Probable Rainfall in Gdańsk in View of Climate Change

Abstract

One of the manifestations of climate changes is the occurrence of a greater number of precipitation events, characterized by greater rain intensity that affects the economic stability of cities. Gdańsk is an example of a city in which such events have occurred since the beginning of the twenty-first century. Due to the altitude differences in the area of Gdańsk city (between -2 m and 180 m a.s.l.), the occurrence of extreme atmospheric precipitation almost immediately causes hydrological effects in the water network consisting of several streams of montane character, which flow eastwards from the plateau of the Kashubian Lakeland. Meteorological stations of the National Meteorological Service (IMGW-PIB) are located in the coastal zone (Port Północny/Northern Port, Świbno) and in the highest part of the city (the Rębiechowo airport). Because this is insufficient, the city of Gdańsk has been expanding the local rain monitoring network since 2001, currently having reliable 10-year observation data sequences. The said network is operated by the Gdańsk Water municipal company.Climate changes resulting in different characteristics of rainfall episodes in Gdańsk naturally influence the determination of the probability of their occurrence. According to the rainfall model developed by Bogdanowicz and Stachy at the turn of the 20th and 21st centuries, at least 4 rainfall events lasting for over 8 hours in the last 17 years should be classified as a 100-year rain event. One of these extended the parameters of a 300-year rain event; whereas we asses the rain in the year 2016, when even 170 mm of rainfall was recorded on July 14, as at least a 500-year rain event. During this period, several-minute events were also recorded, which also exceeded the parameters of a 100-year rain event.The paper presents precipitation models for the region of Gdańsk. Based on the maximum annual daily rainfall from Rębiechowo meteorological station from the years 1974-2017, an analysis of changes in precipitation values corresponding to certain probabilities of occurrence was conducted. An assessment was also made of the projected decrease in the value of precipitation in relation to hydro-technical constructions, road-engineering structures, and rainwater drainage systems in view of changing legal regulations, as well as the latest trends related to the management of rainwater.

Hydraulic Analysis of Causes of Washout of Gdynia-Orłowo Sea-Shore During the Flood in the Kacza River Estuary

“…It is impossible to determine precisely how the rainfall was distributed over Gdynia area and how big values of water flow rate in the river were as there is no control over the Kacza river catchment basin. However, it is probable that summary rainfall height could be similar to that measured in the same time at the station Gdańsk Oliwa (170,2 mm) and Gdańsk Osowa (161,9 mm) [5]. The so high daily rainfall amount was a direct cause that the Kacza river overflowed its banks in many sections of its full length.…”

“…In the affluent crosssection (Szyprów street) there was assumed a water flow rate in the form of a hypothetical hydrograph of 20 m 3 /s culmination corresponding to the flood situation in the estuary section of the river. For simulation of the flood the following temporal variability of flow rate was assumed : (T [h],Q [m 3 /s]): (0,0), (3,5), (6,20), (9,20), (12,5). At the confluent cross-section( Gdansk Bay) free -water outflow into the sea was assumed.…”

“…In this century we have had to do with urban area flooding both in Gdańsk in 2001, 2010 and 2016 [2] as well as in Sopot and Gdynia in 2016 [9]. Additionally, a tendency to occurrence of heavy rainfalls of summary heights exceeding 100 mm [5] is a cause of elevated risk to urban area flooding in Three-city. This paper presents a hydraulic analysis of causes of a seashore washout at the Kacza river estuary in Gdynia-Orłowo during the flood of 2016.…”

The Impact of Spatiotemporal Changes in Land Development (1984–2019) on the Increase in the Runoff Coefficient in Erbil, Kurdistan Region of Iraq

“…The composite CN for each sub-basin was derived and used as the input for the SCS-CN modeling in HEC-HMS (Table 5). The hydrological modeling reveals that flash flooding caused by more frequent rainfall events (with a smaller probability distribution [47,63]) is increased more by urban growth than by large storm events. Erbil is undergoing an observable horizontal expansion.…”

Impact of the Artificial Strait in the Vistula Spit on the Hydrodynamics of the Vistula Lagoon (Baltic Sea)

“…Some lagoons have been extensively converted for brackish-water fish ponds (e.g., the lagoons south of Madras), shellfish aquaculture (i.e., lakes on Hokkaido Island [3]), or cage culture, which is widespread around the world [4]. Changing climatic conditions [5,6] over the next century are likely to increase marine influences in lagoons, by the action of wind and storm surges. The paper presents some possibility of flood relief by the example of the proposed cut channel on the Vistula Lagoon transboundary water body.…”