Appendix 2: Rainfall Analysis

All data used in this analysis were extracted from the Bureau of Meteorology Climate Database.

Regional rainfall analysis in the Australian Capital Region is complicated by several factors including:

  1. Intermittent coverage at specific locations. While the Bureau of Meteorology has a considerable number of volunteer rainfall observers, many of the sites have gaps within the records. Although there are several excellent long-term rainfall sites available and still open in the region, there are many more that have records of varying length that do overlap. If one site closed, the Bureau of Meteorology attempted to open another site close by. Averaging between several nearby sites with data highly correlated with that at the chosen site can be used as a simple method of filling gaps in the record.
  2. Missing data. While rainfall does vary both spatially and temporally in the short term, analysis of data from nearby sites indicates that in cases where there are overlapping records for a long period of time there are frequently high correlations on a month by month basis between these sites. This means that linear regression can be used to calculate values to fill the missing months in these records.

Selection of Sites

The main rainfall site chosen to represent the location within each Local Government Area (LGA) was that site that was still open and with the longest continuous record. Gaps in the data were then filled using linear regression with data for surrounding sites with overlapping records:

  1. Comparisons were made with sites with suitable data that were as close as possible both for the period 2004-2008 and for the period pre-2004.
  2. Provided the correlation values were over 0.8, linear regression formulae obtained from these comparisons were then used to calculate the missing values for the site chosen to be the main site for the region.
  3. Where a number of sites needed to be used to fill the gaps, such as at Goulburn, and the correlation values were less than 0.8, then an average of the values calculated for the main site from each alternative site was used.

Data for the LGAs fall into 4 categories

1. The site has a full record with no gaps. The sites in this category are:

Queanbeyan

Tumbarumba

Moruya Heads

Taralga

2. The site has a few individual months missing in the record. The sites in this category are:

Adaminaby*

Tumut

Bombala (Bukalong)

Narooma (Bodalla)

Young (Wombat)

Crookwell

Braidwood (Wallace St)

3. The site has a series of months/years missing. The sites in this category are:

Goulburn (Kippilaw)

Eden (Caravan Park)

Bega (Newton Rd)

Cootamundra (Landgrove)

Boorowa

Harden (Murrumburrah)

Bungendore (Gidleigh)

Cabramurra*

4. The comparison with another nearby site is sufficient to develop a time series that precedes the date when the site was opened. The sites in this category are:

Cooma (Kiaora)

Yass

Gundagai (Mt. Horeb)

* The derived monthly rainfall data developed for Adaminaby and Cabramurra used in this analysis can only be treated as indicative, as there was a lack of good quality data from nearby sites for comparison. Although an Automatic Weather Station (AWS) has been installed at Cabramurra, the correlation with data from the manual site before it was closed is not as high as would be expected given the proximity of the new to the old site. Relationships with data from sites near to Cabramurra are also affected by the differences in altitude in the region.

The selected sites and the secondary sites used to fill data gaps for this analysis are listed below, with the main site in red in each case.

Adaminaby Approx Distance Lat Long Elevation R2 valuewith 72100
Alpine Tourist Park 1886-2008 071000 0.4 km 36.00S 148.77E 1015 m  
Eucumbene Trout Farm 1973-2008 071043 30.7 km 36.27S 148.72E 1050 m 0.68420.7548 (post 2004)
Buckenderra 2003-2008 071026 20.2 km 36.18S 148.76E 1198 m 0.7742

 

Bega Approx Distance Lat Long Elevation R2 valuewith 69002
Bega (Newton Rd) 1879-2008 069002 5.6 km 36.69S 149.84E 50 m  
Bega AWS 1992-2008 069139 7 km 36.67S 149.82E 41 m 0.8813 0.9827 (Post 2004)
Candelo PO 1887-2008 069013 21 km 36.77S 149.7E 109 m 0.8784

 

Bombala Approx Distance Lat Long Elevation R2 valuewith 70009
Bukalong 1857-2008070009 14 km 36.8S 149.2E 785 m  
Bombala (Therry St) 1885-2008 070005 1.2 km 36.91S 149.24E 705 m  
Bombala AWS 1994-2008 070328 9 km 37.00S 149.23E 761 m 0.8769 0.8412 (Post 2004)

 

Boorowa Approx Distance Lat Long Elevation R2 valuewith 70220
Boorowa PO 1882-2008 070220 0.4 km 34.44S 148.72E 488 m  
Murringo 1968-2008 073109 16 km 34.43S 148.54E 530 m 0.8675

 

Braidwood Approx Distance Lat Long Elevation R2 valuewith 69010
Braidwood (Wallace St) 1887-2008 069010 0.2 km 34.45S 149.8E 643 m  
Braidwood Racecourse 1985-2008 069132 3.2 km 35.43S 149.78E 665 m 0.9297

 

Bungendore Approx Distance Lat Long Elevation R2 valuewith 70035
Bungendore (Gidleigh) 1886-2008 070035 7 km 35.31S 149.47E 725 m  
Bungendore PO 1890-2008 070011   35.25S 149.44E 698 m 0.9077

 

Cabramurra Approx Distance Lat Long Elevation R2 valuewith 72091
Cabramurra 1955-1999 072091 12.5 km 35.94S 148.38E 1475 m  
Cabramurra AWS 1996-2008 072161 12.9 km 35.94S 148.38E 1482 m 0.5133
Tooma 1997-2008 070028 35.9 km 35.9S 148.18S 585 m 0.6836

 

Cooma Approx Distance Lat Long Elevation R2 valuewith 70054
Cooma (Kiaora) 1904-2008 070054 6.2 km 36.2S 149.06E 870 m  
Cooma Visitors C 1973-2008 070278 0.4 km 36.23S 149.12E 778 m 0.9257
Cooma(Lambie St) 1858-1982 070023 0.5 km 36.23S 149.12E 812 m 0.899

 

Cootamundra Approx Distance Lat Long Elevation R2 valuewith 73022
Landgrove 1891-2008 073022 11.9 km 34.65S 148.16E 460 m  
Cootamundra PO 1889-1996 073009 1.1 km 34.64S 148.02E 318 m 0.8918
Cootamundra A/P 1995-2008 073142 2.3 km 34.63S 148.04E 335 m 0.8824 0.8884 (post 2004)

 

Crookwell Approx Distance Lat Long Elevation R2 valuewith 70025
Crookwell PO 1883-2008 070025 0.3 km 34.46S 149.47E 887 m  
Crookwell(HolbrowSt) 1997-2008 070225 1 km 34.46S 149.46E 895 m 0.9127 0.9611 (Post 2004)
Gundowringa 1945-2008 070069 13 km 34.54S 149.57E 838 m 0.82040.8572 (Post 2004)

 

Eden Approx Distance Lat Long Elevation R2 valuewith 69015
Eden Caravan Park 1870-2008 069015 1.6 km 37.06S 149.91E 9 m  
Pambula 1909-2008 069024 16 km 36.93S 149.87E 10 m 0.8596 0.9459 (post 2004)
Candelo PO 1887-2008 069013 38 km 36.77S 149.7E 109 m 0.7157
Wyndham PO 1890-2008 069066 27 km 36.93S 149.65E 300 m 0.7289

 

Goulburn Approx Distance Lat Long Elevation R2 valuewith 70055
Kippilaw 1886-2008 070055 12.3 km 34.75S 149.6E 647 m  
Springfield 1930-2008 070077 17.8 km 34.9S 149.67E 665 m 0.8162 0.8803 (post 2004)
Hillwood 1960-2008 070147 21 km 34.56S 149.74E 740 m 0.80010.7802 (post 2004)
Pomery 1901-2008 070071 23 km 34.65S 149.5E 685 m 0.8009 0.8662 (post 2004)

 

Gundagai Approx Distance Lat Long Elevation R2 valuewith 72154
Mt Horeb (Marathon) 1926-2008 072154 17 km 35.22S 148.03E 285 m  
Gundagai 1892-1971 073015   35.07S 148.10E 216 m 0.887

 

Harden Approx Distance Lat Long Elevation R2 valuewith 73029
Murrumburrah Old PO 1884-2008 073029 2 km 34.55S 148.35E 370 m  
Harden 1892-2008073016   34.56S 148.37E 430 m 0.9353
Murringo 1968-2008 073109 21 km 36.77S 149.7E 109 m 0.7997

 

Moruya Approx Distance Lat Long Elevation
Moruya Heads 069018 1875-2008 7 km 35.91S 150.15E 17 m

 

Narooma Approx Distance Lat Long Elevation R2 valuewith 69036
Bodalla PO 1876-2008 069036   36.09S 150.5E 42 m  
Narooma 1910-2008 069022 14.6 km 36.21S 150.14S 25 m 0.8179 0.8789 (post 2004)
Moruya Heads 1876-2008 069018 21 km 35.91S 150.15E 109 m 0.8784

Queanbeyan Approx Distance Lat Long Elevation
Queanbeyan B C 1871-2008 070072 0.6 km 35.36S 149.23E 580 m

 

Taralga Approx Distance Lat Long Elevation
Taralga PO 070080 1882-2008 0.2 km 34.4S 149.82E 845 m

 

Tumbarumba Approx Distance Lat Long Elevation
Tumbarumba P.O 072043 1882-2008 1.4 km 35.78S 148.01E 645 m

 

Tumut Approx Distance Lat Long Elevation R2 valuewith 72044
Tumut (Wattle Cres) 1886-2008 072044   35.32S 148.23E 300 m  
Blowering Dam 1955-2008 072056 10 km 35.39S 148.26 308 m 0.9058 0.8507 (post 2004)

 

Yass Approx Distance Lat Long Elevation R2 valuewith 70091
Yass (Linton Hostel) 1898-2008 070091 1.2 km 34.83S 148.91 520 m  
Yass 1877-1913 070108 2.1 km 34.85S 148.9E na 0.9811
Derringullen 1898-2006 070028 11 km 34.74S 148.89S 595 m 0.887

 

Young Approx Distance Lat Long Elevation R2 valuewith 73041
Wombat 1888-2008 073041 15 km 34.41S 148.18E 503 m  
Young Airport AWS1994-2008 073138 9 km 34.25S 148.25E 380 m 0.8677 0.906 (post 2004)

 

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