The response of flow duration curves to afforestation
The response of flow duration curves to afforestation
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DOI：
10.1016/j.jhydrol.2005.01.006
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发表时间：
2005-08
影响因子：
6.4
通讯作者：
Patrick N.J. Lane;A. Best;K. Hickel;Lu Zhang
中科院分区：
文献类型：
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作者：
Patrick N.J. Lane;A. Best;K. Hickel;Lu Zhang
以平均年为基础，以树木代替牧草或其他矮种作物的水文效应是相当清楚的。对年流量持续时间曲线（FDC）所描述的流态的影响不太确定。提出了一种评估人工林建设对森林覆盖率影响的方法。分析的出发点是假设降雨和植被年龄是蒸散发的主要驱动因素。一个关键的目标是消除降雨信号的变异性，使流量的变化完全归因于人工林的蒸散。提出了一种方法：(1)将模型拟合到观测到的FDC百分位数年时间序列；即以年降雨量和人工林年龄为参数的每一年记录的第10个百分位数，(2)用长期平均值代替年降雨量变化以获得气候调整后的FDC，(3)量化FDC百分位数随人工林年龄的变化。数据来自澳大利亚、南非和新西兰的10个流域。该模型能够表示10个汇水区中8个汇水区大部分百分位数的流量变化，特别是10 - 50百分位数。调整后的fdc显示出流量减少的变化模式，其中确定了两种类型的响应（组）。第一类集水区的零流量日数大幅增加，低流量比高流量受影响更大。第二组集水区在所有百分位数上显示出更均匀的流量减少。这种差异可能部分由储存特性来解释。模拟的流量减少与已发表的配对集水区实验结果一致。进行了另一项分析，以表征造林对第1组集水区零流量天数（Nzero）的影响。这个模型表现得特别好，当根据气候进行调整时，表明Nzero显著增加。零流量日法可用于确定任何给定流量的发生变化对造林的响应。本研究所采用的方法在消除降雨变率方面令人满意，并为人工林建设的水文影响提供了有用的见解。这种方法为理解流域对造林的响应提供了一种方法，在这种情况下，没有配对的流域数据。
The hydrologic effect of replacing pasture or other short crops with trees is reasonably well understood on a mean annual basis. The impact on flow regime, as described by the annual flow duration curve (FDC) is less certain. A method to assess the impact of plantation establishment on FDCs was developed. The starting point for the analyses was the assumption that rainfall and vegetation age are the principal drivers of evapotranspiration. A key objective was to remove the variability in the rainfall signal, leaving changes in streamflow solely attributable to the evapotranspiration of the plantation. A method was developed to (1) fit a model to the observed annual time series of FDC percentiles; i.e. 10th percentile for each year of record with annual rainfall and plantation age as parameters, (2) replace the annual rainfall variation with the long term mean to obtain climate adjusted FDCs, and (3) quantify changes in FDC percentiles as plantations age. Data from 10 catchments from Australia, South Africa and New Zealand were used. The model was able to represent flow variation for the majority of percentiles at eight of the 10 catchments, particularly for the 10–50th percentiles. The adjusted FDCs revealed variable patterns in flow reductions with two types of responses (groups) being identified. Group 1 catchments show a substantial increase in the number of zero flow days, with low flows being more affected than high flows. Group 2 catchments show a more uniform reduction in flows across all percentiles. The differences may be partly explained by storage characteristics. The modelled flow reductions were in accord with published results of paired catchment experiments. An additional analysis was performed to characterise the impact of afforestation on the number of zero flow days (Nzero) for the catchments in group 1. This model performed particularly well, and when adjusted for climate, indicated a significant increase in Nzero. The zero flow day method could be used to determine change in the occurrence of any given flow in response to afforestation. The methods used in this study proved satisfactory in removing the rainfall variability, and have added useful insight into the hydrologic impacts of plantation establishment. This approach provides a methodology for understanding catchment response to afforestation, where paired catchment data is not available.