scholarly journals Applications of digital baseflow separation techniques for model validation, Wairarapa valley, New Zealand

2021 ◽  
Author(s):  
◽  
Lucas Everitt
Keyword(s):  
New Zealand ◽  
Digital Filters ◽  
Model Performance ◽  
High Water ◽  
Surface Flow ◽  
Catchment Scale ◽  
Baseflow Separation ◽  
The Difference ◽  
Recursive Digital Filters

<p>The representation of groundwater processes in hydrological models is crucial, as the connectivity between groundwater and surface water is significant. It is particularly important for regions such as the Wairarapa that experience high water stresses. Intensified agriculture has increased demand for irrigation, which can lead to depletion and degradation of reservoirs. This study compared observed streamflow records to TopNet-0 and TopNet-GW model outputs at points along the Mangatarere stream, a sub-catchment in the Wairarapa valley, New Zealand. Model performance was assessed using a suite of quantitative and qualitative comparisons. This analysis aimed to assess the similarities and differences between observed flow and the model outputs with respect to their model structures. Baseflow estimates from recursive digital filters were also compared at these sites to assess the groundwater representation of the models. The investigation can be considered representative of the wider Ruamahanga catchment, as the geology and hydrology in the region is relatively analogous. Flow infilling and baseflow separation was undertaken at 13 Wairarapa flow gauges to provide considerations to the model outputs. Options investigated for flow infilling included a straight infill or calculation of the flow difference at each point. Potential multipliers included a long-term or a monthly option. The difference infill, coupled with the long-term multiplier, was found to be the optimum method. Independent baseflow estimates included a Q90/Q50 flow duration curve index and indices generated from the Eckhardt and Bump & Rise recursive digital filters. The two digital filters produced similar statistics but were found to employ uncertain parameters that significantly affect outputs. TopNet-GW benefitted from up-to-date calibrations and as such produced generally excellent simulations in comparison to observed streamflow. With the addition of the deep groundwater conceptual reservoir in the structure of the model, simulated flow baseflow index estimates and graphical assessment of flow recession curves indicate TopNet-GW reproduces groundwater processes well despite potential over-representation of baseflow at the expense of high flow periods during peak flows. These findings highlight the importance of combining subsurface and surface flow dynamics to resolve water management issues and improve model performance at the catchment scale.</p>

scholarly journals Applications of digital baseflow separation techniques for model validation, Wairarapa valley, New Zealand

2021 ◽  
Author(s):  
◽  
Lucas Everitt
Keyword(s):  
New Zealand ◽  
Digital Filters ◽  
Model Performance ◽  
High Water ◽  
Surface Flow ◽  
Catchment Scale ◽  
Baseflow Separation ◽  
The Difference ◽  
Recursive Digital Filters

<p>The representation of groundwater processes in hydrological models is crucial, as the connectivity between groundwater and surface water is significant. It is particularly important for regions such as the Wairarapa that experience high water stresses. Intensified agriculture has increased demand for irrigation, which can lead to depletion and degradation of reservoirs. This study compared observed streamflow records to TopNet-0 and TopNet-GW model outputs at points along the Mangatarere stream, a sub-catchment in the Wairarapa valley, New Zealand. Model performance was assessed using a suite of quantitative and qualitative comparisons. This analysis aimed to assess the similarities and differences between observed flow and the model outputs with respect to their model structures. Baseflow estimates from recursive digital filters were also compared at these sites to assess the groundwater representation of the models. The investigation can be considered representative of the wider Ruamahanga catchment, as the geology and hydrology in the region is relatively analogous. Flow infilling and baseflow separation was undertaken at 13 Wairarapa flow gauges to provide considerations to the model outputs. Options investigated for flow infilling included a straight infill or calculation of the flow difference at each point. Potential multipliers included a long-term or a monthly option. The difference infill, coupled with the long-term multiplier, was found to be the optimum method. Independent baseflow estimates included a Q90/Q50 flow duration curve index and indices generated from the Eckhardt and Bump & Rise recursive digital filters. The two digital filters produced similar statistics but were found to employ uncertain parameters that significantly affect outputs. TopNet-GW benefitted from up-to-date calibrations and as such produced generally excellent simulations in comparison to observed streamflow. With the addition of the deep groundwater conceptual reservoir in the structure of the model, simulated flow baseflow index estimates and graphical assessment of flow recession curves indicate TopNet-GW reproduces groundwater processes well despite potential over-representation of baseflow at the expense of high flow periods during peak flows. These findings highlight the importance of combining subsurface and surface flow dynamics to resolve water management issues and improve model performance at the catchment scale.</p>

Eco-hydrology interactions between trees, soil and water in terrestrial and wetland areas: The effect of tree planting on water flow dynamics in Wairarapa Wetlands, New Zealand

2021 ◽  
Author(s):  
◽  
Tapuwa Marapara
Keyword(s):  
New Zealand ◽  
Hydraulic Properties ◽  
Forested Wetlands ◽  
High Water ◽  
Flood Mitigation ◽  
Forested Wetland ◽  
Soil Hydrology ◽  
Catchment Scale ◽  
Soil And Water

<p>During the last two decades there has been increasing interest in the role of forests and wetlands as flood mitigating tools due to growing concerns regarding the sustainability of many traditional engineering flood defences such as dykes, sea walls and dams. In forests, the role is facilitated by the interaction between trees, soil and water. Specifically trees reduce surface runoff and prevent flooding through increased evapotranspiration and canopy interception and enhance physical and hydraulic properties of soil that are critical for the absorption and retention of flood waters by the soil. It is increasingly realised that the answer to flood mitigation is not a blanket recommendation to “plant trees”. This is because the role of trees varies spatially and temporally as a function of climate, topography, rainfall properties, soil type and condition, catchment scale and geology, among others. For example, where trees are present in wetlands, particularly forested wetlands, the mechanisms by which trees interact with soil and water are similar to that in forests but because of a high water table, the impact of trees may be reduced. Therefore, the mere presence of forests and forested wetlands will not necessarily deliver flood risk management.  The purpose of this study was to explore the effectiveness of trees as flood mitigating tools under various bio-geo climatic factors in forests and forested wetland environments. Three forms of investigation were followed to fulfil this purpose.  A detailed literature review was carried out to assess the role of trees and forests as flood mitigation tools under changing climate, topography, species type, rainfall properties, soil type and condition, catchment scale and geology. A field experiment was carried out to collect data and analyse the effect of trees on soil physical and hydraulic properties that include bulk density, saturated hydraulic conductivity, soil organic carbon, soil moisture content, matric potential and soil moisture retention in a previously forested wetland undergoing restoration in New Zealand. A spatially explicit decision support tool, the Land Use Capability Indicator (LUCI) was then used to determine appropriate areas where intervention can be targeted to optimise the role of trees as flood mitigating tools in previously forested wetlands undergoing restoration.  The detailed review identified a major data gap in the role of trees under hydric conditions (high water table), along with uncertainties on their effectiveness in large catchments (>˜40 km²) and in extreme rainfall events. The field experiment provided the first set of soil hydrology data from an ephemeral wetland in New Zealand showing the benefits of newly established trees in improving hydraulic conductivity of soils. The soil hydrology data is a useful baseline for continuous monitoring of the forested wetlands undergoing restoration. The use of the Land Use Capability Indicator was its first application for the optimisation of flood mitigation in a forested wetland. Its suggested target areas are not necessarily conducive for survival of some tree species, although if suitable species are established, flood risk mitigation could be maximised. Further research on what native species are best for what conditions and in what combinations is recommended, to increase survival in the proposed target areas.</p>

scholarly journals Application of recursive digital filter (RDF) methods for baseflow separation: study at Brantas watershed

2019 ◽  
Vol 9 (3) ◽  
pp. 626-640
Author(s):  
Indarto Indarto ◽  
Elida Novita ◽  
Sri Wahyuningsih ◽  
Nur Defitri Herlinda ◽  
Entin Hidayah
Keyword(s):  
Digital Filters ◽  
Optimal Parameter ◽  
Dry Season ◽  
Rainfall Data ◽  
Coefficient Of Determination ◽  
Calibration Period ◽  
Calibration Process ◽  
Baseflow Separation ◽  
Daily Discharge ◽  
Recursive Digital Filters

Baseflow is an important component affecting the availability of water in the river during the dry season. Availability of water in the dry season is useful for water resources management. This research aims to test and to compare six recursive digital filters (RDF) methods for calculating baseflow and baseflow index. This research was conducted in Brantas Watershed. Two outlets (sub-watersheds) located at Kertosono and Ploso were used.  Daily discharge from 1996 to 2015 of the two outlets above was used as main input for this study. While rainfall data were used to determine the calibration period. The sequence procedures of this research, consist of: (1) inventory of daily discharge and rainfall data, (2) data processing, (3) calibration, (4) validation, and (5) evaluation of models’ performances.  Six (6) methods of baseflow separation based on recursive digital filters were evaluated. The calibration process was carried out for periods 1996 to 2005.  The periods from July to September was assumed to be the peak of the dry season and then selected for calibration process.  The parameter values were calibrated using the data from dry season for each year. Furthermore, the average value of parameters obtained from calibration period then used to separate baseflow in validation process (periods 2006 to 2015). The result of separation both in calibration and validation are then evaluated using root mean square error (RMSE), coefficient of determination (R²) and FDC. This research shows that the Lyne-Hollick and EWMA filters perform better than other methods. In Brantas Kertosono sub-watershed, the optimal parameter value for Lyne Hollick algoritmh (αly) = 0.995 dan for EWMA filter (αew) = 0.003 and in Brantas Ploso sub-watershed (αly ) = 0.99 dan (αew) = 0.003.

scholarly journals Eco-hydrology interactions between trees, soil and water in terrestrial and wetland areas: The effect of tree planting on water flow dynamics in Wairarapa Wetlands, New Zealand

2021 ◽  
Author(s):  
◽  
Tapuwa Marapara
Keyword(s):  
New Zealand ◽  
Hydraulic Properties ◽  
Forested Wetlands ◽  
High Water ◽  
Flood Mitigation ◽  
Forested Wetland ◽  
Soil Hydrology ◽  
Catchment Scale ◽  
Soil And Water

<p>During the last two decades there has been increasing interest in the role of forests and wetlands as flood mitigating tools due to growing concerns regarding the sustainability of many traditional engineering flood defences such as dykes, sea walls and dams. In forests, the role is facilitated by the interaction between trees, soil and water. Specifically trees reduce surface runoff and prevent flooding through increased evapotranspiration and canopy interception and enhance physical and hydraulic properties of soil that are critical for the absorption and retention of flood waters by the soil. It is increasingly realised that the answer to flood mitigation is not a blanket recommendation to “plant trees”. This is because the role of trees varies spatially and temporally as a function of climate, topography, rainfall properties, soil type and condition, catchment scale and geology, among others. For example, where trees are present in wetlands, particularly forested wetlands, the mechanisms by which trees interact with soil and water are similar to that in forests but because of a high water table, the impact of trees may be reduced. Therefore, the mere presence of forests and forested wetlands will not necessarily deliver flood risk management.  The purpose of this study was to explore the effectiveness of trees as flood mitigating tools under various bio-geo climatic factors in forests and forested wetland environments. Three forms of investigation were followed to fulfil this purpose.  A detailed literature review was carried out to assess the role of trees and forests as flood mitigation tools under changing climate, topography, species type, rainfall properties, soil type and condition, catchment scale and geology. A field experiment was carried out to collect data and analyse the effect of trees on soil physical and hydraulic properties that include bulk density, saturated hydraulic conductivity, soil organic carbon, soil moisture content, matric potential and soil moisture retention in a previously forested wetland undergoing restoration in New Zealand. A spatially explicit decision support tool, the Land Use Capability Indicator (LUCI) was then used to determine appropriate areas where intervention can be targeted to optimise the role of trees as flood mitigating tools in previously forested wetlands undergoing restoration.  The detailed review identified a major data gap in the role of trees under hydric conditions (high water table), along with uncertainties on their effectiveness in large catchments (>˜40 km²) and in extreme rainfall events. The field experiment provided the first set of soil hydrology data from an ephemeral wetland in New Zealand showing the benefits of newly established trees in improving hydraulic conductivity of soils. The soil hydrology data is a useful baseline for continuous monitoring of the forested wetlands undergoing restoration. The use of the Land Use Capability Indicator was its first application for the optimisation of flood mitigation in a forested wetland. Its suggested target areas are not necessarily conducive for survival of some tree species, although if suitable species are established, flood risk mitigation could be maximised. Further research on what native species are best for what conditions and in what combinations is recommended, to increase survival in the proposed target areas.</p>

A Problem of Long - Term Digital Preservation: Difference in Humanities and Natural Sciences

2014 ◽  
Vol 3 ◽  
pp. 183-195
Author(s):  
Elena Macevičiūtė
Keyword(s):  
Social Sciences ◽  
Digital Preservation ◽  
Dynamic Activity ◽  
Private Companies ◽  
Time Line ◽  
Digital Documents ◽  
Whole Process ◽  
The Difference ◽  
Technological Science

The article deals with the requirements and needs for long-term digital preservation in different areas of scholarly work. The concept of long-term digital preservation is introduced by comparing it to digitization and archiving concepts and defined with the emphasis on dynamic activity within a certain time line. The structure of digital preservation is presented with regard to the elements of the activity as understood in Activity Theory. The life-cycle of digitization processes forms the basis of the main processing of preserved data in preservation archival system.The author draws on the differences between humanities and social sciences on one hand and natural and technological science on the other. The empirical data characterizing the needs for digital preservation within different areas of scholarship are presented and show the difference in approaches to long-term digital preservation, as well as differences in selecting the items and implementing the projects of digital preservation. Institutions and organizations can also develop different understanding of preservation requirements for digital documents and other objects.The final part of the paper is devoted to some general problems pertaining to the longterm digital preservation with the emphasis of the responsibility for the whole process of safe-guarding the cultural and scholarly heritage for the re-use of the posterior generations. It is suggested that the longevity of the libraries in comparison with much shorter life-span of private companies strengthens the claim of memory institutions to playing the central role in the long-term digital preservation.

Plant mortality and seedling recruitment responses to flupropanate in grassland populations of Nassella trichotoma

2017 ◽  
Vol 70 ◽  
pp. 160-164 ◽  
Author(s):  
G.W. Bourdôt ◽  
S. Jackman ◽  
D.J. Saville
Keyword(s):  
New Zealand ◽  
Dose Response ◽  
Sodium Salt ◽  
Seedling Recruitment ◽  
Residual Activity ◽  
Application Rate ◽  
Plant Mortality ◽  
Complete Control ◽  
Bio Synthesis

Flupropanate (sodium 2,2,3,3 tetrafluoropropanate), a slow-acting lipid bio- synthesis-inhibiting herbicide, was recently registered in New Zealand as Taskforce (745 g/L flupropanate as the sodium salt) for the selective and long-term control of Nassella trichotoma (nassella tussock) in pastures. In five dose-response experiments in permanent hill pastures in Canterbury, conducted between 2012 and 2016, we measured the efficacy of the herbicide against established plants of N. trichotoma and its residual activity against recruiting seedlings. Mortality, as an average across the five sites, was 93% 1.5 years after applying 1.49 kg flupropanate/ha (the label-recommended rate), and 100% at 2.98 kg/ha. This indicates that an application rate higher than the label rate will be necessary for complete control of a N. trichotoma infestation. The presence of 1,000 and 6,250 visible seedlings of N. trichotoma/ha in the autumn 3.2 and 2.1 years after applying 1.49 kg flupropanate/ha (at a Greta Valley and Scargill site respectively) indicates that the herbicide’s soil residues had decayed within 12 months to a concentration lower than necessary to kill the germinating seedlings of N. trichotoma.

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