Sandbehov för att motverka stranderosion utmed Skånes sydkust under perioden 2017–2100 / Estimation of required beach nourishment volumes along the south coast of Sweden during 2017–2100
Beach erosion is expected to increase as the sea level rises during the coming decades. A retreating coastline threatens infrastructure, settlements, nature habitats, and at the same time increases the flood risk in low-lying areas. On the Swedish south coast, beach erosion is a problem at present likely to increase due to the sea level rise. For maintaining the beaches and protecting the hinterland, beach nourishment is generally the preferred method. Cost effective and environmental friendly beach nourishment projects are dependent on marine borrow areas for sand. Outside the Swedish south coast there are several identified suitable marine sand extraction sites. Sand is, however, a limited resource and the construction industry in Sweden has begun to show interest in marine sand as material for concrete production. Therefore, the municipalities along the Swedish south coast need to quantify the expected demand for sand in order to maintain their beaches. A methodology was derived in this study to estimate the sand volume needed to maintain a beach based on the historical coastal morphological evolution and the expected increase in erosion due to sea level rise. The methodology has been applied on the Swedish south coast. Sand volume needed to maintain beaches, for a scenario where the mean sea level rises with 1 meter until year 2100 and including the observed long-term morphological evolution due to gradients in the longshore transport, is calculated to be approximately 44 million m3. The required volume corresponds to 6 % of the potential volume for marine sand extraction in the area. To preserve the sandy beaches for future generations, a minimum of 44 million m3 sand should be earmarked for beach nourishment purposes in the marine spatial plans.
High-resolution ensemble flood forecasting: a case study in Höje Å, Sweden / Högupplösta ensembleprognoser för översvämningar: en fallstudie i Höje Å
The number and impacts of pluvial floods are likely to increase with the growth of our cities and as extreme weather is anticipated to intensify with climate change. Improved preparedness is needed which may be attained owing to recent development of high-resolution hydro-meteorological observations and forecasts as well as geographical data. This paper investigates the capacity of the HYPE model for rainfall-runoff modelling and ensemble forecasting at hourly resolution. The analysis includes evaluation and application of several new highresolution data sources: radar-based precipitation (HIPRAD), urban land-use data (EEA Urban Atlas) and high-resolution ensemble forecasts (MEPS). These components are finally integrated in a forecasting prototype for a catchment in southern Sweden. The results showed that HYPE, forced with HIPRAD and with land-use from Urban Atlas, performed well with a long-term Nash-Sutcliffe Efficiency > 0.8 at hourly level. Analysis of selected pluvial-type high-flow events close to an urban area indicated a good representation of fast runoff. The application of MEPS forecasts has been demonstrated for a few single events with promising results. Overall, it is concluded that the 1-hour forecasts provide added value compared with the 1-day time step and that an increased resolution in time and space is important to accurately forecast pluvial-type events.
Historiska stormhändelser som underlag vid riskanalys / Studie av översvämningarna 1872 och 1904 längs Skånes syd- och ostkust
On November 13, 1872 an extreme flood occurred in the coastal areas surrounding the South Baltic Sea. An extreme storm surge in combination with high waves caused the death of about 300 people and more than 15,000 people lost their homes. Along the coast of Scania, southern Sweden, at least 23 people were killed and more than 100 houses were destroyed. Hundreds of fishermen lost their source of income when boats and fishing equipment were damaged by the waves and pulled offshore. During the night before New Years Eve in 1904 the Scania coast was again hit by a severe storm. This storm in 1904 was not as extreme as the storm in 1872. The damage was less extensive but of a different character, because railroads had been built along parts of the coast. This study presents information about the storms in 1872 and 1904 that is analysed with respect to the evolution of risk awareness, vulnerability, and societies resilience over time. After the storms, the coastal communities in Scania recovered quickly through governmental subsidies, voluntary work, and charity. If the 1872 storm would repeat itself today, the damage to buildings and infrastructure would be far worse and in some areas, human lives and health would be at risk. Meanwhile, the coastal communities of today are much richer, home insurances are more common, and fewer people depend on income from fishery. Studies of historical storm events that occurred before the start of systematic wave and water level measurements are important complements to risk analyses based on statistical extreme value models whose reliability is limited by the length of the data series. Increased risk awareness leads in itself to risk mitigation. Through understanding and remembering historical storm events and their consequences, individuals and the society can make informed decisions about the level of risk they are willing to accept to live near the coast.
Genom att under vintern lagra dricksvatten i den sedimentära berggrunden kan kommuner säkra och transportera en hel årsförbrukning av vatten. Metoden som undersöks i Kristianstad kan vara lösningen på Sveriges vattenbrist under sommaren.