Hannu, Ahti Lepistö, Anne Tolvanen, Marianne Bechmann, Katarina Kyllmar, Artti Juutinen, Hannah Wenng et al. "Potential impacts of a future Nordic bioeconomy on surface water quality". Ambio 49, n. 11 (12 settembre 2020): 1722–35. http://dx.doi.org/10.1007/s13280-020-01355-3.

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Abstract (sommario):

Abstract Nordic water bodies face multiple stressors due to human activities, generating diffuse loading and climate change. The ‘green shift’ towards a bio-based economy poses new demands and increased pressure on the environment. Bioeconomy-related pressures consist primarily of more intensive land management to maximise production of biomass. These activities can add considerable nutrient and sediment loads to receiving waters, posing a threat to ecosystem services and good ecological status of surface waters. The potential threats of climate change and the ‘green shift’ highlight the need for improved understanding of catchment-scale water and element fluxes. Here, we assess possible bioeconomy-induced pressures on Nordic catchments and associated impacts on water quality. We suggest measures to protect water quality under the ‘green shift’ and propose ‘road maps’ towards sustainable catchment management. We also identify knowledge gaps and highlight the importance of long-term monitoring data and good models to evaluate changes in water quality, improve understanding of bioeconomy-related impacts, support mitigation measures and maintain ecosystem services.

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36

Rankinen, Katri, Pirkko Valpasvuo-Jaatinen, Anni Karhunen, Kaarle Kenttämies, Suvi Nenonen e Ilona Bärlund. "Simulated nitrogen leaching patterns and adaptation to climate change in two Finnish river basins with contrasting land use and climatic conditions". Hydrology Research 40, n. 2-3 (1 aprile 2009): 177–86. http://dx.doi.org/10.2166/nh.2009.059.

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Abstract (sommario):

Inorganic nitrogen (N) loading was simulated by the catchment scale INCA-N model from two large river basins with contrasting land use. The main aim was to analyze the timing and origin of inorganic N loading and the effectiveness of different water protection methods. Predicted changes in precipitation and temperature increases the nutrient load from catchments to water bodies in future climate. The total inorganic N load from the forested Simojoki river basin located in northern Finland was about 5% of that from the Loimijoki river basin in south western Finland. In the Loimijoki river basin agriculture dominated inorganic N loading. When applying realistic water protection methods (limits on manure spreading) the simulated inorganic N load from the river basin decreased by 11%. With more drastic methods (no manure spreading + catch crop) a decrease up to 34% was achieved. In the Simojoki river basin there were several equally significant sources, so suitable combinations of different water protection measures would be the most efficient way to decrease the inorganic N load. As the inorganic N load may be composed of very different sources, depending on land use in the river basin, efficient allocation of water protection measures requires detailed analysis of different sources of loading.

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37

Gustafsson, Lars-Göran, Doug J. Lumley, Claes Lindeborg e Jan Haraldsson. "Integrating a Catchment Simulator into Wastewater Treatment Plant Operation". Water Science and Technology 28, n. 11-12 (1 dicembre 1993): 45–54. http://dx.doi.org/10.2166/wst.1993.0645.

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Abstract (sommario):

A catchment model which describes the hydrological and hydrodynamic processes in the catchment to the Rya wastewater treatment plant in Göteborg, Sweden is presented. The model uses hydrological models (MouseNAM) of 20 subcatchments and a hydrodynamic model (MousePIPE) of the tunnel system to make flow and CSO predictions. The catchment model has been used to evaluate several different operating strategies of the plant's pumping station and will be implemented as an operating tool. Efforts are under way to establish hydraulic and mass transport models for the pumping station and primary settling so that a loading model for the activated sludge process can be defined.

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38

Persson, K., J. Jarsjö e G. Destouni. "Diffuse hydrological mass transport through catchments: scenario analysis of physical and biogeochemical uncertainty effects". Hydrology and Earth System Sciences Discussions 8, n. 3 (12 maggio 2011): 4721–52. http://dx.doi.org/10.5194/hessd-8-4721-2011.

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Abstract (sommario):

Abstract. This paper develops and investigates the applicability of a scenario analysis approach to quantify and map the effects of physical and biogeochemical variability, cross-correlation and uncertainty on expected hydrological mass loading from diffuse sources. The approach enables identification of conservative assumptions, uncertainty ranges, as well as pollutant/nutrient release locations and situations for which further investigations are most needed in order to reduce the most important uncertainty effects. The present scenario results provide different statistical and geographic distributions of advective travel times for diffuse hydrological mass transport, and show that neglect or underestimation of the physical advection variability implies substantial risk to underestimate pollutant and nutrient loads to downstream surface and coastal waters. This is particularly true for relatively high catchment-characteristic product between average attenuation rate and average advective travel time, for which mass delivery would be near zero under assumed transport homogeneity but can be orders of magnitude higher for variable transport conditions. A scenario of high advection variability, combined with a relevant average biogeochemical mass attenuation rate, emerges consistently from the example catchment results as a generally reasonable, conservative assumption for estimating maximum diffuse mass loading when the prevailing physical and biogeochemical variability and cross-correlation are uncertain. The geographic mapping of advective travel times for this high-variability scenario identifies also directly the potential hotspot areas with large mass loading to downstream surface and coastal waters, as well as their opposite, the potential lowest-impact areas within the catchment.

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39

Chittleborough, D. J., J. W. Cox e D. P. Stevens. "Pathways of phosphorus, nitrogen, and carbon movement over and through texturally differentiated soils, South Australia". Soil Research 37, n. 4 (1999): 679. http://dx.doi.org/10.1071/sr98082.

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One method for preventing the degradation of water supplies through contamination with phosphorus (P), nitrate (NO3), and dissolved organic carbon (DOC) is to restrict movement of these contaminants from the catchment into water bodies. The purpose of the study was to quantify and characterise the proportion of NO3, P, and DOC moving from duplex soils by overland flow and through-flow on a sub-catchment scale, and to characterise soil properties that influence their movement. Two sites in the Adelaide Hills (South Australia) with contrasting duplex soils were instrumented to collect overland flow and through-flow from the soils A and B horizon. Each site contained 2 sub-catchments in close proximity. Sub-catchments were well defined by the natural topography sloping from hillcrest to a stream headwater. Soil type, especially the degree of texture contrast, the macroporosity, and the proportion of clay in the B horizon, had a large influence on the pathways of water, and therefore P, DOC, and NO3 movement. Environmentally significant concentrations of P (>0�1 mg/L) and NO3-N (>0�5 mg/L) moved overland and through these soils in 1997. High DOC loads (25 mg/L), which would also impact on water treatment costs, moved through some soils. Significant loading of P moved through and over soils in both dissolved (0�5 mg/L) and particulate (0�3 mg/L) forms. Consequently, through-flow cannot be ignored as a contributor to P in streams and both dissolved and particulate P must be measured under these conditions to define the full impact of P. The findings from this research have implications for research on catchment management to restrict DOC and nutrient movement into waterways.

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40

Wheater, H. S., D. Peach e A. Binley. "Characterising groundwater-dominated lowland catchments: the UK Lowland Catchment Research Programme (LOCAR)". Hydrology and Earth System Sciences 11, n. 1 (17 gennaio 2007): 108–24. http://dx.doi.org/10.5194/hess-11-108-2007.

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Abstract. This paper reports on a major UK initiative to address deficiencies in understanding the hydro-ecological response of groundwater-dominated lowland catchments. The scope and objectives of this national programme are introduced and focus on one of three sets of research basins – the Pang/Lambourn Chalk catchments, tributaries of the river Thames in southern England. The motivation for the research is the need to support integrated management of river systems that have high ecological value and are subject to pressures that include groundwater abstraction for water supply, diffuse pollution, and land use and climate change. An overview of the research programme is provided together with highlights of some current research findings concerning the hydrological functioning of these catchments. Despite the importance of the Chalk as a major UK aquifer, knowledge of the subsurface movement of water and solutes is poor. Solute transport in the dual porosity unsaturated zone depends on fracture/matrix interactions that are difficult to observe; current experimental and modelling research supports the predominance of matrix flow and suggests that slow migration of a time-history of decades of nutrient loading is occurring. Groundwater flows are complex; catchments vary seasonally and are ill-defined and karst features are locally important. Groundwater flow pathways are being investigated using natural and artificial geochemical tracers based on experimental borehole arrays; stream-aquifer interaction research is using a combination of geophysics, borehole array geochemistry and longitudinal profiles of stream flow and solutes. A complex picture of localised subsurface inflows, linked to geological controls and karst features, and significant longitudinal groundwater flow below the river channel is emerging. Management implications are discussed. Strategies to control surface application of nutrients are expected to have little effect on groundwater quality for several decades, and new modelling tools for decision support have been developed to represent these effects. Conventional modelling approaches are limited by the complexities of the subsurface system; catchment areas are difficult to define, hence tracking pollutant pathways to stream receptors is also problematic. Conventional distributed groundwater models have difficulty in capturing key aspects of the groundwater system. This raises important questions concerning the confidence that can be placed in models as routinely used for decision support and the level of knowledge required for catchment management to be placed on a secure scientific foundation.

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LINJAMA, J., M. PUUSTINEN e J. KOSKIAHO. "Implementation of automatic sensors for continuous monitoring of runoff quantity and quality in small catchments". Agricultural and Food Science 18, n. 3-4 (3 gennaio 2009): 417–27. http://dx.doi.org/10.23986/afsci.5957.

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Development of new automatic sensor-based techniques has expanded the possibilities for intensive monitoring of water quality in small catchments. In this study turbidity and concentration of nitrate-N were monitored with probes in the Savijoki catchment, which has been observed with traditional methods for decades. Particular attention was paid to implementation of the equipment, calibration of the probes and calculation methods. All equipment functioned technically well during the one year monitoring period. Calibration of turbidity and nitrate-N proved that the sampled values agree well with the probe results. However, it seems that loading estimates made with the traditional method are not very reliable for individual years. The research period in this study was exceptional with its many runoff peaks in winter. It is not possible to catch the peaks with traditional monitoring, why the results and comparisons between automatic probes and traditional monitoring cannot be generalized. However, the results proved that novel monitoring techniques have to be continued and extended. In further studies the calculation methods need developed and improved to be to get reliable loading estimations from the sensor data as simply as possible. In a changing climate, the monitoring, loading estimations, and consequently the assessment of the effect of agricultural water protection measures will probably turn even more difficult and challenging.;

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42

Verburg, P., J. Horrox, E. Chaney, J. C. Rutherford, J. M. Quinn, R. J. Wilcock e C. W. Howard-Williams. "Effects of nutrient loading on the trophic state of Lake Brunner". Marine and Freshwater Research 64, n. 5 (2013): 436. http://dx.doi.org/10.1071/mf12128.

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Lake Brunner, an oligotrophic monomictic lake on the West Coast of the South Island of New Zealand, is under pressure from urban expansion and increased farming activity, which has led to concern for the effects on water quality in the lake. Epilimnetic nitrogen, phosphorus and chlorophyll a concentrations have increased since 1992, and Secchi depth decreased. This suggests an increased algal productivity caused by increased nutrient inputs, further supported by increased hypolimnetic oxygen depletion since 1992. These observations are likely to have resulted from enhancement of pasture drainage and effluent inputs from expanding dairy farms. The Vollenweider model predicted a mean phosphorus concentration in the lake close to that observed, from estimated catchment loading, suggesting that the Vollenweider model adequately estimated the retention of phosphorous. With the Vollenweider model the effects of potential future loading scenarios were explored. Modelling suggested that a 70% increase in phosphorus loading could turn the lake into a mesotrophic state. Trend analysis of total phosphorus suggests that, with present land uses in the catchment (intensive dairy farming) continuing to develop at the same rate using the same land management practises, this transition to a mesotrophic state will occur by 2040.

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MIYAMOTO, Takuto, Kazuhisa A. CHIKITA, Yoshitaka SAKATA, Yasunori OCHIAI, Md Motaleb HOSSAIN, Hideo OHYAGI e Isao KUDO. "Loading processes of major ions in a forested catchment: Observations and modelling". Journal of Japanese Association of Hydrological Sciences 46, n. 1 (2016): 39–57. http://dx.doi.org/10.4145/jahs.46.39.

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44

Morrison, G. M., D. M. Revitt e J. B. Ellis. "Sources and storm loading variations of metal species in a gullypot catchment". Science of The Total Environment 80, n. 2-3 (maggio 1989): 267–78. http://dx.doi.org/10.1016/0048-9697(89)90081-8.

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45

Rosli, Nurul Ruhayu Mohd, e Khairun Yahya. "Trends of Sediment Loading in Catchment Areas of Pinang River in Malaysia". APCBEE Procedia 5 (2013): 128–33. http://dx.doi.org/10.1016/j.apcbee.2013.05.023.

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46

Wright, G. G., A. C. Edwards, J. G. Morrice e K. Pugh. "North East Scotland River Catchment Nitrate Loading in Relation to Agricultural Intensity". Chemistry and Ecology 5, n. 4 (ottobre 1991): 263–81. http://dx.doi.org/10.1080/02757549108035255.

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47

Persson, K., J. Jarsjö e G. Destouni. "Diffuse hydrological mass transport through catchments: scenario analysis of coupled physical and biogeochemical uncertainty effects". Hydrology and Earth System Sciences 15, n. 10 (20 ottobre 2011): 3195–206. http://dx.doi.org/10.5194/hess-15-3195-2011.

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Abstract. This paper quantifies and maps the effects of coupled physical and biogeochemical variability on diffuse hydrological mass transport through and from catchments. It further develops a scenario analysis approach and investigates its applicability for handling uncertainties about both physical and biogeochemical variability and their different possible cross-correlation. The approach enables identification of conservative assumptions, uncertainty ranges, as well as pollutant/nutrient release locations and situations for which further investigations are most needed in order to reduce the most important uncertainty effects. The present scenario results provide different statistical and geographic distributions of advective travel times for diffuse hydrological mass transport. The geographic mapping can be used to identify potential hotspot areas with large mass loading to downstream surface and coastal waters, as well as their opposite, potential lowest-impact areas within the catchment. Results for alternative travel time distributions show that neglect or underestimation of the physical advection variability, and in particular of those transport pathways with much shorter than average advective solute travel times, can lead to substantial underestimation of pollutant and nutrient loads to downstream surface and coastal waters. This is particularly true for relatively high catchment-characteristic product of average attenuation rate and average advective travel time, for which mass delivery would be near zero under assumed transport homogeneity but can be orders of magnitude higher for variable transport conditions. A scenario of high advection variability, with a significant fraction of relatively short travel times, combined with a relevant average biogeochemical mass attenuation rate, emerges consistently from the present results as a generally reasonable, conservative assumption for estimating maximum diffuse mass loading, when the prevailing physical and biogeochemical variability and cross-correlation are uncertain.

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Tanner, C. C., M. L. Nguyen e J. P. S. Sukias. "Constructed wetland attenuation of nitrogen exported in subsurface drainage from irrigated and rain-fed dairy pastures". Water Science and Technology 51, n. 9 (1 maggio 2005): 55–61. http://dx.doi.org/10.2166/wst.2005.0287.

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Nitrogen removal performance is reported for constructed wetlands treating subsurface drainage from irrigated and rain-fed dairy pastures in North Island, New Zealand. Flow-proportional sampling of inflow and outflow concentrations were combined with continuous flow records to calculate mass balances for the wetlands. Drainage flows from the irrigated catchment were 2.5–4 fold higher and N exports up to 5 fold higher per unit area than for the rain-fed catchment. Hydraulic and associated N loadings to the wetlands were highly pulsed, associated with rainfall, soil water status, and irrigation events. Transient pulses of organic nitrogen were an important form of N loss from the rain-fed landscape in the first year, and were very effectively removed in the wetland (>90%). Median nitrate concentrations of ∼10 g m−3 in the drainage inflows were reduced by 15–67% during passage through the wetlands and annual nitrate-N loads by 16–61% (38–317 g N m−2 y−1). Generation in the wetlands of net ammoniacal-N and organic-N (irrigated site) partially negated reduction in nitrate-N loads. The results show that constructed wetlands comprising 1–2% of catchment area can provide moderate reductions in TN export via pastoral drainage, but performance is markedly influenced by variations in seasonal loading and establishment/maturation factors.

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Ding, Weitian, Urumu Tsunogai, Fumiko Nakagawa, Takashi Sambuichi, Masaaki Chiwa, Tamao Kasahara e Ken'ichi Shinozuka. "Stable isotopic evidence for the excess leaching of unprocessed atmospheric nitrate from forested catchments under high nitrogen saturation". Biogeosciences 20, n. 3 (16 febbraio 2023): 753–66. http://dx.doi.org/10.5194/bg-20-753-2023.

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Abstract. Owing to the elevated loading of nitrogen through atmospheric deposition, some forested ecosystems become nitrogen saturated, from which elevated levels of nitrate are exported. The average concentration of stream nitrate eluted from upstream and downstream of the Kasuya Research forested catchments (FK1 and FK2 catchments) in Japan were more than 90 µM, implying that these forested catchments were under nitrogen saturation. To verify that these forested catchments were under the nitrogen saturation, we determined the export flux of unprocessed atmospheric nitrate relative to the entire deposition flux (Matm/Datm ratio) in these catchments; because the Matm/Datm ratio has recently been proposed as a reliable index to evaluate nitrogen saturation in forested catchments. Specifically, we determined the temporal variation in the concentrations and stable isotopic compositions, including Δ17O, of stream nitrate in the FK catchments for more than 2 years. In addition, for comparison, the same parameters were also monitored in the Shiiba Research forested catchment (MY catchment) in Japan during the same period, where the average stream nitrate concentration was low, less than 10 µM. While showing the average nitrate concentrations of 109.5, 90.9, and 7.3 µM in FK1, FK2, and MY, respectively, the catchments showed average Δ17O values of +2.6 ‰, +1.5 ‰, and +0.6 ‰ in FK1, FK2, and MY, respectively. Thus, the average concentration of unprocessed atmospheric nitrate ([NO3-atm]) was estimated to be 10.8, 5.1, and 0.2 µM in FK1, FK2, and MY, respectively, and the Matm/Datm ratio was estimated to be 14.1 %, 6.6 %, and 1.3 % in FK1, FK2, and MY, respectively. The estimated Matm/Datm ratio in FK1 (14.1 %) was the highest ever reported from temperate forested catchments monitored for more than 1 year. Thus, we concluded that nitrogen saturation was responsible for the enrichment of stream nitrate in the FK catchments, together with the elevated NO3-atm leaching from the catchments. While the stream nitrate concentration ([NO3-]) can be affected by the amount of precipitation, the Matm/Datm ratio is independent of the amount of precipitation; thus, the Matm/Datm ratio can be used as a robust index for evaluating nitrogen saturation in forested catchments.

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Nagafuchi, O., T. Inoue e S. Ebise. "Runoff pattern of pesticides from paddy fields in the catchment area of Rikimaru reservoir, Japan". Water Science and Technology 30, n. 7 (1 ottobre 1994): 137–44. http://dx.doi.org/10.2166/wst.1994.0327.

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Patterns of runoff behaviours in concentration and loading of pesticides from paddy fields have been intensively observed in the catchment area of Rikimaru Reservoir, mainly during the regular application period of fungicide during the summer. The runoff characteristics of three pesticides (pyroquilone, isoprothiolane and flutolanil) from paddy fields to the drainage river differed from one another due to their water solubilities. The linear correlation between the water solubilities and the amounts of pesticide runoff loadings from paddy fields to the drainage river and reservoir during dry weather days was confirmed as good on log-log paper. To reduce the risk to raw water for drinking in the reservoir the method of irrigation water management for paddy fields should be improved.

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