Flagstaff area stream flow and rainfall - 2008-2019. Appendix C

This is Appendix C to the Flagstaff area stream flow 2008-2019 technical report. This appendix provides raw data on rainfall.

Flagstaff, Arizona has unique surface water hydrology due to climate, geology, and vegetation. The area experiences extremely low rainfall-runoff in natural undisturbed areas. This “complacent” watershed condition leads to dramatic shifts in flow and flooding when disturbances such as urbanization, wildfire, or even forest thinning are introduced to the landscape. Using 57 stream and rain gauges this report provides preliminary data to inform managers, engineers, and scientists on both the complacent and “violent” watershed characteristics of the Flagstaff area. This is the first regional surface water hydrology report since the 1988 US Geological Survey report on flood frequency in the Flagstaff area. Preliminary results indicate that previous flood frequency analyses provide a much higher predicted flood flow than empirical gauge results have observed. In some sites the over-prediction of regional regressions is over twice observed values. The hope is that this preliminary report will provide a “stepping stone” towards a greater understanding of the hydrologic drivers and stream character of the area. More data, over a longer time period, is required for making defensible predictions of rainfall-runoff, flood frequency, and flood mitigation design in the Flagstaff area.

本文件为《弗拉格斯塔夫地区2008-2019年溪流流量技术报告》的附录C，本附录提供降雨原始数据。
亚利桑那州弗拉格斯塔夫地区因气候、地质与植被条件，拥有独特的地表水水文（surface water hydrology）特征。该区域自然未受干扰区域的降雨径流（rainfall-runoff）水平极低，这种“惰性”流域状态会在城市化、野火乃至森林疏伐等扰动作用于地表后，引发流量与洪水的剧烈变化。
本报告依托57处溪流与雨量监测站点生成初步数据，以供管理人员、工程师及科研人员了解弗拉格斯塔夫地区“惰性”与“暴发性”两类流域特征。本报告为1988年美国地质调查局（U.S. Geological Survey）发布弗拉格斯塔夫地区洪水频率研究报告以来，首份区域地表水水文领域专项报告。
初步结果显示，过往洪水频率分析得出的预测洪水流量远高于实测站点的观测结果，部分监测站点的区域回归模型预测值较观测值高出两倍以上。
本初步报告旨在为深入理解该区域水文驱动因子与溪流水文特征提供“垫脚石”式的研究基础。若要对弗拉格斯塔夫地区的降雨径流、洪水频率及洪水减灾设计做出严谨可信的预测，仍需获取更长时间序列的更多监测数据。