Spelling suggestions: "subject:"levelrise"" "subject:"sealevels""
171 |
Hurricane Storm Surge Sedimentation on the McFaddin National Wildlife Refuge, Texas: Implications for Coastal Marsh AggradationHodge, Joshua B. 05 1900 (has links)
This study uses the storm surge sediment beds deposited by Hurricanes Audrey (1957), Carla (1961), Rita (2005) and Ike (2008) to investigate spatial and temporal changes in sedimentation rates on the McFaddin National Wildlife Refuge in Southeast Texas. Fourteen sediment cores were collected along a transect extending from 90 to 1230 meters inland from the Gulf Coast. Storm-surge-deposited sediment beds were identified by texture, organic content, carbonate content, the presence of marine microfossils, and Cesium-137 dating. The hurricane-derived sediment beds are marker horizons that facilitate assessment of marsh sedimentation rates from nearshore to inland locations as well as over decadal to annual timescales. Near the shore, on a Hurricane Ike washover fan, where hurricane-derived sedimentation has increased elevation by up to 0.68 m since 2005, there was no measurable marsh sedimentation in the period 2008-2014. Farther inland, at lower elevations, sedimentation for the period 2008-2014 averaged 0.36 cm per year. The reduction in sedimentation in the period 2008-2014 on the nearshore part of the marsh is likely due to reduced flooding in response to increased elevation from hurricane storm surge sediment deposition. These results provide valuable knowledge about the sedimentary response of coastal marshes subject to storm surge deposition and useful guidance to public policy aimed at combating the effects of sea level rise on coastal marshes along the Gulf of Mexico.
|
172 |
Mapping Landcover/Landuse and Coastline Change in the Eastern Mekong Delta (Viet Nam) from 1989 to 2002 using Remote SensingSOHAIL, ARFAN January 2012 (has links)
There has been rapid change in the landcover/landuse in the Mekong delta, Viet Nam. The landcover/landuse has changed very fast due to intense population pressure, agriculture/aquaculture farming and timber collection in the coastal areas of the delta. The changing landuse pattern in the coastal areas of the delta is threatened to be flooded by sea level rise; sea level is expected to rise 33 cm until 2050; 45 cm until 2070 and 1 m until 2100. The coastline along the eastern Mekong delta has never been static, but the loss of mangrove forests along the coast has intensified coastline change. The objective of the present study is to map the changes in landcover/landuse along the eastern coast of the Mekong delta; and to detect the changes in position of the eastern coastline over the time period from 1989 to 2002.To detect changes in landuse, two satellite images of the same season, acquired by the TM sensor of Landsat 5 and the ETM+ sensor of Landsat 7 were used. The TM image was acquired on January 16, 1989 and ETM+ image was acquired on February 13, 2002. The landcover/landuse classes selected for the study are water, forest, open vegetation, soil and shrimp farms. Image differencing and post classification comparison are used to detect the changes between two time periods. Image to image correction technique is used to align satellite images. Maximum likelihood supervised classification technique is used to classify images. The result of the classification consists of five classes for 1989 and 2002, respectively. Overall accuracies of 87.5% and 86.8%, with kappa values of 0.85 and 0.84 are obtained for landuse 1989 and landuse 2002, respectively. The overall accuracy for the change map is 82% with kappa value 0.80. Post classification comparison is carried out in this study based on the supervised classification results. According to the results obtained from the post classification comparison, a significant decrease of 48% in forest and a significant increase of 74% in open vegetation and 21% in shrimp farms area observed over the entire study area. The coastline obtained by the combination of histogram thresholding and band ratio showed an overall advancement towards the South China Sea. The results showed that new land patches emerged along the eastern coast. The amount of new land patches appeared along the coast of the Mekong delta is approximately 2% of the entire study area.
|
173 |
Naturbaserade lösningar som det nya normala? : Fyra skånska kustkommuners perspektiv på naturbaserade lösningar inom klimatanpassningsarbetet / Nature-based solutions like the new normal? : Four southern Swedish coastal municipalities' perspectives on nature-based solutions in climate adaptation workMartis, Jennie January 2022 (has links)
Behovet av klimatanpassning i kustområden är stort, och fortsätter öka världen över. Naturbaserade lösningar (NBS) är flexibla och multifunktionella åtgärder som samverkar med naturliga processer, vilket gör dem anpassningsbara till förändrade förhållanden, till skillnad från hårda kustskydd. Genom denna studies kvalitativa intervjuer med fyra skånska kustkommuner har förutsättningar för NBS att främja klimatanpassning visats vara på god väg. Kustkommunerna ser NBS som ett självklart förstahandsval inom kustskydd. NBS har fått större genomslag i och med ökat samarbete på lokal, regional, nationell och internationell nivå genom nätverk och projekt, vilket har möjliggjort stort utbyte av praktiska lärdomar och kunskap om NBS, naturliga processer och klimatförändringars effekt i kustområden. Samverkan är en viktig del i klimatanpassningsarbetet där samlad expertis bidrar till gemensam förståelse för NBS funktion och mervärden. Idag finns konsensus om ett naturbaserat arbetssätt, där tjänstepersoners och eldsjälars kunskap, intresse och engagemang spelar en avgörande roll för det kommunala arbetet med NBS. Deltagande i NBS-projekt ger mer praktisk erfarenhet och synliggör åtgärdernas positiva effekter, vilket i sin tur kan skapa lokala politiska incitament för att integrera och använda NBS ytterligare i klimatanpassningsarbetet. Dock påträffas flertalet svårigheter, i huvudsak gällande förlegad lagstiftning som inte är kompatibel med NBS flexibilitet, tidskrävande och komplicerade tillståndsprocesser samt frånvaron av uttalat tillvägagångssätt gällande gränsöverskridande åtgärder för hur kommuner, myndigheter samt enskilda fastighetsägare ska samarbeta och dela på ansvaret. För att kunna normalisera och skala upp implementering behöver NBS bli inkluderade som standardalternativ vid beslut om olika kustskyddsåtgärder. Svenska kustkommuner kommer behöva ta ställning och diskutera acceptansen för klimatförändringars olika grad av påverkan i kustområden, där obekväma beslut och övervägandet av andra strategier såsom förändrad markanvändning och planerad reträtt väntas bli mer påträngande. Studiens resultat kan förhoppningsvis uppmuntra naturbaserade insatser inom svenskt klimatanpassningsarbete ytterligare, för att säkerhetsställa levande kustområden där natur och samhällen kan bevaras och klimatsäkras för dagens och framtida klimatförändringar. / The need for climate adaptation in coastal areas is great, and continues to increase worldwide. Nature-based solutions (NBS) are flexible and multifunctional measures that interact with natural processes, which makes them adaptable to changing conditions, as opposed to hard coastal protection. Through this study's qualitative interviews with four southern Swedish coastal municipalities, the conditions for NBS to promote climate adaptation have been shown to be on the right track. The coastal municipalities see NBS as an obvious first choice in coastal protection. NBS have had a greater breakthrough by increased cooperation at local, regional, national and international level through networks and projects, which has enabled a great exchange of practical lessons and knowledge about NBS, natural processes and the effect of climate change in coastal areas. Collaboration is an important part of the climate adaptation work, where collective expertise contributes to a common understanding of NBS' function and co-benefits. Today, there is consensus on a nature-based approach, where the knowledge, interest and commitment of officials and champions play a crucial role in the municipal work with NBS. Participation in NBS projects provides more practical experience and highlights the positive effects of the measures, which in turn can create local political incentives to further integrate and implement NBS in climate adaptation work. However, many difficulties are encountered, mainly regarding outdated legislation that is not compatible with NBS flexibility, time-consuming and complicated permit processes, and the absence of a stated approach regarding cross-border measures for how municipalities, authorities and individual property owners should cooperate and share responsibility. To be able to normalize and scale up implementation, NBS needs to be included as a standard alternative when deciding on various coastal protection measures. Swedish coastal municipalities will need to take a stand and discuss acceptance of climate change's different level of impact in coastal areas, where uncomfortable decisions and the consideration of other strategies such as changed land-use and planned retreat are expected to become more intrusive. The results of the study can hopefully encourage nature-based initiatives in Swedish climate adaptation work further, to ensure living coastal areas where nature and communities can be preserved and climate-secured for current and future climate change.
|
Page generated in 0.0284 seconds