【作者】 王幼奇；

【导师】 邵明安；

【作者基本信息】 西北农林科技大学 ， 土壤学， 2008， 硕士

【摘要】 黄土高原水蚀风蚀交错带水资源时空分配不均,全年雨量和降水频率极低,干旱缺水成为制约该地区农业生产和生态环境改善的主要因素。因此在该地区合理利用有限的水资源、选择适宜的植被来恢复当地的自然生态环境和社会生产生活环境是重要的科学问题。本文利用微型称重式蒸渗仪、中型称重式蒸渗仪、水面蒸发皿和天气发生器研究了该地区4种典型植被蒸散量及其变化过程,建立了作物系数(KC)、水面蒸发系数(KP)的计算公式计算参考作物蒸散量,以及利用气象资料对天气发生器进行适用性的评价,主要结论如下:(1)本研究年度,整个生育期内4种植被的株高和盖度的变化过程均呈“S”型曲线规律。4种植被的蒸散耗水顺序为,茵陈蒿>柠条>苜蓿>谷子。其中谷子的蒸散耗水量为254.8mm,苜蓿的蒸散耗水量为316.9mm,柠条的蒸散耗水量为343.4mm,茵陈蒿的蒸散耗水量为361.9mm。(2)水面蒸发皿处于不同下垫面对于它的水面蒸发值是存在影响的。5种下垫面的水面蒸发量的顺序为:裸地>柠条>谷子>苜蓿>茵陈蒿。裸地水面蒸发总量为976.2mm,谷子水面蒸发总量为948.5mm,苜蓿水面蒸发总量为898.7mm,柠条裸地水面蒸发总量为941.8mm,茵陈蒿水面蒸发总量为866.6mm。(3)分析5种不同下垫面的水面蒸发值与最高温、最低温、相对湿度、辐射和风速的相关性发现,水面蒸发值与相对湿度、辐射相关性最高,其中与相对湿度呈负相关,与风速呈正相关。利用相对湿度和风速为参数,采用线性回归的方法建立了KP的计算公式。同时以Penman-Monteith公式为基础,对利用KP公式计算的5种参考作物蒸散量进行差异性和相关性分析,结果表明利用蒸发皿方法计算参考作物蒸散量在神木六道沟流域是可行的。(4)根据FAO-56推荐的方法利用3次多项式拟合了谷子、苜蓿、柠条和茵陈蒿4种植被的基础作物系数公式,同时从公式中计算出4种植被不同时期的基础作物系数。谷子初期、中期和成熟期的作物系数分别为0.23、0.43、0.24,茵陈蒿的作物系数分别为0.58、0.67、0.62,苜蓿和柠条初期和生育期的作物系数分别为0.48、0.52和0.45、0.57。用分段作物系数计算出的蒸散量与实际蒸散量能较好的吻合。(5)利用微型和中型称重式蒸渗仪研究了谷子的棵间蒸发和蒸散,发现神木六道沟流域的降水总量和谷子的耗水量基本相等,同时在谷子的抽穗期到灌浆期出现了阶段性的缺水,在谷子整个生育期内棵间蒸发占总耗水量的44%,E/ET与叶面积指数以及10cm土壤含水量均呈很好的指数函数关系,其相关系数R2均在0.8以上且呈现出极显著的相关性。(6)利用黄土高原地区西安、兰州、太原、银川、呼和浩特、延安6个气象站50年日气象资料,对LARS-WG天气发生器在黄土高原的适应性进行了检验,结果表明,不论从年值分布还是月值分布,最高温和最低温的模拟值和实测值之间都存在很好的线性相关性关系。对于降水量的模拟除西安站LARS-WG对中大雨强的模拟频次偏多外,其它5个站点的模拟效果均很好。太阳辐射的年值和月均值的模拟效果也较为满意。利用实测和模拟的气象数据计算了1991-2000年10年的日参考作物蒸散量,通过相对误差和相关性分析可知LARS-WG天气发生器对黄土高原ET0的模拟效果非常好。同时利用模拟的气象资料结合谷子和茵陈蒿全生育期的作物系数,计算了榆林地区1991-2010年谷子和茵陈蒿的耗水量。更多还原

【Abstract】 The water-wind erosion crisscross on the Loess Plateau is a special region. The distribution of precipitation is unbalance and evapotranspiration is higher so deficit of water becomes a key problem to sustainable development of the agriculture in this area. Therefore it is important to use limited water resources and choose feasible vegetation to improve ecological and social environment. In this dissertation, a large weighing lysimeter, micro weighing lysimeter and evaporation pan are used in this experiment to study evapotranspiration of the four plants and establish KC and KP equations. Meantime weather generator is also tested on the Loess Plateau. The main results obtained from this study are as follows:(1) Change of vegetations height and coverage complies with“S”curve during the different growing stages. The order of water consumption is as follow: Artemisia capillaris Thunb> Korshinsk Peashrub > alfalfa > Millet. The evapotranspiration were 254.8mm, 316.9mm, 343.4mm and 361.9mm for Millet, alfalfa, Korshinsk Peashrub and Artemisia capillaris Thunb respectively.(2) The effect of different environment to evaporation of the pan is different. The order of pan of evaporation is as follow: Bare land> Korshinsk Peashrub land> millet land> alfalfa land> Artemisia capillaris Thunb land. The pan evaporation of no plant was 976.2mm, The pan evaporation of Korshinsk Peashrub was 948.5mm, The pan evaporation of millet was 898.7mm, The pan evaporation of alfalfa was 941.8mm, The pan evaporation of Artemisia capillaris Thunb was 866.6mm.(3) The air temperature, relative humidity, solar radiation and wind speed were analyzed. The relationships among the evaporation of the pan, relative humidity and solar radiation are higher than the relationship between the evaporation of the pan and others. The evaporation of the pan became higher as relative humidity decreased and wind speed increased. The Kp estimated by relative humidity, wind speed and solar radiation can be used to compute ET0 combined with observed data from 20cm pan. There is a satisfactory correlation between ET0 of 20cm pan and Penman-Monteith method.(4) Crop water demands for four different vegetations were measured using a weighing lysimeter located in water-wind erosion crisscross on the Loess Plateau. The results showed that the relationship between crop coefficients and days after seeding can be represented by a third-order polynomial equation. The estimated values of the basal crop coefficients for millet at four growth stages were 0.23, 0.43 and 0.24 for initial, mid and late season. The estimated values of the basal crop coefficients for Artemisia capillaris Thunb at four growth stages were 0.58, 0.67 and 0.62 for initial, mid and late season. The estimated values of the basal crop coefficients for alfalfa at three growth stages were 0.48 and 0.52 for initial and mid season. The estimated values of the basal crop coefficients for Korshinsk Peashrub at three growth stages were 0.45 and 0.57 for initial and mid season respectively.(5) Large weighing lysimeter and micro-lysimeter are used to determine the daily alteration processes of soil evaporation and transpiration of millet in its growth stages. Precipitation can satisfy the need of millet but in some key growth stages the precipitation was deficit. In the millet growth stages about 44% of the total field evapotranspiration is consumed by the soil evaporation under canopy. The relationship between E/ET and leaf area index are analyzed as well as the relationship between E/ET and soil moisture at 10cm depth. The results show that both the correlation coefficients are higher than 0.8.(6) This study was conducted to calibrate LARS-WG with 50 year daily precipitation, temperature,and solar radiation during data of six meteorological sites on the Loess Plateau of China. Meantime, we stimulated future climate conditions on the Loess Plateau. The results showed that annual and monthly distribution of daily maximum and minimum temperature and solar radiation can be simulated accurately. However, annual precipitation and its monthly distribution was little greater than observed values. The estimated ET0 by LARS-WG is well consistent with calculated ET0 from climate factors. Meantime we use LARS-WG and KC to estimate water consumption of millet and Artemisia capillaris Thunb from 1991 to 2010.更多还原