<p> The Penman combination model for potential evapotranspiration, using the improved wind function of Businger (1956), and measured net radiation, was tested for daily and hourly totals, over an irrigated perennial ryegrass surface at Simcoe, Norfolk County, Southern Ontario. The standard measurement of evapotranspiration was the energy balance method, using the Bowen ratio. The component fluxes of the energy balance were evaluated for ninety-seven hours on ten separate days. A comparison is made of two days with markedly different moisture availability to show how the magnitude of the component fluxes changed. Also the effect of the plant on the evaporative flux is examined. On days when water was non-limiting the model gave excellent results for hourly and daily totals: within 5% of measured evapotranspiration. When water became limiting the model overestimated by as much as 30%. It is further shown that the Penman model appears to be more sensitive to changes in the evaporative flux than the water equivalent of net radiation, The relationship of cumulative dry matter production of the crop and cumulative potential evapotranspiration was examined and was found to be linear for most of the field season, substantiating the hypothesis of Penman (1962).</p> / Thesis / Master of Arts (MA)

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Land Use Land Cover Change (LULCC) is a major component of global environmental change, which could result in huge impacts on biodiversity, water yield and quality, climate, soil condition, food security and human welfare. Of all the LULCC types, urbanization is considered to be the most impactful one. Monitoring past and current urbanization processes could provide valuable information for ecosystem services evaluation and policy-making. The National Land Cover Database (NLCD) provides land use land cover data covering the entire United States, and it is widely used as land use land cover data input in numerous environmental models. One major drawback of NLCD is that it is updated every five years, which makes it unsatisfactory for some models requiring land use land cover data with a higher temporal resolution. This dissertation integrated a rich time series of Landsat imagery and NLCD to achieve annual urban change mapping in the Washington D.C. metropolitan area by using time series data change point detection methods. Three different time series change point detection methods were tested and compared to find out the optimal one. One major limitation of using the above time series change point detection method for annual urban mapping is that it relies heavily on NLCD, thus the method is not applicable to near-real time monitoring of urban change. To achieve the near real-time urban change identification, this research applied machine learning-based classification models, including random forest and Artificial Neural Networks (ANN), to automatically detect urban changes by using a rich time series of Landsat imagery as inputs. Urban growth could result in a higher probability of flooding by reducing infiltration and evapotranspiration (ET). ET plays an important role in stormwater mitigation and flood reduction, thus assessing the changes of ET under different urban growth scenarios could yield valuable information for urban planners and policy makers. In this study, spatial-explicit annual ET data at 30-m resolution was generated for Virginia Beach by integrating daily ET data derived from METRIC model and Landsat imagery. Annual ET rates across different major land cover types were compared, and the results indicated that converting forests to urban could result in a huge deduction in ET, thus increasing flood probability. Furthermore, we developed statistical models to explain spatial ET variation using high resolution (1m) land cover data. The results showed that annual ET will increase with the increase of the canopy cover, and it would decrease with the increase of impervious cover and water table depth. / Doctor of Philosophy / Motoring past and current urbanization processes is of importance in terms of ecosystem services evaluation and policy-making because urban growth has huge impacts on the environment. First, this dissertation designed and compared three different methods for annual urban change mapping in Washington D.C. metropolitan area by using a rich time series of Landsat imagery and National Land Cover Database (NLCD). Then, machine-learning based classification models were implemented to achieve near real-time urban change identification. Finally, spatially-explicit evapotranspiration (ET) data for Virginia Beach, a case study location, were generated and annual ET rates for major land cover types were compared to assess the urbanization's impacts on ET.

Mountain Lake in Giles County, Virginia, has a documented history of severe natural lake-level changes involving groundwater seepage [Jansons, 2004] that extend over the past 4200 years [Cawley, 1999], and as of December 2010 the lake was about 2% full by volume. Situated in the Valley and Ridge physiographic province on the axis of a plunging anticline and straddling contacts between three upper Ordovician and lower Silurian formations, the lake is one of two natural lakes in Virginia. A daily water balance, geophysical surveying with dipole-dipole electrical resistivity, and chemical sampling have shed light on the nature of flow to and from the lake, including: 1) the steady nature of net groundwater outflow, 2) the seasonal response to precipitation of a forested first-order drainage system in fractured rock, 3) the influence of a fault not previously discussed in literature regarding the lake, and 4) the possibility of flow pathways through karst features. Results from a water balance indicate steady lake drainage and significant recharge when vegetation is dormant, particularly during rain-on-snow melt events. The resistivity profiles display a highly heterogeneous subsurface and reveal low-resistivity areas that suggest flow pathways to and from the lake. Well logs, satellite images, and outcrop observations appear to confirm the presence of a fault to the east of the lake. Chemical evidence suggests that karst features may be present in the upper Reedsville-Trenton formation underlying the lakebed. / Master of Science

Gao, Xuehua. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 83-96). / Abstracts in English and Chinese. / List of Figures --- p.viii / List of Tables --- p.x / Symbols --- p.xi / Acronyms --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background and Motivation --- p.1 / Chapter 1.2 --- Study Site: Pearl River Basin --- p.3 / Chapter 1.3 --- Study Objectives --- p.4 / Chapter Chapter 2 --- Literature Review --- p.5 / Chapter 2.1 --- Methods for Determining ETa --- p.6 / Chapter 2.2 --- Limitations of Current Studies on ETa --- p.15 / Chapter Chapter 3 --- Methodology and Data --- p.17 / Chapter 3.1 --- Modelling Framework and Procedure --- p.17 / Chapter 3.2 --- Complementary Relationship Models --- p.19 / Chapter 3.3 --- Long-Term Water Balance Models --- p.22 / Chapter 3.4 --- Spatial Interpolation --- p.25 / Chapter 3.5 --- Trend Analysis --- p.26 / Chapter 3.6 --- Meteorological and Hydrological Data Sets --- p.29 / Chapter Chapter 4 --- Estimation of Actual Evapotranspiration --- p.40 / Chapter 4.1 --- Selection of Water Balance Model --- p.40 / Chapter 4.2 --- Selection of Complementary Relationship Model --- p.46 / Chapter 4.3 --- Calibration of Granger & Grey´ةs Model --- p.48 / Chapter 4.4 --- Estimation of A ctual Evapotranspiration --- p.48 / Chapter 4.5 --- Validation of Granger & Grey ´ةs Model --- p.49 / Chapter Chapter 5 --- Spatio-Temporal Variations of Actual Evapotranspiration --- p.50 / Chapter 5.1 --- Annual ETa --- p.50 / Chapter 5.2 --- Seasonal ETa --- p.56 / Chapter 5.3 --- Summary --- p.63 / Chapter 5.4 --- Discussion of the Changing Climatic Factors --- p.64 / Chapter Chapter 6 --- Sensitivity Analysis of Actual Evapotranspiration to Climatic Variables --- p.66 / Chapter 6.1 --- Sensitivity Curves and Sensitivity Coefficients --- p.66 / Chapter 6.2 --- Procedures and Results --- p.61 / Chapter 6.3 --- Implications of Sensitivity Coefficients for Water Resources Management --- p.77 / Chapter Chapter 7 --- Conclusion --- p.79 / Chapter 7.7 --- Summary --- p.79 / Chapter 7.2 --- Conclusion --- p.80 / Chapter 7.3 --- Implication --- p.81 / Chapter 7.4 --- Limitation and Future Work --- p.82 / References --- p.83 / ","

Subsurface drainage (SSD) has been used to remove excess water from fields in the United States upper Midwest for more than a century, but only since the last decade in the Red River Basin of the North in North Dakota (ND). The water leaving from a SSD system can affect both the quality and quantity of water that flows to a surface water system. Therefore, determination of the water balance components is the first step to study the impact of SSD on water quantity, while evapotranspiration (ET), one of the most important components in the water balance, needs to be accurately measured for SSD field. A field experiment was conducted to study the water balance in SSD and undrained (having no artificial drainage system) fields in southeast ND. The field had three different water management systems: 22 ha undrained (UD), 11 ha subsurface drained, and the remaining 11 ha subsurface drained and subsurface irrigated. The ET rates were measured directly using an eddy covariance (EC) system for the SSD and UD fields. The changes in water table were monitored in 8 wells installed in both fields. Rainfall, SSD drainage volume, and soil moisture at six different depths at two locations were measured in both fields. The measurements were conducted in the growing seasons of 2009 and 2010. The ET rates were calculated for two different field crops: Com (Zea Mays) in 2009 and soybean (Glycine Max) in 2010. Crop coefficient (Kc) value was also developed using the ET measured by the EC system and the reference ET (ETref) estimated using the American Society of Civil Engineers Environmental and Water Resources Institute (ASCE-EWRI, alfalfa) method. The ETref was also estimated using the ASCE-EWRI grass and the Jensen Haise (JH) methods. The results indicated that the water table in the SSD field was lower during spring and fall than that in the UD field. The shallow water table and high soil moisture content in the spring and fall have resulted in higher ET rates in the UD field. In the summer, SSD field has favorable soil moisture at the root zone depth; the ET in the SSD field was 30% and 13% higher than that in UD field in summer 2009 and 2010, respectively. For the entire growing season, the ET in the SSD field was 15% higher compared to UD field and the difference was minimal in 2010. Though there were differences in the ET values, they were not statistically different. However, difference in magnitude of ET during summer 2009 yielded a statistical difference. During the peak growing season in July and August, the Kc values were greater in the SSD field due to healthy crops. / USDA (Grants CSREES NRI 2008-35102-19253) / USDA NRCS / North Dakota Agricultural Experiment Station / North Dakota State Water Commission / North Dakota Water Resource Research Institute / North Dakota Department of Health

Call number: LD2668 .T4 1979 S74 / Master of Science

3 pp. / Similar Fact Sheets for Payson & Flagstaff / This publication is intended as a brief Fact Sheet that provides estimates of turfgrass consumptive use for Prescott.

3 pp. / Similar titles for Payson and Prescott / This publication is intended to be a brief Fact Sheet that provides estimates of turf consumptive use for the Flagstaff area. The publication should find utility in both irrigation management and water resource management and planning.

In our country farmers have to face many difficulties because of the poor irrigation system. During flood situation, excessive waters will be staged in paddy field producing great loss and pain to farmers. So, proper Irrigation mechanism is an essential component of paddy production. Poor irrigation methods and crop management are rapidly depleting the country’s water table. Most small hold farmers cannot afford new wells or lawns and they are looking for alternative methods to reduce their water consumption. So proper irrigation mechanism not only leads to high crop production but also pave a way for water saving techniques. Automation of irrigation system has the potential to provide maximum water usage efficiency by monitoring soil moistures. The control unit based on Artificial Neural Network is the pivotal block of entire irrigation system. Using this control unit certain factors like temperature, kind of the soil and crops, air humidity, radiation in the ground were estimated and this will help to control the flow of water to acquire optimized results. / Water is an essential resource in the earth. It is also essential for irrigation, so irrigation technique is essential for agriculture. To irrigate large area of lands is a tedious process. In our country farmers are not following proper irrigation techniques. Currently, most of the irrigation scheduling systems and their corresponding automated tools are in fixed rate. Variable rate irrigation is very essential not only for the improvement of irrigation system but also to save water resource for future purpose. Most of the irrigation controllers are ON/OFF Model. These controllers cannot give optimal results for varying time delays and system parameters. Artificial Neural Network (ANN) based intelligent control system is used for effective irrigation scheduling in paddy fields. The input parameters like air, temperature, soil moisture, radiations and humidity are modeled. Using appropriate method, ecological conditions, Evapotranspiration, various growing stages of crops are considered and based on that the amount of water required for irrigation is estimated. Using this existing ANN based intelligent control system, the water saving procedure in paddy field can be achieved. This model will lead to avoid flood in paddy field during the rainy seasons and save that water for future purposes.