<p>Controlled drainage is a management strategy designed to mitigate water quality issues caused by subsurface drainage. To improve controlled drainage system management and better understand its hydrological and environmental effects, this study analyzed water table recession rate, as well as drain flow, nitrate and phosphorus loads of both free and controlled drainage systems, and simulated the hydrology of a free drainage system to evaluate surface runoff and ponding at the Davis Purdue Agricultural Center located in Eastern Indiana. </p> <p>Statistical analyses, including paired watershed approach and paired t-test, indicated that controlled drainage had a statistically significant effect (<i>p</i>-value <0.01) on the rate of water table fall and reduced the water table recession rate by 29% to 62%. The slower recession rate caused by controlled drainage can have negative impacts on crop growth and trafficability by causing the water table to remain at a detrimental level for longer. This finding can be used by farmers and other decision-makers to improve the management of controlled drainage systems by actively managing the system during storm events. </p> <p>A method was developed to estimate drain flow during missing periods using the Hooghoudt equation and continuous water table observations. Estimated drain flow was combined with nutrient concentrations to show that controlled drainage decreased annual nitrate loads significantly (p<0.05) by 25% and 39% in two paired plots, while annual soluble reactive phosphorus (SRP) and total phosphorus (TP) loads were not significantly different. These results underscore the potential of controlled drainage to reduce nitrate losses from drained landscapes with the higher level of outlet control during the non-growing season (winter) providing about 70% of annual water quality benefits and the lower level used during the growing season (summer) providing about 30%. </p> <p>Three different methods including monitored water table depth, a digital photo time series and the DRAINMOD model simulations were used to determine the generation process of surface ponding and runoff and the frequency of incidence. The estimated annual water balance indicated that only 7% of annual precipitation contributed to surface runoff. Results from both simulations and observations indicated that all of the ponding events were generated as a result of saturation excess process rather than infiltration excess.</p> <p>Overall, nitrate transport through controlled drainage was lower than free drainage, indicating the drainage water quality benefits of controlled drainage, but water table remained at a higher level for longer when drainage was controlled. This can have negative impacts on crop yields, when water table is above a detrimental level, and can also increase the potential of nutrient transport through surface runoff since the saturation excess was the main reason for generating runoff at this field.</p>

A cana-de-açúcar tornou-se a cultura com maior expansão nos últimos anos no estado de São Paulo, tendência que deve continuar, considerando sua importância como matéria prima para a produção de açúcar e etanol. Essa expansão acontece principalmente sobre áreas que eram ocupadas por pastagens. Pelas atividades necessárias para o estabelecimento da cultura de cana-de-açúcar, é esperado um aumento da erosão de solos e uma alteração no balanço hídrico. Com esses antecedentes, objetivou-se quantificar experimentalmente o impacto na erosão dos solos e a modificação do balanço hídrico no primeiro metro de solo, causado pela substituição de pastagem por cana-de-açúcar. Foram construídas parcelas de escoamento (20 x 5 \'M POT.2\') sob pastagem e sob plantio novo de cana-de-açúcar (três repetições cada) em uma fazenda com solo do tipo Neossolo Quartzarênico no município de Itirapina-SP. Foi instalada uma estação meteorológica para medir a precipitação e a umidade do solo a 30, 60 e 90 cm de profundidade, e para coletar os parâmetros necessários para calcular a evapotranspiração pelo método de Penman-Monteith. Calhas foram instaladas ao nível do solo para quantificar a interceptação do dossel de cana-de-açúcar. O balanço hídrico para ambos os cultivos foi determinado em escala diária. Após cada evento de precipitação, foi quantificada a perda de solos e o escoamento superficial Durante o primeiro ano, a perda de solo sob pastagem foi de 0,26 Mg/ha.ano (adicionalmente, 0,32 Mg/ha foram coletados devido à perturbação do solo para implantação do experimento), enquanto cana-de-açúcar produziu 2,58 Mg/ha.ano. No segundo período chuvoso, a perda de solo sob pastagem diminui para 0,04 Mg/ha, e sob cana-de-açúcar registrou 0,47 Mg/ha. Estes resultados indicam que a substituição de pastagem por cana-de-açúcar aumentou a produção de sedimentos durante o primeiro ano em 2,32 Mg/ha; no segundo período, com o uso da cobertura de palha no solo sob cana-de-açúcar, o aumento foi de 0,43 Mg/ha. Depois de quatro meses de crescimento, o dossel da cana-de-açúcar intercepta 40% da precipitação. O escoamento superficial no primeiro ano foi de 56,1 mm, e diminuiu para 11,8 mm no segundo período por efeito da palha na superfície do solo. Nos mesmos períodos, o escoamento superficial na pastagem foi de 40,5 mm e 30,4 mm, respectivamente. Apesar da menor infiltração sob cana-de-açúcar, o solo apresenta maior umidade devido ao gradeamento que aumenta a porosidade, e portanto, a capacidade de armazenamento de água no solo. A percolação sob cana-de açúcar é menor que sob pastagem devido à maior evapotranspiração da cultura. / Sugarcane became the culture with the highest expansion in recent years in the state of São Paulo. This trend will continue considering its importance as raw material for the production of sugar and ethanol. The expansion occurs primarily on areas that are currently occupied by pastures, causing impacts on soil and water. Due to the necessary activities for the establishment of the sugarcane culture, a soil erosion increase and a water balance change are expected. With this background, the objective of this work was to experimentally quantify the change in soil erosion and modification of water balance in the first meter of soil caused by the substitution of pasture by sugarcane. Runoff plots were constructed (20 x 5 \'M POT.2\') under pasture and new sugarcane planting (three replicates each) on a farm with Quartzarenic Neosol (Typic Quartzipsamments) soil in the municipality of Itirapina-SP. A weather station to measure rainfall and soil moisture at 30, 60 and 90 cm depth, and to collect the necessary parameters to calculate the evapotranspiration by Penman-Monteith method was installed. Gutters were installed at ground level to quantify the interception of the sugarcane canopy. After every precipitation event the soil loss and the drainage were quantified, and the daily water balance was determined for both soil uses. During the first year, the pasture had a soil loss of 0.26 Mg/ha.yr (additional 0.32 Mg/ha.yr were collected due to the disturbance of the soil during experiment installation), while sugarcane produced 2.58 Mg/ha.yr. In the second rainy season, the losses under pasture decreased to 0.04 Mg/ha and sugarcane recorded 0.47 Mg/ha. These results indicate that the replacement of pasture by sugarcane increased the sediment production during the first year by 2.32 Mg/ha in the second period, covering the soil under sugarcane with straw, the difference decreased to 0.43 Mg/ha. After four months of growth, the sugarcane canopy intercepts 40% of the precipitation. The runoff in the first year was 56.1 mm, decreasing to 11.8 mm in the second period, due to the presence of straw on the soil surface. In the same periods, runoff under pasture was 40.5 mm and 30.4 mm, respectively. Although there is less infiltration under sugar cane, the soil presents higher moisture due to the porosity increase by grating. The percolation under sugarcane is lower than in pasture due to a higher crop evapotranspiration.

This study examined nonpoint source pollution via tributaries to Pineview Reservoir. Since few literature values of export coefficients are available for snowfall-dominated watersheds such as Pineview, locally scaled rates were quantified using an upstream-downstream bracketing technique. Nitrogen and phosphorus grab samples were manually collected and discharge measurements were conducted during the annual study period. Additionally, high-frequency monitoring sensors that measured EC, temperature, turbidity, and water level were deployed at the up- and downstream sites to represent short-duration transport events and to examine watershed processes on a more representative time scale. Daily nutrient loads were estimated from grab samples and flow rates using the Rank- Data (RD) distribution method and, using surrogate relationships for discharge and total phosphorus (TP) concentration from high-frequency sensors, half-hour TP loads were calculated. Short-duration snow melt events were identified by turbidity spikes and increased air temperatures as well as, in some cases, hydrograph peaks. During these events, export coefficients from 0.31 to 0.54 g TP/ha/hr were observed for low and high elevation snow melt events. While losses to ground water were observed for one study reach, the study reach with positive load gains had annual export coefficients of 0.018 g TP/ha/hr from high-frequency loads and 7.5e-5 g NOx-N/ha/hr, 3.5e-6 g SRP/ha/hr, and 9.1e-6 g TP/ha/hr from RD loads. These rates were 1,000 to 2,000 times greater than available literature values typical of rainfall-dominated watersheds. This study showed the importance of erosive, snow melt events on nutrient transport and the need for high-frequency monitoring representing short-duration events for accurate estimation of export coefficients. Management strategies to reduce nutrients from tributaries should focus on erosion control in the Pineview Reservoir watershed.

Maps of runoff-depth have been found to be useful tools in a variety of water resource applications. Producing such maps can be a challenging and expensive task. One of the standard methods of producing these maps is to use a manual procedure based on gaged runoff data, topographic and past runoff-depth maps, and the expert opinion of hydrologists. This thesis examined five new automated procedures for producing runoff-depth contour maps to see if the maps produced by these procedures had similar accuracy and characteristics when compared to the manual procedure. An uncertainty analysis was used to determine the accuracy of the automated procedure maps by withholding gaged runoff data from the creation of the contour maps and then interpolating estimated runoff back to these sites from the maps produced. Subtracting gaged runoff from estimated runoff produced interpolation error values. The mean interpolation error was used to define the accuracy of each map and was then compared to a similar study by Rochelle, et al., (1989) conducted on a manual procedure map.

Microplastic pollution as a global environment problem in marine systems has substantially raised public concern in recent years. In 2016, the Swedish Environmental Protection Agency performed a study about potential sources and pathways of microplastics spreading to the marine environment. Microplastics from artificial turfs have been recognized as the second most important source of microplastic emission in Sweden. Between 1640 to 2460 tons per year of microplastics are estimated to be lost from artificial turfs. The lost microplastics are potentially transported to stormwater wells by runoff during rainfall events, eventually reaching marine environments. This study aims to track microplastics from artificial turfs to stormwater wells. Since the research of microplastic in stormwater has so far shown to be limited, field work and laboratory analysis have been developed in this study. Four artificial football fields located in Stockholm municipality were taken as sampling sites. First, pathways for microplastics from artificial turfs to stormwater were investigated. Second, the characteristics of microplastic granulates infill used in the football fields have been analyzed. Finally, stereo microscopy was used to visually identify microplastics in stormwater. The results showed that rainfall as a driving force of runoff process contributes to microplastics transport from artificial turfs to stormwater. During this transport process, a fraction of microplastics is captured by the soil. The size of microplastic granulates identified not only in stormwater but also in stormwater sediments is typically between 1 mm to 3 mm. Due to its limitations, stereo microscopy is quite a subjective method for identifying microplastics and thus not suitable for quantitative analysis, since microplastic particles are comparable in size to and visually difficult to differentiate from organic particles co-occurring in stormwater. In order to accurately quantify the amounts of microplastics transported to stormwater systems from artificial turfs, it is necessary to develop new methods for microplastics identification. This study presented an attempt in this direction, highlights its limitations, and discusses more suitable alternatives.

A hybrid computer program is developed to simulate the outflow hydrographs of two urban watersheds located within Salt Lake County, Utah. The gaged outflow of the watersheds provided a checkpoint for comparing the observed and the simulated final outflow hydrographs. The outflow hydrographs for each subzone of the two watersheds were obtained by abstracting interception, infiltration and depression storage from each subzone hyetograph. The outflow of the subzones were routed to the Jordan River, the final outflow point of the two watersheds. The final hydrographs of the watersheds were combined and compared with the gaged flow. The uniquenesses of this systems model are the flexibility in varying hyetographs, variable loss rates, combination of subzone hydrographs, and the combination of watershed hydrographs. Subzone hydrographs can also be plotted for visual inspection as well as obtaining numerical values. With a variety of input and output data, designers and planners can visually perceive urban runoff characteristics. The systems model should be a tool used by those interested in urban runoff characteristics.

PFAS is a relatively new group of contaminants with unique characteristics, which in the early 21st century was understood being dangerous for both humans and the environment. In 2008, EFSA published a report on guidelines for human intake of PFAS. Target and limit values for ground and surface water around the world has been based on the information in the EFSA report. In the end of 2018, EFSA published a new preliminary report with new target values for PFAS, well below the target values published in 2008. Frösö Park in Östersund, Sweden, is polluted by PFAS from the time that the Swedish Armed Forces were active in the area. While the Swedish Armed Forces exercised their activities at Frösö Park, large amounts of aqueous fire-fighting foams were used, mainly for training purposes. AFFF at that time contained a mixture of many highly fluorinated chemicals known as PFAS, a collective name of more than 4,700 chemicals consisting of carbon-fluorine bonds. PFAS are, more or less, persistent, bioaccumulative and toxic. This study focuses on PFAS11, which Sweden has target and limit values for in respect of ground water and surface water (lake and sea). PFOS is the most common PFAS chemical and the most commonly occurring PFAS chemical at the Frösö Park area. Today, there is a combined urban runoff and waste water network at the Frösö Park area. The internal water conduit system is currently being examined in order to, eventually, disconnect the urban runoff from the waste water network in order to instead release the urban runoff to Storsjön in the immediate area. As the urban runoff has high levels of PFAS, it must be purified before it is discharged to the recipient. High levels of PFAS has been found in the sewage treatment plant. The sewage treatment plant is not able to purify the water from PFAS, which means that the pollution is discharged into Östersund’s drinking water source, Storsjön. The Municipality of Östersund wanted this thesis as the study will include newsworthy information and provide the municipality more knowledge about the PFAS issues in the Frösö Park area. The aim of this thesis is to examine how the urban runoff from the Frösö Park area can be handled to prevent PFAS leaking out in Östersund’s drinking water source, Storsjön. The thesis describes in a comprehensive way how different purification methods work and the function of the different methods based on the conditions that exist in the Frösö Park area. The purification methods for urban runoff are sedimentation methods, biofilters, and how additives with chemicals can affect the purification of urban runoff. After the urban runoff purification, the purification steps focused on PFAS are sorption methods, chemical redox methods, membrane methods and excavation methods. Based on previous reports for the Frösö Park area, existing data has been compiled into maps, figures and diagrams in order to clearly describe the current PFAS situation. The scientific literature presented herein has been selected by specific keywords in databases. The literature has been supplemented with materials provided by the municipality, tips from researchers and personal contact with other industry-related actors. In the purification steps focused on purifying particles, organic materials and metals in urban runoff, a barrier that restricts the flow of water is proposed, tentatively a dam, wetland or lamellar sedimentation, followed by sand filtration. A large advantage with a barrier restricting the flow of water is the possibility to control the water flow to the next purification step. In the purification steps focused on purifying the water from PFAS, purification with activated carbon, nanofiltration, ion exchange method or sonochemical oxidation are proposed. The purification methods are proposed because of the existing knowledge of the methods and the pollution situation for the Frösö Park area. The research for PFAS with new purification methods, target and limit values for humans and the nature as well as future costs for decontamination and health-related costs means that PFAS currently is a priority contaminant taken seriously. Advantages and disadvantages of the purification methods are presented herein, however, the issues with PFAS are very complex and the purification methods work differently depending on the conditions they are exposed to. In this thesis, the most interesting new information regarding PFAS has been compiled to show the current knowledge situation in order to facilitate for relevant actors to continue their work with the PFAS issues in the future.

An in-situ water-induced soil erosion study of two years duration was conducted at a low slope of about 10%, and also on steep slopes of about 50%, 60% and 70% at the experimental site located at a soil and water research area contiguous to the Department of Agricultural Engineering and Applied Mathematics of the Visayas State College of Agriculture (ViSCA). ViSCA is located in the town of Baybay at the island of Leyte in humid tropical Philippines (latitude of 10 degrees 44' north and longitude of 124 degrees 48' east). The study has the following aims, namely: 1) to investigate the effect of local farming practices on soil erosion, particularly at steep slopes; 2) to study the hydrology and soil erosion processes in steep slope conditions in humid tropical climate; and 3) to apply and determine the limitations of a physical process-oriented sediment transport model for water-induced soil erosion model (Griffith University Erosion System Template, GUEST) to a very permeable soil under very high rainfall conditions. In the context of the steep slope experiments at ViSCA: a) across the slope planting of corn is equally effective in controlling soil loss as hedged farming alone or in combination with peanut intercrop; b) across the slope planting of corn in hedged runoff plots is as effective in controlling soil loss as when combined with peanut intercrop; c) farmer’s practice of planting a rowcrop like corn along the slope (providing ready-made downslope pathways for runoff water thus, encouraging flow-driven soil erosion) produces significant soil loss, often larger than from a bare runoff plot; d) hedgerows significantly reduced sediment concentration provided they remain intact; e) "failure" in hedgerows, often results in massive soil loss, being even greater than that in a comparable bare runoff plot. (Failure is manifested by runoff breaching the litter barrier at the base of the hedgerow in a localized position, leading to concentrated flow and extension of rills upslope from base of hedgerow) of hedged runoff plot (even though contour planted) and f) application of stubble in combination with across slope planting in hedged runoff plots (with or without a closely growing intercrop) provided both maximum surface cover (aerial and contact) and protection against soil loss in steep slopes. These conclusions are likely to apply to crops similar to corn, with an intercrop similar to peanut in morphology and root system. These conclusions might also be expected to apply to low slopes, though the effect of such protection might not be as pronounced as in steep slope runoff plots. Soil erosion mechanisms in steep slopes are dominated mainly by the runoff-driven processes of entrainment and re-entrainment. Average sediment concentration c and total soil loss M are shown to be functions of positive coefficient runoff related regressors and a parameter that measures rills formed and permanently imprinted on soil surface, and of negative coefficient regressors related to surface contact cover, at least for the steep slopes considered in this study. The relatively high streampower associated with overland flow on steep slopes suggests that overland flow dominates over rainfall impact as a source of soil sediment concentration. This was confirmed by the low value of the measured ratio of soil sediment concentration shed by net-rainfall detachment trays to that lost from the bare runoff plots. On the effect of surface contact cover on average sediment concentration c, the following findings were made, namely: a) surface contact cover of only about 20% to 30% is sufficient to reduce c to low levels, assuming the cover is well distributed; b) an "exponential-decay" form of relationship existed between surface contact cover and the average sediment concentration from the non-bare soil without normalizing with respect to sediment concentration from a reference bare soil runoff plot; and c) such nonlinear relationship is indicative of the dominating runoff processes of entrainment and re-entrainment compared to the linear form of relationships if rainfall –driven processes of detachment and re-detachment dominate. In runoff dominated soil erosion processes, surface contact cover (including both living and dead vegetative cover close enough to the soil surface to impede overland flow) is more significant in curtailing soil erosion than aerial surface cover. ...continued.

Runoff from road construction and maintenance sites is responsible for erosion and deposition of sediments in the receiving water bodies. In addition to soil particles from erosion, runoff also transports other pollutants such as rubber, toxic metals, automobile fluids, car exhausts (which settle with the rain), pesticides, fertilizers, and other debris. Compost has been used effectively as a valuable soil amendment to aid plant growth. Berms (mounds) of compost placed at the top or bottom of steep slopes can be used to slow the velocity of water and provide additional protection for receiving waters. However, a downside of the application of composted organic material is the potential degradation of runoff water quality. Overloading with nitrogen and phosphorus causes eutrophication, which reduces the suitability of waterways for beneficial uses. A field testing of the berms coupled with a laboratory analysis of the testing water will provide a basis for the impact of the compost berms on the runoff water quality. The study of the impact of compost on the runoff water quality was investigated. The objective of this study was to evaluate the performance of berms made from various materials such as dairy manure compost, yard waste compost and composted bio-solids mixed with wood chips in a ratio of 50:50 on the runoff water quality, as well as, the sediment removal efficiencies. Field tests were performed on the berms to simulate conventional rainfall runoff and the tested water was collected as time-weighted samples and analyzed in the laboratory. Several variables were investigated during this study. Results of this investigation demonstrated that the effectiveness of this application was hampered by the structural instability of the berm. A 100% failure rate was observed in the berms tested. Optimum performance was observed in yard waste compost berms, which introduced the least amount of contaminants into the water. However, some masking effect could be present due to berm failures. In fact, the actual sediment removal by the berms could not be determined. The study of compost filter berms showed some evidence of the existence of first flush effect.

The purpose of this study was to evaluate variations of the Natural Resources Conservation Service (NRCS) curve number (CN) method for estimating near real-time runoff for naturalized flow, using high resolution radar rainfall data for watersheds in various agro-climatic regions of Texas. The CN method is an empirical method for calculating surface runoff which has been tested on various systems over a period of several years. Many of the findings of previous studies indicate the need to develop variations of this method to account for regional and seasonal changes in weather patterns and land cover that might affect runoff. This study seeks to address these issues, as well as the inherent spatial variability of rainfall, in order to develop a means of predicting runoff in near real-time for water resource management. In the past, raingauge networks have provided data for hydrologic models. However, these networks are generally unable to provide data in real-time or capture the spatial variability associated with rainfall. Radar networks, such as the Next Generation Weather Radar (NEXRAD) of the National Weather Service (NWS), which are widely available and continue to improve in quality and resolution, can accomplish these tasks. In general, a statistical comparison of the raingauge and NEXRAD data, where both were available, shows that the radar data is as representative of observed rainfall as raingauge data. In this study, watersheds of mostly homogenous land cover and naturalized flow were used as study areas. Findings indicate that the use of a dry antecedent moisture condition CN value and an initial abstraction (Ia) coefficient of 0.1 produced statistically significant results for eight out of the ten watersheds tested. The urban watershed used in this study produced more significant results with the use of the traditional 0.2 Ia coefficient. The predicted results before and during the growing season, in general, more closely agreed with the observed runoff than those after the growing season. The overall results can be further improved by altering the CN values to account for seasonal vegetation changes, conducting field verification of land cover condition, and using bias-corrected NEXRAD rainfall data.