[Show abstract][Hide abstract] ABSTRACT: Over the last five years, the Paso del Norte Watershed Council’s Coordinated Water Resources Database and GIS Project (Project) was developed to provide improved access to regional water resources data for regional water stakeholders to make timely decisions in water operations and flood control. This report presents major components of the Project developed from August of 2005 through July of 2007 through funding provided by the United States Bureau of Reclamation (USBR) through the Water 2025 Challenge Grant Program to the El Paso Water Utilities, Texas A&M University, and New Mexico State University. Additional documentation of related Project activities is provided through final project reports being submitted by the City of Las Cruces (CLC) and Elephant Butte Irrigation District (EBID) for the work conducted through linked USBR-funded Projects. Tasks accomplished in the phase of work funded by the USBR include the following specific outcomes, which are detailed in later sections of the report: * Continued compilation and inclusion of new data sources identified as relevant by Project partners and users; * Installation and calibration of additional new monitoring stations and equipment and inclusion of these monitoring sites in web-based GIS map products to fill data gaps and provide additional real-time data; * Linking to additional monitoring sites being implemented by EBID through their Project work and inclusion of these sites and data in web-based GIS map products; * Development and implementation of a user needs survey focusing on new data sets of interest, enhanced access mechanisms, and other suggestions to improve the Project website; * Development and deployment of an online, downloadable Microsoft Access database of Project water resource data to provide search and query functions; * Development and deployment of an online help facility to make the site easier for users to navigate and use; * Exploration of new tools to enhance online data sharing and access; and * Implementation of suggestions compiled in the User Needs Assessment, including resolution of problems related to accessing the Project website using Firefox and Mozilla web browsers. Keywords: Paso del Norte watershed, water resources database, GIS map, ArcIMS, data sharing and transfer, user needs assessment, Rio Grande, Rio Grande Project, gage station, surface water flow, groundwater, downloadable Microsoft Access database.
[Show abstract][Hide abstract] ABSTRACT: The International Boundary and Water Commission (IBWC) is responsible for maintaining a series of flood-control projects beginning in New Mexico and extending along the Rio Grande’s international border dividing the United States and Mexico. A review by the USIBWC indicate that, over time, the flood-control capability of the levees has been compromised, possibly to the point where the level of protection is below original-design capacities. Prior to investing federal monies in the rehabilitation of major flood-system infrastructure, the U.S. Office of Management and Budget requires an economic analysis of expected benefits, or losses avoided with implemented protection measures. Recent flood events along the international border, resulting in significant economic damages and loss of human life, emphasized the need for a timely assessment of impacts of potential flood-control failure. Given a short project time line mandated by IBWC and the large geographic extent of the river- and floodway-levee system, innovative methods were developed to conduct a rapid and preliminary economic assessment of the flood-control infrastructure. Estimates for four major project areas relating only to the U.S.-side of the border only (stretching from Caballo Reservoir in New Mexico to the Rio Grande’s mouth, near Brownsville, TX.) comprise the study’s focus. Millions populate the cities and towns along these economic reaches of the Rio Grande where extensive housing, commerce, industry, tourism, and irrigated agricultural production exist. Areas susceptible to flooding, along with land-use, were identified and quantified through high-resolution map imagery. Estimates of representative residential, commercial, and industrial property values and agricultural production values were developed from property assessment records, economic development councils, crop enterprise budgets and cropping patterns, census data, previous U.S. Army Corps of Engineers’ flooding studies, etc. Gross economic values of flood-control benefits for a sample of each of the land-use types were determined and extrapolated to similar land-use areas in the flood zone. This analytical method provides a rapidassessment of potential flood-control benefits for a single event for each of the four IBWCdesignated flood-control project areas. An aggregate estimate arrived at by summing the potential benefits across all four project areas assumes avoidance of, or protection against, a simultaneous breach in all areas. Baseline economic benefits for agriculture and developed property along the Rio Grande Canalization project are estimated at $13.7 million (basis FY 2004). Comparable estimates for the Rio Grande Rectification project are $139.1 million, while those for the Presidio Valley Flood Control project amount to $2.9 million. The Lower Rio Grande Flood Control project is estimated to provide $167.2 million in flood-control benefits. Combined, the four project areas provide $322.9 million in flood-control protection benefits in the baseline analysis. When preliminary estimates of $183.0 million in other costs (i.e., emergency, roads, utilities, and vehicles) are added to the baseline estimate, the total floodcontrol protection benefits provided by the four project areas increases to $506.0 million.
[Show abstract][Hide abstract] ABSTRACT: In agricultural watersheds, pesticide contamination in surface water mostly occurs during stormflow events. When modelling pesticide fate for risks assessment, the application timing input is one of the main uncertainty sources among all the parameters involved in the river network contaminations process. We therefore aimed to assess the sensitivity of the river network pesticide concentration patterns to application timing shifts within a plausible range of application dates, considering two pre-emergence herbicides (metolachlor and aclonifen) characterised by two different octanol/water partition coefficients (Kow). The Soil and Water Assessment Tool (SWAT) was applied in the 1110 km2 agricultural watershed of the river Save (south-western France), where wheat, maize, sorghum and sunflower are intensively grown. The pesticide application date was changed within a one-month interval and the pesticide concentration at catchment outlet was simulated from March to June 2010. Total metolachlor concentration prediction could be improved by an application timing shift to 3 days later (Daily R2 = 0.22 and PBIAS = − 57%). By testing the behaviour of the two molecules, it was shown that sorption processes were influencing the control of application timing on the transfer to surface water:metolachlor concentration in the channel depended on both discharge and delay between application date and first stormflow event whereas the transfer of aclonifen depended on rainfall intensity for exportation with suspended sediments through surface runoff. At last, the study discusses the potential implications of the sensitivity in terms of regional agricultural management practice design.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we discuss the importance of developing integrated assessment models to support the design and implementation of policies to address water quality problems associated with agricultural pollution. We describe a new modelling system, LUMI-NATE, which links land use decisions made at the field scale in the Upper Mississippi, Ohio and Tennessee Basins through both environmental and hydrological components to downstream water quality effects and hypoxia in the Gulf of Mexico. This modelling system can be used to analyse detailed policy scenarios identifying the costs of the pol-icies and their resulting benefits for improved local and regional water quality. We dem-onstrate the model's capabilities with a simple scenario where cover crops are incentivised with green payments over a large expanse of the watershed.
European Review of Agricultural Economics 06/2014; 41(3):431-459. · 1.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: High nitrate concentrations in streams have become a widespread
problem throughout Europe in recent decades, damaging surface
water and groundwater quality. The European Nitrate Directive
fixed a potability threshold of 50 mg L−1 for European rivers. The
performance of the Soil and Water Assessment Tool model was
assessed in the 1110-km2 Save catchment in southwestern France
for predicting water discharge and nitrate loads and concentrations
at the catchment outlet, considering observed data set uncertainty.
Simulated values were compared with intensive and extensive
measurement data sets. Daily discharge fitted observations (Nash-
Sutcliffe efficiency coefficient = 0.61, R2 = 0.7, and PBIAS = -22%).
Nitrate simulation (1998–2010) was within the observed range
(PBIAS = 10–21%, considering observed data set uncertainty).
Annual nitrate load at the catchment outlet was correlated to the
annual water yield at the outlet (R2 = 0.63). Simulated annual
catchment nitrate exportation ranged from 21 to 49 kg ha−1
depending on annual hydrological conditions (average, 36 kg ha-1).
Exportation rates ranged from 3 to 8% of nitrogen inputs. During
floods, 34% of the nitrate load was exported, which represented 18%
of the 1998–2010 period. Average daily nitrate concentration at the
outlet was 29 mg L-1 (1998–2010), ranging from 0 to 270 mg L−1.
Nitrate concentration exceeded the European 50 mg L−1 potability
threshold during 244 d between 1998 and 2010. A 20% reduction of
nitrogen input reduced crop yield by between 5 and 9% and reduced
by 62% the days when the 50 mg L−1 threshold was exceeded.
Journal of Environmental Quality 01/2014; 43(1):46-54. · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: With enhanced data availability, distributed watershed models for large areas with high spatial and temporal resolution are increasingly used to understand water budgets and examine effects of human activities and climate change/variability on water resources. Developing parallel computing software to improve calibration efficiency has received growing attention of the watershed modeling community as it is very time demanding to run iteratively complex models for calibration. In this research, we introduce a Python-based parallel computing package, PP-SWAT, for efficient calibration of the Soil and Water Assessment Tool (SWAT) model. This software employs Python, MPI for Python (mpi4py) and OpenMPI to parallelize A Multi-method Genetically Adaptive Multi-objective Optimization Algorithm (AMALGAM), allowing for simultaneously addressing multiple objectives in calibrating SWAT. Test results on a Linux computer cluster showed that PP-SWAT can achieve a speedup of 45–109 depending on model complexity. Increasing the processor count beyond a certain threshold does not necessarily improve efficiency, because intensified resource competition may result in an I/O bottleneck. The efficiency achieved by PP-SWAT also makes it practical to implement multiple parameter adjustment schemes operating at different scales in affordable time, which helps provide SWAT users with a wider range of options of parameter sets to choose from for model(s) selection. PP-SWAT was not designed to address errors associated with other sources (e.g. model structure) and cautious supervision of its power should be exercised in order to attain physically meaningful calibration results.
Environmental Modelling and Software 08/2013; 46:208–218. · 4.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pesticides used for crop protection are leached with rainfall events to groundwater and surface water. The bioavailable dissolved fraction threatens the fluvial ecosystems. Pesticide partitioning in the environment is therefore one of the key pesticide fate processes that should be properly formalized for risk assessment. In modelling approaches, the partition coefficient Kd is usually estimated from different empirical models based on laboratory batch studies, such as Karickhoff equation. We first showed that the partition parameter in SWAT was more sensitive in the river network than in the soil. Therefore we sought a new relationship for Kd in rivers, relating Kd to the octanol/water distribution coefficient Kow and to the Total Suspended Matter (TSM) concentration. This relationship was obtained from in-stream measurements of TSM and of Particulate Organic Carbon (POC) sampled from 2007 to 2010 at the outlet of the 1110 km² Save catchment. We also calculated the Kd values of 7 pesticide molecules for both high flow and low flow periods (2009-
2010). We sought a relationship between TSM and the percentage of POC in TSM. We related the organic carbon normalized partition coefficient Koc to Kow. We showed a bias of 0.5 between instream observed Koc average values and Koc values calculated with Karickhoff’s equation. Thus, we expressed Kd depending on the widely literature-related variable Kow and on the commonly observed and simulated TSM concentration: Kd became a variable in time and space depending on simulated TSM concentration. The novel equation can be implemented in the SWAT model.
2013 International SWAT Conference, Toulouse, France; 07/2013
[Show abstract][Hide abstract] ABSTRACT: Climate change is one of the most compelling modern issues and has important implications for almost every aspect of natural and human systems. The Soil and Water Assessment Tool (SWAT) model has been applied worldwide to support sustainable land and water management in a changing climate. However, the inadequacies of the existing carbon algorithm in SWAT limit its application in assessing impacts of human activities on CO2 emission, one important source of greenhouse gasses (GHGs) that traps heat in the earth system and results in global warming. In this research, we incorporate a revised version of the CENTURY carbon model into SWAT to describe dynamics of soil organic matter (SOM)-residue and simulate land-atmosphere carbon exchange. We test this new SWAT-C model with daily eddy covariance (EC) observations of net ecosystem exchange (NEE) and evapotranspiration (ET) and annual crop yield at six sites across the U.S. Midwest. Results show that SWAT-C simulates well multi-year average NEE and ET across the spatially distributed sites and capture the majority of temporal variation of these two variables at a daily time scale at each site. Our analyses also reveal that performance of SWAT-C is influenced by multiple factors, such as crop management practices (irrigated vs. rainfed), completeness and accuracy of input data, crop species, and initialization of state variables. Overall, the new SWAT-C demonstrates favorable performance for simulating land-atmosphere carbon exchange across agricultural sites with different soils, climate, and management practices. SWAT-C is expected to serve as a useful tool for including carbon flux into consideration in sustainable watershed management under a changing climate. We also note that extensive assessment of SWAT-C with field observations is required for further improving the model and understanding potential uncertainties of applying it across large regions with complex landscapes.
Science of The Total Environment 07/2013; 463-464C:810-822. · 3.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Highlights
► The effect of climate change on freshwater availability in Africa was analyzed. ► The ensembles of the future climate projections were fed into SWAT hydrologic model. ► In Africa as a whole, the mean total quantity of water resources is likely to increase. ► For individual subbasins and countries, variations were substantial. ► Prolonged droughts in dry regions, entails an additional challenge to food production.
Journal of Hydrology 02/2013; 480:85–101. · 2.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The partition between dissolved phases and sorbed fractions onto suspended matters explains the dynamic of pesticides across the environmental compartments. In modelling approaches, the partition coefficient Kd is usually estimated from different empirical models linked to the octanol/water distribution coefficient Kow. We tested a new relationship for the partition coefficient Kd in rivers, relating Kd to Kow and to Total Suspended Matter (TSM). This relationship was obtained from the concentration measurements of TSM, of Particulate Organic Carbon (POC) and of 7 pesticide molecules (alachlor, atrazine, DEA, isoproturon, tebuconazole and trifluralin) at the outlet of the River Save. The latter river drains an 1110 km² agricultural watershed where intensive pesticide inputs are supplied each year, mostly herbicides. The relationship between Kd, Kow and TSM and its constants, suitable to the Save environmental context, were implemented in the Soil and Water Assessment Tool (SWAT) to improve pesticide fate modelling in this fluvial environment.
2012 SWAT International Conference, July 18-20, New Delhi, India; 07/2012
[Show abstract][Hide abstract] ABSTRACT: Assessment of pesticide application date shifts on surface water contamination during floods using the SWAT model in the Save catchment (south-western France).
In agricultural watersheds, pesticide contamination in surface water mostly occurs during flood events. Among all the parameters involved in the contaminations risks, the pesticide application date input was changed within a one-month interval using the Soil and Water Assessment Tool (SWAT) in an agricultural watershed in the South-West of France. The Save River drains an 1110 km² area of essentially wheat, corn, sorghum and sunflower grown with intensive pesticide inputs, mostly herbicides. The SWAT model was applied to simulate daily metolachlor and aclonifen transfer at the catchment outlet from January 2008 to June 2010. Metolachlor is a highly soluble and poorly lipophilic herbicide whereas aclonifen is a poorly soluble and highly lipophilic herbicide. A single catchment average application date established by a 3-year survey (2007-2009) was assumed for each land use. Total metolachlor concentration prediction could be improved by an application timing shift to 3 days later (Daily R² = 0.22 and PBIAS = -57%). Total aclonifen concentration prediction could not be improved by any timing shift in the chosen range of dates. By testing the behaviour of the two molecules, it was shown that sorption processes were driving the transfer. Metolachlor concentration in the channel mostly depended on both discharge and delay between application date and first flood event whereas transfer of aclonifen mostly depended on rainfall intensity for exportation with suspended sediments through surface runoff.
2012 SWAT International Conference, July 18-20, New Delhi, India; 07/2012
[Show abstract][Hide abstract] ABSTRACT: Large-scale hydrologic models are being used more and more in watershed management and decision making. Sometimes rapid modeling and analysis is needed to deal with emergency environmental disasters. However, time is often a major impediment in the calibration and application of these models. To overcome this, most projects are run with fewer simulations, resulting in less-than-optimum solutions. In recent years, running time-consuming projects on gridded networks or clouds in Linux systems has become more and more prevalent. But this technology, aside from being tedious to use, has not yet become fully available for common usage in research, teaching, and small to medium-size applications. In this paper we explain a methodology where a parallel processing scheme is constructed to work in the Windows platform. We have parallelized the calibration of the SWAT (Soil and Water Assessment Tool) hydrological model, where one could submit many simultaneous jobs taking advantage of the capabilities of modern PC and laptops. This offers a powerful alternative to the use of grid or cloud computing. Parallel processing is implemented in SWAT-CUP (SWAT Calibration and Uncertainty Procedures) using the optimization program SUFI2 (Sequential Uncertainty FItting ver. 2). We tested the program with large, medium, and small-size hydrologic models on several computer systems, including PCs, laptops, and servers with up to 24 CPUs. The performance was judged by calculating speedup, efficiency, and CPU usage. In each case, the parallelized version performed much faster than the non-parallelized version, resulting in substantial time saving in model calibration.
Environmental Modelling and Software 05/2012; 31:28–36. · 4.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: SWAT: Model Use, Calibration, and Validation SWAT: Model Use, Calibration, and Validation SWAT (Soil and Water Assessment Tool) is a comprehensive, semi-distributed river basin model that requires a large number of input parameters, which complicates model parameterization and calibration. Several calibration techniques have been developed for SWAT, including manual calibration procedures and automated procedures using the shuffled complex evolution method and other common methods. In addition, SWAT-CUP was recently developed and provides a decision-making framework that incorporates a semi-automated approach (SUFI2) using both manual and automated calibration and incorporating sensitivity and uncertainty analysis. In SWAT-CUP, users can manually adjust parameters and ranges iteratively between autocalibration runs. Parameter sensitivity analysis helps focus the calibration and uncertainty analysis and is used to provide statistics for goodness-of-fit. The user interaction or manual component of the SWAT-CUP calibration forces the user to obtain a better understanding of the overall hydrologic processes (e.g., baseflow ratios, ET, sediment sources and sinks, crop yields, and nutrient balances) and of parameter sensitivity. It is important for future calibration developments to spatially account for hydrologic processes; improve model run time efficiency; include the impact of uncertainty in the conceptual model, model parameters, and measured variables used in calibration; and assist users in checking for model errors. When calibrating a physically based model like SWAT, it is important to remember that all model input parameters must be kept within a realistic uncertainty range and that no automatic procedure can substitute for actual physical knowledge of the watershed.
[Show abstract][Hide abstract] ABSTRACT: One of the most important transboundary animal diseases (TADs) in the southern African region is foot-and-mouth disease (FMD). In this region, a pathway for spread of FMD virus is contacts between cattle and certain species of wildlife. The objective of this study was to evaluate contacts between cattle and wildlife in the Kruger National Park (KNP) and the adjacent Limpopo province for the time periods October 2006 to March 2007 and April to September 2007. In this study, 87 livestock owners and 57 KNP field rangers were interviewed. Fifteen (17%) livestock owners reported contacts between wildlife and cattle. More livestock owners reported observing contacts between cattle and all wildlife species during October-March than April-September (p=0.012). However, no difference was found between these periods for contacts between cattle and individual wildlife species. A total of 18 (32%) field rangers reported contacts between cattle and wildlife. The most common species-specific contacts were between cattle and buffalo (63/year), cattle and impala (17/year) and cattle and lion (10/year). There were no significant differences in rangers reporting observed contacts between cattle and wildlife during October-March versus April-September or between rangers reporting observed contacts outside versus within the KNP. Overall, there was no evidence of higher contact rates between cattle and wildlife in the study area during October-March compared to April-September. Contact data collected in this study can be used to better understand the transmission of FMD virus in this region.
Preventive Veterinary Medicine 09/2011; 103(1):16-21. · 2.51 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Simulating irrigation systems by accounting for various water loss rates is necessary while modeling the hydrology of cultivated canal-irrigated watersheds. The existing approaches to modeling canal irrigation use situation-specific optimization procedures. In addition, they are focused on a water management perspective rather than a hydrologic perspective. In this study, an approach is developed to model canal irrigation systems and irrigation best management practices (BMPs) to adequately simulate the water balance of irrigated watersheds. The approach is based on the water requirement of crops, number and frequency of irrigation, and critical crop water requirement stages. Two irrigation BMPs are modeled as water savers rather than physical changes in irrigation appurtenances. Land leveling is modeled by changing model parameters and water management by changes in frequency, timing, and magnitude of irrigation with respect to cumulative precipi-tation. The developed approach was tested with a 1;692 km 2 intensively cultivated, canal-irrigated watershed using the Soil and Water Assessment Tool (SWAT). Test results suggest that the approach captures water balance and observed runoff hydrograph of the study area adequately.
Journal of Hydrologic Engineering 09/2011; 16(9). · 1.62 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The SWAT model was tested at a daily time step to assess the fate of pesticides of a wide range of solubility. SWAT was applied on an 1100km² intensive agricultural catchment (Save river, southwestern France). Simulated pesticide concentrations were compared to data collected at the catchment outlet from July 2009 to June 2010, with weekly measurements during low flow and daily or sub-daily measurements during flood events. SWAT was able to accurately reproduce measured pesticides concentrations during
base flow and flood events, especially concentrations of pesticide in the soluble phase. During the simulation period, simulated preferred pathway for pesticide transport from land area to stream network was surface runoff. Flood events were responsible for most pesticide transfer. The SWAT model hindcasted daily pesticide concentrations back to 1998 and possible water quality policy thresholds exceeding depending on climate.
2011 International SWAT Conference, Toledo, Splain; 05/2011