Basin Analysis Report - Critical Precipitation Zones

[jdduh]

New selection criteria:

• Replace Vol in the Area criterion (i.e., using %_VOL, instead of %_AREA), i.e., select elev zones whose %_VOL > 100% / (2 x zone#).
• Minimum precip threshold (> 20 inches) - select elevation zones with at least 20 inches of annual precip, i.e., select elev zone whose MEAN > 20.
• Total CPZ cannot exceed 2/3 of the AOI precip vol (using %_VOL instead of %_AREA), i.e., sort the elev zones based on %_VOL and select the zones with higher %_VOL until reaching 67%.

[lbross]

Do we want the minimum precipitation threshold and the CPZ minimum % (2/3) to be configurable? The parameters they are replacing are. Yes.

Stop calculating and presenting odds_ratio; Highlight MEAN column in blue instead for those rows that meet this criteria. Orange moves to %_VOL.

[lbross]

Clarifying selection criteria #3. Assume it is OK for the Total CPZ to exceed 2/3 of the AOI precip volume. For example if 3 elevation zones give 60% and adding the 4th brings us to 80%, we do still want to include the 4th.

[lbross]

This is done. The resulting product is better than I expected. See attached samples for our 3 POC AOIs. animas_AOI_prms_critical_precip_zones.pdf animas_AOI_prms_table.pdf arkansas_r_at_salida_critical_precip_zones.pdf arkansas_r_at_salida_table.pdf Elwha_nr_Port_Angeles_critical_precip_zones.pdf Elwha_nr_Port_Angeles_table.pdf

[jdduh]

Here are the update CPZ rules. It also affects how we determine the number of elevation zones.

The elevation interval should not exceed 500 feet. If the calculated interval is larger than 500 feet, then set the interval to 500 and ignore the limit on the number of zone.

• Select only elev zones whose %_VOL > 100% / (2 x zone#). For example, if there are 10 zones, then only zones with more than 5% of precipitation volume are selected.
• Select from the zones that meet criterion 1 above, whose HRU mean precip > 20 inches.
• Total CPZ must not exceed 2/3 of the total precipitation volume of the zones selected by criterion #2. (this is done by sorting the elev zones based on %_VOL and selecting the zones with higher %_VOL right before reaching 66.6667%.)

[lbross]

Just to double-check against the rules defined in the first comment from March 5. The changes are:

1. New algorithm for elevation zones also affecting the elevation zones map
2. The third criteria for total CPZ

Criterium 1 and 2 sound unchanged to me.

FYI: With the current size of the legend, an elevation interval of 500 feet will often create so many classes that they don't all fit on the legend.

[lbross]

See attached for samples with the updated methodology. These are 2 page documents with the table on the second page. These also have the new naming (title) standard. Animas_R_at_Durango_critical_precipitation_zones.pdf Arkansas_R_at_Salida_critical_precipitation_zones.pdf Elwha_at_Mcdonald_Bridge_critical_precipitation_zones.pdf

[lbross]

I made progress with the critical precip zones. The problem was that I wasn't calculating 2/3 of the total precipitation volume of the zones selected correctly. I didn't require the zone to meet BOTH criteria 1 AND 2 before adding it to the running total. I fixed that piece and uploaded new reports to the NRCS portal. The maps should be correct. However, I just realized that the blue shaded cells on the table are still wrong. The cells are painted blue regardless of whether or not they meet criteria #1 which is not correct. I won't have time to fix before I go, but will look at it when I return.

[jdduh]

The latest version on AGOL still has the wrong table. https://nwcc-nrcs.hub.arcgis.com/documents/1a49c3624d3a4ec0813f7dace2860878/explore The total selected zones still have a total %_VOL exceeding 67%.

[lbross]

Criteria 1: Select from all zones whose HRU mean precip > 20 inches. Criteria 2: Select from criteria 1 zones where %_VOL > 100% / (2 x zone#). For example, if there are 10 zones, then only zones with more than 5% of precipitation volume are selected. Criteria 3: Total CPZ must not exceed 2/3 of the total precipitation volume of the zones selected by criterion. Select %_VOL from highest to lowest until percents exceed 67%.

[jdduh]

Please add a description below the CPZ table. Here is an example of the text.

Critical precipitation elevation zone selection criteria: Criterion #1. mean annual precipitation > 20 inches Criterion #2. %_VOL > 100% / (2 x zone#) Criterion #3. higher %_VOL, but the total %_VOL of the selected zones must not exceed 66.67% (i.e., 2/3) Red cells are zones meeting all criteria Blue cells are zones meeting criterion #1 Orange cells are zones meeting criteria #1 and #2

[jdduh]

See the pdf for specific revisions to the table. Please ignore this request. We will only do minor changes instead. See below.

CPZ Table from 08251500_CO_USGS_Watershed-Report.pdf

[jdduh]

1. Change the headings of the following columns.

   • original table's first column heading from VALUE to "Elevation"
   • Label to "Elevation Zone"
   • AREA_DEM to "Zone Area"
   • %_AREA_DEN to "% Zone Area"

2. Hide the following columns

   • SUM, %_AREA, VOL_ACRE_FT

3. Replace the description below the table with the text indicated in the pdf.

4. No need to reorient the page if everything fit on one page.

Let me know if such edits minimize the disruptions of the other charts/tables.

[lbross]

I can't hide the %_AREA because one of the tables has a reference to it. Is that okay? Other than that, most of this is almost done.

[jdduh]

That would be fine.