【作者】 付秋萍；

【导师】 王全九； 张江辉；

【作者基本信息】 西安理工大学 ， 农业水土工程， 2007， 硕士

【摘要】 在新疆等干旱地区,降雨稀少,蒸发强烈,土壤盐碱化严重。防治土壤盐渍化是关系到农业生产发展的重要因素,而减少潜水蒸发,控制地下水位是防止盐渍化的重要措施。因此,研究潜水蒸发和农田排水显得尤为重要。本论文以试验数据为基础,采用理论分析方法,对干旱区潜水蒸发特征和排水系统参数确定方法进行了研究,取得以下研究结果:1.根据新疆潜水蒸发实测数据,对旱区潜水蒸发规律进行了分析,建立了任意埋深和0.25m埋深时潜水蒸发强度的比值N与潜水埋深增幅ΔH之间的幂函数关系,避免了以往公式中因E 0值造成的误差,为潜水蒸发量的精确计算提供了参考。同时,针对经验公式中E 0值对潜水蒸发计算精度的影响进行了分析,结果表明,除细砂和砾石外,若用水面蒸发强度代替埋深为零时的潜水蒸发强度,计算不同埋深下的潜水蒸发量时必将产生较大误差。因此,在潜水蒸发计算中,应选用E 0值为潜水埋深等于零时的土面蒸发强度。2.提出了阿维里扬诺夫经验公式中潜水停止蒸发深度H max和清华公式中潜水极限蒸发强度E max以及η等参数的确定方法,为阿氏公式、清华公式中参数的求解和推广应用提供了一定的参考。选用四种常用潜水蒸发经验公式对实测数据进行了拟合计算,结果表明,在新疆地区清华公式有广泛的通用性;在潜水埋深较浅时,阿氏公式、叶氏公式和幂函数公式拟合精度相对较高,但当潜水埋深较大时拟合较差;幂函数公式拟合值与实测值相差最大;阿氏公式、叶氏公式和幂函数公式对于壤土类拟合精度较粗质土高。该研究为选择适当经验公式计算新疆潜水蒸发量提供了指导。3.根据塔里木盆地实测土壤含盐量及主要组分含量、地下水埋深和矿化度资料,分析了土壤含盐量主要组分变化特征,建立了0-30cm、0-60cm和0-100cm不同土层土壤含盐量与地下水埋深和矿化度三者间函数关系。研究结果显示在旱区土壤积盐与地下水埋深和矿化度存在显著相关性,建立了三者间经验关系,为根据作物耐盐度确定地下水临界深度和地下水管理提供一定指导。4.利用瞬时稳定法分析了仅考虑水分运动和蒸发影响下排水沟(管)间距计算微分方程,并对其进行求解,结果表明,考虑蒸发影响下的排水沟(管)间距均大于仅考虑水分运动下的间距,蒸发对排水作用不容忽视。根据作物耐盐度提出了盐碱地地下水允许深度定义及求解方法,对盐碱地区排水系统的参数确定方法进行了初步探讨。更多还原

【Abstract】 In the arid zone such as Xinjiang and so on, the rainfall is scarce and the evaporation is intense, and consequently, the saline-alkali soil is serious. Prevention and treatment of saline-alkali soil are an important factor relating to the development of agricultural production, but the reduction of phreatic water evaporation, the controlling of groundwater table is important to prevent saline-alkali soil. Therefore, it appears especially important to research the phreatic evaporation and agricultural drainage. Taking the experimential data as a foundation, this paper researched the phreatic evaporation characteristics and the determination method of drainage system’s parameters in the arid region using the theoretical analysis method, and obtained the following findings:1. According to the measured data of phreatic evaporation in Xinjiang, the paper analyzed the laws of phreatic evaporation, the power function was established between the ratio of phreatic evaporation intensity at any depths to that of the depth of 0.25m and the amplify of groundwater depths, the error existed in other formulas which was caused by E 0 will be avoided by using this formula, it provided reference for the accurate calculation of phreatic evaporation quantity. At the meantime, the influence of E 0 to the computation precision of phreatic evaporation was analyzed, the result indicated that, except for fine sand and gravel, if the phreatic evaporation intensity at zero watertable is replaced by the atmosphere evaporation capacity, there will be some big inaccuracy in calculating the evaporation quantity at different watertables. Therefore, we should choose the land surface evaporation intensity at zero watertable as E 0 in the calculation of phreatic evaporation.2. The paper proposed the determination method of the limiting evaporation depth Hmax in Averiyanov empirical formula and the limiting evaporation intensity Emax andηin the Tsinghua formula, which provided certain reference for the parameters calculation and the extending application of these two formulas. Four kinds of commonly used empirical formulas were selected to fit the actual data of phreatic evaporation measured, and the results indicated, the Tsinghua formula has a widespread versatility in Xinjiang; when the groundwater depth is shallow, Averiyanov equation, Ye equation and power function have a relative high precision, but the precision is low when the depth is deep. The difference between the value calculated using power function formula and the actual value is the biggest. The Averiyanov equation, Ye equation and power function fit well in loam than coarse soil. This research provides guidance for selecting the appropriate empirical formula to calculate the phreatic evaporation in Xinjiang.3. According to the Tarim Basin measured soil salt content, the dominate component content of soil salt, degree of mineralization and groundwater table, the features of main component of soil salt were analyzed and the function relationships among soil salt content of the different depths in 0-30cm, 0-60cm and 0-100cm, groundwater table and mineralization degree were established. The results indicated that the salt accumulation in soil had obvious dependency relation with groundwater degree of mineralization and groundwater table in arid region; it can provide guidance for determining groundwater critical depth and groundwater management according to crop’s salt endurance.4. This paper has analyzed the differential equation of spacing calculation under pure draining condition and the condition influenced by evaporation separately using the instantaneous stabilization method, and has solved the equation. The results indicated that, the spacing calculated considering the evaporation influence is bigger than that under pure draining conditon, which announced the non-neglectable affect of evaporation to draining. A new definition and calculation method of groundwater allowable depth was proposed, and the calculation method of drainage system of desalination has been analyzed preliminarily.更多还原