Appendix B: - Data Analysis
B.1 Data Analysis
B.1.1 Flow Analysis
Table B-1: Indicative Design Peak Flows
Return period | River Don | River Tweed |
|---|
Bridge of Alford Peak Flow m3/s | Parkhill Peak Flow m3/s | Lyne Station Peak Flow m3/s | Norham Peak Flow m3/s |
|---|
Single | Pooled | Single | Pooled | Single | Pooled | Single | Pooled |
|---|
2 | 99 | 100 | 136 | 144 | 33 | 35 | 667 | 648 |
5 | 137 | 133 | 178 | 216 | 46 | 50 | 886 | 883 |
10 | 161 | 157 | 206 | 275 | 57 | 62 | 1036 | 1033 |
25 | 189 | 189 | 244 | 369 | 72 | 83 | 1243 | 1229 |
50 | 210 | 217 | 275 | 458 | 86 | 102 | 1412 | 1383 |
75 | 221 | 235 | 294 | 518 | 95 | 116 | 1518 | 1476 |
100 | 229 | 248 | 308 | 566 | 102 | 127 | 1597 | 1544 |
150 | 239 | 268 | 329 | 641 | 112 | 145 | 1714 | 1641 |
200 | 247 | 283 | 345 | 700 | 121 | 158 | 1800 | 1712 |
Table Notes:
1. Single Site Flood Frequency Analysis carried out using data from target site, using Generalised Logistic ( GL) distribution fitted using the method of L-Moments. Does not always provide robust estimates as only reliable up to return periods matching the length of record of the target site (shown in red text above).
2. Pooled distribution is derived by pooling data from the target site along with data from other similar sites.
B.1.2 Rainfall Analysis
Table B-2: Don Catchment Daily Rainfall Totals and Indicative Return Periods August 2004
Duration (days) | Cushnie ( OSNGR 352800 807200) | Insch ( OSNGR 363000 828200) | Tullinessle ( OSNGR 356100 818400) |
|---|
Total rainfall Depth (mm) | Return Period (Years) | Total rainfall Depth (mm) | Return Period (Years) | Total rainfall Depth (mm) | Return Period (Years) |
|---|
0.252 | 66.0 | 590 | 47.7 | 140 | 39.9 | 60 |
0.52 | 66.0 | 163 | 47.7 | 37 | 39.9 | 14.1 |
1 | 66.0 | 38 | 47.7 | 8.3 | 39.9 | 3.4 |
2 | 68.2 | 8.5 | 57.6 | 4.1 | 50.3 | 2.14 |
3 | 74.2 | 5.6 | 61.8 | 2.8 | 54.6 | 1.59 |
4 | 76.4 | 3.6 | 78.9 | 5.5 | 80.1 | 5.1 |
5 | 76.8 | 2.37 | 83.1 | 4.7 | 84.4 | 4.4 |
6 | 82.3 | 2.32 | 85.2 | 3.9 | 86.1 | 3.4 |
7 | 93.2 | 3.1 | 85.2 | 3 | 86.4 | 2.7 |
14 | 121.3 | 3.3 | 112.0 | 3.9 | 117.7 | 3.9 |
15 | 124.4 | 3.3 | 118.7 | 4.8 | 123.0 | 4.4 |
Notes:
1. N Day Rainfall Totals calculated from Daily rainfall data on a fixed duration. Return periods calculated using 1km point FEHDDF model.
2. Return periods calculated hypothetically for 0.5 and 0.25 day as exact duration of rainfall over the 24 hours between readings is unknown.
Table B-3: Tweed Catchment Daily Rainfall Totals and Indicative Return Periods August 2004
Duration (days) | Hallmanor ( OSNGR 321000 635100) | Hawick ( OSNGR 351200 615600) | Cappercleuch ( OSNGR 323900 623200) |
|---|
Total rainfall Depth (mm) | Return Period (Years) | Total rainfall Depth (mm) | Return Period (Years) | Total rainfall Depth (mm) | Return Period (Years) |
|---|
0.252 | 37.6 | 34 | 40.7 | 51 | 48.9 | 57 |
0.52 | 37.6 | 10.8 | 40.7 | 18.9 | 48.9 | 16.4 |
1 | 37.6 | 2.7 | 40.7 | 4.6 | 48.9 | 3.4 |
2 | 61.7 | 4.8 | 57.4 | 4.3 | 72.3 | 3.3 |
3 | 78.1 | 7 | 72.5 | 6.9 | 97.6 | 6.3 |
4 | 115.5 | 32 | 102.9 | 28 | 135.1 | 20.2 |
5 | 125.9 | 34 | 107.9 | 25 | 144.1 | 18.9 |
6 | 126.0 | 24.3 | 107.9 | 18.7 | 144.1 | 13.4 |
7 | 126.2 | 18.5 | 107.9 | 14.5 | 144.3 | 10.1 |
14 | 181.8 | 50 | 153.8 | 48 | 211.8 | 29 |
15 | 182.5 | 45 | 159.9 | 57 | 215.8 | 29 |
Notes:
1. N Day Rainfall Totals calculated from Daily rainfall data on a fixed duration. Return periods calculated using 1km point FEHDDF model.
2. Return periods calculated hypothetically for 0.5 and 0.25 day as exact duration of rainfall over the 24 hours between readings is unknown.