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Huang L, Fang H, Xu X, He G, Zhang X, Reible D. Stochastic modeling of phosphorus transport in the Three Gorges Reservoir by incorporating variability associated with the phosphorus partition coefficient. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 592:649-661. [PMID: 28318698 DOI: 10.1016/j.scitotenv.2017.02.227] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 01/16/2017] [Accepted: 02/28/2017] [Indexed: 06/06/2023]
Abstract
Phosphorus (P) fate and transport plays a crucial role in the ecology of rivers and reservoirs in which eutrophication is limited by P. A key uncertainty in models used to help manage P in such systems is the partitioning of P to suspended and bed sediments. By analyzing data from field and laboratory experiments, we stochastically characterize the variability of the partition coefficient (Kd) and derive spatio-temporal solutions for P transport in the Three Gorges Reservoir (TGR). We formulate a set of stochastic partial different equations (SPDEs) to simulate P transport by randomly sampling Kd from the measured distributions, to obtain statistical descriptions of the P concentration and retention in the TGR. The correspondence between predicted and observed P concentrations and P retention in the TGR combined with the ability to effectively characterize uncertainty suggests that a model that incorporates the observed variability can better describe P dynamics and more effectively serve as a tool for P management in the system. This study highlights the importance of considering parametric uncertainty in estimating uncertainty/variability associated with simulated P transport.
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Affiliation(s)
- Lei Huang
- State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
| | - Hongwei Fang
- State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China.
| | - Xingya Xu
- State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
| | - Guojian He
- State Key Laboratory of Hydro-science and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
| | - Xuesong Zhang
- Joint Global Change Research Institute, Pacific Northwest National Laboratory, 5825 University Research Court, Suite 3500, College Park, MD 20740, USA
| | - Danny Reible
- Department of Civil & Environmental Engineering, Texas Tech University, Lubbock, TX 79409-1023, USA.
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Zimmerman DL, Ver Hoef JM. The Torgegram for Fluvial Variography: Characterizing Spatial Dependence on Stream Networks. J Comput Graph Stat 2017. [DOI: 10.1080/10618600.2016.1247006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Dale L. Zimmerman
- Department of Statistics and Actuarial Science, University of Iowa, Iowa City, Iowa
| | - Jay M. Ver Hoef
- NOAA-NMFS Alaska Fisheries Science Center, Marine Mammal Laboratory, Seattle, Washington
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Peterson EE, Ver Hoef JM, Isaak DJ, Falke JA, Fortin MJ, Jordan CE, McNyset K, Monestiez P, Ruesch AS, Sengupta A, Som N, Steel EA, Theobald DM, Torgersen CE, Wenger SJ. Modelling dendritic ecological networks in space: an integrated network perspective. Ecol Lett 2013; 16:707-19. [DOI: 10.1111/ele.12084] [Citation(s) in RCA: 153] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 10/31/2012] [Accepted: 01/14/2013] [Indexed: 11/26/2022]
Affiliation(s)
- Erin E. Peterson
- CSIRO Division of Mathematics; Informatics and Statistics; Dutton Park; QLD; Australia
| | | | - Dan J. Isaak
- USDA Forest Service; Rocky Mountain Research Station; Boise; ID; USA
| | - Jeffrey A. Falke
- Department of Fisheries and Wildlife; Oregon State University; Corvallis; OR; USA
| | - Marie-Josée Fortin
- Department of Ecology & Evolutionary Biology; University of Toronto; Toronto; ON; Canada
| | - Chris E. Jordan
- NOAA/NMFS/NWFSC Conservation Biology Division; Seattle; WA; USA
| | - Kristina McNyset
- Department of Fisheries and Wildlife; Oregon State University; Corvallis; OR; USA
| | - Pascal Monestiez
- Inra, Unité Biostatistique et Processus Spatiaux; Avignon; France
| | - Aaron S. Ruesch
- School of Environmental and Forest Sciences; University of Washington; Seattle; WA; USA
| | - Aritra Sengupta
- Department of Statistics; The Ohio State University; Columbus; OH; USA
| | - Nicholas Som
- Department of Forest Ecosystems and Society; Oregon State University; Corvallis; OR; USA
| | - E. Ashley Steel
- USDA Forest Service; Pacific Northwest Research Station; Seattle; WA; USA
| | - David M. Theobald
- Department of Fish; Wildlife & Conservation Biology; Colorado State University; Fort Collins; CO; USA
| | - Christian E. Torgersen
- U.S. Geological Survey; Forest and Rangeland Ecosystem Science Center; Cascadia Field Station; School of Environmental and Forest Sciences; University of Washington; Seattle; WA; USA
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Yang X, Jin W. GIS-based spatial regression and prediction of water quality in river networks: a case study in Iowa. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2010; 91:1943-51. [PMID: 20570037 DOI: 10.1016/j.jenvman.2010.04.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Revised: 03/31/2010] [Accepted: 04/19/2010] [Indexed: 05/21/2023]
Abstract
Nonpoint source pollution is the leading cause of the U.S.'s water quality problems. One important component of nonpoint source pollution control is an understanding of what and how watershed-scale conditions influence ambient water quality. This paper investigated the use of spatial regression to evaluate the impacts of watershed characteristics on stream NO(3)NO(2)-N concentration in the Cedar River Watershed, Iowa. An Arc Hydro geodatabase was constructed to organize various datasets on the watershed. Spatial regression models were developed to evaluate the impacts of watershed characteristics on stream NO(3)NO(2)-N concentration and predict NO(3)NO(2)-N concentration at unmonitored locations. Unlike the traditional ordinary least square (OLS) method, the spatial regression method incorporates the potential spatial correlation among the observations in its coefficient estimation. Study results show that NO(3)NO(2)-N observations in the Cedar River Watershed are spatially correlated, and by ignoring the spatial correlation, the OLS method tends to over-estimate the impacts of watershed characteristics on stream NO(3)NO(2)-N concentration. In conjunction with kriging, the spatial regression method not only makes better stream NO(3)NO(2)-N concentration predictions than the OLS method, but also gives estimates of the uncertainty of the predictions, which provides useful information for optimizing the design of stream monitoring network. It is a promising tool for better managing and controlling nonpoint source pollution.
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Affiliation(s)
- Xiaoying Yang
- Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
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Freeman EA, Moisen GG. Evaluating kriging as a tool to improve moderate resolution maps of forest biomass. ENVIRONMENTAL MONITORING AND ASSESSMENT 2007; 128:395-410. [PMID: 17057988 DOI: 10.1007/s10661-006-9322-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Accepted: 02/27/2006] [Indexed: 05/12/2023]
Abstract
The USDA Forest Service, Forest Inventory and Analysis program (FIA) recently produced a nationwide map of forest biomass by modeling biomass collected on forest inventory plots as nonparametric functions of moderate resolution satellite data and other environmental variables using Cubist software. Efforts are underway to develop methods to enhance this initial map. We explored the possibility of modeling spatial structure to make such improvements. Spatial structure in the field biomass data as well as in residuals from the map was investigated across 18 ecological zones in the Interior Western U.S. Exploratory tools included directional graphs of summary statistics, three dimensional maps, Moran's I correlograms, and variograms. Where spatial pattern was present, field and residual biomass were kriged, and predictions made for an independent test set were evaluated for improvement over predictions in the initial biomass map. While kriging has some potential benefit when analyzing the field data and exploring spatial structure, kriging residuals resulted in little or no improvement in the initial biomass map developed using Cubist software. Stationarity assumptions, variogram behavior, and appropriate model fitting strategies are discussed.
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Affiliation(s)
- Elizabeth A Freeman
- U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Forestry Sciences Laboratory, 507 25th Street, Ogden, UT 84401, USA.
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Peterson EE, Merton AA, Theobald DM, Urquhart NS. Patterns of spatial autocorrelation in stream water chemistry. ENVIRONMENTAL MONITORING AND ASSESSMENT 2006; 121:571-96. [PMID: 16897525 DOI: 10.1007/s10661-005-9156-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Accepted: 12/02/2005] [Indexed: 05/05/2023]
Abstract
Geostatistical models are typically based on symmetric straight-line distance, which fails to represent the spatial configuration, connectivity, directionality, and relative position of sites in a stream network. Freshwater ecologists have explored spatial patterns in stream networks using hydrologic distance measures and new geostatistical methodologies have recently been developed that enable directional hydrologic distance measures to be considered. The purpose of this study was to quantify patterns of spatial correlation in stream water chemistry using three distance measures: straight-line distance, symmetric hydrologic distance, and weighted asymmetric hydrologic distance. We used a dataset collected in Maryland, USA to develop both general linear models and geostatistical models (based on the three distance measures) for acid neutralizing capacity, conductivity, pH, nitrate, sulfate, temperature, dissolved oxygen, and dissolved organic carbon. The spatial AICC methodology allowed us to fit the autocorrelation and covariate parameters simultaneously and to select the model with the most support in the data. We used the universal kriging algorithm to generate geostatistical model predictions. We found that spatial correlation exists in stream chemistry data at a relatively coarse scale and that geostatistical models consistently improved the accuracy of model predictions. More than one distance measure performed well for most chemical response variables, but straight-line distance appears to be the most suitable distance measure for regional geostatistical modeling. It may be necessary to develop new survey designs that more fully capture spatial correlation at a variety of scales to improve the use of weighted asymmetric hydrologic distance measures in regional geostatistical models.
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Affiliation(s)
- Erin E Peterson
- CSIRO Mathematical & Information Sciences, Queensland Bioscience Precinct, 306 Carmody Road, St. Lucia, QLD, 4067, Australia.
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Peterson EE, Urquhart NS. Predicting water quality impaired stream segments using landscape-scale data and a regional geostatistical model: a case study in Maryland. ENVIRONMENTAL MONITORING AND ASSESSMENT 2006; 121:615-38. [PMID: 16967209 DOI: 10.1007/s10661-005-9163-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Accepted: 12/19/2005] [Indexed: 05/11/2023]
Abstract
In the United States, probability-based water quality surveys are typically used to meet the requirements of Section 305(b) of the Clean Water Act. The survey design allows an inference to be generated concerning regional stream condition, but it cannot be used to identify water quality impaired stream segments. Therefore, a rapid and cost-efficient method is needed to locate potentially impaired stream segments throughout large areas. We fit a set of geostatistical models to 312 samples of dissolved organic carbon (DOC) collected in 1996 for the Maryland Biological Stream Survey using coarse-scale watershed characteristics. The models were developed using two distance measures, straight-line distance (SLD) and weighted asymmetric hydrologic distance (WAHD). We used the Corrected Spatial Akaike Information Criterion and the mean square prediction error to compare models. The SLD models predicted more variability in DOC than models based on WAHD for every autocovariance model except the spherical model. The SLD model based on the Mariah autocovariance model showed the best fit (r(2) = 0.72). DOC demonstrated a positive relationship with the watershed attributes percent water, percent wetlands, and mean minimum temperature, but was negatively correlated to percent felsic rock type. We used universal kriging to generate predictions and prediction variances for 3083 stream segments throughout Maryland. The model predicted that 90.2% of stream kilometers had DOC values less than 5 mg/l, 6.7% were between 5 and 8 mg/l, and 3.1% of streams produced values greater than 8 mg/l. The geostatistical model generated more accurate DOC predictions than previous models, but did not fit the data equally well throughout the state. Consequently, it may be necessary to develop more than one geostatistical model to predict stream DOC throughout Maryland. Our methodology is an improvement over previous methods because additional field sampling is not necessary, inferences about regional stream condition can be made, and it can be used to locate potentially impaired stream segments. Further, the model results can be displayed visually, which allows results to be presented to a wide variety of audiences easily.
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Affiliation(s)
- Erin E Peterson
- CSIRO Mathematical & Information Sciences, Queensland Bioscience Precinct, 306 Carmody Road, St. Lucia, QLD, Australia.
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Massoud MA, El-Fadel M, Scrimshaw MD, Lester JN. Factors influencing development of management strategies for the Abou Ali River in Lebanon I: spatial variation and land use. THE SCIENCE OF THE TOTAL ENVIRONMENT 2006; 362:15-30. [PMID: 16313946 DOI: 10.1016/j.scitotenv.2005.09.079] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 08/23/2005] [Accepted: 09/10/2005] [Indexed: 05/05/2023]
Abstract
Surface water bodies are progressively subject to increasing stress as a result of environmentally degrading processes primarily related to anthropogenic activities. This study assesses and examines the impact of land use and land-based activities on the spatial variation in water quality of the Abou Ali River in North Lebanon. It is the first detailed study of its kind in Lebanon and adds to the existing knowledge by shedding light on a relatively small Mediterranean river in a developing country where there is a paucity of such studies. The assessment was conducted at the end of the dry season in 2002 and 2003 and the end of the wet season in 2003 and 2004. The study has demonstrated the importance of anthropogenic influences on the water quality of the Abou Ali River Basin, as concentrations of most contaminants were higher at locations with greatest human activity. The most adversely affected area was the section of the river that flows through an entirely urbanized and highly populated region, the Tripoli conurbation. Upstream rural sites were enriched by contaminants primarily from non-point sources such as agricultural runoff and poultry litter whereas contaminant concentrations at the urban sites were enriched by a combination of sewage discharge and flow of contaminants from upstream. If the Abou Ali River is to be utilized as a managed water resource and its water quality sustained, point source discharges will require treatment and land use management must be planned to minimize the impact of diffuse source pollution on the river. A high priority should be given to the implementation and enforcement of the precautionary and polluter pays principles. Moreover, an effective legal, economic and institutional framework is required to encourage investment in waste reduction and control and to introduce environmentally sound practices.
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Affiliation(s)
- May A Massoud
- Environmental Processes and Water Technology Research Group, Department of Environmental Science and Technology, Faculty of Life Sciences, Imperial College London, London SW7 2AZ, UK
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