scholarly journals The Influence of Permanent Grasslands on Nitrate Nitrogen Loads in Modelling Approach

2014 ◽  
Vol 21 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Maria Śmietanka
Keyword(s):  
Water Pollution ◽  
Land Use ◽  
Management Practices ◽  
Nitrate Nitrogen ◽  
Swat Model ◽  
Arable Land ◽  
Intensive Agriculture ◽  
Catchment Management ◽  
Small Catchment ◽  
Nitrogen Loads

Abstract The water pollution in areas with intensive agriculture is growing rapidly. Computer model is a tool which can help in finding solutions for water pollution reduction and help in creation of catchment management plans. In this research the SWAT model (Soil and Water Assessment Tool) was used to test the influence of introduction of permanent grasslands into the catchment on nitrate nitrogen load in surface water. Small catchment of upper Zgłowi?czka River in central Poland with intensive agriculture was chosen as a test site. Model was fed with data about land use, soils, weather, elevation and management practices and calibrated and validated using flow data and nitrate nitrogen loads data. Then 2 scenarios with land use change were tested. A part of arable land was changed into permanent grasslands. The results show that permanent grasslands are effective in reducing nitrate nitrogen load. The load was reduced by 19% when permanent grasslands constituted 10% of arable land and by 38% with permanent grasslands taking up 20% of arable land.

LUU CHECKER: A Web-based Tool to Incorporate Emerging LUs in the SWAT Model

2019 ◽  
Vol 35 (5) ◽  
pp. 723-731 ◽  
Author(s):  
Gurdeep Singh ◽  
Dharmendra Saraswat ◽  
Naresh Pai ◽  
Benjamin Hancock
Keyword(s):  
Land Use ◽  
Management Practices ◽  
Assessment Tool ◽  
Urban Forest ◽  
Swat Model ◽  
Land Use Changes ◽  
Web Based ◽  
Large Size ◽  
Hydrologic Response Unit ◽  
User Friendly

Abstract. Standard practice of setting up Soil and Water Assessment Tool (SWAT) involves use of a single land use (LU) layer under the assumption that no change takes place in LU condition irrespective of the length of simulation period. This assumption leads to erroneous conclusions about efficacy of management practices in those watersheds where land use changes (LUCs) (e.g. agriculture to urban, forest to agriculture etc.) occur during the simulation period. To overcome this limitation, we have developed a user-friendly, web-based tool named LUU Checker that helps create a composite LU layer by integrating multiple years of LU layers available in watersheds of interest. The results show that the use of composite LU layer for hydrologic response unit (HRU) delineation in 2474-km2 L’Anguile River Watershed in Arkansas was able to capture changed LU at subbasin level by using LU data available in the year 1999 and 2006, respectively. The web-based tool is applicable for large size watersheds and is accessible to multiple users from anywhere in the world. Keywords: Land use, Web-based tool, SWAT, LUU Checker.

scholarly journals The Assessment of Climate Change and Land-Use Influences on the Runoff of a Typical Coastal Basin in Northern China

2020 ◽  
Vol 12 (23) ◽  
pp. 10050 ◽  
Author(s):  
Junfang Liu ◽  
Baolin Xue ◽  
Yuhui Yan
Keyword(s):  
Climate Change ◽  
Land Use ◽  
River Basin ◽  
Swat Model ◽  
Arable Land ◽  
Resource Planning ◽  
Northern China ◽  
Combine Data ◽  
Runoff Change ◽  
Verification Period

Land use and climate change are the two major driving factors of watershed runoff change, and it is of great significance to study the influence of watershed hydrological processes on water resource planning and management. This study takes the Changyang River basin as the study area, builds a SWAT model and explores the applicability of the SWAT model in the basin. Moreover, we combine data on land use and climate change in different periods to construct a variety of scenario models to quantitatively analyze the impacts of different scenarios on runoff. The results show that the R2 and Ensof the model are 0.71 and 0.68 in the calibration period, respectively, and those in the verification period are 0.68 and 0.65, respectively, indicating that the SWAT model has good applicability in simulating the runoff of the Changyang River basin. Under the comprehensive scenario of land use and climate change on runoff, we found that land use and climate change have a certain contribution to the change in runoff. Therefore, the runoff of the basin increased by 0.22 m3/s, in which land-use change caused the runoff in the basin to increase by 0.07 m3/s attributed to the decreased area of arable land and the increased area of urban land in the basin. Moreover, climate change has caused the runoff in the basin to increase by 0.13 m3/s, mainly influenced by the increased precipitation. The results show that climate change has a more significant effect on runoff in the basin.

scholarly journals Assessing branched tetraether lipids as tracers of soil organic carbon transport through the Carminowe Creek catchment (southwest England)

2020 ◽  
Vol 17 (12) ◽  
pp. 3183-3201 ◽  
Author(s):  
Jingjing Guo ◽  
Miriam Glendell ◽  
Jeroen Meersmans ◽  
Frédérique Kirkels ◽  
Jack J. Middelburg ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Membrane Lipids ◽  
Arable Land ◽  
Small Catchment ◽  
Bed Sediments ◽  
Core Sediments ◽  
History Of ◽  
Carbon Dioxide Co2 ◽  
Lake Core

Abstract. Soils represent the largest reservoir of organic carbon (OC) on land. Upon mobilization, this OC is either returned to the atmosphere as carbon dioxide (CO2) or transported and ultimately locked into (marine) sediments, where it will act as a long-term sink of atmospheric CO2. These fluxes of soil OC are, however, difficult to evaluate, mostly due to the lack of a soil-specific tracer. In this study, a suite of branched glycerol dialkyl glycerol tetraethers (brGDGTs), which are membrane lipids of soil bacteria, is tested as specific tracers for soil OC from source (soils under arable land, ley, grassland, and woodland) to sink (Loe Pool sediments) in a small catchment located in southwest England (i.e. Carminowe Creek draining into Loe Pool). The analysis of brGDGTs in catchment soils reveals that their distribution is not significantly different across different land use types (p>0.05) and thus does not allow land-use-specific soil contributions to Loe Pool sediments to be traced. Furthermore, the significantly higher contribution of 6-methyl brGDGT isomers in creek sediments (isomerization ratio (IR) = 0.48±0.10, mean ± standard deviation (SD); p<0.05) compared to that in catchment soils (IR = 0.28±0.11) indicates that the initial soil signal is substantially altered by brGDGT produced in situ. Similarly, the riverine brGDGT signal appears to be overwritten by lacustrine brGDGTs in the lake sedimentary record, indicated by remarkably lower methylation of branched tetraethers (MBT5ME′=0.46±0.02 in creek bed sediments and 0.38±0.01 in lake core sediments; p<0.05) and a higher degree of cyclization (DC = 0.23±0.02 in creek bed sediments and 0.32±0.08 in lake core sediments). Thus, in this small catchment, brGDGTs do not allow us to trace soil OC transport. Nevertheless, the downcore changes in the degree of cyclization and the abundance of isoprenoid GDGTs produced by methanogens in the Loe Pool sediment do reflect local environmental conditions over the past 100 years and have recorded the eutrophication history of the lake.

scholarly journals Representation of seasonal land-use dynamics in SWAT+ for improved assessment of blue and green water consumption

2021 ◽  
Author(s):  
Anna Msigwa ◽  
Celray James Chawanda ◽  
Hans Charles Komakech ◽  
Albert Nkwasa ◽  
Ann van Griensven
Keyword(s):  
Land Use ◽  
Water Consumption ◽  
Agricultural Land ◽  
Mean Squared Error ◽  
Swat Model ◽  
Green Water ◽  
Small Catchment ◽  
Growing Seasons ◽  
Land Use Dynamics ◽  
Set Up

Abstract. In most (sub)-tropical African cultivated regions, more than one cropping cycle exists following the (one or two) rainy seasons. During the dry season, an additional cropping cycle is possible when irrigation is applied, which could result in 3 cropping seasons. In most agro-hydrological model applications such as SWAT+ in Africa, only one cropping season per year is represented. In this paper, we derived dynamic and static trajectories from seasonal land-use maps to represent the land- use dynamics following the major growing seasons, for the purpose of improving simulated blue and green water consumption from simulated evapotranspiration (ET) in SWAT+. This study builds upon earlier research that proposed an approach on how to incorporate seasonal land use dynamics in the SWAT+ model but mainly focused on the temporal pattern of LAI and tested the approach in a small catchment (240 km2). Together with information obtained from the cropping calendar, we implemented agricultural management operations for the dominant trajectory of each agricultural land-use class for the Kikuletwa basin (6650 km2 area coverage) in Tanzania. A comparison between the default SWAT+ (with static land use representation) set up, and a dynamic SWAT+ model (with seasonal land use representation) is done by spatial mapping of the evapotranspiration (ET) results. The results show that ET with seasonal representation is closer to remote sensing estimations, giving higher performance than default: the Root Mean Squared Error decreased from 181 to 69 mm/year; the percent bias decreased from 20 % to 13 % and Nash Sutcliffe Efficiency increased from −0.46 to 0.4. It is concluded that representation of seasonal land-use dynamics produces better ET results which provide better estimations of blue and green agricultural water consumption.

scholarly journals Improved SWAT vegetation growth module for tropical ecosystem

2017 ◽  
Author(s):  
Tadesse Alemayehu ◽  
Ann van Griensven ◽  
Willy Bauwens
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Soil Moisture ◽  
Management Practices ◽  
Assessment Tool ◽  
Swat Model ◽  
Evergreen Forest ◽  
Tropical Ecosystem ◽  
Area Index ◽  
Vegetation Growth

Abstract. The Soil and Water Assessment Tool (SWAT) is a globally applied river basin eco-hydrological simulator in a wide spectrum of studies, ranging from land use change and climate change impacts studies to research for the development of best water management practices. However, SWAT has limitations in simulating the seasonal growth cycles for trees and perennial vegetation in tropics, where the major plant growth controlling factor is the rainfall (via soil moisture) rather than temperature. Our goal is to improve the vegetation growth module of the SWAT model for simulating the vegetation parameters such as the leaf area index (LAI) for tropics. Therefore, we present a modified SWAT version for the tropics (SWAT-T) that uses of a simple but robust soil moisture index (SMI) – a quotient of the rainfall (P) and reference evapotranspiration (PET) – to initiate a new growing season after a defined dry season. Our results for the Mara Basin (Kenya/Tanzania) show that the SWAT-T simulated LAI corresponds well with the Moderate Resolution Imaging Spectroradiometer (MODIS) LAI for evergreen forest, savanna grassland and shrubs, indicating that the SMI is a reliable proxy to dynamically initiate a new growing cycle. The water balance components (evapotranspiration and flow) simulated by the SWAT-T exhibit a good agreement with remote sensing-based evapotranspiration (RS-ET) and observed flow. The SWAT-T simulator with the proposed improved vegetation growth module for tropical ecosystem could be a robust tool for several applications including land use and climate change impact studies.

scholarly journals Urban Green Spaces—An Underestimated Resource in Third-Tier Towns in Poland

Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 453
Author(s):  
Marcin Feltynowski ◽  
Jakub Kronenberg
Keyword(s):  
Land Use ◽  
Satellite Imagery ◽  
Management Practices ◽  
Green Space ◽  
Arable Land ◽  
Green Spaces ◽  
Landsat 8 ◽  
Interconnected System ◽  
Urban Green ◽  
Urban Green Spaces

Urban green spaces are frequently presented as being important for urban quality of life and urban development in general, but more detailed interpretations and discussions are typically confined to large urban centers, the so-called first- and second-tier cities. Not enough attention has been paid to smaller urban units, the third-tier towns. The main goal of this article is to investigate the share and types of urban green spaces in five selected towns in Poland. We compare different sources of data based on satellite imagery and land-use maps with those used in public statistics, to check whether town authorities are managing all potential green spaces or only a selected part of them. We find that the predominantly used data, based on what is classified as “urban green space” for the purposes of public statistics, obscure the complexity of urban green spaces and focus on the narrowly understood formally managed public green spaces (which occupy 3.5–5.7% of town areas). Meanwhile, based on other sources, such as the national land-use map (BDOT10k), Urban Atlas, and satellite imagery (Landsat 8), what is considered to be green space turns out to cover 50–80% of the town area. The latter large numbers are associated with the predominance of arable land, grasslands, and forests, overlooked in any green space management practices based on data and definitions adopted for the purposes of public statistics. The situation found in our five case study towns resembles that identified in larger cities in Poland, and it exhibits the inadequacy of public statistics definitions and the related management practices, hindering the management of urban green spaces as an interconnected system of urban green infrastructures.

scholarly journals Nitrogen and dissolved organic carbon (DOC) losses from an artificially drained grassland on organic soils

2014 ◽  
Vol 11 (2) ◽  
pp. 3023-3064 ◽  
Author(s):  
B. Tiemeyer ◽  
P. Kahle
Keyword(s):  
Land Use ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Arable Land ◽  
Shallow Groundwater ◽  
Organic Soils ◽  
N Losses ◽  
Total N ◽  
Dynamic Component ◽  
Small Catchment

Abstract. Nitrate-nitrogen (NO3-N) as well as dissolved organic carbon (DOC) and nitrogen (DON) concentrations and losses were studied for three respectively two years in a small catchment dominated by a degraded peatland used as intensive grassland. Concentrations in the shallow groundwater were spatially and temporally very variable with NO3-N being the most dynamic component (7.3 ± 12.5 mg L–1). Average NO3-N concentrations of 10.3 ± 5.4 mg L–1 in the ditch draining the catchment and annual NO3-N losses of 19, 35 and 26 kg ha–1 confirmed drained peatlands as an important source of diffuse N pollution. The highest NO3-N losses occurred during the wettest year. Resulting from concentrations of 2.4 ± 0.8 mg L–1, DON added further 4.5 to 6.4 kg ha–1 to the N losses and thus formed a relevant component of the total N losses. Ditch DOC concentrations of 24.9 ± 5.9 mg L–1 resulted in DOC losses of 66 kg ha–1 in the wet year 2006/07 and 39 kg ha–1 in the dry year 2007/08. Both DOC and N concentrations were governed by hydrological conditions, but NO3-N reacted much faster and clearer on rising discharge rates than DOC which tended to be higher under dryer conditions. In the third year of the study, the superposition of a very wet summer and land use changes from grassland to arable land in a part of the catchment suggests that under re-wetting conditions with a high groundwater table in summer, NO3-N would diminish quickly, while DOC would remain on a similar level. Further intensification of the land use, on the other hand, would increase N losses to receiving water bodies.

scholarly journals A comprehensive sensitivity and uncertainty analysis for discharge and nitrate-nitrogen loads involving multiple discrete model inputs under future changing conditions

2019 ◽  
Vol 23 (3) ◽  
pp. 1211-1244 ◽  
Author(s):  
Christoph Schürz ◽  
Brigitta Hollosi ◽  
Christoph Matulla ◽  
Alexander Pressl ◽  
Thomas Ertl ◽  
...  
Keyword(s):  
Land Use ◽  
Point Source ◽  
Case Studies ◽  
Environmental Variables ◽  
Nitrate Nitrogen ◽  
Swat Model ◽  
Sources Of Uncertainty ◽  
Environmental Systems ◽  
Model Setup ◽  
The Impact

Abstract. Environmental modeling studies aim to infer the impacts on environmental variables that are caused by natural and human-induced changes in environmental systems. Changes in environmental systems are typically implemented as discrete scenarios in environmental models to simulate environmental variables under changing conditions. The scenario development of a model input usually involves several data sources and perhaps other models, which are potential sources of uncertainty. The setup and the parametrization of the implemented environmental model are additional sources of uncertainty for the simulation of environmental variables. Yet to draw well-informed conclusions from the model simulations it is essential to identify the dominant sources of uncertainty. In impact studies in two Austrian catchments the eco-hydrological model Soil and Water Assessment Tool (SWAT) was applied to simulate discharge and nitrate-nitrogen (NO3--N) loads under future changing conditions. For both catchments the SWAT model was set up with different spatial aggregations. Non-unique model parameter sets were identified that adequately reproduced observations of discharge and NO3--N loads. We developed scenarios of future changes for land use, point source emissions, and climate and implemented the scenario realizations in the different SWAT model setups with different model parametrizations, which resulted in 7000 combinations of scenarios and model setups for both catchments. With all model combinations we simulated daily discharge and NO3--N loads at the catchment outlets. The analysis of the 7000 generated model combinations of both case studies had two main goals: (i) to identify the dominant controls on the simulation of discharge and NO3--N loads in the two case studies and (ii) to assess how the considered inputs control the simulation of discharge and NO3--N loads. To assess the impact of the input scenarios, the model setup, and the parametrization on the simulation of discharge and NO3--N loads, we employed methods of global sensitivity analysis (GSA). The uncertainties in the simulation of discharge and NO3--N loads that resulted from the 7000 SWAT model combinations were evaluated visually. We present approaches for the visualization of the simulation uncertainties that support the diagnosis of how the analyzed inputs affected the simulation of discharge and NO3--N loads. Based on the GSA we identified climate change and the model parametrization as being the most influential model inputs for the simulation of discharge and NO3--N loads in both case studies. In contrast, the impact of the model setup on the simulation of discharge and NO3--N loads was low, and the changes in land use and point source emissions were found to have the lowest impact on the simulated discharge and NO3--N loads. The visual analysis of the uncertainty bands illustrated that the deviations in precipitation of the different climate scenarios to historic records dominated the changes in simulation outputs, while the differences in air temperature showed no considerable impact.

scholarly journals Modelling Transport of Nitrogen Compounds in Geita Wetland along Mtakuja River

2018 ◽  
Vol 37 (2) ◽  
pp. 89-106
Author(s):  
Ezrael J. Massawe ◽  
Richard Kimwaga ◽  
Fredrick Mwanuzi
Keyword(s):  
Land Use ◽  
Management Practices ◽  
Assessment Tool ◽  
Swat Model ◽  
Nitrogen Loading ◽  
Model Parameters ◽  
Nitrogen Compounds ◽  
Land Use And Management ◽  
The Impact ◽  
Monitoring Stations

The impacts of excessive nitrogen loading to streams in a watershed occur in the receiving waters such as rivers at the outlet of the watershed. To quantify the impacts of land use and management practices on the nitrogen loading at the watershed outlet, simulation models are needed that can both predict the nitrogen loading at the edge of individual fields and predict the fate of nitrogen as it moves through the river network to the watershed outlet. This paper presents the results of a model analysis for describing the processes governing transformations and transport of nitrogen compounds (NO3-N and NH4-N) through Mtakuja River in the Geita wetland. The model was made in Soil and Water Assessment Tool (SWAT), a watershed model developed to assess the impact of land management practices on water, sediment and agricultural chemical yields with varying soils, land use and management conditions. Two monitoring stations namely MTSP1 and MTSP2 were established along Mtakuja River. A set of SWAT model inputs representative of the water conditions was collected from the established monitoring stations. The model was calibrated and validated for the prediction of flow and nitrogen compounds (NO3-N and NH4-N) transport, against a set of measured mean monthly monitoring data. Sensitive model parameters were adjusted within their feasible ranges during calibration to minimize model prediction errors. At the gauging station MTSP2, the calibration results showed that the model predicted mean monthly flow within 18% of the measured mean monthly flow with the r2 coefficient and Nash-Sutcliffe (NSE) were 0.84 and 0.82, respectively. At the water quality monitoring station MTSP2, the calibration results showed the model predicted nitrogen compounds (NO3-N and NH4-N) loadings within 21% and 23% of their respective measured mean monthly loadings. The mean monthly comparisons of r 2 values for nitrogen compounds ranged from 0.77 to 0.81 while the Nash-Sutcliffe Efficiency (NSE) values were between 0.72 and 0.73. The model results and field measurements demonstrated that about 70% of the annual nitrogen compounds loadings which would otherwise reach Lake Victoria are retained in the wetland. The Mtakuja river model can therefore be used for prediction of nitrogen compounds (NO3-N and NH4-N) transformation processes in the Geita wetland.

scholarly journals The potential for land use change to reduce flood risk in mid-sized catchments in the Myjava region of Slovakia

2017 ◽  
Vol 47 (2) ◽  
pp. 95-112 ◽  
Author(s):  
Peter Rončák ◽  
Evelin Lisovszki ◽  
Ján Szolgay ◽  
Kamila Hlavčová ◽  
Silvia Kohnová ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Erosion ◽  
River Basin ◽  
Surface Runoff ◽  
Management Practices ◽  
Agricultural Land ◽  
Arable Land ◽  
Land Use Management ◽  
Land Use Scenarios ◽  
The Impact

AbstractThe effects of land use management practices on surface runoff are evident on a local scale, but evidence of their impact on the scale of a watershed is limited. This study focuses on an analysis of the impact of land use changes on the flood regime in the Myjava River basin, which is located in Western Slovakia. The Myjava River basin has an area of 641.32 km2and is typified by the formation of fast runoff processes, intensive soil erosion, and muddy floods. The main factors responsible for these problems with flooding and soil erosion are the basin’s location, geology, pedology, agricultural land use, and cropping practices. The GIS-based, spatially distributed WetSpa rainfall-runoff model was used to simulate mean daily discharges in the outlet of the basin as well as the individual components of the water balance. The model was calibrated based on the period between 1997 and 2012 with outstanding results (an NS coefficient of 0.702). Various components of runoff (e.g., surface, interflow and groundwater) and several elements of the hydrological balance (evapotranspiration and soil moisture) were simulated under various land use scenarios. Six land use scenarios (‘crop’, ‘grass’, ‘forest’, ‘slope’, ‘elevation’ and ‘optimal’) were developed. The first three scenarios exhibited the ability of the WetSpa model to simulate runoff under changed land use conditions and enabled a better adjustment of the land use parameters of the model. Three other “more realistic” land use scenarios, which were based on the distribution of land use classes (arable land, grass and forest) regarding permissible slopes in the catchment, confirmed the possibility of reducing surface runoff and maximum discharges with applicable changes in land use and land management. These scenarios represent practical, realistic and realizable land use management solutions and they could be economically implemented to mitigate soil erosion processes and enhance the flood protection measures in the Myjava River basin.

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