Lahar-induced disturbance of naturalresources and recovery from volcanic disaster at the Ruapehu volcano, North Island, New Zealand

了解如何管理火山周围土地资源的可持续环境，是世界土地管理的重点。新西兰和日本的地质特征非常相似，两国在土地资源灾害方面有着相同的经历。本项目侧重于预测火山泥流对土地资源的干扰，如生态系统、景观、当地居民面积和生命线工具。此外，最近发展起来的火山灾害预警系统和恢复技术也很重要。我们也有兴趣比较50年前发生的火山泥流和2005年之后的预测。2007年3月18日，新西兰鲁阿佩胡山山顶的火山口湖突破了1995- 1996年火山喷发形成的火山屏障，导致130万立方米的水迅速释放。洪水沿着旺格胡河上游陡峭的峡谷带着雪、冰、岩石碎片和冲积物迅速膨胀，形成泥石流，然后在流向155公里外的塔斯曼海的过程中，向下游转变为高浓度的、富含沉积物的溪流。由于在火山泥流爆发前10年就建立了一个全面的预警系统，没有人丧生，基础设施的破坏也降到最低。1953年爆发的火山泥流造成了唐吉外的铁路灾难，151人丧生。火山泥流在火山口湖下游7公里处的Whangaehu峡谷中以多峰泥石流的形式流动。自动泥流测量设备，包括水位计、流速传感器、电导率采样器和地震仪，已安装在沿水流路径的关键地点，并辅以由自动监测摄影机和观察小组拍摄的连续照片。峡谷内平均流速30公里/小时，4分钟内水位上升8.2米。泥流淤积造成多处河床淤积，河道形态受到环境扰动。

Understanding how we can manage a sustainable environment for land resources around volcano must be emphasized for the land management in the world. Both geological features in New Zealand and Japan is very similar and they have a same experiences with disaster on land resources. This program focus on the prediction of lahar-induced disturbance on land resources, such as ecosystem, landscape, local residence area, and life-line instruments. Furthermore the warning system of volcanic hazard and the restoration skill evolved recently can be important. We also have an interest in comparing both lahar-flows occurred at 50years ago and predicted after 2005.On 18 March 2007 the summit Crater Lake of Mt. Ruapehu, New Zealand, breached a barrier of tephra emplaced by eruptions in 1995-96, resulting in the rapid release of 1.3 million m3 of water. The flood rapidly bulked by entraining snow, ice, rock debris and alluvium along the steep gorge of the upper Whangaehu River to form a debris flow that then transformed downstream into a hyper-concentrated and then sediment-laden stream flow during its passage to the Tasman Sea 155 km away. No lives were lost' and infrastructural damage was minimal due to a comprehensive warning system developed in the decade before the lahar. A previous break-out lahar in 1953 caused a railway disaster at Tangiwai with the loss of 151 lives. The lahar flowed as a multi-peaked debris flow in the Whangaehu gorge, 7 km downstream of Crater Lake. Automatic lahar measuring equipment, including water level gauges, flow velocity sensors, conductivity samplers and seismographs were installed at key sites along the flow path, and were supplemented by sequential photographs captured by automatic monitoring cameras and observer teams. Flow velocity averaged 30 km/hr and water level rose by 8.2 m in 4 minutes in the gorge. The lahar caused riverbed aggradation in many places and environmental disturbance to the channel regime.