Effects of sheep grazing episodes on sediment and nutrient loss in overland flow

Soil Research ◽  
2004 ◽  
Vol 42 (2) ◽  
pp. 213 ◽  
Author(s):  
A. H. Elliott ◽  
W. T. Carlson
Keyword(s):  
Overland Flow ◽  
Infiltration Rate ◽  
Nutrient Loss ◽  
Late Winter ◽  
Nutrient Loads ◽  
Sheep Grazing ◽  
Bare Ground ◽  
Nitrogen And Phosphorus ◽  
Particulate Nutrients ◽  
Grass Growth

The effect of sheep grazing on the loss of sediment and nutrients in overland flow was investigated on a hill-country farm in the Waikato, New Zealand. The losses were measured in runoff produced artificially with small (0.5 m2) and large (1050 m2) rainfall simulators. Immediately after intensive winter grazing, rainfall applied at high intensity increased concentrations by a factor of 13–16 for sediment and particulate nutrients, 33–76 for dissolved reactive phosphorus and ammonium-nitrogen, and 5–7 for dissolved organic nitrogen and phosphorus. During summer, when there was less removal of vegetative cover, there was a smaller effect of grazing. The concentrations of sediment and particulate nutrients in overland flow were strongly correlated with the percentage of bare ground. The concentrations returned to background levels within 6 weeks after grazing, and the infiltration rate and ground cover also recovered from grazing in this time. The small rainfall simulator experiments showed that the infiltration rate decreases with grazing, which results in greater runoff after grazing. The greater runoff combines with the increased concentrations to give higher loads after grazing. In late winter, the infiltration rates were approximately half the summer values and the soil erodibility was approximately double, so the risk of high sediment and nutrient loads is greatest in winter, especially considering the higher rainfall and lower grass growth. The management implications are that exposure of bare ground associated with intensive grazing should be avoided, especially in winter.

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.

Geo-informatics based Morphometric Analysis of a Reservoir Catchment in Shivalik Foothills of North-West India

2021 ◽  
Vol 58 (03) ◽  
pp. 286-299
Author(s):  
Mahesh Chand Singh ◽  
Rohit Singh ◽  
Abrar Yousuf ◽  
Vishnu Prasad
Keyword(s):  
Form Factor ◽  
Soil Erosion ◽  
Morphometric Analysis ◽  
Overland Flow ◽  
Infiltration Rate ◽  
Elongation Ratio ◽  
Alos Palsar ◽  
Bifurcation Ratio ◽  
Runoff Potential ◽  
Drainage Texture

The present study examined 35 morphometric parameters related to stream/drainage network, catchment geometry, and relief aspects for hydrological characterization of the Thana Dam catchment using geospatial tools and techniques. The dam catchment was delineated using the high-resolution Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) Digital Elevation Model (DEM) data in ArcGIS 10.4.1 software using the Arc Hydro tools. The catchment is comprised of 4th order stream, obtained using a stream threshold value of 100 m length. The lower values of elongation ratio (0.61), circularity ratio (0.22), and form factor (0.29) indicated higher soil erosion potential, mainly due to their inverse relationship with land erodibility. Moreover, the higher values of stream frequency (15.7), drainage density (>5.0), drainage texture (7.48 km-1), and mean bifurcation ratio (4.08-6.33) indicated higher runoff potential, which would intensify the soil erosion, mainly due to their direct relationship with erodibility. Bifurcation ratio, elongation ratio, circulatory ratio, form factor, altogether indicated an elongated shape of the catchment with a fine drainage texture. The higher values of bifurcation ratio and texture ratio of the catchment also indicated severe overland flow (low infiltration rate) with a limited scope for groundwater recharge in the area, which in turn might significantly encourage the soil erosion. Overall, it was concluded that the catchment has a huge runoff potential resulting in high soil erosion due to its fine texture, impermeable subsurface material, steep slope, low infiltration rate, limited vegetation, longer duration of overland flow, and higher surface runoff. The morphometric analysis was found to be suitable for identifying catchment shape and the factors affecting hydrologic conditions and erodibility of the catchment. Thus, Geo-informatics based morphometric analysis of a reservoir catchment can be useful to study the erosion potential in relation to hydrologic (rainfall-runoff relationship) and other related land characteristics (e.g., relief, slope, infiltration rate, etc.).

A hysteretic model for rainfall-runoff of a simplifed catchment 

2021 ◽  
Author(s):  
Denis Flynn ◽  
Warren Roche
Keyword(s):  
Overland Flow ◽  
Previous History ◽  
Infiltration Rate ◽  
Nonlinear Phenomenon ◽  
Hysteretic Model ◽  
Rainfall Runoff ◽  
Total Runoff ◽  
History Of ◽  
Preisach Operator ◽  
Rainfall Runoff Model

<div>The soil can be modelled as a porous medium in which the three phases of matter coexist and produce the emergent phenomenon of hysteresis.</div><div>Rate-independent hysteresis is a nonlinear phenomenon where the output depends not only on the current input but also the previous history of inputs to the system. In multiphase porous media such as soils, the hysteresis is in the relationship between the soil-moisture content, and the capillary pressure.</div><div>In this work, we develop a simplified hysteretic rainfall-runoff model consisting of the following subsystems that capture much of the physics of flow through a slab of soil:</div><div>1) A slab of soil where rainfall enters and if enough water is present in the soil, it will subsequently drain into the groundwater reservoir. This part of the model is represent by ODE with a Preisach operator.</div><div>2) A runoff component: If the rainfall exceeds the maximum infiltration rate of the soil, the excess will become surface runoff. This part of the model is represented by a series of two hysteretic reservoirs instead of the two linear reservoirs in the literature.</div><div>3) A ground water storage and outflow subsystem component: this is also modelled by a hysteretic reservoir. Finally, the outputs from the groundwater output and the overland flow are combined to give the total runoff. We will examine this model and compare it with non-hysteretic case both qualitatively and quantitively.</div>

Consequences of nutrient load reductions for carbon and alkalinity dynamics within the region of freshwater influence of River Elbe

2021 ◽  
Author(s):  
Johannes Paetsch ◽  
Helmuth Thomas
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Sulfate Reduction ◽  
Biogeochemical Model ◽  
Time Interval ◽  
Nutrient Loads ◽  
Organic Matter Degradation ◽  
Strong Decrease ◽  
Nitrogen And Phosphorus ◽  
River Elbe

<p>Since the early eighties of the 20<sup>th</sup> century nitrogen and phosphorus loads of the River Elbe, a river entering the North European Shelf at the southeastern coast, have decreased by a factor of about four. This resulted in a reduction of the eutrophication status in the adjacent German Bight and the coastal waters west of Denmark. In addition, benthic carbon and alkalinity pools have changed due to 1- changed carbon loads and, 2- changed decay pathways of benthic organic carbon.</p><p>We investigate the consequences of observed nutrient and organic loads by rivers with a 3D-biogeochemical model including a 3D-early diageneses model within the sediment for the time 1979 - 2014.   </p><p>The results show a strong decrease of benthic carbon rather due to decreasing nutrient loads and subsequent autochthonous biological production than changes in organic loads. The export of inorganic carbon from the sediment is related to the magnitude of benthic organic carbon and cannot explain the strong decrease of the benthic POC pool. During the time until the early nineties aerobic degradation increases, whereas denitrification and sulfate reduction as organic matter degradation pathway decreases.</p><p>Alkalinity production due to benthic organic matter degradation decreases over the first half of the investigated time interval and keeps constant during the second half. Denitrification and sulfate reduction dominate the mechanisms decreasing the alkalinity export. Benthic nitrification consuming alkalinity strongly increases during the first half of the time dampening the decrease of alkalinity export.</p>

scholarly journals Reducing Nitrogen and Phosphorus Losses from Different Crop Types in the Water Source Area of the Danjiang River, China

2019 ◽  
Vol 16 (18) ◽  
pp. 3442 ◽  
Author(s):  
Mengjing Guo ◽  
Tiegang Zhang ◽  
Jing Li ◽  
Zhanbin Li ◽  
Guoce Xu ◽  
...  
Keyword(s):  
Total Nitrogen ◽  
Total Phosphorus ◽  
Unit Area ◽  
Nitrogen Concentration ◽  
Source Area ◽  
Water Source ◽  
Nutrient Loss ◽  
Phosphorus Concentration ◽  
Nitrogen And Phosphorus ◽  
Bare Land

Nitrogen and phosphorus are essential for plant growth and are the primary limiting nutrient elements. The loss of nitrogen and phosphorus in agricultural systems can cause the eutrophication of natural water bodies. In this paper, a field simulated rainfall experiment was conducted in a typical small watershed of the Danjiang River to study the nutrient loss process of nitrogen and phosphorus in slope croplands subjected to different crops and tillage measures. The characteristics of the runoff process and nutrient migration of different slope treatments were studied, which were the bare-land (BL, as the control), peanut monoculture (PL), corn monoculture (CL), bare land (upper slope) mixed with peanut monoculture (lower slope) (BP), corn and peanut intercropping (TCP), corn and soybean intercropping (TCS), downslope ridge cultivation (BS) slope, and straw-mulched (SC), respectively. The results showed that the runoff of CL, SC, TCS, BS, BP, PL and TCP slope types were 93%, 75%, 51%, 39%, 28%, 12%, and 6% of the those of the bare land, respectively. The total nitrogen concentration in runoff on different slope types decreased in the order of BP > PL > BS > SC > TCP > BL > CL > TCS. The BL was characterized with the highest NRL-TN (the loss of total nitrogen per unit area), with the value of 1.188 kg/hm2, while those of the TCP is the smallest with the value of 0.073 kg/hm2. The total phosphorus concentration in runoff decreasd in the order of BS > BP > PL > BL > TCP > SC > CL > TCS. The PRL-TP (the loss of total phosphorus per unit area) of BL is the largest (0.016 kg/hm2), while those of TCP is the smallest (0.001 kg/hm2). These indicate that the loss of nitrogen is much higer than that of phosphorus. The loss of nitrogen in runoff is dominated by nitrate nitrogen, which accounts for 54.4%–78.9% of TN. Slope croplands in the water source area should adopt the tillage measures of TCP and PL.These measures can reduce 85% of the runoff of nitrogen and phosphorus compared to the bare land. The results may assist in agricultural non-point source pollution control and help promote improved management of the water environment in the Danjiang River’s water source area.

scholarly journals Land Management Impacts on Soil Water Erosion and Loss of Nutrients

Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 35 ◽  
Author(s):  
Telak ◽  
Bogunovic ◽  
Rodrigo-Comino
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Land Management ◽  
Sediment Yield ◽  
Management Practices ◽  
Overland Flow ◽  
Organic Matter Content ◽  
Nutrient Loss ◽  
Plant Residues ◽  
Significant Difference

Humans are the driving factor of soil erosion and degradation. Therefore, sustainable land management practices should be developed and applied. The aim of this study was to determine land management impacts on soil properties, soil loss and nutrient loss in 3 different treatments; grass-covered vineyard (GCV), tilled vineyard (TV), and tilled hazelnut orchard (HO). The study area is located in Orahovica, Croatia (45°31′ N, 17°51′ E; elevation 230 m) on ~7° slope. The soil under the study area was classified as a Stagnosol. 8 rainfall simulations (58 mm h−1, during 30 min, over 0.785 m2 plots) were performed at each treatment where the next data were noted: ponding time, runoff time, and collection of overland flow. Soil samples were taken for determination of mean weight diameter (MWD), water stable aggregates (WSA), P2O5 content, and organic matter content. Analyses of sediment revealed concentrations of P2O5 and N. All three treatments had significantly different values of MWD (GCV 3.30 mm; TV 2.94 mm; HO 2.16 mm), while WSA and organic matter significantly differs between GCV and HO. The infiltration rate showed no significant difference between treatments. Sediment yield was significantly the highest at the TV (21.01 g kg−1 runoff), while no significant difference was noted between GCV (2.91) and HO (6.59). Sediments of GCV treatment showed higher concentrations of P2O5 and N, compared to TV and HO. Nutrients loss was highest in the TV (450.3 g P2O5 ha−1; 1891.7 g N ha−1) as a result of highest sediment yield, despite the fact GCV had the highest nutrients concentrations. Results indicate that land management (and/or tillage) affects soil properties and their stability. Even tough HO was tilled and had the lowest values of organic matter, WSA, and MWD, measurements were performed immediately after tillage where the plant residues reduced potential erodibility of the soil. Such results reveal that tillage should be avoided in vineyard and hazelnut production in order to prevent soil and nutrient losses.

scholarly journals Flood water quality and marine sediment and nutrient loads from the Tully and Murray catchments in north Queensland, Australia

2009 ◽  
Vol 60 (11) ◽  
pp. 1123 ◽  
Author(s):  
Jim Wallace ◽  
Lachlan Stewart ◽  
Aaron Hawdon ◽  
Rex Keen ◽  
Fazlul Karim ◽  
...  
Keyword(s):  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Large Contribution ◽  
Nutrient Loads ◽  
Nitrogen And Phosphorus ◽  
Annual Average ◽  
Nitrogen Loads ◽  
Flood Flows

Current estimates of sediment and nutrient loads from the Tully–Murray floodplain to the Great Barrier Reef lagoon are updated by taking explicit account of flood events. New estimates of flood discharge that include over-bank flows are combined with direct measurements of sediment and nutrient concentrations in flood waters to calculate the loads of sediment and nutrient delivered to the ocean during 13 floods that occurred between 2006 and 2008. Although absolute concentrations of sediment and nutrient were quite low, the large volume of water discharged during floods means that they make a large contribution (30–50%) to the marine load. By not accounting for flood flows correctly, previous estimates of the annual average discharge are 15% too low and annual loads of nitrogen and phosphorus are 47% and 32% too low respectively. However, because sediments may be source-limited, accounting for flood flows simply dilutes their concentration and the resulting annual average load is similar to that previously estimated. Flood waters also carry more dissolved organic nitrogen than dissolved inorganic nitrogen and this is the opposite of their concentrations in river water. Consequently, dissolved organic nitrogen loads to the ocean may be around twice those previously estimated from riverine data.

scholarly journals Future socioeconomic conditions may have a larger impact than climate change on nutrient loads to the Baltic Sea

AMBIO ◽  
2019 ◽  
Vol 48 (11) ◽  
pp. 1325-1336 ◽  
Author(s):  
Alena Bartosova ◽  
René Capell ◽  
Jørgen E. Olesen ◽  
Mohamed Jabloun ◽  
Jens Christian Refsgaard ◽  
...  
Keyword(s):  
Climate Change ◽  
Baltic Sea ◽  
Dynamic Modelling ◽  
Climate Change Scenarios ◽  
Nutrient Loads ◽  
The Baltic Sea ◽  
Nitrogen And Phosphorus ◽  
Socioeconomic Drivers ◽  
The Baltic ◽  
The Impact

Abstract The Baltic Sea is suffering from eutrophication caused by nutrient discharges from land to sea, and these loads might change in a changing climate. We show that the impact from climate change by mid-century is probably less than the direct impact of changing socioeconomic factors such as land use, agricultural practices, atmospheric deposition, and wastewater emissions. We compare results from dynamic modelling of nutrient loads to the Baltic Sea under projections of climate change and scenarios for shared socioeconomic pathways. Average nutrient loads are projected to increase by 8% and 14% for nitrogen and phosphorus, respectively, in response to climate change scenarios. In contrast, changes in the socioeconomic drivers can lead to a decrease of 13% and 6% or an increase of 11% and 9% in nitrogen and phosphorus loads, respectively, depending on the pathway. This indicates that policy decisions still play a major role in climate adaptation and in managing eutrophication in the Baltic Sea region.

scholarly journals Catchment modelling of sediment, nitrogen and phosphorus nutrient loads with SedNet/ANNEX in the Tully - Murray basin

2009 ◽  
Vol 60 (11) ◽  
pp. 1091 ◽  
Author(s):  
J. D. Armour ◽  
L. R. Hateley ◽  
G. L. Pitt
Keyword(s):  
Biophysical Model ◽  
Nutrient Loads ◽  
Inorganic N ◽  
Nitrogen And Phosphorus ◽  
Total N ◽  
Hill Slope ◽  
Eastern Australia ◽  
North Eastern ◽  
Wet Tropics ◽  
The Impact

A long-term, annual-average catchment biophysical model (SedNet/ANNEX) was used to calculate sediment, nitrogen (N) and phosphorus (P) loads in the Tully–Murray catchment of north-eastern Australia. A total of 119 000 t year–1 of suspended sediment, equivalent to 430 kg ha–1 year–1, was calculated to be exported to the Great Barrier Reef (GBR). Most of the sediment (64%) was generated from hill-slope erosion. The modelled load of dissolved inorganic N (1159 t year–1 or 4.2 kg N ha–1 year–1) was similar to that from other wet tropics catchments in Queensland with similar areas of sugarcane. Sugarcane produced 77% of this load. The annual loads of total N and total P were 2319 t and 244 t, respectively. Simulations (scenarios) were run to evaluate the impact of improved land management on pollutant loads to the GBR. A combination of improved cultivation and fertiliser management of sugarcane and bananas (99% of cropping land) and restoration of the most degraded riparian areas reduced sediment by 23 000 t year–1 (18%) and dissolved inorganic N by 286 t year–1 (25%). However, this reduction is much less than the reduction of 80% that may be needed in the catchment to meet target chlorophyll loads in the marine environment.

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