Wetter, but not wet enough – limited greenhouse gas mitigation effects of submerged drains and blocked ditches in an intensively used grassland on fen peat

2021 ◽  
Author(s):  
Sebastian Heller ◽  
Peter Gatersleben ◽  
Sebastian Oehmke ◽  
Ullrich Dettmann ◽  
Melanie Bräuer ◽  
...  
Keyword(s):  
Water Management ◽  
Ghg Emissions ◽  
Water Levels ◽  
Greenhouse Gas Mitigation ◽  
First Year ◽  
Management Options ◽  
Groundwater Levels ◽  
The North ◽  
Fodder Quality ◽  
Additional Release

<p>The vast majority of peatlands in the North German Plain are cultivated as grassland. Intensive drainage measures are a prerequisite for conventional agricultural use of peatlands, but this practice causes high emissions of greenhouse gases (GHG), mainly carbon dioxide (CO<sub>2</sub>). Thus, raising the water levels is necessary to reduce or stop CO<sub>2</sub> emissions. Water management options such as submerged drains (SD) and ditch blocking (DB) are discussed as a potential compromise between maintaining the trafficability for intensive grassland use and reducing the GHG emissions. Furthermore, grassland renewal is regularly practiced to improve the fodder quality for dairy farming; however, this might cause additional release of GHGs, especially nitrous oxide (N<sub>2</sub>O). Here, we present results of a four-year study on the GHG emissions from an intensively used grassland on fen peat equipped with SD and DB. Additionally, the effect of grassland renewal by shallow ploughing and direct sowing was evaluated.</p><p>The target groundwater levels were set to -0.30 m below ground. In the first year, the water management system was optimized. In the following years, mean annual water levels at the parcels with SD were -0.23 m and at the parcels with DB -0.37 m. The groundwater level at the SD parcels was around 0.18 m higher than at the conventionally drained control parcels. Thus, water management by SD enabled us to even surpass the target water levels. However, year two and three of the study were dryer than usual, the differences between the SD parcels and the control parcels are expected to be lower in wet years. DB, in contrast, raised the water levels only marginally.</p><p>During the first three years, control parcels with ditch drainage emitted 27-49 t CO<sub>2</sub>-eq. ha<sup>-1</sup> a<sup>-1</sup>. This is within the typical range of emissions from grasslands on fen peat in Germany. On average, the parcels with SD showed slightly lower emissions than the drained control parcels, but these were highly variable (16-60 t CO<sub>2</sub>-eq. ha<sup>-1</sup> a<sup>-1</sup>). Due to similar groundwater levels the emissions from the parcel with DB (23-43 t CO<sub>2</sub>-eq. ha<sup>-1</sup> a<sup>-1</sup>) were comparable to the drained control parcels. Reasons for the high CO<sub>2</sub> emissions despite increased groundwater levels by SD remain so far unclear. Both types of grassland renewal lead to higher N<sub>2</sub>O emissions during the first year after renewal. Afterwards, effects became ambiguous.  </p><p>Results from the fourth measurement year (2020) will be presented as well. So far, the data seems to support the results of the previous years.</p>

scholarly journals An updated water balance for the Grootfontein aquifer near Mahikeng

Water SA ◽  
2018 ◽  
Vol 44 (1 January) ◽  
Author(s):  
JE Cobbing
Keyword(s):  
Water Balance ◽  
Public Interest ◽  
Water Levels ◽  
Domestic Water ◽  
Groundwater Levels ◽  
North West ◽  
The Public ◽  
The North ◽  
Increasing Risk ◽  
Natural Spring

The Grootfontein Aquifer, part of the important North West dolomite aquifers, supplies about 20% of Mahikeng’s domestic water needs. Over-abstraction caused the large natural spring draining the aquifer to disappear in 1981, and groundwater levels have since fallen nearly 30 m in the vicinity of the former spring. Analysis of water levels and a water balance using recent assessments of groundwater abstractions confirm past work describing the hydrogeological functioning of the aquifer, and suggest that current abstractions need to fall by between 19 and 36 ML/day (7 and 13 Mm3/a) to bring the aquifer back into longterm balance. Continued over-abstraction at Grootfontein implies increasing risk to Mahikeng’s water supply, and illuminates the larger challenge of ensuring groundwater use in the North West dolomites that is sustainable and in the public interest.

Evaluation of surface and groundwater management strategies for drained sulfidic soil using numerical simulation models

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 569 ◽  
Author(s):  
B. G. Blunden ◽  
B. Indraratna
Keyword(s):  
Water Management ◽  
Agricultural Land ◽  
Management Strategies ◽  
Pyrite Oxidation ◽  
Water Levels ◽  
Acid Sulfate Soils ◽  
Drain Water ◽  
Management Options ◽  
Acid Sulfate ◽  
Sulfate Soils

The effective management of acid sulfate soils is a major issue for many coastal regions in Australia. Simulations were conducted to evaluate 4 different water management strategies that could be applied to agricultural land on the south coast of New South Wales, Australia, to minimise acid generation from acid sulfate soils. The water management strategies are compared with the existing extensively drained situation which generates and discharges large quantities of acidic pyrite oxidation products. The 4 water management strategies include elevated drain water levels using a weir, 25 mm irrigation on a 7- or 14-day cycle, and elevated drain water levels with irrigation. All of these strategies were designed to minimise the generation of acid by reducing the transport of oxygen to the sulfidic soil. Simulations were conducted for weather and site conditions experienced during a 12-month period starting in July 1997. Model simulations showed that maintenance of elevated drain water levels using a weir in the drain significantly reduced the amount of acid generated by 75% and 57%, at 10 and 90 m distance from the drain, respectively, by comparison with the existing drained state. The addition of 25 mm irrigation on a 14-day cycle to the weir simulation reduced the oxidation of pyrite by a further 1–2%. Application of irrigation only on a 7-day cycle also reduced the acid generated by 89% and 94% at 10 and 90 m distance from the drain, respectively, by comparison with the existing drained state. Irrigation on a 14-day cycle was not as successful in reducing pyrite oxidation as either the 7-day irrigation or weir strategies. Evaluation of the 4 water management options showed that significant improvements can be made with respect to the amount of acid generated by relatively simple and cost-effective land management practices.

scholarly journals Impacts of climate variability on wetland salinization in the North American Prairies

2013 ◽  
Vol 10 (11) ◽  
pp. 13475-13503
Author(s):  
U. Nachshon ◽  
A. Ireson ◽  
G. van der Kamp ◽  
S. R. Davies ◽  
H. S. Wheater
Keyword(s):  
Chemical Composition ◽  
North American ◽  
Meteorological Data ◽  
Climatic Variability ◽  
Summer Rainfall ◽  
Pond Water ◽  
Water Levels ◽  
Water Volume ◽  
Groundwater Levels ◽  
The North

Abstract. The glaciated plains of the North American continent, also known as the "prairies", are a complex hydrological system characterized by hummocky terrain, where wetlands, containing seasonal or semi-permanent ponds, occupy the numerous topographic depressions. The prairie subsoil and many of its water bodies contain high salt concentrations, in particular sulfate salts, which are continuously cycled within the closed drainage basins. The period between 2000 and 2012 was characterized by an unusual degree of climatic variability, including severe floods and droughts, and this had a marked effect on the spatial distribution, water levels and chemical composition of wetland ponds. Understanding the geochemical and hydrological processes under changing environmental conditions is needed in order to better understand the risk and mitigate the impacts of future soil and water salinization. Here we explore salt dynamics in the prairies using field observations from St. Denis, Saskatchewan, taken over the last 40 yr. Measurements include meteorological data, soil salinity, groundwater levels and pond water volume, salinity, and chemical composition. The record includes periods of exceptional snow (1997, 2007) and periods of exception rainfall (2010, 2012), both of which resulted in unusually high pond water levels. However, severe salinization only occurred in response to extreme summer rainfall. We hypothesize that since rainfall and snowmelt activate different hydrological pathways, they have markedly different impacts on salinization. We propose that a wet condition associated with high snowmelt conditions does not pose a strong threat to salinization, which has important implications for agricultural planning. Whilst this hypothesis is consistent with our conceptual understanding of the system, it needs to be tested further at a range of field sites in the prairies.

Effects of grassland renewal and submerged drains on greenhouse gas exchange at an intensively managed bog peat soil

2020 ◽  
Author(s):  
Liv Sokolowsky ◽  
Bärbel Tiemeyer ◽  
Ullrich Dettmann ◽  
Merten Minke ◽  
Jeremy Rüffer ◽  
...  
Keyword(s):  
Water Management ◽  
Management System ◽  
Reference Site ◽  
Grassland Management ◽  
Water Levels ◽  
Water Management System ◽  
Groundwater Levels ◽  
Tile Drains ◽  
Project Site ◽  
Grass Sward

<p>Intact peatland ecosystems are efficient sinks of atmospheric carbon dioxide (CO<sub>2</sub>). Disturbance, e.g. by drainage to transform peatlands into agricultural land, causes high emissions of the greenhouse gases (GHG) CO<sub>2</sub> and nitrous oxide (N<sub>2</sub>O). Our Project “Gnarrenburger Moor” focuses on the evaluation of the effects of submerged drains on GHG emissions and dissolved solute losses from bog peat under intensive grassland management. Due to installation of the water management system, grassland renewal was necessary at one of our two experimental grassland sites, both being located in Northwest Germany and subjected to similar management in the past. Here, we report on the initial year of the project, which was dominated by the impact of grassland renewal as target groundwater levels were only reached after several months.</p><p>The reference site, representing common region-specific grassland management on peat, is deeply drained by tile drains, while submerged drains were installed at the project site to achieve constantly high water levels of 30 to 40 cm below ground. Both sites are equipped with eddy covariance towers for CO<sub>2</sub> measurements and 6 plots for manually measuring N<sub>2</sub>O and methane (CH<sub>4</sub>) with closed chambers. Water samples for the analysis of phosphorus and nitrogen species are collected from ditches, tile drains and suction plates at 15, 30 and 60 cm depths. Measurements started in March 2019, i.e. approximately one month before the grassland renewal. The mechanical renewal involved mulching of the old grass sward and grading the surface of the site. Due to very dry conditions, growth of grass species was poor and the site was mulched and re-seeded again in July 2019. Target groundwater levels were reached in September 2019.</p><p>During the initial year of our study, grassland renewal substantially dominated the response of the system. From April to November, net ecosystem exchange of the project site was approximately 400 g C m<sup>-2</sup> higher than that of the reference site. When including carbon input and output from organic fertilizer and harvest on the reference site, the project site is still by far (around 140 g C m<sup>-2</sup>) a larger source. When the bare soil and raising groundwater levels coincided between July and September, N<sub>2</sub>O fluxes and dissolved nitrogen and phosphorus concentrations drastically increased at the project site. N<sub>2</sub>O fluxes were partially 100 times higher than at the reference site. The next years will show whether an operational water management system and a fully developed grass sward will turn the project site with submerged drains into a smaller source of GHGs than the reference site.</p>

scholarly journals Impacts of climate variability on wetland salinization in the North American prairies

2014 ◽  
Vol 18 (4) ◽  
pp. 1251-1263 ◽  
Author(s):  
U. Nachshon ◽  
A. Ireson ◽  
G. van der Kamp ◽  
S. R. Davies ◽  
H. S. Wheater
Keyword(s):  
Chemical Composition ◽  
North American ◽  
Meteorological Data ◽  
Climatic Variability ◽  
Pond Water ◽  
Water Levels ◽  
Salt Transport ◽  
Water Volume ◽  
Groundwater Levels ◽  
The North

Abstract. The glaciated plains of the North American continent, also known as the "prairies", are a complex hydrological system characterized by hummocky terrain, where wetlands, containing seasonal or semi-permanent ponds, occupy the numerous topographic depressions. The prairie subsoil and many of its water bodies contain high salt concentrations, in particular sulfate salts, which are continuously cycled within the closed drainage basins. The period between 2000 and 2012 was characterized by an unusual degree of climatic variability, including severe floods and droughts, and this had a marked effect on the spatial distribution, water levels and chemical composition of wetland ponds. Understanding the geochemical and hydrological processes under changing environmental conditions is needed in order to better understand the risk and mitigate the impacts of future soil and water salinization. Here we explore salt dynamics in the prairies using field observations from St. Denis, Saskatchewan, taken mostly over the last 20 years. Measurements include meteorological data, soil moisture, soil salinity, groundwater levels and pond water volume, salinity, and chemical composition. The record includes periods of exceptional snow (1997, 2007) and periods of exception rainfall (2010, 2012), both of which resulted in unusually high pond water levels. Measurements indicated that severe pond salinization only occurred in response to extreme summer rainfall. It is hypothesized that since rainfall water infiltrates through the soil towards the depressions, while snowmelt water flows mainly as surface water over frozen soils, they have markedly different impacts on salt transport and pond salinization. Whilst this hypothesis is consistent with our conceptual understanding of the system, it needs to be tested further at a range of field sites in the prairies.

scholarly journals Seasonal effects of controlled drainage on field water balance and groundwater levels

2021 ◽  
Author(s):  
Heidi Salo ◽  
Aleksi Salla ◽  
Harri Koivusalo
Keyword(s):  
Water Management ◽  
Water Balance ◽  
Model Performance ◽  
Shallow Groundwater ◽  
Seasonal Effects ◽  
Controlled Drainage ◽  
Management Options ◽  
Data Set ◽  
Groundwater Levels ◽  
Field Water Balance

Abstract Adaptive water management solutions such as controlled drainage have raised interest in Nordic areas due to climate variability. It is not fully known how controlled drainage affects seasonal field water balance or can help in preventing water scarcity during dry growing seasons (GSs). The objective was to simulate the effects of controlled drainage on field hydrology using a well-tested, process-based hydrological model. The FLUSH model was calibrated and validated to an experimental field. The model performance with non-local input data was moderate but acceptable for running the controlled drainage scenarios to test the response of the water management method to meteorological forcing. Simulation results showed that controlled drainage reduced drain discharge while increasing surface layer runoff and shallow groundwater outflow. Groundwater depths from the scenario simulations demonstrated that controlled drainage could keep the depth closer to the soil surface, but the effect diminished during the dry conditions. Controlled drainage can be used to change the water flow pathways but has a secondary effect compared with the primary meteorological drivers. The field data set and FLUSH formed a novel computational platform to study the impacts of different water management options on the whole water balance and spatial variability of groundwater depths.

Using groundwater levels and Specific Yield to Estimate the Recharge, South of Erbil, Kurdistan Region, Iraq

2018 ◽  
Vol 7 (4) ◽  
pp. 191
Author(s):  
Sherwan Sh. Qurtas
Keyword(s):  
Unconfined Aquifer ◽  
Middle Part ◽  
Water Levels ◽  
Specific Yield ◽  
Aquifer System ◽  
Groundwater Levels ◽  
Monitoring Wells ◽  
Water Table Fluctuation Method ◽  
Recharge Estimation ◽  
Fluctuation Method

Recharge estimation accurately is crucial to proper groundwater resource management, for the groundwater is dynamic and replenished natural resource. Usually recharge estimation depends on the; the water balance, water levels, and precipitation. This paper is studying the south-middle part of Erbil basin, with the majority of Quaternary sediments, the unconfined aquifer system is dominant, and the unsaturated zone is ranging from 15 to 50 meters, which groundwater levels response is moderate. The purpose of this study is quantification the natural recharge from precipitation. The water table fluctuation method is applied; using groundwater levels data of selected monitoring wells, neighboring meteorological station of the wells, and the specific yield of the aquifers. This method is widely used for its simplicity, scientific, realistic, and direct measurement. The accuracy depends on the how much the determination of specific yield is accurate, accuracy of the data, and the extrapolations of recession of groundwater levels curves of no rain periods. The normal annual precipitation there is 420 mm, the average recharge is 89 mm, and the average specific yield is around 0.03. The data of one water year of 2009 and 2010 has taken for some technical and accuracy reasons.

Integrated waste water management for a small river basin - a case study

1998 ◽  
Vol 38 (11) ◽  
pp. 87-95
Author(s):  
R. Fenz ◽  
M. Zessner ◽  
N. Kreuzinger ◽  
H. Kroiss
Keyword(s):  
Waste Water ◽  
Water Management ◽  
River Basin ◽  
Rural Areas ◽  
Urban Areas ◽  
Waste Water Treatment ◽  
Point Of View ◽  
Political Issue ◽  
The North ◽  
Waste Water Management

In Austria approximately 70% of the population is connected to sewerage and to biological waste water treatment plants. Whereas the urban areas are already provided with these facilities to a very high extent, effort is still needed in rural areas to meet the requirements of the Austrian legislation. The way, this task should be solved has provoked much controversy. It is mainly the question, whether centralised or decentralised sewage disposal systems are preferable from the ecological and economical point of view, that became a political issue during the last 5 years. The Institute for Water Quality and Waste Management was asked to elaborate a waste water management concept for the Lainsitz River Basin, a mainly rural area in the north of Austria discharging to the Elbe river. Both ecological and economical aspects should be considered. This paper presents the methodology that was applied and the criteria which were decisive for the selection of the final solution.

Lake and inland dunes as interconnected Systems: The story of Lake Tresssee and an adjacent dune field (Schleswig-Holstein, North Germany)

The Holocene ◽  
2020 ◽  
pp. 095968362098168
Author(s):  
Christian Stolz ◽  
Magdalena Suchora ◽  
Irena A Pidek ◽  
Alexander Fülling
Keyword(s):  
Water Level ◽  
Bronze Age ◽  
Environmental Changes ◽  
High Water ◽  
Alluvial Fan ◽  
Water Levels ◽  
Lake Area ◽  
Dune Field ◽  
The North ◽  
Sand Drift

The specific aim of the study was to investigate how four adjacent geomorphological systems – a lake, a dune field, a small alluvial fan and a slope system – responded to the same impacts. Lake Tresssee is a shallow lake in the North of Germany (Schleswig-Holstein). During the Holocene, the lake’s water surface declined drastically, predominately as a consequence of human impact. The adjacent inland dune field shows several traces of former sand drift events. Using 30 new radiocarbon ages and the results of 16 OSL samples, this study aims to create a new timeline tracing the interaction between lake and dunes, as well, as how both the lake and the dunes reacted to environmental changes. The water level of the lake is presumed to have peaked during the period before the Younger Dryas (YD; start at 10.73 ka BC). After the Boreal period (OSL age 8050 ± 690 BC) the level must have undergone fluctuations triggered by climatic events and the first human influences. The last demonstrable high water level was during the Late Bronze Age (1003–844 cal. BC). The first to the 9th century AD saw slightly shrinking water levels, and more significant ones thereafter. In the 19th century, the lake area was artificially reduced to a minimum by the human population. In the dunes, a total of seven different phases of sand drift were demonstrated for the last 13,000 years. It is one of the most precisely dated inland-dune chronologies of Central Europe. The small alluvial fan took shape mainly between the 13th and 17th centuries AD. After 1700 cal. BC (Middle Bronze Age), and again during the sixth and seventh centuries AD, we find enhanced slope activity with the formation of Holocene colluvia.

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