水保所知识产出(1956---)知识库

本研究以黑河中游典型绿洲春小麦农田为研究对象，将涡度相关观测系统与经典
土壤物理学研究方法相结合，对黑河中游绿洲可灌溉农田的水热平衡特征进行了分析
和研究。分析认为净辐射通量(Net radiation, Rn) 除了受到太阳辐射因素的影响，与下
垫面的植被覆盖条件密切相关，随着植被盖度的增加而增大。地表短波反射则随植被
盖度的增加而减小。由于受到冬灌后地表结冰影响，研究区农田短波反射率最大值通
常出现于冬灌之后。生育期春小麦农田感热通量(Sensible heat flux, H)由于受到太阳辐
射和地表植被条件的双重影响，保持一个相对稳定的状态，在净辐射通量中的占比通
常低于 20%。潜热通量(Latent heat flux. LE)在生育期的变化特征与感热通量相反，呈
现由小变大再减小的趋势，且消耗了大部分净辐射能量，最大消耗占比超过 60%。农
田土壤热通量(Soil heat flux, S)在季节性变化上出现两个高峰期，分别出现于春小麦
生育前期和末期。涡度相关观测结果分析显示，研究区春小麦生育期农田能量闭合度
处于 0.72-0.82 之间，最大值出现于春小麦植被盖度最大时。影响涡度相关系统观测
结果能量闭合度的因素主要包括研究区下垫面环境条件，设备因素，区域气象因素，
以及数据处理过程中造成的误差等。另外对于能量平衡方程中热储通量的人为忽略也
是一个重要的影响因素。分析结果显示，考虑能量平衡中的热储通量项能够明显提高
能量闭合度，提高幅度超过 10%。
春小麦农田生育期(3 月中旬-7 月中旬)的主要补水方式包括灌溉和天然降水。其
中农田灌水是主要的补水方式，占总的补水量的 90%以上。农田闲置阶段(7 月中旬-
11 月中旬)的主要补水方式为天然降水和地下水补给。其中地下水补给起到主要作用，
占到该阶段补水量的 70%以上。冬灌储墒期农田(11 月中旬-次年 3 月中旬)的主要补
水方式是单次冬灌补水。占到总补给量的 97.4%。储墒期灌水冻结固化是农田土壤储
水的根本方式。对春小麦生育期农田的水量平衡分析中，农田补水量的主要消耗方式
是农田蒸散和地下水渗漏，各自所占比例分别为 75% 和 19%。另有 6%的补水量用
于增加土壤水分含量或存储与植物体内。利用 CO 2 -H 2 O 浓度脉冲负相关关系对蒸散
量进行分离分析，结果显示作物蒸腾作用是蒸散量耗水的主要方式，占到总的蒸散量的 72%。从各耗散途径所占消耗份额可以看出，在春小麦生育期的农田补水量中，约
有一半的水量因蒸发或渗漏而不能被作物利用。对于水资源缺少的干旱区内陆河流域，
低效的农田灌水造成了水资源的极大浪费，需要对目前的灌溉方式进一步进行研究和
改进。
关键词 净辐射，能量闭合，水量平衡，涡度相关

Based on the combination of eddy covariance system and soil physical experimental
method, researches were conducted to determine the water and energy balance in the wheat
fields located on the middle oasis of Heihe River, which is the second largest inland river in
China. The results showed that the net radiation (Rn) was closely related to the vegetation
coverage over the surface. As the increase in vegetation coverage, the Rn became large.
Conversely, the reflected short-wave radiation decreased with coverage increase. The largest
shortwave reflectance presented at the winter irrigation later because of the freezing effect
of irrigated water on the earth surface. During growth period of wheat, the sensible heat
fluxes (H) stayed in a relatively stable state. The H were controlled by the solar radiation
and filed cover situation. In net radiation flux, the proportion of H was no more than 20%.
Opposite to the sensible heat fluxes, the latent heat fluxes (LE) showed the variation trend
from low to high and then reducing. Moreover, the LE consumed the most of the net radiation
energy with a proportion more than 60%. The soil heat fluxes present two protuberances
over time in a year. One was at the beginning of growth period and another was at the end
of this period. According to the observation from the eddy covariance system, the energy
closure during growth period was in the range of 0.72-0.82. The largest value of closure
emerged at the time of the maximum value of leaf area index (LAI). The main factors
influencing the energy closure included the topography, equipment precision, meteorological
conditions and data processing. Additionally, the arbitrary ignoring of the heat storage fluxes
term in energy balance function was one of the important causes to reduce the energy closure.
After considering the heat storage fluxes, the energy closure increased more than 10%.
The main water sources for the wheat field during growth period were from the
precipitation and irrigation. Among, the irrigation was the leading approach accounting for
90% percent. The main water supply for the idle period of wheat field were the precipitation   and groundwater. The water from groundwater accounted for 70% in the whole water supply
in this period. During winter, the water stored in the soil were mostly from the winter
irrigation occurred in the middle of November. After winter irrigation, there were about 50%
of the irrigated water stored in the soil porosity with a solid phase. The main consumption
ways of supplied water in such field were evapotranspiration (ET) and deep infiltration. The
results showed that more than 75% supplied water was consumed by ET and 19% water
were consumed by infiltration. There was about 6% water consumed by soil water storage
and vegetation body. According to the portioning result from the CO 2 -H 2 O fluctuation
correlation model, the transpiration flux took the most contribution to ET. The ratio of T/ET
was 72%. From the portion of each consuming approaches, approximately half supplied
water was consumed by evaporation and deep infiltration ineffectively instead of absorption
by crops. The non-available water was a great waste of resources in arid inland river basin
with limited water resources. The sequential studies was necessary to improve the irrigation
mode.
Keywords: net radiation, energy closure, water balance, eddy covariance