198,485 research outputs found
Calibration and Validation of SWAT for the Upper Maquoketa River Watershed, June 2005
No full textA validation study has been performed using the Soil and Water Assessment Tool
(SWAT) model with data collected for the Upper Maquoketa River Watershed (UMRW),
which drains over 16,000 ha in northeast Iowa. This validation assessment builds on a
previous study with nested modeling for the UMRW that required both the Agricultural
Policy EXtender (APEX) model and SWAT. In the nested modeling approach, edge-offield
flows and pollutant load estimates were generated for manure application fields with
APEX and were then subsequently routed to the watershed outlet in SWAT, along with
flows and pollutant loadings estimated for the rest of the watershed routed to the
watershed outlet. In the current study, the entire UMRW cropland area was simulated in
SWAT, which required translating the APEX subareas into SWAT hydrologic response
units (HRUs). Calibration and validation of the SWAT output was performed by
comparing predicted flow and NO3-N loadings with corresponding in-stream
measurements at the watershed outlet from 1999 to 2001. Annual stream flows measured
at the watershed outlet were greatly under-predicted when precipitation data collected
within the watershed during the 1999-2001 period were used to drive SWAT. Selection
of alternative climate data resulted in greatly improved average annual stream
predictions, and also relatively strong r2 values of 0.73 and 0.72 for the predicted average monthly flows and NO3-N loads, respectively. The impact of alternative precipitation data shows that as average annual precipitation increases 19%, the relative change in average annual streamflow is about 55%. In summary, the results of this study show that SWAT can replicate measured trends for this watershed and that climate inputs are very important for validating SWAT and other water quality models
Modelagem hidrológica e avaliação de diferentes métodos de calibração para o modelo SWAT
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Ambiental, Florianópolis, 2015.Um dos principais desafios enfrentados pela modelagem hidrológica é a calibração eficiente dos parâmetros do modelo. O objetivo deste estudo foi testar métodos de calibração hierárquicos para o modelo Soil and Water Assessment Tool (SWAT) considerando variações da bacia. A área de estudo foi a bacia hidrográfica do Rio Negrinho, localizada no estado de Santa Catarina, com uma área de 198,5 km². Antes da primeira simulação os dados de entrada foram pré-processados: os dados de chuva (1999-2012) foram interpolados pelo método da Krigagem Simples com Diferentes Médias Locais e Elevação como Variável Externa, e um filtro automático foi usado para separar o escoamento superficial e de base a partir da vazão medida. Uma análise de sensibilidade dos parâmetros foi realizada e do total, 15 parâmetros foram selecionados. A calibração do modelo foi feita usando o algoritmo Sequential Uncertainty Fitting (SUFI2), utilizando testes de crescente complexidade. A série de vazões observadas foi dividida em períodos distintos de calibração e validação (Split Sample Test) sendo que os resultados obtidos para o intervalo mensal foram considerados aceitáveis com um coeficiente de Nash?Sutcliffe (NSE) =0,5 e Pbias=±25%. Na análise de cada ano separadamente (Differential Split-Sample Test) a calibração e validação dos anos úmidos (2008 a 2012) foi mais eficiente que dos anos secos (2003 a 2007). No processo de validação do modelo para uma bacia com uso do solo semelhante (Proxy-Catchment Test), o modelo não foi eficiente para o ajuste dos picos de vazões (NSE de 0), porém, houve uma compensação dos volumes na estimativa do balanço hídrico (Pbias de 0,1%). Os resultados indicam que a eficiência do modelo SWAT depende da quantidade de dados disponíveis e do período de calibração. Para simulação de cenários climáticos e de mudanças de uso do solo o modelo deve ser calibrado e validado usando dados espacialmente bem distribuídos e uma série de vazões suficientemente representativa que considere períodos secos e úmidos.Abstract : One of the main challenges facing hydrological modeling is the effective calibration of model parameters. The aim of this study was exemplified a calibration scheme for the Soil and Water Assessment Tool (SWAT) model by considering land use and climate changes. The study area was the Rio Negrinho watershed (198,5 km²), located in Santa Catarina State, Brazil. Before the first simulation, input data were preprocessed: rainfall data (1999 to 2012) were interpolated using Simple Kriging with Varying Local Means with Elevation as External variable, and an automated digital filter technique was used to separate baseflow from the measured streamflow. A parameter sensitivity analysis was carried out and 15 parameters were selected. Model calibration was performed with the Sequential Uncertainty Fitting (SUFI2) Algorithm through increasing complexity tests. The measured flow series was first divided into calibration and validation periods(Split Sample Test) wherein the predicted monthly flow matched the measured values, with a Nash?Sutcliffe coefficient (NSE) =0.5 and Pbias<±25%. When wet and dry periods were considered separately (Differential Split-Sample Test) the NSE values of wet years (2008 a 2012) were higher than dry years values (2003 a 2007). In the SWAT validation for a watershed with similar land use (Proxy-Catchment Test), the model could not capture the flow peaks well (NSE of 0), however, the water balance volumes were compensated (Pbias of 0.1%). The case study demonstrates that SWAT performance vary largely, depending on the spatial scale and calibration period. SWAT model can be used in further studies to simulate land use and climate change scenarios however it must be calibrated and validated using data spatially well distributed and recorded series segment including dry and wet periods
Hydrologic Simulations of the Maquoketa River Watershed Using SWAT Working Paper 09-WP 49,June 2009
No full textThis paper describes the application of the Soil and Water Assessment Tool (SWAT)
model to the Maquoketa River watershed, located in northeast Iowa. The inputs to the model
were obtained from the Environmental Protection Agency’s geographic information/database
system called Better Assessment Science Integrating Point and Nonpoint Sources (BASINS).
Climatic data from six weather stations located in and around the watershed, and measured
streamflow data from a U.S. Geological Survey gage station at the watershed outlet were
used in the sensitivity analysis of SWAT model parameters as well as its calibration and
validation for watershed hydrology and streamflow. A sensitivity analysis was performed
using an influence coefficient method to evaluate surface runoff and base flow variations in response to changes in model input hydrologic parameters. The curve number, evaporation
compensation factor, and soil available water capacity were found to be the most sensitive
parameters among eight selected parameters when applying SWAT to the Maquoketa River
watershed. Model calibration, facilitated by the sensitivity analysis, was performed for the period 1988 through 1993, and validation was performed for 1982 through 1987. The model performance was evaluated by well-established statistical methods and was found to explain at least 86% and 69% of the variability in the measured stream flow data for the calibration and validation periods, respectively. This initial hydrologic modeling analysis will facilitate future applications of SWAT to the Maquoketa River watershed for various watershed analysis, including water quality
Karst SWAT hydrological modeling at large and regional scale: the case study of the island of Crete
No full textKarst landscape covers approximately 20% of the earth’s surface and provides about 50% of the world’s drinking water. In Europe soluble carbonate rocks covers 35% of whole continent and are widespread in particular in Southern, therefore the karst processes are very significant components of the physical geography of the Mediterranean basins. The aim of this study was to apply SWAT model integrated with a karst-flow model in Crete Island (6,669 km2) characterized by karst-dominant geomorphology.The Crete SWAT model was developed using DEM of 25 m pixel size subdividing the Island in 352 sub-basins with an average area of 20 km2. The combined model (KSWAT) simulated the contribution of the extended karst areas to the discharge of 47 springs. KSWAT was calibrated and validated using a network of 22 monitoring stations and 47 springs respectively for the period 1980-2009 and 1973-2009. The combined model was able to estimate water balance of the whole Crete in different hydrological conditions supporting management decisions regarding public water supply. The KSWAT model was tested also in a large scale version on Crete SWAT model based on DEM 100 m pixel size subdividing the Island in 23 sub-basins with an average area of 127 km2 in order to assess the applicability of karst-model in the current setup of SWAT in macro regions at pan European scale. The results of this study will be presented and discussed together to provide a SWAT modelling protocol to adopt in karst regions.JRC.H.1 - Water Resource
Development and Conflict: The Economic Impacts of Civil War in Swat: Pakistan
No full textViolent conflicts have economic causes and economic consequences. In addition to the lost lives, injuries and the overall scale of human suffering that conflicts create, they also destroy assets and institutions. The consequences, the intensities of conflicts and their linkages with human endeavours to protect people from critical threats are not only a major national, but also an international developmental challenge. The terrorist attacks in the United States in 2001 drastically changed the paradigm and the epicentres of conflicts to something much different from the 20th century. In the changed paradigm, terrorist planning and attacks are largely considered to be originating from Muslim countries, masterminded by internationally linked organisations like Al Qaeda. These organisations are considered to be the source and Western countries to be revenge targets, particularly the United States because of its foreign policy repercussions in Muslim countries. Considering this fact, this thesis examines global conflicts and their links with income, economic development and democracy from 2000-2009, the period which fundamentally transformed the nature of global intrastate conflicts. This study is expected to be the first attempt to cover the period and to have a specific focus on Muslim majority countries, using similar econometric techniques and variables to those applied to broad global analyses.
This study then moves from global analysis to focus on the micro household effects of the recent violent civil conflict involving the Taliban in Swat, Pakistan. A visible gap in economics-based conflict-orientated research was identified, with no apparent studies of post-conflict livelihoods in Swat. This thesis seeks to fill the void, and investigates losses of key household assets and their impact on determining post-conflict livelihood choices in Swat. Using survey data from 275 randomly sampled households in five out of the seven affected tehsils of Swat district, several statistical and modelling techniques are used to assess how and to what extent the conflict, which became civil war, has affected household livelihoods in Swat. Specifically the following relationships were considered and examined: (i) assets and income portfolios of households, and the quantitative extent of damages to conflict-affected household assets; (ii) asset endowment and its impact in prioritising post-conflict livelihood strategies; and (iii) possible alternative livelihood opportunities resulting from positive post-conflict interventions in the regional economy, which effectively results in livelihood revival.
It was found that households lost human, physical, natural, social, and financial assets, and the post-conflict environment constrained their income and employment opportunities. Their expenditures increased and as a coping strategy, many sold their assets. The limited and damaged asset endowments (physical, financial and natural) were identified as major constraints to pursuing known livelihood choices or adopting more rewarding ones, in the shattered infrastructural and physical economic environment of Swat. Finally, in finding appropriate revival options, and by using simulation modelling, this thesis suggests an integrated development framework to enhance the regional economy and household livelihoods. This revival of pre-war thriving sectors is expected to decrease economic incentives to join militant groups such as the Taliban
The Soil and Water Assessment Tool:Historical Development, Applications, and Future Research Directions, 2007
No full textThe Soil and Water Assessment Tool (SWAT) model is a continuation of nearly 30 years of
modeling efforts conducted by the U.S. Department of Agriculture (USDA), Agricultural
Research Service. SWAT has gained international acceptance as a robust interdisciplinary
watershed modeling tool, as evidenced by international SWAT conferences, hundreds of
SWAT-related papers presented at numerous scientific meetings, and dozens of articles
published in peer-reviewed journals. The model has also been adopted as part of the U.S.
Environmental Protection Agency’s BASINS (Better Assessment Science Integrating Point &
Nonpoint Sources) software package and is being used by many U.S. federal and state
agencies, including the USDA within the Conservation Effects Assessment Project. At
present, over 250 peer-reviewed, published articles have been identified that report SWAT
applications, reviews of SWAT components, or other research that includes SWAT. Many of
these peer-reviewed articles are summarized here according to relevant application categories such as streamflow calibration and related hydrologic analyses, climate change impacts on hydrology, pollutant load assessments, comparisons with other models, and sensitivity analyses and calibration techniques. Strengths and weaknesses of the model are presented, and recommended research needs for SWAT are provided
Application of SWAT model on three watersheds within the Venice Lagoon Watershed (Italy) : source apportionment and scenario analysis
No full textAim of this study was the analysis of the source apportionment of three river basins within the Venice Lagoon Watershed (VLW), in the North-Eastern part of Italy, which on the whole cover about 700 km2 (i.e. about 35% of the VLW surface area). The three watersheds are characterised by a very intensive agriculture and landfarming systems. Moreover, in this area the groundwater recharge to surface waters significantly contributes to the total load discharged into the Venice Lagoon. SWAT model application allowed to describe the hydrologic and agricultural characteristics of the watersheds and to assess the source apportionment in terms of point and diffuse sources. Furthermore, SWAT model allowed the evaluation of the benefit due to the application of agri-environmental measures through the simulation of a “better-business” agricultural scenario versus the “business-as-usual” scenario. Out of a total annual nutrient load of about 2200 tNy-1 and of about 140 tPy-1, the dry weather diffuse sources (i.e. groundwater/spring recharge and tributary/irrigation channels coming from bordering watersheds) resulted to be the most important (65% in case of nitrogen and 35% in case of phosphorus). SWAT outputs indicated a runoff load contribution of about 20% of the total nitrogen load and of about 30% of the total phosphorus load; agricultural runoff resulted to be about 2/3 of this runoff load. The simulation of the Better Business scenario indicated a possible reduction in the agricultural runoff loads of about 50% in case of nitrogen and of about 15% in case of phosphorus, which corresponds to a decrease in the total annual load of about 5-7%
Estudo hidrossedimentológico da bacia hidrográfica do Rio Negrinho - SC com o modelo SWAT
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia AmbientalO município de Rio Negrinho vem sofrendo com alteração da quantidade e qualidade da água devido a substituição da mata nativa por reflorestamento de pinus e acelerada urbanização. Visto isso, o presente estudo teve como objetivo analisar espacialmente os processos hidrossedimentológicos na bacia do Rio Negrinho - SC através do modelo SWAT. Foram realizado o monitoramento hidrossedimentológico, formação de banco de dados espaciais e tabulares, determinação das sub-bacias, calibração e validação do modelo, análises estatísticas, avaliação espacial da produção de água e de sedimentos e verificação da tolerância de perda de solos nas sub-bacias. Os dados simulados pelo modelo foram comparados com os dados observados de vazão em dois pontos de monitoramento da bacia e os dados de concentração de sedimento em um ponto da bacia. O desempenho do modelo foi analisado a partir do NASH (coeficiente de Nash-Sutcliffe), R2 (coeficiente de correlação), Erro médio (EM) e CMR (Coeficiente de massa residual). Os valores de NASH variaram de 0,48 a 0,61 para dados de vazão e 0,43 para dados de sedimento. Analisando o balanço hídrico da bacia o coeficiente de variação da precipitação, vazão e evapotranspiração mensal foi de 23%, 20% e 30% respectivamente. Já o armazenamento de água no solo variou muito pouco ao longo do ano, apresentando coeficiente de variação de 8,7%. Comparada a tolerância de perda de solos com os dados de produção de sedimento da bacia foi possível evidenciar que 11% da área da bacia apresentaram produção de sedimento maior que a tolerância.The Rio Negrinho city has been suffering from the quantitative and qualitative modification of water due to replacement of native forests by pine tree reforestation and accelerated urbanization. The objective of the present study was, therefore, to spatially analyze hydrosedimentological processes in the Negrinho river basin # SC through the SWAT model. Hydrosedimentological monitoring, construction of spatial databases and table, determination of sub-basins, the model calibration and validation, statistical analysis, spatial assessment of water and sediment yield and verification of soil loss tolerance in each sub-basin were carried out. The values simulated with the model were compared with the observed data of discharge at two monitoration points and of sediment concentration at one point in the basin. The model performance was evaluated with the coefficient of Nash-Sutcliffe (NASH), the correlation coefficient (R2), the average error (MS) and coefficient of residual mass (CRM). The NASH values were from 0.48 to 0.61 for the discharge data and 0.43 for the sediment data. Analyzing the water balance of the basin the coefficient of variation of the monthly precipitation, evapotranspiration and flow were 23%, 20% and 30%, respectively. The water storage in the soil varied little throughout the year, showing its coefficient of variation of 8.7%. Comparing to soil loss tolerance with the sediment production data, it was shown that 11% of the basin area would have more sediment production than the tolerated value
Institutions and Forest Management: A Case Study from Swat, Pakistan
No full textDeforestation in the North western part of Pakistan is a long standing problem. The Forestry Department, as formal managers of the forest resources, has been undergoing a long reform process aimed at improving its performance. This reform process has not resulted in less deforestation. From the policy perspective this has been leading to stated intentions to further reform the Forestry Department, the question is whether organizational reform is the answer. We think there are more limiting bottlenecks to sustainable forest management in Pakistan. De facto property rights are not as simple as denoted by statutory law. In this article we explore the mechanisms behind the deforestation and try to uncover mechanisms to reverse the process. Although our conclusions are not very optimistic, we provide a framework for determining the bottlenecks in the management of common resources from the perspective of institutions. We show that in circumstances where institutional change is necessary we are faced with a trade-off between the transaction costs related to the enforcement of “improved” institutional arrangements and the transaction costs improving enforceable institutional arrangements. Incurring these transaction costs only makes sense if the benefits from improved institutional arrangements outweigh them and the transition costs. When we relate this dilemma to the management regime of the forest in North west Pakistan, we identify at the one end of the spectrum the ideal forest management system; at the other end we see the spontaneous evolution of self organization. The current situation is an intermediate form with an incoherent set of external interventions and strategic reactions by different agents in the local communities. The emergent system of management is the one producing the present dismal outcome.New institutional Economics, Corruption, Forestry, Swat
Occurrence of metolachlor and trifluralin losses in the Save river agricultural catchment during floods
No full textRising pesticide levels in streams draining intensively managed agricultural land have a detrimental effect on aquatic ecosystems and render water unfit for human consumption. The Soil and Water Assessment Tool (SWAT) was applied to simulate daily pesticide transfer at the outlet from an agriculturally intensive catchment of 1110 km2 (Save river, south-western France). SWAT reliably simulated both dissolved and sorbed metolachlor and trifluralin loads and concentrations at the catchment outlet from 1998 to 2009. On average, 17 kg of metolachlor and 1 kg of trifluralin were exported at outlet each year, with annual rainfall variations considered. Surface runoff was identified as the preferred pathway for pesticide transfer, related to the good correlation between suspended sediment exportation and pesticide, in both soluble and sorbed phases. Pesticide exportation rates at catchment outlet were less than 0.1% of the applied amount. At outlet, SWAT hindcasted that (i) 61% of metolachlor and 52% of trifluralin were exported during high flows and (ii) metolachlor and trifluralin concentrations exceeded European drinking water standards of 0.1 µg L−1 for individual pesticides during 149 (3.6%) and 17 (0.4%) days of the 1998–2009 period respectively. SWAT was shown to be a promising tool for assessing large catchment river network pesticide contamination in the event of floods but further useful developments of pesticide transfers and partition coefficient processes would need to be investigated
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