Dissertation > Excellent graduate degree dissertation topics show

Modification of the White Method and Its Application to Groundwater Evapotranspiration

Author: LiHongBo
Tutor: HouGuangCai
School: Chinese Geology University (Beijing)
Course: Environmental Engineering
Keywords: evaporatranspiration groundwater regime modified Whitemethod Hailiutu watershed
CLC: P641.8
Type: Master's thesis
Year: 2012
Downloads: 47
Quote: 1
Read: Download Dissertation

Abstract


The climate in arid environments is characterized by low precipitation and highpotential evapotranspiration, and water requirement has increased dramatically innorthern China.Groundwater dependent ecosystems are widely distributed in aridand semi-arid areas. Evapotranspiration of groundwater (ETG) is often a significantcomponent of the water budget. ETGis notoriously difficult to measure directly dueto its inherent complexities and small scale spatial and temporal variations. Themain methods are water balance methods, extinction depth methods andgroundwater regime methods. For water balance methods, the precision depend onother water balance components. For small scale and short time, the calculationaccuracy is very low. For extinction depth methods，they use energy balance ormicrometeorological variables to determine potential evapotranspiration. Due todifferent hydrogeological conditions, the coefficient is difficult to acquire. Becauseof the advantages of diurnal water-table fluctuations, it is widely adopted by manyecohydrogeologists to estimate ETG. White (1932) published a method of estimatingETGon diurnal fluctuations in the groundwater level. The four key assumptions forthe White method are:(1) evapotranspiration by plants causes diurnal water-tablefluctuations,(2) evapotranspiration is negligible relative to the groundwater inflowbetween00:00and04:00,(3) the rate of groundwater inflow to the site is constantthroughout the day, and (4) specific yield is the volume of water extracted from thesaturated zone.The assumptions have been proven particularly problematic.Sometimes that may be introducing error in estimated results. To wide theapplication of White method, many research works have been done. Hays (2003)and Loheide (2005) published a method of estimating inflow. Loheide (2005)presented the readily available specific yield to assess White method.Based on the summaries of former researches on estimating ETGusing diurnalwater-table fluctuations, summarizing the precision and applications of three maingroundwater regime methods (the White method and the modified White method: the Hays method and the Loheide method). By modifying the Loheide method, anew method was developed to calculate evapotranspiration (ETG).(1) The quadraticfunction is found using the detrended observations.(2) The specific yield is givendifferent values between day and night.(3) As groundwater level contains muchnoise,a new technique was developed to removing these effects. Using ProcessingModflow to verify this modified method. The precision goes up by10%.The modified method was used to estimate groundwater evapotranspiration inthe Hailiutu watershed using the measured groundwater level. The result indicatesthat riparian zone evapotranspiration is17.2mm/d.The proposed method plays asignificant role in groundwater sustainable development in arid environmentstheoretically and practically.

Related Dissertations

  1. Impact of Closing Self-prepare Wells on Groundwater Regime and Adaptive Strategies,P641.8
  2. Numcrical Simulation Study of Groundwater by Feflow in Baojixia Irrigation on Loess Plateau,P641.8
  3. Study on Ecological Groundwater Level and the Amount of Regulation in Plain Region of Western Jilin Province,P641.8
  4. Study on the Prediction Methods of Water Quality and Water Levels in Riverside Well Field,P641.7
  5. On Collocation of Agricultural Water Resource at the Local Level in Purple Hilly Area of Sichuan Basin,S273
  6. Application of Feflow to Groundwater Flow Simulation,P641.8
  7. Study on Dynamic Space Structure of Groundwater on Land Use,P641.8
  8. Study on Groundwater Resources Information System in South Xinjiang Based on Mixing System Architecture,P641.8
  9. Study on Ecology-Oriented Groundwater Resource Assessment in Arid Area,P641.8
  10. Study on Rational Exploitation and Utilization of Groundwater Resources of WeiSan Village Drinking Water Area in Hua County,P641.8
  11. Study on Groundwater Resource Development of Piedmont Alluvial Plain in Baying River,P641.8
  12. Groundwater Vulnerability Assessment Based on Numerical Simulation,P641.8
  13. Analysis of Two-dimension Groundwater Flow Patterns and Transformation Rules,P641.2
  14. Evaluation on the Reasonable Yield of Groundwater in the Wulanmulun River Valley, Shaanxi Province,P641.8
  15. Hydrochemical Evolution Process Simulation of Unconfined Aquifer in Jinghuiqu Irrigation District of Shaanxi Province,P641.3
  16. A Modified Calculation Model for Groundwater Glowing to Horizontal Seepage Wells and Its Application,P641.8
  17. The Impact of Artificial Fill on the Water Table and Countermeasures in a Mountainous Area,P641.2
  18. Analysis of Hydrochemical Characteristics and Delineation of Groundwater Protection Area in Siboshu Well Field,P641.8
  19. Study on the Chemicals Evolution Pattern and the Optimal Exploration Method of Groundwater at the Sand Blown Areas,P641.8
  20. Evaluation of Hydrochemistry Characteristics and Groundwater Quality in Dawukou District of Shizuishan,P641.3
  21. Comparative Study on the Methods for Determining Hydrogeological Parameters in Leaky Confined Aquifers by Transient Flow Pumping Test,P641.2

CLC: > Astronomy,Earth Sciences > Geology > Hydrogeology and Engineering Geology > Hydrogeology (groundwater hydrology ) > Groundwater resource management
© 2012 www.DissertationTopic.Net  Mobile