Impact of Flash Flood Events on the Coastal Waters Around Madeira Island: The “Land Mass Effect”

The Island Mass Effect has been primarily attributed to nutrient enhancement of waters surrounding oceanic islands due to physical processes, whereas the role of land runoff has seldom been considered. Land runoff can be particularly relevant in mountainous islands, highly susceptible to torrential rainfall that rapidly leads to flash floods. Madeira Island, located in the Northeast Atlantic Ocean, is historically known for its flash flood events, when steep streams transport high volumes of water and terrigenous material downstream. A 22-year analysis of satellite data revealed that a recent catastrophic flash flood (20 February 2010) was responsible for the most significant concentration of non-algal Suspended Particulate Matter (SPM) and Chlorophyll-a at the coast. In this context, our study aims to understand the impact of the February 2010 flash flood events on coastal waters, by assessing the impact of spatial and temporal variability of wind, precipitation, and river discharges. Two specific flash floods events are investigated in detail (2 and 20 February 2010), which coincided with northeasterly and southwesterly winds, respectively. Given the lack of in situ data documenting these events, a coupled air-sea-land numerical framework was used, including hydrological modeling. The dynamics of the modeled river plumes induced by flash floods were strongly influenced by the wind regimes subsequently affecting coastal circulation, which may help to explain the differences between observed SPM and Chlorophyll-a distributions. Model simulations showed that during northeasterly winds, coastal confinement of the buoyant river plume persisted on the island’s north coast, preventing offshore transport of SPM. This mechanism may have contributed to favorable conditions for phytoplankton growth, as captured by satellite-derived Chlorophyll-a in the northeastern coastal waters. On the island’s south coast, strong ocean currents generated in the eastern island flank promoted strong vertical shear, contributing to vertical mixing. During southwesterly winds, coastal confinement of the plume with strong vertical density gradient was observed on the south side. The switch to eastward winds spread the south river plume offshore, forming a filament of high Chlorophyll-a extending 70 km offshore. Our framework demonstrates a novel methodology to investigate ocean productivity around remote islands with sparse or absent field observations.

Description of historical and future projection simulations by the global coupled E3SMv1.0 model as used in CMIP6

This paper documents the experimental setup and general features of the coupled historical and future climate simulations with the first version of the U.S. Department of Energy (DOE) Energy Exascale Earth System Model (E3SMv1.0). The future projected climate characteristics of E3SMv1.0 at the highest emission scenario (SSP5-8.5) designed in the Scenario Model Intercomparison Project (ScenarioMIP) and the SSP5-8.5 greenhouse gas (GHG) only forcing experiment are analyzed with a focus on regional responses of atmosphere, ocean, sea-ice, and land. Due to its high climate sensitivity, E3SMv1.0 is one of the CMIP6 models with the largest surface warming by the end of the 21st century under the high-emission SSP5-8.5 scenario. The global mean precipitation change is highly correlated to the global temperature change, while the spatial pattern of the change in runoff responds to the precipitation changes. The oceanic mixed layer generally shoals throughout the global ocean. The sea ice, especially in the Northern Hemisphere, rapidly decreases with large seasonal variability. The annual mean AMOC is overly weak with a slower change relative to other CMIP6 models. We detect a significant polar amplification in E3SMv1.0 from the atmosphere, ocean, and sea ice. Comparing the SSP5-8.5 all-forcing experiment with the GHG-only experiment, we find that the unmasking of the aerosol effects due to the decline of the aerosol loading in the future projection period causes accelerated warming in SSP5-8.5 all-forcing experiment. While the oceanic climate response is mainly controlled by the GHG forcing, the land runoff response is impacted primarily by forcings other than GHG over certain regions. However, the importance of the GHG forcing on the land runoff changes grows in the future climate projection period compared to the historical period.

Efficiency of underground retention systems and reduction of urban floods in Tepic, Mexico

Many cities in Mexico experience recurrent floods, caused by changes in land use, the modification of surface and land runoff, the artificialization of areas initially intended for infiltration and recharge of groundwater and, in general, the insufficiency and deficiency of the local networks of urban drainage, incapable to evacuate the annual surpluses of precipitation. In this sense, the objective of this study evaluates the efficiency of an underground system of retention of rainwater in one of the main avenues of the city of Tepic, Mexico: Avenida Tecnologico. To this end, an analysis of the thematic contents and on-site inspection assisted by geographic information systems is carried out. Based on the systems approach and the logic of a qualitative model, it is concluded that the capacity of urban storm water networks for water evacuation is exceeded dimensionally. Also, it can be observed that retention systems can mitigate the urban entropy generated by the floods.

Seasonal variability of meiobenthic assemblages inhabiting the Nottinghambukta tidal flat, SW Spitsbergen

The aim of the work was to describe the variability of a group of meiobenthos inhabiting a tidal flat in Nottinghambukta which is influenced by the diverse conditions of a seasonal as well as multi-annual cyclicity. Samples were collected in five series, i.e. during the Arctic spring (2001), summer (2000 and 2001) and autumn (2001). The material for qualitative analysis was collected from sites with different hydrological characteristics. The following major meiobenthic taxa were found: Metazoa, i.e. Nematoda and Crustacea (Ostracoda and Copepoda-Harpacticoida), and Foraminifera. Unstable conditions in the bay result in a seasonal variability in the species composition as well as an uneven colonisation of the Nottinghambukta area by meiobenthos. The lowest taxonomic diversity occurs in summer, but it increases in autumn when the land runoff ceases. Based on the conducted analysis, it can be concluded that the inflow of seawater in autumn brings on the occurrence of new taxa, which probably inhabit the bay temporarily until the summer season during which the highly variable conditions cause a change in the species composition. For the series of samples collected in July 2000 and 2001, the species composition for Harpacticoida was determined. The taxonomic diversity of the harpacticoid assemblage inhabiting the bay was observed in the two subsequent years. Moreover, during the study duration a considerable decrease was observed in the abundance of Ostracoda in Nottinghambukta.

APLIKASI SISTEM INFORMASI GEOGRAFI UNTUK PENGHITUNGAN KOEFISIEN ALIRAN DAERAH ALIRAN SUNGAI (DAS) CILIWUNG

According to Cook, drainage basin characteristics factor yielding high surface stream are 1. Relief 2. Infiltration 3. Landuse, and 4. Drainage density. These physical parameter is use to determine runoff coefficient of catchment area, with application of Geographical Information System (GIS) application on Ciliwung catcment area above Depok. Steps to analyse of runoff coefficient are scoring of each classification of relief, infiltration, landuse and drainage density, and then all of the four maps which have score are overlay to become a map of unit land. Runoff coefficient hereinafter is calculated and found out that runoff coefficient of Ciliwung catchment area is 0, 58. Katakunci : GIS, SIG, metode Cook, metode Bridge Branch, runoff coeffisient, catchment area, DAS, Ciliwung, relief, infiltration, landuse, drainage density, informasi, peta tematik.

Constraints on Paleoclimate from 11.5 to 5.0 ka from Shoreline dating and Hydrologic Budget Modeling of Baqan Tso, Southwestern Tibetan Plateau

Abstract14C dating of shoreline deposits of closed-basin lake Baqan Tso in the western Tibetan Plateau shows that lake level regressed from the undated highstand (46 m above modern, 4.3 × modern surface area) of likely earliest Holocene age by 11.5 ka, and remained larger than modern until at least ≈ 5.0 ka. The shoreline record broadly matches other regional climate records, with lake level closely following Northern Hemisphere summer insolation overprinted by sub-millennial lake-level oscillations. A model coupling modern land runoff and lake surface heat closely reproduces estimated modern precipitation of ≈ 240 mm/yr. We estimate that the Baqan Tso basin required ≈ 380 mm/yr precipitation to sustain the maximum early Holocene lake area, a 55% increase over modern. Precipitation increases, not glacial meltwater, drove lake-level changes, as Baqan Tso basin was not glaciated during the Holocene. Our estimate assumes early Holocene insolation (≈ 1.3% overall increase), and mean annual increases of 2°C in temperature, and 37% in relative humidity. We additionally developed a Holocene precipitation history for Baqan Tso using dated paleolake areas. Using the modern and early Holocene model results as end-members, we estimate precipitation in the western Tibetan Plateau which was 300–380 mm/yr between 5.0 and 11.5 ka, with error of ± 29–57 mm/yr (± 12–15%).