姚淑霞, 张铜会, 赵传成. 科尔沁沙地土壤水分动态分析及其概率密度函数模拟[J]. 水科学进展, 2013, 24(1): 62-72.
引用本文: 姚淑霞, 张铜会, 赵传成. 科尔沁沙地土壤水分动态分析及其概率密度函数模拟[J]. 水科学进展, 2013, 24(1): 62-72.
YAO Shuxia, ZHANG Tonghui, ZHAO Chuancheng. Analysis of soil moisture dynamics and its probability density function simulation in Horqin Sand Land[J]. Advances in Water Science, 2013, 24(1): 62-72.
Citation: YAO Shuxia, ZHANG Tonghui, ZHAO Chuancheng. Analysis of soil moisture dynamics and its probability density function simulation in Horqin Sand Land[J]. Advances in Water Science, 2013, 24(1): 62-72.

科尔沁沙地土壤水分动态分析及其概率密度函数模拟

Analysis of soil moisture dynamics and its probability density function simulation in Horqin Sand Land

  • 摘要: 基于Laio土壤水分动态随机模型(Laio模型),利用2006-2010年5~9月土壤水分连续监测数据及日降水资料,分析科尔沁沙地固定沙丘和沙质草地生长季根系层土壤水分动态及其与降水格局的关系,研究点尺度土壤水分概率密度函数,并对Laio模型涉及的13个参数进行了敏感性分析。结果表明:① 研究区年降水的季节分配极不均匀,主要集中在4~10月的生长季,占全年降水量的93%;0~5 mm降水事件占全年降水事件的73%,但其降水量只占全年降水量的25%;降水间隔期以0~10 d为主,占全年无降水期的38%,其频数最高,占全年间隔期频数的87%。② 固定沙丘和沙质草地根系层厚度分别为0~100 cm和0~70 cm,沙质草地根系层土壤水分显著高于固定沙丘;两类沙地7月份的土壤水分都显著高于生长季其他月份。③ 两类沙地生长季根系层土壤水分均服从正态分布;通过Laio模型得到了两类沙地生长季根系层土壤水分概率密度函数p(s),其峰值及峰值出现的位置和峰的阔度均与观测结果很接近,说明Laio模型能对科尔沁沙地土壤水分概率密度函数进行较好的模拟。④ Laio模型涉及的13个参数中,对p(s)最为敏感的参数是降水频率λ、平均降水量α、最大蒸散量Emax、水分胁迫点s*和凋萎系数sw,主要影响p(s)曲线的峰值。

     

    Abstract: The soil moisture dynamics in the root zone of plants is studied through model simulation and observations. The simulation is done with the stochastic model for soil moisture dynamics developed by Laio et al. (Laio model). The observation covers a range of elements including growing season soil moisture and daily precipitation in fixed dunes and sandy grasslands of Horqin Sand Land for the period 2006-2010. The relationship between the soil moisture dynamics and the precipitation pattern is also analyzed. The probabilistic density function (PDF, or p(s)) of soil moisture is estimated using the Laio model. A sensitivity analysis is performed for the 13 parameters of the model. Results show that: ① the seasonal distribution of precipitation appears to be very uneven in the study area. The precipitation amount between April and October can account for 93% of the annual total precipitation. Precipitation events of 5 mm or less contribute only 25% of the annual total precipitation, but can comprise 73% of the total events. 38% of dry periods (intervals between precipitation events) are 10 days or less, which can account for 87% of the total dry periods during a year; ② on fixed dunes and sandy grasslands, the root zone depth is between 0-10 cm and 0-70 cm, respectively. The value of root-zone soil moisture in sandy grasslands is significantly higher than that in fixed dunes. In both cases, the highest soil moisture occurs in July relative to other growing season months; ③ the values of root-zone soil moisture during growing seasons follow a normal distribution on both fixed dune and sandy grassland. The peak value, the position and the scope of p(s) obtained by the Laio model are in good agreement with observations, indicating the Laio model is able to estimate the p(s) of soil moisture in Horqin Sand Land; ④ the estimation of the peak value of p(s) is more sensitive to the 5 parameters of the Laio model, which are the arrival rate of rainfall events (λ), the mean rainfall depth (α), the average daily maximum evapotranspiration rate (Emax), the soil moisture level at which plants begin closing stomata (s*) and the permanent wilting point (sw).

     

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