Although knowledge of sediment transport has improved over the last 25 years, our understanding of bedload transfer and sediment delivery is still based on a limited set of observations or on models that make assumptions on hydraulic and sediment transport processes. This study utilises repeat lidar survey data of the River Caldew above the City of Carlisle in the UK to investigate the balance of erosion and deposition associated with channel switching from an engineered and managed single thread channel to a naturalising incipient wandering system. Over the 11-year survey period (four bankfull flood events) around 271,000 m3 of sediment were delivered to the river and floodplain and 197,000 m3 eroded suggesting that storage rates of around 7000 m3/annum occurred. The balance of erosion and deposition is influenced by channelisation with very restricted overbank sedimentation and only limited local and transient in-channel bar deposition along the engineered reach (8000 m3 eroded). This contrasts with the activity of the naturalising reach downstream where a developing wandering channel system is acting to store coarse sediment in-stream as large bar complexes and the associated upstream aggrading plane bed reaches and overbank as splay deposits (87,000 m3 stored). Such behavior suggests that naturalisation of channelised systems upstream of flood vulnerable urban areas can have a significant impact on sediment induced flooding downstream. This conclusion must, however, be moderated in the light of the relatively small volumes of material needed to instigate local aggradation in over-capacity urban channels.
The objective of the study is to create a flood hazard model of Tarlac River and to calibrate the model based on data gathered from the Philippine Atmospheric Geophysical and Astronomical Services Administration. The study employed analytical method wherein the 1D flood modeling was utilized. GIS, DEM data, rainfall data, river analysis system, HEC-GeoRAS, hydrologic modeling system, and HEC-GeoHMS were utilized. The different flood models revealed that Tarlac River is not expected to be overtopped by flood water as regards the different extreme rainfall events considered in the present study. The RAS model simulation was based on the concept that there is no base flow observed within the river reach before the occurrence of any extreme rainfall event. Henceforth, there is still no 100 percent assurance that the river reach will not be overtopped with the occurrence of initial base flow in combination with the occurrence of higher extreme rainfall events. Further studies or investigations should be delved into such combination of events. Possible levee breach of the Tarlac River as well as the possible incorporation of flood mitigating interventions in future modeling scenarios can be likewise considered.
Even when individuals are aware of and well educated about environmental issues like climate change they often take little action to mitigate these problems. Yet catastrophic events, like disasters, have the potential to rupture or disrupt complacency toward environmental problems, forcing individuals to consider the potential effects of human activity on the environment as they expose how environmentally harmful practices put people at risk. This article is based on focus group interviews with 46 residents of High River, Alberta, a rural community hardest hit by the 2013 Southern Alberta flood. It examines if and how experiencing the flood prompted residents to think about the environment or interact with it in new ways. Findings suggest that residents voice a contradiction- while they believe that pre-flood human activity like deforestation, river diversion, and home-building altered the environment and placed communities like their own at risk, they also argue that natural forces like disasters are immune to human efforts to control them. Residents feel their environment is less stable and predicable since the flood, and they worry more about toxicity and associated environmental health risks. The article concludes with a discussion of the implications of these findings for environmental sociology and public policy.
Slavoljub Dragićević, Ivan Novković, I. Carevic
et al.
The territory of eastern Serbia is characterized by a variety of igneous, sedimentary and metamorphic rocks formed through different paleogeographic developments. As a result of varied natural conditions, the region is vulnerable to various geohazards, such as earthquake, landslide, excessive erosion, flood, rockfall, cave collapse and subsidence. The occurrence of any geohazard depends on the intensity of the process causing it. An assessment of each type of hazard or combination of all hazards is necessary for this region of Serbia which accommodates major power-generation, industrial and mining facilities and has rich mineral resources. Depopulation of eastern Serbia reduces the ability of local communities to invest in the hazard control works. This assessment of the geohazards begins with the reference to the available seismic maps and proceeds with the research in the landslide, potential flood and excessive erosion hazards, then rockfall and rock collapse. Research results suffice to prepare a generalized geohazard map of eastern Serbia showing areas vulnerable to particular natural hazards and to estimate a total area endangered by hazardous processes. The purpose of this work is to locate and classify areas of potential hazards on which future protective actions may be based.