
Fig. 1.
A – Localisation of the study area on the DEM background: 1 – Kolonia Celejów catchment, 2 – macroregions border, 3 – mesoregions border, 4 – the Vistula channel, 5 – stream channel; B – Relief and hydrological conditions of the studied catchment in Kolonia Celejów (Hillshade Relief Model – DEM: https://mapy.geoportal.gov.pl): 1 – catchment border, 2 – rainfall station, 3 – hydrological station, 4 – spring, 5 – periodical stream, 6 – seeps and exudates, 7 – pond.

Fig. 2.
Measurement of snowmelt flow at the hydrometric cross-section closing the gully catchment (photo by J. Rodzik).

Fig. 3.
Distribution of annual sums of precipitation and annual volumes of water runoff from the gully catchment for the years 2003–2022; precipitation classifcation according to Kaczorowska (1962): Vd – extremely dry year, D – dry year, N – average, W – wet, Vw – extremely wet and blue dotted line means the average precipitation for total period.

Fig. 4.
Distribution of half-year precipitation and water runoff from studied gully catchment in Kolonia Celejów in 2003–2022; c-p – cold half-year, w-p – warm half-year.

Fig. 5.
Monthly precipitation total sum and runoff between 2003 and 2022 in the studied gully catchment.
Table 1.
Hydrological results of mostly effective rainfalls in the Kolonia Celejów in 2003-2022.
| Date of rainfall | Coefficient | Remarks | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Rainfall sum [mm] | Max rain intensity [mm·min.−1] | Rain efficiency3 | Max discharge [dm·s−1] | Total surface runoff [m3] | Runoff surface index [mm] | Runoff coefficient [%] | Max spec. runoff [dm3·s−1·km−2] | ||
| 4.V.2005 | 64.5 | 0.6 | 38.7 | 167.8 | 1620.0 | 1.3 | 2.0 | 135.5 | downpour |
| 31.VII.2005 | 34.3 | 2.4 | 82.3 | 283.6 | 932.7 | 0.8 | 2.2 | 228.7 | downpour |
| 4.VIII.2005 | 17.8 | 0.9 | 16.0 | 59.1 | 181.2 | 0.1 | 0.8 | 47.7 | downpour |
| 18.VIII.2006 | 14.9 | 2.9 | 43.2 | 57.0 | 205.3 | 0.2 | 1.1 | 41.2 | downpour |
| 20.VIII.2006 | 28.0 | 2.4 | 67.2 | 193.4 | 766.7 | 0.6 | 2.2 | 156.0 | downpour |
| 10.06.2009 | 24.3 | 1.1 | 26.7 | 146.1 | 433.5 | 0.3 | 1.4 | 117.8 | downpour, damp ground, |
| 23.VIII.2009 | 33.9 | 0.5 | 17.0 | 65.1 | 500.9 | 0.4 | 1.2 | 52.5 | continuous rain, dry ground |
| 14.VI.2010 | 30.1 | 1.5 | 45.2 | 273.0 | 704.6 | 0.6 | 1.9 | 220.2 | continuous rain, damp ground |
| 18.VII.2010 | 38.4 | 1.9 | 73.0 | 473.6 | 1784.0 | 1.4 | 3.7 | 381.9 | downpour, dry ground, |
| 6.VIII.2010 | 24.7 | 1.4 | 34.6 | 273.0 | 624.9 | 0.5 | 2.0 | 220.2 | continuous rain, damp ground |
| 31.VIII–2.IX.2010 | 100.2 | 0.6 | 60.1 | 81.3 | 7084.6 | 5.7 | 5.7 | 65.6 | continuous rain, damp ground |
| 6.VII.2011 | 24.3 | 0.8 | 19.4 | 300.0 | 2253.6 | 1.8 | 7.5 | 241.9 | continuous rain, damp ground |
| 18.VII.2011 | 18.2 | 1.4 | 25.5 | 163.8 | 665.6 | 0.5 | 2.9 | 132.1 | continuous rain, damp ground |
| 20.VII.2011 | 27.2 | 1.5 | 40.8 | 372.7 | 2198.4 | 1.8 | 6.5 | 300.6 | continuous rain, damp ground |
| 1.VII.2012 | 20.8 | 1.3 | 27.0 | 273.0 | 624.9 | 0.5 | 2.4 | 220.2 | continuous rain, dry ground, |
| 4.VII.2012 | 25.2 | 1.9 | 47.9 | 423.7 | 922.6 | 0.7 | 3.0 | 341.7 | continuous rain, damp ground |
| 11.VI.2013 | 38.4 | 1.4 | 53.8 | 714.8 | 5253.8 | 4.2 | 11.0 | 576.5 | continuous rain, damp ground |
| 23.VI.2013 | 19.0 | 1.6 | 30.4 | 863.2 | 5641.1 | 4.5 | 23.9 | 696.1 | downpur, damp ground |
| 27.04.2014 | 14.5 | 1.5 | 21.8 | 84.3 | 4286.5 | 3.5 | 23.8 | 68.0 | continuous rain, wet ground |
| 15–16.05.14 | 29.3 | 0.3 | 8.8 | 201.1 | 9931.3 | 8.0 | 27.3 | 162.2 | continuous rain, damp ground |
| 16–18.05.14 | 36.6 | 0.5 | 18.3 | 247.5 | 10508.2 | 8.5 | 23.2 | 199.6 | continuous rain, wet ground |
| 29.05.2014 | 11.7 | 0.4 | 4.7 | 62.3 | 2028.1 | 1.6 | 14.0 | 50.2 | continuous rain, dump ground |
| 7.08.2014 | 18.31 | 4.82 | 88.3 | 108.9 | 909.5 | 0.7 | 4.0 | 87.8 | continuous rain, dump ground |
| 26–27.05.2015 | 34.1 | 0.4 | 13.6 | 38.7 | 1416.1 | 1.1 | 3.3 | 31.2 | continuous rain, wet ground |
| 27.07.2016 | 11.9 | 1.3 | 15.5 | 171.0 | 730.2 | 0.6 | 4.9 | 137.9 | downpur, dry ground |
| 29.07.2016 | 31.4 | 1.6 | 50.2 | 232.9 | 1574.9 | 1.3 | 4.0 | 187.8 | downpur, wet ground |
| 31.07.2016 | 7.8 | 0.8 | 6.2 | 338.9 | 1098.1 | 0.9 | 11.4 | 273.3 | downpur, wet ground |
| 9–11.08.2016 | 46.7 | 1.3 | 60.7 | 828.1 | 10320.3 | 8.3 | 17.8 | 667.8 | continuous rain, dry ground |
| 19–20.07.2017 | 64.7 | 1.6 | 103.5 | 665.5 | 6540.0 | 5.3 | 8.2 | 536.7 | continuous rain, dry ground |
| 20.07.20l7 | 18.6 | 1.4 | 26.0 | 752.1 | 2370.0 | 1.9 | 10.3 | 606.5 | downpur, wet ground |
| 19–20.08.2017 | 34.8 | 0.7 | 24.4 | 37.9 | 605.3 | 0.5 | 1.4 | 30.6 | downpur, damp ground |
| 29.10.2017 | 24.3 | 0.8 | 19.4 | 81.1 | 1272.8 | 1.0 | 4.2 | 65.4 | continuous rain, damp ground |
| 16.07.2018 | 29.5 | 0.9 | 26.6 | 110.4 | 1213.8 | 1.0 | 3.3 | 89.0 | continuous rain, damp ground |
| 19.07.2018 | 30.8 | 1.9 | 58.5 | 358.7 | 2360.5 | 1.9 | 6.2 | 289.3 | downpur, damp ground |
| 27.05.2019 | 14.4 | 1.6 | 23.0 | 112.7 | 857.8 | 0.7 | 4.8 | 90.9 | continuous rain, damp ground |
| 29.06.2020 | 12.8 | 0.6 | 7.7 | 132.1 | 711.0 | 0.6 | 4.5 | 106.5 | downpur, wet ground |
| 26–27.09.2020 | 49.0 | 0.3 | 14.7 | 14.1 | 831.1 | 0.7 | 1.4 | 11.4 | continuous rain, damp ground |
| 13.10.2020 | 18.7 | 0.3 | 5.6 | 30.4 | 907.1 | 0.7 | 3.9 | 24.5 | continuous rain, wet ground |
| 29.07.2021 | 15.1 | 0.8 | 12.1 | 209.8 | 2518.7 | 2.0 | 13.5 | 169.2 | downpur, damp ground |
| 23–24.08.2021 | 84.31 | 0.8 | 67.4 | 95.5 | 7348.7 | 5.9 | 7.0 | 77.0 | continuous rain, damp ground |
| 11.09.2022 | 16.9 | 0.1 | 1.7 | 27.6 | 1913.8 | 1.5 | 9.1 | 22.3 | continuous rain, wet ground |
Table 2.
Monthly sums of total surface runoff (m3) in the Kolonia Celejów catchment in 2003–2022.
| Year | XI | XII | I | II | III | IV | V | VI | VII | VIII | IX | X | Cool halfyear | Warm halfyear | Annual runoff | Runoff days | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| all | > 40 m3 | ||||||||||||||||
| 2003 | 954 | 370 | 9537 | 637 | 22422 | 1040 | 700 | 653 | 564 | 307 | 293 | 455 | 34960 | 2972 | 37932 | – | – |
| 2004 | 257 | 430 | 194 | 1343 | 1030 | 830 | 926 | 689 | 722 | 107 | 45 | 51 | 4084 | 2540 | 6624 | – | – |
| 2005 | 64 | 14 | 5 | 0 | 7246 | 7 | 1705 | 38 | 774 | 450 | 3 | 0 | 7336 | 2970 | 10306 | – | – |
| 2006 | 0 | 0 | 0 | 0 | 16320 | 347 | 35 | 10 | 1 | 1230 | 0 | 0 | 16667 | 1276 | 17943 | – | – |
| 2007 | 0 | 0 | 0 | 191 | 56 | 0 | 17 | 74 | 1 | 8 | 1097 | 0 | 246 | 1197 | 1443 | 23 | 4 |
| 2008 | 0 | 0 | 5 | 0 | 0 | 0 | 38 | 0 | 0 | 0 | 0 | 0 | 5 | 38 | 43 | 5 | 0 |
| 2009 | 0 | 0 | 0 | 0 | 95 | 0 | 34 | 1742 | 693 | 655 | 86 | 1025 | 95 | 4236 | 4330 | 74 | 22 |
| 2010 | 540 | 234 | 0 | 39 | 2228 | 400 | 666 | 1390 | 2697 | 3180 | 6500 | 942 | 3442 | 15374 | 18816 | 303 | 83 |
| 2011 | 739 | 615 | 2418 | 1425 | 2326 | 805 | 1616 | 943 | 11798 | 1516 | 510 | 1064 | 8328 | 17446 | 25774 | 356 | 130 |
| 2012 | 1286 | 1602 | 2104 | 3585 | 4417 | 566 | 519 | 1040 | 4049 | 827 | 20 | 1236 | 13561 | 7691 | 21252 | 204 | 118 |
| 2013 | 1030 | 628 | 1987 | 3479 | 3572 | 5794 | 3554 | 16455 | 3649 | 84 | 0 | 0 | 16490 | 23742 | 40232 | 278 | 166 |
| 2014 | 0 | 0 | 1122 | 342 | 285 | 5457 | 28216 | 3659 | 1696 | 4106 | 1248 | 2345 | 7205 | 41270 | 48475 | 300 | 100 |
| 2015 | 541 | 2112 | 6820 | 1426 | 2947 | 2306 | 5088 | 6244 | 5048 | 1985 | 1332 | 1304 | 16152 | 21001 | 37152 | 358 | 208 |
| 2016 | 1546 | 1379 | 7954 | 3546 | 2550 | 857 | 677 | 114 | 9350 | 19612 | 0 | 0 | 17832 | 29753 | 47585 | 272 | 127 |
| 2017 | 1380 | 5291 | 4983 | 17055 | 2408 | 2640 | 1531 | 58 | 16448 | 933 | 7237 | 15859 | 33756 | 42066 | 75822 | 280 | 217 |
| 2018 | 3994 | 3750 | 3985 | 5132 | 11589 | 3041 | 1943 | 231 | 4717 | 44 | 215 | 225 | 31492 | 7375 | 38866 | 267 | 205 |
| 2019 | 94 | 2638 | 4099 | 4238 | 4063 | 1946 | 3091 | 534 | 19 | 91 | 108 | 83 | 17078 | 3926 | 21004 | 222 | 150 |
| 2020 | 458 | 0 | 179 | 2265 | 1974 | 0 | 936 | 2417 | 354 | 507 | 1742 | 5781 | 4876 | 11736 | 16612 | 206 | 116 |
| 2021 | 2205 | 394 | 0 | 4514 | 2980 | 4118 | 1128 | 899 | 4306 | 10215 | 3135 | 1059 | 14210 | 20741 | 34951 | 246 | 174 |
| 2022 | 729 | 58 | 2322 | 5647 | 2155 | 10496 | 2169 | 27 | 304 | 0 | 2255 | 550 | 21406 | 5305 | 26711 | 237 | 139 |
| 2003–2022 | 791 | 976 | 2386 | 2743 | 4533 | 2032 | 2729 | 1861 | 3360 | 2293 | 1291 | 1599 | 13461 | 13133 | 26594 | 227* | 122* |

Fig. 6.
Monthly water runoff sums distribution from the loess gully catchment Kolonia Celejów in the 20-year period 2003–2022.
Table 3.
Annual outflow rates from the gully catchment
| Year | Precipitation total sum | Runoff | Runoff surface index | Runoff coefficient |
|---|---|---|---|---|
| [mm] | [m3] | [mm] | [%] | |
| 2003 | 426 | 37932 | 30.6 | 7.2 |
| 2004 | 555 | 6624 | 5.3 | 1.0 |
| 2005 | 554 | 10306 | 8.3 | 1.5 |
| 2006 | 580 | 17943 | 14.5 | 2.5 |
| 2007 | 563 | 1443 | 1.2 | 0.2 |
| 2008 | 593 | 43 | 0.0 | 0.0 |
| 2009 | 591 | 4330 | 3.5 | 0.6 |
| 2010 | 650 | 18816 | 15.2 | 2.3 |
| 2011 | 635 | 25774 | 20.8 | 3.3 |
| 2012 | 555 | 21252 | 17.1 | 3.1 |
| 2013 | 559 | 40232 | 32.4 | 5.8 |
| 2014 | 611 | 48475 | 39.1 | 6.4 |
| 2015 | 552 | 37152 | 30.0 | 5.4 |
| 2016 | 635 | 47585 | 38.4 | 6.0 |
| 2017 | 711 | 75822 | 61.1 | 8.6 |
| 2018 | 541 | 38866 | 31.3 | 5.8 |
| 2019 | 441 | 21004 | 16.9 | 3.8 |
| 2020 | 728 | 16612 | 13.4 | 1.8 |
| 2021 | 608 | 34951 | 28.2 | 4.6 |
| 2022 | 342 | 26711 | 21.5 | 6.3 |
| 2003–2022 | 572 | 26594 | 21.4 | 3.7 |

Fig. 7.
Average monthly precipitation total sums and runoff in the gully catchment: A – nival period 2003–2006, B – steady period 2007–2009, C – pluvial period 2010–2018, D – variable period 2019–2022.
Table 4.
Periodicity of water runoff from the Kolonia Celejów gully for the years 2003–2022
| Type of period | Unit | Nival | Steady | Pluvial | Variable | Total series | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Years (XI–X) | 2003-2006 | 2007-2009 | 2010-2018 | 2019-2022 | 2003–2022 | |||||||||
| Data type | Min | Max | Mean | Min | Max | Mean | Min | Max | Mean | Min | Max | Mean | Mean | |
| Precipitation sum year | [mm] | 426 | 584 | 536 | 563 | 593 | 582 | 541 | 711 | 605 | 342 | 728 | 504 | 572 |
| Days >10 mm | [–] | 10 | 20 | 14 | 13 | 15 | 14 | 11 | 21 | 14 | 6 | 25 | 14 | 15 |
| Precipitation max daily | [mm] | 19.0 | 64.5 | 35.6 | 25.4 | 32.5 | 28.9 | 23.6 | 61.0 | 37.3 | 17.5 | 40.8 | 26.5 | 33.5 |
| Snow max thickness* | [mm] | 320 | 440 | 355 | 140 | 260 | 210 | 110 | 460 | 228 | 30 | 260 | 178 | 241 |
| Days with snow cover* | [–] | 84 | 159 | 113 | 34 | 80 | 58 | 27 | 118 | 64 | 5 | 59 | 39 | 68 |
| Outflow total | [x103 m3] | 6.6 | 37.9 | 18.2 | 0.04 | 4.2 | 1.9 | 18.8 | 75.8 | 39.3 | 16.6 | 35.0 | 24.8 | 26.6 |
| a) cold half-year (XI–IV) | 4.1 | 35.0 | 15.8 | 0.01 | 1.0 | 0.4 | 3.4 | 33.8 | 16.5 | 4.9 | 21.4 | 14.4 | 13.5 | |
| b) warm half-year (V–X) | 1.24 | 3.0 | 2.4 | 0.03 | 3.2 | 1.5 | 7.4 | 42.0 | 22.9 | 3.9 | 20.8 | 10.4 | 13.1 | |

Fig. 8.
Multi-year distribution of the precipitation total sums and annual runoff between 2003 and 2022 from the gully catchment. Position of X axis determines the average annual water runoff from the catchment.
Table 5.
Segmental regression models of the rainfall/gully water runoff relationship.
| Data | Equation | Determination coefficient (R2) | Break point (b) |
|---|---|---|---|
| Monthly | y = 68x + 487 and y = 18.4x + 5235 | 0.62 | 2216.0 |
| Half year: XI–IV | y = 26.3x - 1377 and y = –47.8x + 29783 | 0.63 | 13461.0 |
| Half year: V–X | y = 11.5x – 853 and y = –6.9x + 29353 | 0.73 | 196.8 |
| Hydrological year | y = 9.4x + 7610 and y = 96.6x – 10434 | 0.79 | 26593.0 |
| Average monthly: 2003–2022 | y = 16x + 747 and y = –8.6x + 3464 | 0.64 | 2216.0 |
| 2003–2006 | y = 6 x + 98.6 and y = 2782x – 80825 | 0.99 | 1517.0 |
| 2007–2009 | y = 0.5 x + 3.4 and y = –12 x + 1153 | 0.90 | 161.6 |
| 2010–2018 | y = 18.3 x + 1193 and y = 29.7x + 2534 | 0.82 | 3277.6 |
| 2019–2022 | y = 2.8 x + 1216 and y = –24.3x + 4372 | 0.80 | 2068.4 |

Fig. 9.
Response of a loess gully catchment water runoff to a downpours series depending on the preceding conditions: A – during the dry period, B – during the wet period.