Measurement and modeling of soil-water dynamics and evapotranspiration of drained peatland soils
Measurement and modeling of soil-water dynamics and evapotranspiration of drained peatland soils
复制标题
排水泥炭地土壤水动力学和蒸散量的测量和建模
DOI：
--
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
G. Wessolek
中科院分区：
文献类型：
--
作者：
K. Schwärzel;J. Šimůnek;M. Genuchten;G. Wessolek
天然泥炭土是养分、有机成分和水的重要汇。当泥炭土被排干用于农业生产时，可能会造成严重的环境问题，这可能会使它们在景观中的作用从汇变为源。为了成功地恢复和保护泥炭土，了解不同气候和地下水条件下排水泥炭土的土壤水分动态和需水量至关重要。为此，我们对不同地下水位的泥炭土进行了一系列的渗湿仪实验。测定了草地下泥炭土的蒸散发速率和毛细向上通量，利用TDR探针和张力仪监测了生长季土壤水分动态。利用HYDRUS-1D的扩展版本对渗滤仪数据进行模拟，从而使用Penman-Monteith方程计算ET。试验了一种基于物理的方法来预测冠层阻力作为土壤根区平均压头的函数。数值模拟结果与蒸渗仪观测到的土壤水分动态密切相关，与不同地下水位蒸散发速率的实测差异一致。除了平均气候条件外，还利用标定后的不同地下水位的数值模型评价了极端干湿天气条件对生长季蒸散发和地下水补给的影响。干旱年份的蒸散速率很大程度上取决于地下水位向上的毛细流，因此取决于土壤的水力特性。而在湿润年份，蒸散发主要受大气蒸发需求的控制，受土壤水力特性的影响较小。
Natural peat soils serve as important sinks for nutrients, organic components, and water. Peat soils can pose major environmental problems when they are drained for agricultural production, which may change their role in the landscape from a sink to a source. To successfully restore and conserve peat soils, it is important to understand the soil-moisture dynamics and water demand of drained peat soils for different climate and groundwater conditions. For this purpose, we conducted a series of lysimeter experiments with peat soils subject to different groundwater levels. Evapotranspiration (ET) rates and upward capillary fluxes in peat soils under grass were measured, while TDR probes and tensiometers were used to monitor the soil-water dynamics in the lysimeter during the growing season. The lysimeter data were simulated using an extended version of HYDRUS-1D to enable ET calculations using the Penman-Monteith equation. A physically based approach was tested to predict the canopy resistance as a function of the average pressure head of the soil root zone. The numerical simulations closely followed the observed soil-moisture dynamics in the lysimeter and were consistent with measured differences in ET rates for different groundwater levels. Besides average climate conditions, the effects of extreme dry and wet weather conditions on ET and groundwater recharge during the growing season were evaluated using the calibrated numerical model for different groundwater levels. Evapotranspiration rates during dry years depended very much on upward capillary flow from the water table and hence on the soil hydraulic properties. During wet years, however, ET was controlled mostly by the evaporative demand of the atmosphere, and much less by the soil hydraulic properties.