Browsing by Author "Andales, Allan A., committee member"

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Open Access
Assessing irrigation canal seepage reduction using polymer sealants
(Colorado State University. Libraries, 2024) Lund, Ahmad Abdur Rehman, author; Scalia, Joseph, IV, advisor; Gates, Timothy K., advisor; Venayagamoorthy, S. Karan, committee member; Andales, Allan A., committee member
Irrigation canals around the world experience varying degrees of seepage losses, with several potential adverse consequences and influenced by numerous factors. A synthesis and interpretation of field seepage data from peer-reviewed literature (impact factor >1.5) on seepage measurement and control reveals several key insights: (i) seepage rates differ significantly due to diverse field conditions; (ii) the inflow-outflow method is the most reliable for measuring canal seepage in the field; and (iii) polymer sealants (PSs) offer a cost-effective alternative for reducing seepage in irrigation canals. Compared to conventional liners (CLs) such as concrete, geomembranes, or masonry, PSs are not only more affordable but also can be applied selectively, allowing for seepage when the surface water supply is sufficient and groundwater recharge is desirable. Studies show PSs can reduce seepage by 64% to 88%, while CLs achieve reductions of 53% to 95%, highlighting the potential of PSs for further research and application. However, best field application techniques for PSs, the uncertainty in evaluating effectiveness, and ambiguity in potential environmental impacts require more comprehensive investigation. The most widely researched PS for reducing canal seepage is linear anionic polyacrylamide (LAPAM), a synthetic polymer sealant (SPS). When applied to canal water, LAPAM forms flocs through cation bridging with divalent cations (Mg2+ and Ca2+) commonly found in canal water, which settle along the canal perimeter and reduce hydraulic conductivity. Observed seepage reduction from field trials of LAPAM that had been conducted prior to this study on three mid-sized canals (two in Colorado, USA and one in Sindh, Pakistan) using the recommended inflow-outflow method for seepage testing were analyzed. The average pre-LAPAM seepage rate was approximately 0.32 m/day, while the post-LAPAM rate dropped to 0.04 m/day, with results demonstrating seepage reductions between 69% and 100%. An uncertainty analysis of the pre- and post-LAPAM tests indicated an 85% probability that the seepage reductions were due to the LAPAM treatment. While LAPAM has proven effective, the long-term environmental impact of LAPAM treatment remains uncertain, underscoring the need to explore natural alternatives to synthetic polymer sealants. Biopolymer sealants (BPSs) were identified and evaluated through both laboratory and field experiments, designed to mirror the approach used with LAPAM. These experiments were conducted in triplicate (lab) and duplicate (field) to enhance confidence. In the lab, constant head saturated hydraulic conductivity (KSAT) tests simulated irrigation canal perimeter conditions. Five BPSs—pectin citrus (PC), cellulose hydroxyethyl ether (CHE), pullulan desalinated (PD), sodium alginate low viscosity (SALV), and xanthan gum (XG)—were initially tested and compared against LAPAM. The pre-and post-polymer KSAT values revealed that PC, PD, and XG achieved average reductions exceeding 40%, which was used as the threshold for further exploration. Subsequent testing under conditions more representative of irrigation canals identified XG as the most effective BPS. Alternative application rates were assessed, with 20 mg/L identified as the preferred concentration, as higher concentrations did not significantly enhance KSAT reduction. Long-term performance tests in the lab showed that XG, at 40 mg/L, can reduce hydraulic conductivity by over 90% for 9–10 months and by 60–70% over 1.5 months at 20 mg/L. These findings were validated using seepage tests in the field, where XG applied to a 3-km earthen canal reach at 20 mg/L reduced seepage by up to 63% over a month (at which time the canal was taken out of service). While the use of SPSs may still be justified for controlling canal seepage, this research shows that BPSs such as XG, have the potential to replace SPSs for canal sealing. However, further work is needed to optimize application methods and dosage rates, to better understand working mechanisms, to demonstrate long-term effectiveness, and to assess scalability across diverse field conditions.
Open Access
Changes in golf course fairway soils under effluent water irrigation
(Colorado State University. Libraries, 2010) Skiles, David John, author; Qian, Yaling, advisor; Andales, Allan A., committee member; Koski, Tony, committee member
As the use of effluent irrigation increases, salinity and sodicity issues associated with its use continue to be of great concern to the golf course industry. The purpose of our research was to (i) observe salinity accumulation patterns on 4 fairways of two effluent water irrigated golf courses using 2 different types of sensors and to (ii) determine long-term changes in soil chemistry in soils under effluent water irrigation on golf course fairways. Temporal and spatial accumulation patterns were measured using a network of in-situ soil sensors located at two depths 15 and 30 cm for 5TE sensors and 8 and 19cm for Turf Guard sensors (TG2). Sensors measured electrical conductivity (EC), volumetric soil water content (SWC), and soil temperature data were collected continuously during the 2008 and 2009 growing seasons. Correlation was observed between 5TE sensor-measured soil salinity vs. saturated paste extracted soil salinity (r = 0.77). A significant exponential relationship was observed between TG2 sensor-measured soil salinity vs. saturated paste extracted soil salinity (R² = 0.97). In-ground measurements indicated that salinity can vary widely across a seemingly homogenous golf course fairway in a manner reflective of the underlying soil physical characteristics. Plots exhibiting low and high salinities presented opposite seasonal trends at Heritage Golf Course. Strong correlation was observed between average soil salinity and mean soil water content (r =0.76), soil salinity and the percentage of sand in the soil texture composition (r = -0.63) for Heritage fairway 1. High salinity was found on fairway 19 at Common Ground Golf Course. However, the salinity level as high as 10.6 dS/m is not a result of water reuse, but a historical geological contribution. Drainage appears to be vital in maintaining low soil salinity levels under effluent irrigation in clay soils. Slow to infiltrate, percolate and difficult to leach; predominately clay soils irrigated with effluent water can accumulate soil salinity over time. Our data suggested that a robust drainage network in predominantly clay soils irrigated with effluent could better manage salinity accumulation associated with poor drainage. To determine long-term changes in soil chemistry in soils under effluent water irrigation on golf course fairways, soil testing data was provided by the superintendent for the years of 1999, 2000, 2002, 2003, and 2009 for Heritage Golf Course in Westminster, Colorado. Soil samples were tested by Brookside Laboratories, Inc, New Knoxville, OH. Parameters of each soil sample tested included pH, extractable salt content (calcium, magnesium, potassium, sodium, iron, manganese, copper, zinc, phosphorus, and boron), base saturation percent of calcium, magnesium, potassium and sodium, soil organic matter (SOM), and cation exchange capacity (CEC). Regression analysis was used to evaluate the changes in individual soil parameters over time after the use of effluent water for irrigation. Soil pH, CEC, extractable aluminum, copper, manganese and iron along with both base saturation percentages and exchangeable percentages of calcium and magnesium did not change over time. The strongest indications of change are seen for extractable boron (R² = 0.56), Bray II extracted phosphate (R² = 0.56), and sodium base saturation percentage (R² = 0.44). The regression analysis indicated that B, P, and sodium increased linearly during the 8 year's irrigation with effluent water. Further studies are needed to determine if these parameters would continue to increase or would stabilize. Continued accumulation of sodium could eventually result in loss of soil structure.
Open Access
Evaluation of analytical footprint models and energy balance closure methods over cotton in Texas panhandle
(Colorado State University. Libraries, 2011) Joy, Stuart L., author; Chávez, José Luis, advisor; Ham, Jay, committee member; Andales, Allan A., committee member
Eddy covariance (EC) systems are being used to measure sensible heat (H) and latent heat (LE) fluxes in order to determine crop water use or evapotranspiration (ET). However, EC systems tend to systematically underestimate H and LE fluxes; thus, a lack of energy balance closure. The reliability of EC measurements depends on meeting certain meteorological assumptions; the most important of such are a horizontal homogeneity, stationarity, and non-advective conditions. Over heterogeneous surfaces the spatial context of the measurement must be known in order to properly interpret the magnitude of the heat flux measurement results. Over the past two decades there has been a proliferation of `heat flux source area' (i.e., footprint) modeling studies but only a few that explore the accuracy of models over heterogeneous agricultural land. A composite ET estimate was created by using the estimated footprint weights for an EC system in the upwind corner of four fields and separate ET estimates from each of these fields. Three analytical footprint models were evaluated by comparing the composite ET to the measured ET. All three models performed consistently with an average MBE of about -0.03 mm h-1 (-4.4%) and RMSE of 0.09 mm h-1 (10.9%). The same three footprint models were then used to adjust measured ET to account for the fraction of the footprint that extended beyond the field of interest. The effectiveness of the footprint adjustment was determined by comparing adjusted ET estimates with lysimetric ET measurements from within the same field. This correction decreased the absolute hourly ET MBE by 8% and the RMSE by 1%. The energy balance is rarely closed with the EC method and therefore the energy balance was closed by adjusting the H and LE heat fluxes by first assuming the H was measured accurately and applying the entire residual to the LE (LEC) heat flux and secondly by assuming the Bowen ratio (BRC) was measured accurately and adjusting both H and LE while conserving the BR. The application of energy balance closure to uncorrected EC heat fluxes showed better agreement between EC and lysimeter ET. There was not a significant difference between the BRC and LEC methods when applied to uncorrected heat fluxes. The analytical footprint models developed by Schuepp et al. (1990), Hsieh et al. (2000), and Kormann and Meixner (2001) all gave a reliable estimate of the footprint for heterogeneous agricultural land under highly advective conditions. Care should be taken when using the EC system to measure ET early in the growth stage of a crop when the surface is smooth because the footprint will extend farther upwind. Correcting the EC heat fluxes for coordinate rotation, density, spectral attenuation, and sonic temperature heat flux and then applying the proposed correction considering the footprint resulted in the most accurate estimate of hourly EC based ET with a MBE of 0.01 mm h-1 (0.6 to 1.5%) and RMSE of 0.10 to 0.11 mm h-1 (10.6 to 11.66%).
Open Access
Evaluation of the Kipp and Zonen large aperture scintillometer for estimation of sensible heat flux over irrigated and non-irrigated fields in southeastern Colorado
(Colorado State University. Libraries, 2012) Rambikur, Evan H., author; Chávez, José L., advisor; Andales, Allan A., committee member; Ham, Jay M., committee member; Gates, Timothy K., committee member
The aim of this work was to assess the performance of the Kipp and Zonen Large Aperture Scintillometer (LAS; Delft, Netherlands) to predict surface sensible heat flux (H). The LAS was introduced approximately 30 years ago and has been marketed as an indirect tool for the estimation of vegetation evapotranspiration (ET). Several tests have shown the LAS to be a fairly robust tool for prediction of H, both over homogeneous and heterogeneous surfaces. However, the Kipp and Zonen LAS has been criticized for overestimation of H and for significant inter-sensor deviation in H. Field experiments were performed in 2011 using three Kipp and Zonen LAS units over two different surfaces to assess the accuracy and inter-sensor variability. Accuracy was evaluated based on reference measurements from eddy covariance (EC) instrumentation, which provides direct measurement of sensible and latent heat fluxes. Notably the EC method has been criticized for systematic underestimation of the sensible and/or latent heat flux, but is nonetheless a common tool used to validate LAS data. The first experimental test site was predominantly dry and uniform grassland located near Timpas, CO. At this site, all three LAS units were deployed together for some time in order to assess inter-sensor variability and an EC system was installed for some duration of the LAS deployment. The EC system was subsequently moved to the second site, which was the Colorado State University (CSU) Arkansas Valley Research Center (AVRC) near Rocky Ford, CO. At the AVRC, one LAS unit was set up over irrigated alfalfa. Results from the inter-LAS comparison suggested that there may be some inherent variability between 6-11% in LAS-predicted H (HLAS) and that the physical alignment of the LAS is critical for maintaining good performance. Testing different methods for estimation of the friction velocity (u*) variable revealed bias between the logarithmic wind profile (LWP) result and the EC measurement. Linear regression slopes between 0.94 and 1.35 were found for HLAS with respect to EC-derived H (HEC) for the Timpas site - dependent on the LAS unit, the LAS alignment, and the u* method. The overall conclusion was that HLAS was reasonably accurate, partially due to the potential of HEC being underestimated on the basis of lack of energy balance closure. For the CSU AVRC (irrigated) site, HLAS was generally observed to be greater than HLAS by 20-30%. However, heat flux source area differences between the LAS and EC units may have contributed to some of the observed biases. Further, the overall conclusion of reasonable accuracy of HLAS was made, again partially due to potential for H underestimation by the EC system. It is recommended, nonetheless, for future applications to calibrate the Kipp and Zonen LAS to a reliable reference on the basis of observed inter-sensor variability. Further, the benefit of the LAS is judged to be higher for a scenario of limited or no irrigation than for one of full irrigation, since the contribution of H to the overall energy balance would be relatively small for a full irrigation scenario.
Open Access
Performance evaluations and calibrations of soil water content/potential sensors for agricultural soils in eastern Colorado
(Colorado State University. Libraries, 2011) Varble, Jordan L., author; Chávez, José L., advisor; Andales, Allan A., committee member; Butters, Greg L., committee member; Trout, Thomas J., committee member
To view the abstract, please see the full text of the document.
Open Access
Responses of four shrub species to four levels of irrigation in a semi-arid environment
(Colorado State University. Libraries, 2012) Smith, Jason F., author; Klett, James E., advisor; Andales, Allan A., committee member; Bauerle, William L., committee member
In response to a severe regional drought that afflicted much of Colorado in 2002, Colorado State University initiated a study to determine the impacts of progressively decreasing irrigation treatments on some common shrub species. Irrigation treatments were based on the evapotranspiration of a short reference crop (ETo). In 2008, four shrub species were planted for trialing: Cornus sericea L. 'Isanti' (redosier dogwood), Hydrangea arborescens L. 'Annabelle' (smooth hydrangea), Physocarpus opulifolius (L.) Maxim. 'Monlo' (Diablo® ninebark) and, Salix pupurea L. 'Nana' (arctic blue willow). In addition to the shrubs, Poa pratensis L. (Kentucky bluegrass) was used as a control. After giving the shrubs and turf one growing season to establish, treatments were applied in 2009 and 2010. The study was comprised of a field component and a lysimeter component. The field component had four treatments based on ETo (0%, 25%, 50%, and 100%) and the lysimeter component had three treatments (25%, 50%, and 100%). All four species were planted in the field component and only the redosier dogwood and smooth hydrangea were planted in the lysimeter component due to space limitations. Data collection in both components included canopy height and width, visual ratings, predawn leaf water potentials, end of season leaf area, and end of season leaf fresh/dry weights. The field component also included soil moisture readings, osmolality, and infrared readings of the Kentucky bluegrass. The lysimeter component required daily weight measurements during dry down periods. As watering amounts increased for the field dogwoods, ninebarks, and willows various characteristics (overall stress, aesthetic appeal, size, osmolality) were also positively affected. However, all tested replicates of these three species in the 0% treatment appeared acceptable for landscape use, as well. The hydrangeas in the 100% treatment had the highest visual ratings. In addition, the water potentials were more negative in the 100% treatment. Due to the visual ratings and water potential data, it suggests that smooth hydrangea needs more than 100% ETo to improve growth and performance. All of the field hydrangeas in the 0% treatment were unacceptable for landscape use and were close to death, however, 80% of the replications survived until the conclusion of the experiment. As such, the smooth hydrangea can survive a short period without water and should recover when water becomes available. The lysimeter dogwoods and hydrangeas adjusted their growth habits based on water availability. Water was used on a daily basis at a faster rate as the irrigation treatments increased. The lysimeter shrubs in the 100% treatment used more water on a daily basis than the 50% treatment and the 50% treatment used more than the 25% treatment. The increased water use affected plant growth and if more water was available to the dogwood and hydrangea, a larger plant resulted.