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 An improved SWAT vegetation growth module and its evaluation for four tropical ecosystems

2017 ◽  
Vol 21 (9) ◽  
pp. 4449-4467 ◽  
Author(s):  
Tadesse Alemayehu ◽  
Ann van Griensven ◽  
Befekadu Taddesse Woldegiorgis ◽  
Willy Bauwens
Keyword(s):  
Management Practices ◽  
Assessment Tool ◽  
Wide Spectrum ◽  
Growth Cycle ◽  
Evergreen Forest ◽  
Water Balance Components ◽  
Tropical Ecosystems ◽  
Area Index ◽  
Vegetation Growth ◽  
The Tropics

Abstract. The Soil and Water Assessment Tool (SWAT) is a globally applied river basin ecohydrological model used in a wide spectrum of studies, ranging from land use change and climate change impacts studies to research for the development of the best water management practices. However, SWAT has limitations in simulating the seasonal growth cycles for trees and perennial vegetation in the tropics, where rainfall rather than temperature is the dominant plant growth controlling factor. Our goal is to improve the vegetation growth module of SWAT for simulating the vegetation variables – such as the leaf area index (LAI) – for tropical ecosystems. Therefore, we present a modified SWAT version for the tropics (SWAT-T) that uses a straightforward but robust soil moisture index (SMI) – a quotient of rainfall (P) and reference evapotranspiration (ETr) – to dynamically initiate a new growth cycle within a predefined period. 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 shrubland. This indicates that the SMI is reliable for triggering a new annual growth cycle. The water balance components (evapotranspiration and streamflow) simulated by the SWAT-T exhibit a good agreement with remote-sensing-based evapotranspiration (ET-RS) and observed streamflow. The SWAT-T model, with the proposed vegetation growth module for tropical ecosystems, can be a robust tool for simulating the vegetation growth dynamics in hydrologic models in tropical regions.

scholarly journals A Review of SWAT Model Application in Africa

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1313
Author(s):  
George Akoko ◽  
Tu Hoang Le ◽  
Takashi Gomi ◽  
Tasuku Kato
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Hydrological Modeling ◽  
Assessment Tool ◽  
Swat Model ◽  
Data Availability ◽  
Mitigation Measures ◽  
Model Parameterization ◽  
Basin Scale

The soil and water assessment tool (SWAT) is a well-known hydrological modeling tool that has been applied in various hydrologic and environmental simulations. A total of 206 studies over a 15-year period (2005–2019) were identified from various peer-reviewed scientific journals listed on the SWAT website database, which is supported by the Centre for Agricultural and Rural Development (CARD). These studies were categorized into five areas, namely applications considering: water resources and streamflow, erosion and sedimentation, land-use management and agricultural-related contexts, climate-change contexts, and model parameterization and dataset inputs. Water resources studies were applied to understand hydrological processes and responses in various river basins. Land-use and agriculture-related context studies mainly analyzed impacts and mitigation measures on the environment and provided insights into better environmental management. Erosion and sedimentation studies using the SWAT model were done to quantify sediment yield and evaluate soil conservation measures. Climate-change context studies mainly demonstrated streamflow sensitivity to weather changes. The model parameterization studies highlighted parameter selection in streamflow analysis, model improvements, and basin scale calibrations. Dataset inputs mainly compared simulations with rain-gauge and global rainfall data sources. The challenges and advantages of the SWAT model’s applications, which range from data availability and prediction uncertainties to the model’s capability in various applications, are highlighted. Discussions on considerations for future simulations such as data sharing, and potential for better future analysis are also highlighted. Increased efforts in local data availability and a multidimensional approach in future simulations are recommended.

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 Quantitative Attribution of Runoff Attenuation to Climate Change and Human Activity in Typical Mountainous Areas: An Enlightenment to Water Resource Sustainable Utilization and Management in North China

2020 ◽  
Vol 12 (24) ◽  
pp. 10395
Author(s):  
Yufei Jiao ◽  
Jia Liu ◽  
Chuanzhe Li ◽  
Wei Wang ◽  
Fuliang Yu ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Water Resources ◽  
Water Resource ◽  
Human Activities ◽  
North China ◽  
Assessment Tool ◽  
Swat Model ◽  
Data Series ◽  
Sustainable Utilization

The influence of climate change and human activities on hydrological elements has increased along with increasing dependence on water resources. Therefore, quantitative attribution of hydrological elements has received wide attention. In this study, the double mass curve (DMC) is used to assess the abrupt change point of the hydrological data series, based on which the periods with/without large-scale human activities causing runoff attenuation are separated. The land use transition matrix is then employed to analyze the land use types at different historical stages, and the sensitivities of the runoff attenuation to different land use/cover change (LUCC) categories are quantified. A soil and water assessment tool (SWAT) model that considers the underlying surface is constructed with six designed scenarios of different climate and LUCC conditions. Taking three typical mountainous basins in North China as the study area, the quantitative contributions of climate change and human activities to the water resources are identified. The results of the study have brought enlightenment to the water resource sustainable utilization and management in North China, and the methodologies can be transferred to runoff attribution analysis in water shortage areas.

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 Projection of runoff and sediment yield under coordinated climate change and urbanization scenarios in Doam dam watershed, Korea

2016 ◽  
Vol 8 (2) ◽  
pp. 235-253 ◽  
Author(s):  
Young Do Kim ◽  
Jung Min Kim ◽  
Boosik Kang
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Climate Model ◽  
Assessment Tool ◽  
Global Climate ◽  
Global Climate Model ◽  
Swat Model ◽  
Intergovernmental Panel ◽  
Runoff Change ◽  
Rate Of Increase

A hydro-environmental model chain in the Doam dam basin, Korea, was developed for an impact assessment under the Intergovernmental Panel on Climate Change's A1B scenario. The feasible downscaling scheme composed of an artificial neural network (ANN) and non-stationary quantile mapping was applied to the GCM (Global Climate Model) output. The impacts under climate and land use change scenarios were examined and projected using the Soil and Water Assessment Tool (SWAT) model. The daily SWAT model was calibrated and validated for 2003–2004 and 2006–2008, respectively. Meanwhile the monthly SS (suspended solids) was calibrated and validated for 1999–2001 and 2007–2009, respectively. The simulation results illustrated that under the assumption of 1–5% urbanization of the forest area, the hydrologic impact is relatively negligible and the climate change impacts are dominant over the urbanization impacts. Additionally the partial impacts of land use changes were analyzed under five different scenarios: partial change of forest to urban (PCFUr), to bare field, to grassland, to upland crop (PCFUp), and to agriculture (PCFA). The analysis of the runoff change shows the highest rate of increase, 73.57% in April, for the PCFUp scenario. The second and third highest rate increases, 37.83% and 31.45% in May, occurred under the PCFA and PCFUr scenarios, respectively.

scholarly journals Modeling Hydrologic Response to Land Use and Climate Change in the Krueng Jreu Sub Watershed of Aceh Besar

2016 ◽  
Vol 5 (3) ◽  
Author(s):  
Teuku Ferijal ◽  
Mustafril Bachtiar ◽  
Dewi Sri Jayanti ◽  
Dahlan Jafaruddin
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Agricultural Land ◽  
Assessment Tool ◽  
Irrigation System ◽  
Swat Model ◽  
Model Performance ◽  
Primary Source ◽  
Surface Flow ◽  
Water Yield

Soil and Water Assessment Tool (SWAT) model was used to simulate impact of landuse and climate change on water resources in Krueng Jreu subwatershed located in Aceh Province – Indonesia. The subwatershed is a primary source of water to irrigated 233.52 km2 paddy field area through a surface irrigation system. The model performance was considerably good in predicting streamflow. The coefficients of determination varied between 0.58 and 0.72, while the Nash-Sutcliffe coefficients (ENS) ranged between 0.65-0.72 and the percentage bias were in the range of -0.36 to 2.30. Scenarios were applied to the best fit model to evaluate watershed responses to land use and climate changes. The model predicted increases in both runoff and water yield by 1% and 0.1% respectively as the result of increasing 15% settlement area. When all agricultural land within subwatershed converted to forest, water yield would increase by 1% during dry period and runoff contribution would decrease by 5%. Increases in surface flow by 23.6% and water yield by 15.1% were found under scenario of increasing 10% of daily precipitation. Increasing in evapotranspiration caused by an increase of 1.5⁰C in daily air temperature would decrease surface flow and water yield by 0.8% and 1.3%, respectively. Combination scenarios of changes in daily temperature and precipitation would increase evapotranspiration rate, annual water yield and runoff contribution.

scholarly journals The Effects of Land Use and Climate Change on the Water Yield of a Watershed in Colombia

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 285 ◽  
Author(s):  
Sandra R. Villamizar ◽  
Sergio M. Pineda ◽  
Gustavo A. Carrillo
Keyword(s):  
Climate Change ◽  
Land Use ◽  
South America ◽  
Amazon Basin ◽  
Assessment Tool ◽  
Swat Model ◽  
Water Yield ◽  
Distributed Hydrological Model ◽  
Climate Scenarios ◽  
Effects Of Land Use

Land use and climate are two determinant factors of water yield within a watershed. Understanding the effects of these two variables is key for the decision-making process within watersheds. Hydrologic modeling can be used for this purpose and the integration of future climate scenarios to calibrated models widens the spectrum of analysis. Such types of studies have been carried out in many areas of the world, including the Amazon Basin of South America. However, there is a lack of understanding on the effect of land use/land cover and climate change on Andean watersheds of this continent. Our study focused on the evaluation of water yield under different land use and climate scenarios using the semi-distributed hydrological model known as the Soil and Water Assessment Tool (SWAT) model. We worked on the Tona watershed (Colombia, South America), the most important source of water for a metropolitan population. Our results compared water yield estimates for historical conditions (1987–2002) with those of future combined scenarios for land use and climate for the 2006–2050 period. The modeling effort produced global estimates of water yield (average annual values) and, at the subwatershed level, identified strategic areas on which the protection and conservation activities of water managers can be focused.

scholarly journals Hydrologic evaluation and effects of climate change on the Nong Han Lake Basin, northeastern Thailand

2019 ◽  
Vol 11 (4) ◽  
pp. 992-1000
Author(s):  
Jirawat Supakosol ◽  
Kowit Boonrawd
Keyword(s):  
Climate Change ◽  
Assessment Tool ◽  
Swat Model ◽  
Climate Projections ◽  
Lake Basin ◽  
Model Soil ◽  
Regional Climates ◽  
Water Assessment ◽  
Effective Water ◽  
Northeastern Thailand

Abstract The purpose of this study is to investigate the future runoff into the Nong Han Lake under the effects of climate change. The hydrological model Soil and Water Assessment Tool (SWAT) has been selected for this study. The calibration and validation were performed by comparing the simulated and observed runoff from gauging station KH90 for the period 2001–2003 and 2004–2005, respectively. Future climate projections were generated by Providing Regional Climates for Impacts Studies (PRECIS) under the A2 and B2 scenarios. The SWAT model yielded good results in comparison to the baseline; moreover, the results of the PRECIS model showed that both precipitations and temperatures increased. Consequently, the amount of runoff calculated by SWAT under the A2 and B2 scenarios was higher than that for the baseline. In addition, the amount of runoff calculated considering the A2 scenario was higher than that considering the B2 scenario, due to higher average annual precipitations in the former case. The methodology and results of this study constitute key information for stakeholders, especially for the development of effective water management systems in the lake, such as designing a rule curve to cope with any future incidents.

scholarly journals Prioritization of Sub-Watersheds to Sediment Yield and Evaluation of Best Management Practices in Highland Ethiopia, Finchaa Catchment

Land ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 650
Author(s):  
Wakjira Takala Dibaba ◽  
Tamene Adugna Demissie ◽  
Konrad Miegel
Keyword(s):  
Soil Erosion ◽  
Best Management Practices ◽  
Sediment Yield ◽  
Soil Loss ◽  
Crop Production ◽  
Management Practices ◽  
Assessment Tool ◽  
Swat Model ◽  
Sediment Yields ◽  
Soil And Water

Excessive soil loss and sediment yield in the highlands of Ethiopia are the primary factors that accelerate the decline of land productivity, water resources, operation and function of existing water infrastructure, as well as soil and water management practices. This study was conducted at Finchaa catchment in the Upper Blue Nile basin of Ethiopia to estimate the rate of soil erosion and sediment loss and prioritize the most sensitive sub-watersheds using the Soil and Water Assessment Tool (SWAT) model. The SWAT model was calibrated and validated using the observed streamflow and sediment data. The average annual sediment yield (SY) in Finchaa catchment for the period 1990–2015 was 36.47 ton ha−1 yr−1 with the annual yield varying from negligible to about 107.2 ton ha−1 yr−1. Five sub-basins which account for about 24.83% of the area were predicted to suffer severely from soil erosion risks, with SY in excess of 50 ton ha−1 yr−1. Only 15.05% of the area within the tolerable rate of loss (below 11 ton ha−1yr−1) was considered as the least prioritized areas for maintenance of crop production. Despite the reasonable reduction of sediment yields by the management scenarios, the reduction by contour farming, slope terracing, zero free grazing and reforestation were still above the tolerable soil loss. Vegetative contour strips and soil bund were significant in reducing SY below the tolerable soil loss, which is equivalent to 63.9% and 64.8% reduction, respectively. In general, effective and sustainable soil erosion management requires not only prioritizations of the erosion hotspots but also prioritizations of the most effective management practices. We believe that the results provided new and updated insights that enable a proactive approach to preserve the soil and reduce land degradation risks that could allow resource regeneration.

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