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The Research for the Groundwater Table Dynamic Variety on Changwu Tableland

Author: ZhangPan
Tutor: LiuWenZhao
School: Northwest University of Science and Technology
Course: Land resources and space technology
Keywords: Changwu Time series analysis Water Resources Groundwater level Loess Plateau
CLC: P641.74
Type: Master's thesis
Year: 2010
Downloads: 96
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Abstract

Groundwater is an important part of the water resources, groundwater situation in recent years, most parts of China are not optimistic. Over the years, the the Changwu groundwater resources scarcity, coupled with blind development and over-exploitation, causing groundwater levels in the region continued to decline, leading to deteriorating water supply and demand situation. Therefore, there is an urgent need in-depth analysis of groundwater dynamic characteristics, and on this basis to predict future trends, and thus a more scientific and rational use and management of water resources. Changwu groundwater resource-poor, a detailed analysis of the information and the achievements of the previous studies, combined with nearly 50 years of the study area, precipitation data analysis, a preliminary understanding of the local groundwater level changes and their impact factors. At the same time the use of time series analysis theory to analyze and forecast the dynamic characteristics of the study area, the groundwater level. Calculate the water level dynamic trend component using polynomial fitting using harmonic analysis to extract the periodic terms and the random component with self-regressive (AR) model simulation, the three components will be superimposed water level forecasting model. With SAS software to establish groundwater level dynamic modeling and prediction model based on the Changwu five monitoring wells monthly average water depth of information, analysis, and simulation and prediction accuracy of the model. The main research contents and conclusions are as follows: (1) Changwu County Bureau of Meteorology to provide the location of the study area, the analysis of the precipitation data (1957 to 2008), season the uneven distribution of rainfall seen in the study area, the rainfall season becomes higher; Fung, dry years the number closer to occur the ADPRO years less than occurred even dry years. Occurred in the past 52 years in a period of five sections of the low precipitation period and four more precipitation. (2) analysis, data retention 32 years of the most complete of 552 monitoring wells water depth of 25.3 m from the surface down to 31.84 m, that is, the water level fell to 6.54 m per year dropped by an average of 0.2 m. 1976 to 20 years in 1995, the well water is the water level decreased slowly, dropped by an average of 0.1 m per year; obvious downward trend from 1996 to 2008 period, the average annual rate of 0.4 m. In recent years, increasing groundwater level decline can be seen from the forecast results, if not scientific management and control of mining, well water level will continue to decline. (3) the use of water depth data analysis of time series analysis Changwu five typical monitoring wells and their depth model for the establishment of the groundwater table. Cycle entry analysis model that the groundwater level changes of the study area, there are two main cycles: a cycle length of one year, which reflects the changes in the seasonal cycle of the water table in a year. Another cycle length of 7.4 to 10 years, and the cycle gradually increase with the growth of time, years of cyclical changes consistent with the area's precipitation. (4) the use of groundwater depth time analysis to establish the study area (five monitoring wells) model fitting precision and prediction accuracy are required. The model can better anti Yang local groundwater level dynamic variation and predict changes in well water water level under the same conditions in the constraints next time. Large changes when constraints built the prediction error of the model will naturally increase. This requires us to update the original modeling data, and to create a new model (that is obtained by adding a new observation data re-modeling), in order to improve the accuracy of the forecast.

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CLC: > Astronomy,Earth Sciences > Geology > Hydrogeology and Engineering Geology > Hydrogeology (groundwater hydrology ) > Groundwater Survey and Exploration > Groundwater dynamic long-term observation
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