A Study On The Influence Factors And Calculation Method For Phreatic Water In Xinjiang Plain Area

Xinjiang plain area belongs to the arid area which faces the problem of water shortages, aggravated by strong evaporation. The evaporation of phreatic water will not only cause the loss of groundwater, but also soil salinization, affecting the growth of plants. Therefore, to study and to summarize the pattern of phreatic water evaporation in arid areas has great significance for conserving water resources and protecting the ecological environment. This paper, built on previous studies, designed lysimeter experiments at Changji experimental station in North Xinjiang and Bazhou experimental station in South Xinjiang, to observe the evaporation of phreatic water, soil moisture, etc.. Based on data of phreatic water evaporation, the major influence factors for phreatic water evaporation, namely, the burial depth of phreatic level, soil conditions, atmospheric evaporation capacity, surface coverage and groundwater salinity, were qualitatively analyzed. Moreover, the relationships between phreatic water evaporation and each influence factor were established using statistial methods. The empirical formulas for calculating phreatic water evaporation coefficients under the conditions of clay, fine sand and sand gravel, were formulated respectively. Hydrus-1D software was employed to perform numerical simulation of phreatic water evaporation at various burial depths (1.5m-5m) under clay condition. The reliability of this model was verified through model recognition.This paper lied in the consideration of the influence of phreatic water salinity on its evaporation. The analysis of the relationship between phreatic water evaporation and its salinity using lysimeter observation data under high salinity preliminarily revealed the variation pattern of phreatic water evaporation with its salinity:regardless of specific phreatic water salinity, under the same soil condition, phreatic water of different burial depths had different evaporations; within the burial depth limit for evaporation, phreatic water evaporation decreased with the increase of burial depth; under the same soil condition and groundwater burial depth, phreatic water evaporation decreased when the salinity increased.