WEBVTT 00:00:00.066 --> 00:00:06.999 00:00:07.000 --> 00:00:08.933 00:00:08.933 --> 00:00:10.533 00:00:10.533 --> 00:00:12.699 00:00:12.700 --> 00:00:14.666 00:00:14.666 --> 00:00:16.399 00:00:16.400 --> 00:00:18.533 00:00:18.533 --> 00:00:20.166 00:00:20.166 --> 00:00:21.999 00:00:22.000 --> 00:00:24.100 00:00:24.100 --> 00:00:26.666 00:00:26.666 --> 00:00:28.799 00:00:28.800 --> 00:00:30.666 00:00:30.666 --> 00:00:32.132 00:00:32.133 --> 00:00:33.666 00:00:33.666 --> 00:00:35.966 00:00:35.966 --> 00:00:37.899 00:00:37.900 --> 00:00:40.466 00:00:40.466 --> 00:00:42.466 00:00:42.466 --> 00:00:44.699 00:00:44.700 --> 00:00:47.466 This lesson will cover stream flow 00:00:47.466 --> 00:00:49.799 estimates and NHD, plus high resolution. 00:00:49.800 --> 00:00:50.900 00:00:50.900 --> 00:00:53.100 Enhanced runoff method or EROM, 00:00:53.100 --> 00:00:55.633 is the method used to compute estimates 00:00:55.633 --> 00:00:58.333 of the mean annual flow from the 00:00:58.333 --> 00:01:00.699 NHD plus flowline features in the 00:01:00.700 --> 00:01:03.066 NHD plus high resolution network. 00:01:03.066 --> 00:01:05.866 The flow in cubic feet per second 00:01:05.866 --> 00:01:07.932 reflects the average annual flow 00:01:07.933 --> 00:01:10.299 from 1971 to 2000 time period. 00:01:10.300 --> 00:01:12.033 Flow and velocity estimates are 00:01:12.033 --> 00:01:14.199 important parts of the NHD plus 00:01:14.200 --> 00:01:16.033 high resolution package and are 00:01:16.033 --> 00:01:18.233 included for all network flow lines. 00:01:18.233 --> 00:01:19.999 This allows the NHD plus high 00:01:20.000 --> 00:01:21.833 resolution to be used in riverine 00:01:21.833 --> 00:01:23.399 fate and transport models. 00:01:23.400 --> 00:01:25.133 Models which simulate the movement 00:01:25.133 --> 00:01:26.899 of contaminants as they move 00:01:26.900 --> 00:01:28.333 through the River network. 00:01:28.333 --> 00:01:30.233 This presentation covers the basics of 00:01:30.233 --> 00:01:32.333 how flow rate estimates are calculated. 00:01:32.333 --> 00:01:34.499 00:01:34.500 --> 00:01:36.866 The NHD plus high resolution packages 00:01:36.866 --> 00:01:39.332 are delivered in a geodatabase. 00:01:39.333 --> 00:01:41.499 Each geodatabase represents a vector 00:01:41.500 --> 00:01:44.266 processing unit or VPU. NHD plus high 00:01:44.266 --> 00:01:46.432 resolution flow rates are calculated 00:01:46.433 --> 00:01:48.599 for all network flow lines in a VPU. 00:01:48.600 --> 00:01:50.333 There are many tables 00:01:50.333 --> 00:01:51.999 included in the geodatabase. 00:01:52.000 --> 00:01:54.133 We will consider the following 00:01:54.133 --> 00:01:55.999 tables in this presentation. 00:01:56.000 --> 00:01:58.766 The first table is that NHD plus 00:01:58.766 --> 00:02:02.232 EROM MA or EROM mean annual table. 00:02:02.233 --> 00:02:04.799 This is the table that contains flow 00:02:04.800 --> 00:02:07.233 estimates for all NHD flowline features 00:02:07.233 --> 00:02:10.199 in the NHD plus high resolution network. 00:02:10.200 --> 00:02:13.266 The second table is the NHD plus EROM QAMA, 00:02:13.266 --> 00:02:15.366 or EROM quality assurance 00:02:15.366 --> 00:02:16.899 mean annual table. 00:02:16.900 --> 00:02:19.400 This table contains the gauge and EROM 00:02:19.400 --> 00:02:22.633 flows for users to do their own analysis. 00:02:22.633 --> 00:02:24.833 The file layout is designed to facilitate 00:02:24.833 --> 00:02:26.233 graphical and statistical analysis. 00:02:26.233 --> 00:02:28.033 It's useful for users who want 00:02:28.033 --> 00:02:29.866 to look at graphs or additional 00:02:29.866 --> 00:02:31.466 statistics about the stream. 00:02:31.466 --> 00:02:34.532 gages used in the flow estimates. 00:02:34.533 --> 00:02:38.099 The third table is the NHD plus EROM QA 00:02:38.100 --> 00:02:41.833 report or the EROM Quality Assurance report. 00:02:41.833 --> 00:02:43.366 This report contains comparisons 00:02:43.366 --> 00:02:46.099 of the EROM flow estimates on the 00:02:46.100 --> 00:02:48.333 observed flows from real stream gauges. 00:02:48.333 --> 00:02:50.366 The report is stored as a table. 00:02:50.366 --> 00:02:53.866 Note that no example is shown. 00:02:53.866 --> 00:02:55.899 The first table we will discuss is 00:02:55.900 --> 00:02:58.266 the NHD plus EROM mean annual table. 00:02:58.266 --> 00:02:59.499 As you can see, 00:02:59.500 --> 00:03:01.800 the table has many attributes we will 00:03:01.800 --> 00:03:04.200 cover just the five highlighted fields. 00:03:04.200 --> 00:03:09.533 The first is the QAMA the alias for this field is FlowEstARunoffMA 00:03:09.533 --> 00:03:09.566 this field is Flo asked a runoff MA 00:03:09.566 --> 00:03:14.266 or Flow Estimate A Runoff Mean Annual. 00:03:14.266 --> 00:03:16.766 This is the initial estimate of the flow. 00:03:16.766 --> 00:03:19.299 Second is QBMA. 00:03:19.300 --> 00:03:22.233 The alias for this field is 00:03:22.233 --> 00:03:25.833 FlowEstBExcessETMA or flow estimate 00:03:25.833 --> 00:03:28.599 B Excess Evapotranspiration Mean Annual. 00:03:28.600 --> 00:03:30.333 Q is a variable in hydrology 00:03:30.333 --> 00:03:32.133 equations that stands for discharge, 00:03:32.133 --> 00:03:33.999 which is why you're seeing Q 00:03:34.000 --> 00:03:35.566 in the field name. 00:03:35.566 --> 00:03:38.799 The third relevant field is QCMA 00:03:38.800 --> 00:03:42.400 alias FlowEstCRefGageRegressMA. 00:03:42.400 --> 00:03:44.500 Or Flow Estimate 00:03:44.500 --> 00:03:46.600 C Reference Gage Regression 00:03:46.600 --> 00:03:50.266 Mean Annual. Fourth is QDMA, alias Flow 00:03:50.266 --> 00:03:54.199 FlowEstDAdditionRemovalMA or Flow Estimate 00:03:54.200 --> 00:03:57.066 D Edition Removal Mean Annual. 00:03:57.066 --> 00:03:58.266 Finally, 00:03:58.266 --> 00:04:01.132 QEMA alias FlowEstEGageAdjustedMA 00:04:01.133 --> 00:04:05.399 or Flow Estimate E Gage Adjusted 00:04:05.400 --> 00:04:06.666 Mean Annual. 00:04:06.666 --> 00:04:08.599 Each of these five fields represents 00:04:08.600 --> 00:04:10.800 an iteration to refine the accuracy of 00:04:10.800 --> 00:04:12.800 the estimated flow for the flow line. 00:04:12.800 --> 00:04:14.966 Let's walk through a real world example 00:04:14.966 --> 00:04:17.132 to illustrate how each of the five 00:04:17.133 --> 00:04:19.199 fields refines the flow estimate. 00:04:19.200 --> 00:04:20.833 00:04:20.833 --> 00:04:23.366 The explanation for estimates of flow 00:04:23.366 --> 00:04:26.499 is broken down into steps A through F. 00:04:26.500 --> 00:04:28.900 Steps A and B compute natural flow steps, 00:04:28.900 --> 00:04:31.666 C, D, and E adjust natural flow values 00:04:31.666 --> 00:04:33.766 based on observed gage data 00:04:33.766 --> 00:04:35.699 and known flow transfers. 00:04:35.700 --> 00:04:39.566 Step F performs QAQC analysis. 00:04:39.566 --> 00:04:41.066 The image on the slide 00:04:41.066 --> 00:04:42.266 shows the drainage basin 00:04:42.266 --> 00:04:44.199 for Pitkin Creek a Creek 5 miles 00:04:44.200 --> 00:04:46.500 West of Vail Ski Resort in Colorado. 00:04:46.500 --> 00:04:48.233 Note the catchments of all the 00:04:48.233 --> 00:04:50.033 flow lines have been aggregated so 00:04:50.033 --> 00:04:52.199 you can see the entire drainage of 00:04:52.200 --> 00:04:54.066 Pitkin Creek in pink locations of 00:04:54.066 --> 00:04:57.699 stream gauges are shown as red dots. 00:04:57.700 --> 00:04:58.733 In step a, 00:04:58.733 --> 00:05:00.499 initial estimates of mean annual 00:05:00.500 --> 00:05:03.366 flow are based on a grid from a flow 00:05:03.366 --> 00:05:05.099 balanced model of surface runoff 00:05:05.100 --> 00:05:07.366 published by McCabe and Wolock 00:05:07.366 --> 00:05:10.232 in 2011 each 900 meter by 900 meter. 00:05:10.233 --> 00:05:12.566 Grid cell symbolizes natural runoff or 00:05:12.566 --> 00:05:15.499 mean water year runoff in millimeters. 00:05:15.500 --> 00:05:17.266 00:05:17.266 --> 00:05:19.832 Zooming into Pitkin Creek drainage you can 00:05:19.833 --> 00:05:22.166 see the individual run off grid cells. 00:05:22.166 --> 00:05:25.132 The flow rates for each of the flow lines 00:05:25.133 --> 00:05:27.599 are captured in QAMA. Flow Estimate 00:05:27.600 --> 00:05:29.766 A Runoff Mean Annual. In this and 00:05:29.766 --> 00:05:31.399 following screenshots only the 00:05:31.400 --> 00:05:33.800 record for the most downstream flow 00:05:33.800 --> 00:05:33.900 00:05:33.900 --> 00:05:35.800 line of Picking Creek is shown. 00:05:35.800 --> 00:05:38.833 The QAMA attribute is shown in yellow 00:05:38.833 --> 00:05:42.399 on the far left. 6.1 cubic feet per second. 00:05:42.400 --> 00:05:45.066 In step A, the runoff rasters overlaid with 00:05:45.066 --> 00:05:47.666 the NHD plus high resolution catchments 00:05:47.666 --> 00:05:50.466 to compute runoff within each catchment. 00:05:50.466 --> 00:05:52.732 The catchment runoff values are 00:05:52.733 --> 00:05:55.033 conservatively routed downstream to arrive 00:05:55.033 --> 00:05:57.533 at the first estimate of streamflows for 00:05:57.533 --> 00:05:59.699 each networked NHD flowline feature. 00:05:59.700 --> 00:06:01.633 The flow estimate represents the flow 00:06:01.633 --> 00:06:03.866 at the bottom of each flow line. 00:06:03.866 --> 00:06:05.966 00:06:05.966 --> 00:06:08.532 Step B represents adjustments for losses 00:06:08.533 --> 00:06:11.299 due to excessive Evapotranspiration. 00:06:11.300 --> 00:06:13.800 This method, developed by McCabe and Wolock, 00:06:13.800 --> 00:06:15.833 considers the total available water in 00:06:15.833 --> 00:06:18.233 a given catchment to compute additional 00:06:18.233 --> 00:06:20.199 losses due to evapotranspiration. 00:06:20.200 --> 00:06:22.100 Evapotranspiration losses can exceed the 00:06:22.100 --> 00:06:24.300 total available water in a catchment, 00:06:24.300 --> 00:06:27.400 resulting in a net loss and stream flow. 00:06:27.400 --> 00:06:29.866 This loss of instream flow is a 00:06:29.866 --> 00:06:31.932 significant observed phenomenon, especially 00:06:31.933 --> 00:06:34.033 in arid areas West of the Mississippi River. 00:06:34.033 --> 00:06:34.833 00:06:34.833 --> 00:06:37.133 Estimates of losses made in this 00:06:37.133 --> 00:06:39.433 step or subtracted from the flow 00:06:39.433 --> 00:06:42.133 estimates and are stored in QBMA. 00:06:42.133 --> 00:06:45.299 Flow Estimate B Excess Evapotranspiration mean annual. 00:06:45.300 --> 00:06:45.566 00:06:45.566 --> 00:06:47.732 This estimate gets us a little 00:06:47.733 --> 00:06:49.166 bit closer to natural flow. 00:06:49.166 --> 00:06:51.699 QBMA is shown in yellow in the 00:06:51.700 --> 00:06:53.500 second column from the right. 00:06:53.500 --> 00:06:55.233 Notice that flow estimate B 00:06:55.233 --> 00:06:57.366 matches flow estimate A both showing 00:06:57.366 --> 00:06:59.366 6.1 cubic feet per second. 00:06:59.366 --> 00:07:01.232 This means that there is no 00:07:01.233 --> 00:07:03.599 appreciable loss of flow due to 00:07:03.600 --> 00:07:05.366 evapotranspiration in this area. 00:07:05.366 --> 00:07:08.299 This is expected because Pitkin Creek is 00:07:08.300 --> 00:07:11.433 in a mountainous area at higher elevation. 00:07:11.433 --> 00:07:13.399 Step C is a regression analysis 00:07:13.400 --> 00:07:15.366 using reference stream gauges to 00:07:15.366 --> 00:07:15.466 00:07:15.466 --> 00:07:17.866 provide a further adjustment to flow 00:07:17.866 --> 00:07:19.632 estimates calculated in step B. 00:07:19.633 --> 00:07:21.966 A reference gage is a stream gage that 00:07:21.966 --> 00:07:24.199 is minimally affected by human activities. 00:07:24.200 --> 00:07:24.966 For example, 00:07:24.966 --> 00:07:27.266 there are no dams or other 00:07:27.266 --> 00:07:28.699 flow alterations upstream. 00:07:28.700 --> 00:07:31.033 Gages used in EROM including 00:07:31.033 --> 00:07:32.566 reference gages are screened 00:07:32.566 --> 00:07:32.599 00:07:32.600 --> 00:07:34.500 based on two additional criteria. 00:07:34.500 --> 00:07:35.266 First, 00:07:35.266 --> 00:07:36.832 the NHD plus high Resolution 00:07:36.833 --> 00:07:38.966 drainage area for the gauge must 00:07:38.966 --> 00:07:40.999 be within a certain percentage of 00:07:41.000 --> 00:07:43.133 the NWIS reported drainage area. 00:07:43.133 --> 00:07:45.833 NWIS is the National Water information system. 00:07:45.833 --> 00:07:45.866 00:07:45.866 --> 00:07:46.732 Second, 00:07:46.733 --> 00:07:49.899 the gauge must have a minimum of 10 years 00:07:49.900 --> 00:07:53.500 record in the 1971 to 2000 time period. 00:07:53.500 --> 00:07:55.566 The reference gages used for 00:07:55.566 --> 00:07:57.266 each vector processing unit or 00:07:57.266 --> 00:07:58.766 VPU are shown in the EROM 00:07:58.766 --> 00:08:01.099 QAMA table which we will discuss 00:08:01.100 --> 00:08:03.700 in one of the following slides. 00:08:03.700 --> 00:08:05.866 A log log regression is calculated 00:08:05.866 --> 00:08:08.399 to further refine the flow estimate 00:08:08.400 --> 00:08:10.366 to represent natural conditions. 00:08:10.366 --> 00:08:12.632 The gage adjusted natural flow 00:08:12.633 --> 00:08:15.066 value is captured in QCMA 00:08:15.066 --> 00:08:17.232 Flow Estimate 00:08:17.233 --> 00:08:20.299 C Reference Gage Regression Mean Annual. 00:08:20.300 --> 00:08:21.700 In this example, 00:08:21.700 --> 00:08:23.966 the stream gage shown here is the 00:08:23.966 --> 00:08:24.066 00:08:24.066 --> 00:08:26.266 USGS stream gage at Pitkin Creek. 00:08:26.266 --> 00:08:28.766 Data and descriptive information for the 00:08:28.766 --> 00:08:32.166 gage can be found on the NWIS website. 00:08:32.166 --> 00:08:35.299 If we look up this stream gage at NWIS, 00:08:35.300 --> 00:08:37.566 we see it's gage ID number and it's 00:08:37.566 --> 00:08:39.599 official name. Picking Creek near Minturn, 00:08:39.600 --> 00:08:40.466 Colorado. 00:08:40.466 --> 00:08:43.132 We also see that NWIS records, 00:08:43.133 --> 00:08:45.199 the total upstream drainage for 00:08:45.200 --> 00:08:47.500 this gage at 5.32 square miles. 00:08:47.500 --> 00:08:47.533 00:08:47.533 --> 00:08:49.266 Finally, the gauge has more than 10 00:08:49.266 --> 00:08:50.966 years of continuous record. 00:08:50.966 --> 00:08:52.732 Therefore the gauge at Pitkin Creek 00:08:52.733 --> 00:08:54.433 is suitable as a reference gauge 00:08:54.433 --> 00:08:56.533 and can be used in the regression 00:08:56.533 --> 00:08:57.966 equation to estimate flow. 00:08:57.966 --> 00:08:59.566 00:08:59.566 --> 00:09:01.832 We can also calculate the upstream 00:09:01.833 --> 00:09:04.066 drainage area from this gauge point 00:09:04.066 --> 00:09:06.366 using the NHD plus high resolution in 00:09:06.366 --> 00:09:09.166 a geographic information system or GIS. 00:09:09.166 --> 00:09:11.632 GIS calculates the sum of the areas 00:09:11.633 --> 00:09:14.199 in all the catchments upstream of 00:09:14.200 --> 00:09:16.800 this point is 5.35 square miles. 00:09:16.800 --> 00:09:19.133 The calculated value is within 20% 00:09:19.133 --> 00:09:20.999 of the upstream drainage record 00:09:21.000 --> 00:09:23.333 for this stream gauge in NWIS. 00:09:23.333 --> 00:09:24.733 00:09:24.733 --> 00:09:27.233 A log log regression is calculated 00:09:27.233 --> 00:09:29.533 using the reference gage flows to 00:09:29.533 --> 00:09:31.466 further refine the flow estimate 00:09:31.466 --> 00:09:33.366 to represent natural conditions. 00:09:33.366 --> 00:09:35.499 The gage adjusted natural flow value 00:09:35.500 --> 00:09:38.766 is captured in QCMA Flow Estimate C 00:09:38.766 --> 00:09:40.999 Reference Gage Regression Mean Annual 00:09:41.000 --> 00:09:43.433 attribute this is shown in the center 00:09:43.433 --> 00:09:45.566 yellow column of the attribute table. 00:09:45.566 --> 00:09:47.699 QCMA shows the flow estimate 00:09:47.700 --> 00:09:50.266 is 5.7 cubic feet per second. 00:09:50.266 --> 00:09:53.666 Notice that this is a bit lower than the 6.4 00:09:53.666 --> 00:09:53.766 00:09:53.766 --> 00:09:56.966 cubic feet per second estimate in step B, 00:09:56.966 --> 00:09:58.032 excess evapotranspiration. 00:09:58.033 --> 00:10:00.533 The QCMA values are the best 00:10:00.533 --> 00:10:00.633 00:10:00.633 --> 00:10:02.566 estimate of natural flows. 00:10:02.566 --> 00:10:04.466 00:10:04.466 --> 00:10:08.199 Step D adjust the stream flow for flow 00:10:08.200 --> 00:10:10.533 transfers withdraws and augmentation. 00:10:10.533 --> 00:10:11.966 Man made additions, 00:10:11.966 --> 00:10:13.766 removals and transfers are found 00:10:13.766 --> 00:10:15.932 in the NHD plus flow AR table. 00:10:15.933 --> 00:10:18.533 This table is empty in the beta version 00:10:18.533 --> 00:10:21.799 of NHD plus high Resolution and will be 00:10:21.800 --> 00:10:24.566 built overtime based largely on user input. 00:10:24.566 --> 00:10:27.866 Adjustments in this step are made to QCMA 00:10:27.866 --> 00:10:31.499 the newly adjusted values are stored in QDMA, 00:10:31.500 --> 00:10:35.200 alias FlowEstDAdditionalRemovalMA. 00:10:35.200 --> 00:10:35.233 00:10:35.233 --> 00:10:36.433 00:10:36.433 --> 00:10:39.233 If we look at the data in Pitkin Creek, 00:10:39.233 --> 00:10:41.099 we will find that the adjusted 00:10:41.100 --> 00:10:43.566 value stored in the QDMA are the 00:10:43.566 --> 00:10:45.266 same as the values calculated in 00:10:45.266 --> 00:10:45.366 00:10:45.366 --> 00:10:47.332 step C for the QCMA attribute. 00:10:47.333 --> 00:10:49.566 The reason for the unchanged values is 00:10:49.566 --> 00:10:52.132 the absence of any man made stream flow 00:10:52.133 --> 00:10:53.999 adjustments for Pitkin Creek 00:10:54.000 --> 00:10:57.133 in the NHD plus flow AR table. 00:10:57.133 --> 00:10:59.466 Step E further justs flow estimates 00:10:59.466 --> 00:11:01.599 based on observed gaging station data. 00:11:01.600 --> 00:11:03.900 In this step the network features 00:11:03.900 --> 00:11:06.700 that are upstream from the gage are 00:11:06.700 --> 00:11:09.066 adjusted for observed gage base flow. 00:11:09.066 --> 00:11:11.299 The flow for the downstream features, 00:11:11.300 --> 00:11:13.366 in turn, are calculated using 00:11:13.366 --> 00:11:14.999 adjusted incremental flows for 00:11:15.000 --> 00:11:16.433 affected catchment areas. 00:11:16.433 --> 00:11:17.733 Thus, step E impacts estimates 00:11:17.733 --> 00:11:19.333 downstream from the gage to 00:11:19.333 --> 00:11:20.933 better reflect flow alterations, 00:11:20.933 --> 00:11:22.699 not taken into account 00:11:22.700 --> 00:11:24.933 in the first four steps. 00:11:24.933 --> 00:11:27.766 It is possible for the flow values to 00:11:27.766 --> 00:11:30.099 decrease downstream at flow lines were 00:11:30.100 --> 00:11:32.033 gage is present gage selection criteria 00:11:32.033 --> 00:11:34.666 in this step is the same as in step C. 00:11:34.666 --> 00:11:37.532 Drainage area must be within 20% and must 00:11:37.533 --> 00:11:40.566 have a continuous record of 10 years. 00:11:40.566 --> 00:11:42.232 Only gaging stations linked 00:11:42.233 --> 00:11:44.366 the NHD plus high Resolution 00:11:44.366 --> 00:11:46.466 network are used to adjust flows. 00:11:46.466 --> 00:11:48.432 The flow estimates after adjustments 00:11:48.433 --> 00:11:50.866 in Step E are considered the 00:11:50.866 --> 00:11:52.766 best NHD plus high resolution 00:11:52.766 --> 00:11:54.732 flow estimates for actual flows. 00:11:54.733 --> 00:11:58.566 The value is stored in QEMA 00:11:58.566 --> 00:12:02.432 alias FlowEstEGageAdjustedMA. 00:12:02.433 --> 00:12:04.633 This slide shows the final estimate 00:12:04.633 --> 00:12:06.899 QEMA of 6.1 CFS for Pitkin 00:12:06.900 --> 00:12:08.866 Creek in the last column. 00:12:08.866 --> 00:12:11.266 Note this estimate is very close to the 00:12:11.266 --> 00:12:13.166 initial estimate based on runoff only, 00:12:13.166 --> 00:12:17.199 but this is not always the case. 00:12:17.200 --> 00:12:19.166 Here are the final QEMA 00:12:19.166 --> 00:12:21.432 values in the Pitkin Creek area. 00:12:21.433 --> 00:12:22.799 You can symbolize QEMA 00:12:22.800 --> 00:12:24.533 values in class intervals. 00:12:24.533 --> 00:12:26.633 In the example of Pitkin Creek, 00:12:26.633 --> 00:12:28.166 we use 20 classes. 00:12:28.166 --> 00:12:29.699 As you can see, 00:12:29.700 --> 00:12:31.133 such classification gives you 00:12:31.133 --> 00:12:32.966 an effective map display where 00:12:32.966 --> 00:12:34.699 major and minor streams are 00:12:34.700 --> 00:12:36.333 displayed differently on the map 00:12:36.333 --> 00:12:37.899 based on their flow estimates. 00:12:37.900 --> 00:12:39.833 Step F is a quality assurance 00:12:39.833 --> 00:12:41.966 step to measure the accuracy of 00:12:41.966 --> 00:12:43.666 gage adjusted flow estimates 00:12:43.666 --> 00:12:45.366 on ungaged NHD flowline features 00:12:45.366 --> 00:12:47.699 because Step D uses all gages, 00:12:47.700 --> 00:12:50.266 the flow estimates at the gage locations 00:12:50.266 --> 00:12:53.032 will always match the gauged flow values. 00:12:53.033 --> 00:12:54.999 This means that any statistical analysis 00:12:55.000 --> 00:12:57.700 on the Step E flows compared to gage 00:12:57.700 --> 00:13:00.100 flows will always be a perfect match. 00:13:00.100 --> 00:13:02.566 Step F randomly removes 20% of gages 00:13:02.566 --> 00:13:04.599 from the gage adjustment process and 00:13:04.600 --> 00:13:06.466 repeats the gage adjustment process 00:13:06.466 --> 00:13:08.799 on the remaining 80% of gages. 00:13:08.800 --> 00:13:11.366 Step F then compares the adjusted 00:13:11.366 --> 00:13:13.999 estimates to the actual gage flows. 00:13:14.000 --> 00:13:17.100 The EROM QAMA table captures which 00:13:17.100 --> 00:13:20.066 gages were used in the QA analysis. 00:13:20.066 --> 00:13:21.932 The attribute GageRef contains the 00:13:21.933 --> 00:13:24.599 values of yes for the used gages. 00:13:24.600 --> 00:13:26.700 00:13:26.700 --> 00:13:29.566 The EROM QAMA table and the EROM 00:13:29.566 --> 00:13:32.466 QA report may be used to evaluate the 00:13:32.466 --> 00:13:34.932 accuracy of the reference gage regression 00:13:34.933 --> 00:13:37.699 and the gage adjusted flow estimates. 00:13:37.700 --> 00:13:39.800 Using values found in the EROM QAMA 00:13:39.800 --> 00:13:42.366 table the graph on the slide shows 00:13:42.366 --> 00:13:44.399 the comparison of the actual log 10 00:13:44.400 --> 00:13:46.800 mean flow at the gages and the log 00:13:46.800 --> 00:13:49.666 10 of the EROM mean flow estimates. 00:13:49.666 --> 00:13:52.766 Gage flows are on the X axis and EROM 00:13:52.766 --> 00:13:55.532 flow estimates are on the Y axis. 00:13:55.533 --> 00:13:57.899 The blue diamonds are the runoff flow estimates. 00:13:57.900 --> 00:13:57.933 00:13:57.933 --> 00:14:00.233 The pink squares are the flows adjusted 00:14:00.233 --> 00:14:02.266 with the reference gage regression. 00:14:02.266 --> 00:14:04.466 The red line is where the gage 00:14:04.466 --> 00:14:06.499 and EROM flows would be equal. 00:14:06.500 --> 00:14:08.133 Note how in this region, 00:14:08.133 --> 00:14:09.433 the runoff estimates consistently 00:14:09.433 --> 00:14:11.599 underestimate the gaged flows. 00:14:11.600 --> 00:14:12.400 00:14:12.400 --> 00:14:14.466 Stream flow QA information 00:14:14.466 --> 00:14:16.566 is included in two tables. 00:14:16.566 --> 00:14:19.332 The first output is EROM QAMA table. 00:14:19.333 --> 00:14:21.333 It contains statistical descriptions 00:14:21.333 --> 00:14:23.399 of initial estimates of stream 00:14:23.400 --> 00:14:25.366 flow runoff in a table form. 00:14:25.366 --> 00:14:27.666 The file layout is designed to facilitate 00:14:27.666 --> 00:14:29.232 graphical and statistical analysis. 00:14:29.233 --> 00:14:31.833 It is useful for users who want to look 00:14:31.833 --> 00:14:33.933 at graphs or additional statistics 00:14:33.933 --> 00:14:36.566 for only the reference gages. 00:14:36.566 --> 00:14:38.766 The 2nd output is the report. 00:14:38.766 --> 00:14:40.366 The report contains comparisons 00:14:40.366 --> 00:14:42.332 of the EROM flow estimates 00:14:42.333 --> 00:14:44.333 and the observed gage flows. 00:14:44.333 --> 00:14:46.399 The report is stored as a table. 00:14:46.400 --> 00:14:47.800 00:14:47.800 --> 00:14:50.033 To summarize this lesson, 00:14:50.033 --> 00:14:52.866 we learned how stream flow estimates get 00:14:52.866 --> 00:14:55.266 calculated in NHD plus high resolution. 00:14:55.266 --> 00:14:57.766 It's a global method to assign flow 00:14:57.766 --> 00:15:00.466 rates for the entire United States. 00:15:00.466 --> 00:15:03.266 Many other methods for flow estimation exist, 00:15:03.266 --> 00:15:05.666 especially on a more local level. 00:15:05.666 --> 00:15:07.499 For example, USGS Stream stats 00:15:07.500 --> 00:15:08.966 program calculates flow estimates 00:15:08.966 --> 00:15:10.899 using smaller regional regressions, 00:15:10.900 --> 00:15:12.533 usually presented by state. 00:15:12.533 --> 00:15:14.566 There are many potential uses 00:15:14.566 --> 00:15:16.466 for EROM flow estimates, 00:15:16.466 --> 00:15:18.566 for example flow in combination with 00:15:18.566 --> 00:15:20.966 the flow network allows for time of 00:15:20.966 --> 00:15:22.599 travel studies flow in combination 00:15:22.600 --> 00:15:24.433 with the catchments or watershed 00:15:24.433 --> 00:15:26.666 boundaries can be used to estimate 00:15:26.666 --> 00:15:29.066 water budgets for certain areas. 00:15:29.066 --> 00:15:31.199 Finally, flow estimates can be symbolized. 00:15:31.200 --> 00:15:33.333 To create effective cartographic products, 00:15:33.333 --> 00:15:35.766 as we have seen in the example 00:15:35.766 --> 00:15:37.232 of Pitkin Creek. 00:15:37.233 --> 00:15:37.866 00:15:37.866 --> 00:15:40.532 For further questions related to 00:15:40.533 --> 00:15:43.366 NHD plus high resolution or any 00:15:43.366 --> 00:15:45.666 NHD products, please contact USGS 00:15:45.666 --> 00:15:48.432 support email nhd@usgs.gov.