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首页> 外文会议>Symposium "Sediment dynamics in changing environments" >Impacts of native forest harvesting on in-channel erosion and sediment yields in unmapped headwater catchments
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Impacts of native forest harvesting on in-channel erosion and sediment yields in unmapped headwater catchments

机译：本土林采伐对未映射的椎间膜内部侵蚀和沉积物产量的影响

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The outlets of five unmapped headwater forest catchments on the Mid-North coast of New South Wales, Australia, 0.9-4.2 ha in area, were instrumented between 2002 and 2006 with flat-v weirs to measure streamflow; bed-load traps to measure bed load; and stage-activated automatic pump-samplers to allow water sample collection for analysis of turbidity and suspended-sediment concentration. Pressure transducers were installed in groundwater monitoring wells beneath the surface of each channel to measure subsurface flow. Additionally, 70 channel cross-sections were surveyed at least annually during the trial period while a total of 1037 erosion pins was installed at 180 locations of likely bank or nickpoint erosion and measured at 6-monthly intervals. Harvesting using BMPs occurred in three catchments in 2004, while two catchments were harvested, but total exclusion zones 10 m wide maintained on either side of the channels. On average, the channels flowed for 2-5% of the time. They are ephemeral features and surface flows that did occur were dominated by stormflows (79-95%) with a minor baseflow component. Groundwater monitoring indicated that 58-79% of annual channel flow was transmitted beneath the channel sediments as opposed to surface runoff. Because they flowed infrequently, sediment yields from the channels were extremely low. Pre-harvest values were recorded between 0.001 and 0.05 tonnes per ha per year, which are lower than typically recorded in larger forest catchments. Sediment yields and streamflow peaks increased in all channels following harvesting. However, harvesting using BMPs in selected catchments did not significantly alter the magnitude of the sediment response to harvesting, while channel bank and nickpoint erosion rates remained consistently low during the monitoring period.
机译：在澳大利亚新南威尔士州新南威尔士中北海岸的五个未映射的地下森林集水区的网点在2002年至2006年间在2002年至2006年之间进行了改用，以衡量流流程;床上装载陷阱测量床载;和舞台激活的自动泵采样器，以允许水样收集以分析浊度和悬浮沉积物浓度。压力传感器安装在每个通道表面下方的地下水监测孔中以测量地下流动。此外，在试用期间至少每年调查70个通道横截面，而总共1037个侵蚀引脚安装在180个可能的银行或绰号侵蚀的180个位置，并按6间隔测量。 2004年使用BMP的采集发生在三个集水区中，而两个集水区被收获，但总排除区10米宽在通道的两侧保持。平均而言，通道流动了2-5％的时间。它们是故意特征和表面流动，所发生的暴风雨（79-95％）用次要的基础流量组成。地下水监测表明，58-79％的年度通道流动在通道沉积物下方传播，而不是表面径流。因为它们不经常流动，因此来自通道的沉积物产量极低。预先收获值每年在0.001至0.05吨之间记录，其低于较大的森林集水区中的通常记录。在收获后的所有通道中，沉积物产量和流流峰增加。然而，在所选集中中使用BMP的收获并没有显着改变沉积物对收获的响应的幅度，而在监测期间，渠道库和绰号侵蚀率保持始终如一。

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