哈里斯县，德克萨斯州，使用坎贝尔科学仪器更新防洪系统
图1：Map showing 139 Harris County ALERT/ALERT2 station locations
ALERT2 is a modern communication protocol that improves upon 40 years of tradition within the flood-warning community. ALERT2 has been designed to improve the performance of traditional ALERT flood-warning systems by reliably providing accurate and timely data. Since 2014, Campbell Scientific has provided a line of ALERT2 transmitters and customized solutions designed to meet customers’ specific needs. Over the course of 2015, Harris County Flood Control District (HCFCD) customized and installed a Campbell-based ALERT2 upgrade to their flood-warning system (FWS). HCFCD partnered with two experienced Campbell Scientific integrators to complete the installation and training of personnel on the new hardware: David Haynes of Distinctive AFWS Designs, and Don Van Wie of Telos Services.
背景
德克萨斯州哈里斯县是超过四百万人的家，是美国三百万人民的第三次。哈里斯县FWS的目标是提供准确，实时降雨和阶段数据，以便于之前，期间促进至关重要的决策。在洪水事件之后。哈里斯县FWS依赖于整个郡犹豫和连接的22分水岭支流的139个手掌站。
洪水警告网络最初由1982年安装的13站组成，增长，包括当今的139个HCFCD站（图1）。然而，在34年的系统扩张期间，出现了显着增长的痛苦。网络扩展，老化设备和维护实践在2007年创建了不可接受的数据丢失和质量。Campbell Scientific提供交钥匙FWS解决方案，包括Alert200和Alert210。新万博2019最新活动啊在Telos服务和独特的AFWS设计的帮助下，FWS从上到下进行了审查，该项目出发了竞争出价，最终解决方案是将所有设备替换为定制Campbell Alert2系统。在2015年的夏季和秋季，网络系统地用坎贝尔设备升级。网络以AL200和无线电组成的90个系统（图2）结束，而额外的60个系统使用CR800 DataLogger（图3）。在升级过程中，HCFCD借机还有机会更新所有网站基础架构，包括新的天线，新的5 W太阳能电池板和站点排列。
Figure 2:AL200 station installed in Harris County (A2DCP Type A)
Figure 3:ALERT2 station with datalogger
（哈里斯县的A2DCP类型B）
测量站监控流和河口水列弗el with OTT bubblers and radar sensors, or a pressure transducer from either Druck or Campbell Scientific. Rainfall data is transmitted every time 0.04 in. of rain is measured, while stage is transmitted every time level increases by 0.10 ft of water. Data is transmitted from the remote sites to three Blue Water Design repeater stations in the Huffman, Galveston, and Clodine areas. The repeater stations pass the measurement data along to primary and backup Blue Water Design base stations located at Houston Transtar and the Harris County Appraisal District. Once the data arrives at a base station it is ingested into OneRain’s Contrail software for processing, archiving and dissemination.(www.harriscountyfws.org)
Analysis of System Performance
There are many ways to assess the success of a flood-warning network. For the sake of this article we are going to look at percentage of successful reports during normal conditions (non-storm event) and peak rainfall events for pre-upgrade, during upgrade, and post-upgrade to ALERT2. To analyze reporting success during quiescent conditions, Mark Moore of the HCFCD examined daily, scheduled reports. In 2012, only 82.0% of battery reports arrived as expected. Continued upgrades to the system increased this success rate nominally to 84.9% by 2014. However, the completion of the upgrade to ALERT2 with Campbell Scientific gear increased the percentage of successful daily scheduled reports to 99.5% by the end of 2015 (Figure 4).
Figure 4: Percentage of data received by the base station/database with time.>
Demonstration of the increased ability of the FWS during both event and
quiescent periods. Event successful reports in this context is the percentage of
successful reports during the largest rainfall event of the year for 2012-2014,
and 2016. *(Event data is not available for 2015 because the system was in
transition during the peak rainfall event. It is discussed in more detail in the main text.)
了解干燥期间数据的可用性，可以了解网络性能，但是重大的降雨事件测试系统的真正可靠性和弹性。原始警报网络的一个弱点是由于消息碰撞而导致的数据或传输（在公共频率上立即交谈太多的电台）。警报系统中的通信流量是风暴强度和空间范围的函数;因此，由于需要接收数据的增加，失去数据的可能性在数据最重要的时候也会增加。在系统升级之前，HCFCD中的无线电频率的过载导致大型事件中的高达60％的数量丢失。例如，在2015年的阵亡将士纪念日，哈里斯县获得了过多的雨水，一些评级显示超过7英寸。在不到三个小时内雨量。此时只安装了一个Alert2测试站点，其余的网络仍然是遗产警报。如所设计的，Alert2测试站点在此极端降雨事件中收到了100％的预期数据报告。相比之下，附近的遗产警报站仅收到65％的预期报告。
在系统升级到Alert2期间，HCFCD采取措施降低碰撞中的数据丢失，包括减少后台无线电干扰，安装正确运行的设备，以及使用Alert2集中器中继器。自从坎贝尔设备升级到Alert2，HCFCD可以计算系统可以在观察到任何性能下降之前处理的流量，并相应地计划。
安装在哈里斯县的Alert2网络在安装过程中进行了一次测试，当系统是35％的遗产警报和65％Alert2。靠近2015年10月底，飓风帕里西亚的残余物下降了8英寸。哈里斯县下雨在24小时内。在此风暴期间，从90个Alert2站成功收到了99.6％的传输。自2015年12月，在2015年12月的较小的降雨赛事上进行了一项小降雨事件，自2016年3月的洪水活动进行了测试。在12月份的小雨活动期间，下雨了48小时。对此活动中产生的15,000个报告的分析表明，收到了99.9％的预期报告。
Between March 6 and March 11, 2016, parts of Harris County received 2.5-7.4 in. of rain. Multiple watersheds experienced over-bank conditions during the storm event. Looking at the roughly 13,500 transmissions during this event, the average success rate for receiving data into the database at the base station during the storm event was 99.8%. During the worst hour of the storm, success fell to 98%.
System Maintenance
通过升级到ALERT2硬件和更新下文structure, HCFCD has been able to reduce gage down time and the length of preventative maintenance visits. The site upgrades allow for easier access to equipment. For example, the technician no longer needs to remove the transmitter from the standpipe just to replace a battery. It is also easier to check sensor calibrations because the technician can connect directly to the DCP and view finished values in real-time. The technician will no longer need to check software for decoded messages. The hardware upgrade has also made repairs easier. The components are modular and easy to replace. The technician will no longer need to pull the whole transmitter. Plus off the shelf sensors can be used to replace damaged units without requiring a specialized circular connector.
More responsibility falls on the technician with these upgrades. For example, a poorly tinned wire may cause sensor issues; however, wiring issues are much simpler to diagnose and repair in the field without needing any special equipment. Multiple battery connectors make battery exchange easier and possible without powering down the site. Direct, easy access to the SDI-12 bus allows for easier diagnosis of problems. All this means less money spent on maintenance and repair. This money can be spent on further improving the network. It also means less time spent on site, which is important since many sites are located on roads and bridges, and traffic needs to be diverted while work is being done.
Since field-based preventative maintenance takes less time, HCFCD has decided to add general site management to the visit, including tree trimming, weed eating, etc., to allow for discharge measurements during storm events and better rain capture. Harris County has been working to shift their mind set to include preventative maintenance in the office before a problem arises. For example, as each gage sends a status transmission six times a day, operators watch out for any gage that misses its four hour report. Sync status updates allow HCFCD to confirm that the transmitter is getting a good GPS signal, and repeated instances of high sync status values lead to investigation. Battery reports on a more regular basis allow them to diagnose a failing battery before it goes bad. They have removed six failed batteries from the field before those sites went completely out. In fact, because of the more regular battery reporting, HCFCD hasn’t had a site go inactive due to battery failure.
In conclusion, the HCFCD staff members are confident that the Campbell Scientific ALERT2 upgrades to the FWS will allow the system to fully meet its goal of providing accurate, real-time rainfall and stage data to facilitate crucial decision making before, during, and after flood events. Campbell Scientific would like to thank Mark Moore of HCFCD for sharing his analysis of the pre- and post-upgrade successful reports.
