Evaluating the Effectiveness of Public Television as a Method for Watershed Education

We describe a program that evolved from Cooperative Extension educators\u27 concern about declining attendance at face-to-face workshops on environmental issues. As a result, we developed an education program comprising six television programs; a radio series; Web-based materials; and information supplied to libraries. We randomly selected individuals to complete a written survey assessing their environmental knowledge and commitment pre- and post-broadcast. Our analyses indicate that watching the television programs did not predict significant changes in environmental knowledge or commitment. Our study findings do not strongly support the effectiveness of using local public television as an environmental education tool

Salt Loading from Efflorescence and Suspended Sediments in the Price River Basin

Salinity control is a major component of water management in arid climates and irrigated areas and one of particular concern in the Colorado River Basin. The alts enter the water as it flows over land or moves through the soil or geologic formations. The principal salt collection processes are 1) dissolution from the soil surface during runoff events, 2) transpiration of soil water leaving salt residuals, 3) efflorescence left by evaporating seepage and then dissolved by subsequent runoff, 4) dissolution with weathering of fixed bed channels, 5) salts released by sediments entering the channel from sheet, gulley, and bank erosion, and 6) deep percolation through saline aquifer reaching the stream as base flow. This study examined processes 3 and 5. Salt efflorescence was examined by field observation and instrumentation, laboratory experiments, and mathematical modeling. The field data showed near saturation conditions of sodium sulfate waters below crusts of densities between 0.14 and 0.36 g/cm^2 and which formed over abouta 10-day period following channel cleaning by storm runoff. Laboratory data on salt crusting in soil columns were also used in developing a model which when applied to the Price River Basin estimated that no more than 7.5 percent of the total salt loading comes from salt efflorescence being carried away in the stream flow. The conditions favorable to the accumulation of salt efflorescence are highly saline water just below the soil surface and a source of heat for vaporizing the water. Salt release from suspended sediments was studied by laboratory experimentation with sediment material obtained from various locations in the Price River Basin. The Buckinham Pi Theorem was employed to derive relationships expressing the EC of a sediment water system as a function o fthe controlling factors. The results were presented in two salt release equations, one excluding the effect of initial EC and the other providing for initially saline solutions. The salt release equations were incorporated into an adapted version of the Watershed Erosion and Sediment Transport (WEST) model and applied to a small tributary of Coal Creek. Extrapolation to the entire Price River Basin led to an estimate that about 0.50 percent of the total annual salt load is released from suspened sediments. This study concludes that surface salt sources produce a relatvely small fraction of the total loading. Future studies need to go underground. They need to quantify and examine the flow lines of water movement from mountain source and valley floow recharge areas to points of emergence as base flow in the larger stream channels. They need to investigate the aquifers and their soluble salt content

A Combined Salt Transport-Chemical Equilibrium Model for Calcareous and Gypsiferous Soils

Chemical precipitation-dissolution and cation exchange subroutines were interfaced with an existing water movement-salt transport model. Three model options available for testing the prediction of salt transport and storage were (i) individual ion transport without soil interaction, (ii) precipitation and dissolution of lime and gypsum during transport, and (iii) cation exchange in addition to the precipitation-dissolution reactions. The transport model also predicts relative crop growth and water uptake as affected by soil moisture and salinity. The chemical subroutine used by the second and third options calculated ionic activities, corrected for ionic strength and ion pair formation, and was used to calculate lime and gypsum precipitation and dissolution. Cation activities were also used to calculate Ca, Mg, Na, and K exchange equilibria by a method that allows for addition of any number of exchangeable cations. Values predicted by the three options for EC, SAR and Ca, Mg, Na, A, Cl, SO? and HCO? concentrations were compared to experimental data obtained from a lysimeter study and were only satisfactorily predicted when both chemical precipitations and cation exchange were considered for a gypsiferous and a nongypsiferous soil irrigated with a high, medium, and low CaSO? water at two leaching fractions

Description of Equilibrium Chemistry During Soil-Water Transport

Description of soluble salt leaching through soils and into groundwaters has been the focus of several research studies in recent years (Tanji et al. 1972; Dutt at al. 1972; Oster and Rhoades 1975: Melamed et al. 1977; Jury at al. 1978). The simulation models produced by these investigators have involved various levels of sophistication in the description of the con-comitant processes of soil water transport and chemical reaction of solutes. Mechanistic water flow models (Melamed et al. 1977) often include empirical description of chemistry, while more complete soil chemistry description (Tanji et al. 1972; Dutt et al. 1972) has often been accompanied by a simple water flow model. The result of these facts has been the development of models limited in their transferability to other experimental cases, or models that sometimes produce questionable results when applied to situations for which they were not developed. With these considerations in mind, a detailed simulation model has been developed describing the one—dimensional soil water transport of several ionic species in the presence of chemical precipitation and dissolution and cation exchange. This paper describes the theoretical approaches taken, gives several examples of model validation, and then presents two hypothetical simulation cases that demonstrate model application. The specifics of structure, operation, and validation of this model with experimental data are explained elsewhere (Robbins 1979; Robbins et al. 1980a, b)

Calculating Cation Exchange in a Salt Transport Model

A cation exchange subroutine that can be expanded to include any number of cations was developed and interfaced with a water flow-salt transport model that also contained a lime and gypsum precipitation-dissolution chemistry subroutine. The exchange subroutine was required by the complete model to satisfactorily predict EC, SAR, and specific ion concentration changes with time and depth for a gypsiferous and a nongypsiferous soil irrigated with waters containing three different CaSO? concentrations at two leaching fractions. In his sudy, exchangeable Ca, Mg, Na, and K were considered. Exchangeable K was included for me with high exchangeable and soluble K soils and high K irrigation waters. The additional cation exchange coefficient values needed for K exchange and a method for their calculation is given

A Model of Environmental Transport of Heavy Metals Originating From Stack Derived Particulate Emission in Semi-Arid Regions

Executive Summary

Application of HYDRUS (2D/3D) for Predicting the Influence of Subsurface Drainage on Soil Water Dynamics in a Rainfed-Canola Cropping System

The HYDRUS (2D/3D) model was applied to investigate the probable effects of different subsurface drainage systems on the soil water dynamics under a rainfed-canola cropping system in paddy fields. Field experiments were conducted during two rainfed-canola growing seasons on the subsurface-drained paddy fields of the Sari Agricultural Sciences and Natural Resources University, Mazandaran Province, northern Iran. A drainage pilot consisting of subsurface drainage systems with different drain depths and spacings was designed. Canola was cultivated as the second crop after the rice harvest. Measurements of the groundwater table depth and drain discharge were taken during the growing seasons. The performance of the HYDRUS-2D model during the calibration and validation phases was evaluated using the model efficiency (EF), root mean square error (RMSE), normalized root mean square error (NRMSE) and mean bias error (MBE) measures. Based on the criteria indices (MBE = 0.01–0.17 cm, RMSE = 0.05–1.02 and EF = 0.84–0.96 for drainage fluxes, and MBE = 0.01–0.63, RMSE = 0.34–5.54 and EF = 0.89–0.99 for groundwater table depths), the model was capable of predicting drainage fluxes as well as groundwater table depths. The simulation results demonstrated that HYDRUS (2D/3D) is a powerful tool for proposing optimal scenario to achieve sustainable shallow aquifers in subsurface-drained paddy fields during winter cropping. Copyright © 2017 John Wiley & Sons, Ltd

Nested sampling and spatial analysis for reconnaissance investigations of soil: an example from agricultural land near mine tailings in Zambia

A reconnaissance survey was undertaken on soil near mine tailings to investigate variation in the content of copper, chromium and uranium. A nested sampling design was used. The data showed significant relations between the content of copper and uranium in the soil and its organic matter content, and a significant spatial trend in uranium content with distance from the tailings. Soil pH was not significantly related to any of the metals. The variance components associated with different scales of the sample design had large confidence intervals, but it was possible to show that the random variation was spatially dependent for all spatial models, whether for variation around a constant mean, or with a mean given by a linear effect of organic matter or distance to the tailings. For copper, we showed that a fractal or multifractal random model, with equal variance components for scales in a logarithmic progression, could be rejected for the model of variation around the fixed mean. The inclusion of organic matter as an explanatory factor meant that the fractal model could no longer be rejected, suggesting that the effect of organic matter results in spatial variation that is not scale invariant. It was shown, taking uranium as a case study, that further spatially nested sampling to estimate scale-dependent variance components, or to test a non-fractal model with adequate power, would require in the order of 200–250 samples in total

Pesticide And Transformation Product Detections And Age-Dating Relations From Till And Sand Deposits

Pesticide and transformation product concentrations and frequencies in ground water from areas of similar crop and pesticide applications may vary substantially with differing lithologies. Pesticide analysis data for atrazine, metolachlor, alachlor, acetochlor, and cyanazine and their pesticide transformation products were collected at 69 monitoring wells in Illinois and northern Indiana to document occurrence of pesticides and their transformation products in two agricultural areas of differing lithologies, till, and sand. The till is primarily tile drained and has preferential fractured flow, whereas the sand primarily has surface water drainage and primary porosity flow. Transformation products represent most of the agricultural pesticides in ground water regardless of aquifer material – till or sand. Transformation products were detected more frequently than parent pesticides in both the till and sand, with metolachlor ethane sulfonic acid being most frequently detected. Estimated ground-water recharge dates for the sand were based on chlorofluorocarbon analyses. These age-dating data indicate that ground water recharged prior to 1990 is more likely to have a detection of a pesticide or pesticide transformation product. Detections were twice as frequent in ground water recharged prior to 1990 (82%) than in ground water recharged on or after 1990 (33%). The highest concentrations of atrazine, alachlor, metolachlor, and their transformation products, also were detected in samples from ground water recharged prior to 1990. These age ⁄ pesticide detection relations are opposite of what would normally be expected, and may be the result of preferential flow and ⁄ or ground-water mixing between aquifers and aquitards as evident by the detection of acetochlor transformation products in samples with estimated ground-water ages predating initial pesticide application

Assessment of LEACHN and a simple compartmental model to simulate nitrogendynamics in citrus orchards

A simple compartmental model using a tipping bucket approach for the water dynamics coupled with a nitrogen¿carbon transformations model has been adapted to simulate the soil nitrogen and water balance in mature orange groves on a daily step. This model has been compared with the more mechanistic LEACHN model (the N module of the LEACHM model), which uses Richards¿ equation to simulate soil water movement in unsaturated conditions, the convection¿dispersion equation for solute transport, and that, in addition to including evapotranspiration, N transformations and N plant uptake as in the compartmental model, it also considers gaseous losses due to denitrification and ammonia volatilization, that are not considered in the compartmental model. This comparison was made using data from a three-year experiment in a citrus orchard with two nitrogen fertilization rates. After calibration using the first year data, a reasonable match between simulated and measured values in both models was observed for soil water storage in the whole profile for the validation period (2nd and 3rd year), but the agreement was not so good for the soil mineral nitrogen content. In spite of the differences in the nature and in the complexity of the two models, the soil water dynamics and drainage were well simulated during the whole period by both models. However, the LEACHN model predicted nitrate leaching better than the compartmental model, probably because it considers the nitrogen cycle in a more detailed way. This work is the first calibration and performance evaluation of the LEACHN model for citrus in the Mediterranean area and the results obtained in this study indicate that this model can be a valid tool to evaluate the effects of irrigation and N management on nitrate leaching. The compartmental model has a lower data requirement and calibration is less complex than the LEACHN model and, therefore, may be more appealing for advisory N management purposes.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion under projects, MTM2007-64477-AR07 and INIA-RTA 2011-00136-C04-01.Lidón Cerezuela, AL.; Ramos Mompo, C.; Ginestar Peiro, D.; Contreras Espinosa, WA. (2013). Assessment of LEACHN and a simple compartmental model to simulate nitrogendynamics in citrus orchards. Agricultural Water Management. 121:42-53. doi:10.1016/j.agwat.2013.01.008S425312