Factors controlling longshore variations of beach changes induced by Tropical Storm Eta (2020) along Pinellas County beaches, west-central Florida

Shore & Beach ◽  
2021 ◽  
pp. 75-85
Author(s):  
Jun Cheng ◽  
Francesca Toledo Cossu ◽  
Ping Wang
Keyword(s):  
Water Level ◽  
Wave Height ◽  
Tropical Storm ◽  
Water Levels ◽  
Dominant Factor ◽  
Volume Loss ◽  
Beach Profile ◽  
Central Florida ◽  
West Central ◽  
Elevated Water

Tropical Storm Eta impacted the coast of west-central Florida from 11 November to 12 November 2020 and generated high waves over elevated water levels for over 20 hours. A total of 148 beach and nearshore profiles, spaced about 300 m (984 ft) apart, were surveyed one to two weeks before and one to eight days after the storm to examine the beach changes along four barrier islands, including Sand Key, Treasure Island, Long Key, and Mullet Key. The high storm waves superimposed on elevated water level reached the toe of dunes or seawalls and caused dune erosion and overwash at various places. Throughout most of the coast, the dune, dry beach, and nearshore area was eroded and most of the sediment was deposited on the seaward slope of the nearshore bar, resulting in a roughly conserved sand volume above closure depth. The longshore variation of beach-profile volume loss demonstrates an overall southward decreasing trend, mainly due to a southward decreasing nearshore wave height as controlled by offshore bathymetry and shoreline configurations. The Storm Erosion Index (SEI) developed by Miller and Livermont (2008) captured the longshore variation of beach-profile volume loss reasonably well. The longshore variation of breaking wave height is the dominant factor controlling the longshore changes of SEI and beach erosion. Temporal variation of water level also played a significant role, while beach berm elevation was a minor factor. Although wider beaches tended to experience more volume loss from TS Eta due to the availability of sediment, they were effective in protecting the back beach and dune area from erosion. On the other hand, smaller profile-volume loss from narrow beach did not necessarily relate to less dune/ structure damage. The opposite is often true. Accurate evaluation of a storm’s severity in terms of erosion potential would benefit beach management especially under the circumstance of increasing storm activities due to climate change.

scholarly journals The effects of ENSO, climate change and human activities on the water level of Lake Toba, Indonesia: a critical literature review

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Hendri Irwandi ◽  
Mohammad Syamsu Rosid ◽  
Terry Mart
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Human Activities ◽  
Southern Oscillation ◽  
Climatic Conditions ◽  
Water Levels ◽  
Dominant Factor ◽  
Climate Projections ◽  
Continuous Increase ◽  
The Future

AbstractThis research quantitatively and qualitatively analyzes the factors responsible for the water level variations in Lake Toba, North Sumatra Province, Indonesia. According to several studies carried out from 1993 to 2020, changes in the water level were associated with climate variability, climate change, and human activities. Furthermore, these studies stated that reduced rainfall during the rainy season due to the El Niño Southern Oscillation (ENSO) and the continuous increase in the maximum and average temperatures were some of the effects of climate change in the Lake Toba catchment area. Additionally, human interventions such as industrial activities, population growth, and damage to the surrounding environment of the Lake Toba watershed had significant impacts in terms of decreasing the water level. However, these studies were unable to determine the factor that had the most significant effect, although studies on other lakes worldwide have shown these factors are the main causes of fluctuations or decreases in water levels. A simulation study of Lake Toba's water balance showed the possibility of having a water surplus until the mid-twenty-first century. The input discharge was predicted to be greater than the output; therefore, Lake Toba could be optimized without affecting the future water level. However, the climate projections depicted a different situation, with scenarios predicting the possibility of extreme climate anomalies, demonstrating drier climatic conditions in the future. This review concludes that it is necessary to conduct an in-depth, comprehensive, and systematic study to identify the most dominant factor among the three that is causing the decrease in the Lake Toba water level and to describe the future projected water level.

Influence of elevated water levels on wind field characteristics at a bridge site

2019 ◽  
Vol 22 (7) ◽  
pp. 1783-1795 ◽  
Author(s):  
Hongmiao Jing ◽  
Haili Liao ◽  
Cunming Ma ◽  
Kejian Chen
Keyword(s):  
Wind Speed ◽  
Wind Tunnel ◽  
Water Level ◽  
Wind Field ◽  
Wind Profile ◽  
Water Levels ◽  
Bridge Engineering ◽  
Bridge Site ◽  
Bridge Girder ◽  
Elevated Water

The influence of elevated water levels on wind field characteristics at bridge sites owing to hydroelectric power stations plays an important role in bridge engineering, particularly in mountainous valley regions. To investigate this issue, a comparative experimental study, which uses a topographic model with two water level states for determining the influence on wind field characteristics at the proposed bridge site located in a mountainous valley area, was conducted in the XNJD-3 wind tunnel at Southwest Jiaotong University, Chengdu, PR China. The altitude difference between the two water level states was approximately 200 m, whereas uniform and D-type boundary layer air inflow conditions were adopted during the wind tunnel test, respectively. The wind speed at the bridge girder and profile of the 1/4, mid, and 3/4 spans were recorded during the experiment. The test results indicated that after the water level was raised, the mean wind speed (or speed-up factor) along the bridge girder decreased by approximately 10%, and the values of the wind profile also decreased. However, the wind profile curve shapes remained approximately unchanged, and the wind attack angle was significantly transformed by approximately 5° in certain locations of the bridge girder. Moreover, the variation in the water level had a negligible influence on the turbulence intensities, turbulence integral length scales, probability distribution of fluctuating wind components, and turbulent wind spectra along the bridge girder. Therefore, as the water level in the canyon rises, the wind field characteristics at the bridge site tend to be conducive to bridge safety. Therefore, long-span bridges located in mountainous valley areas should be designed appropriately according to the expected minimum water level of the river.

scholarly journals The Peculiar Hydrology of West-Central Florida’s Sandhill Wetlands, Ponds, and Lakes – Part 1: Physical & Chemical Evidence of Connectivity to a Regional Water-Supply Aquifer

2021 ◽  
Author(s):  
ReNae S Nowicki ◽  
Mark C Rains ◽  
Jason J LaRoche ◽  
Matthew A Pasek
Keyword(s):  
Water Supply ◽  
Water Levels ◽  
Water Geochemistry ◽  
Central Florida ◽  
West Central ◽  
Wetland Water ◽  
Highly Correlated ◽  
Physical And Chemical ◽  
Regional Water ◽  
Chemical Evidence

Abstract The sandhill wetlands, ponds, and lakes of west-central Florida, USA, are an understudied, poorly understood variant of geographically isolated features. Their karst origin and xeric setting impart a characteristic ecohydrology, which is a function of their connectivity to a regional water-supply aquifer. This study describes their general hydrologic character and provides physical and chemical evidence of this connectivity. These findings advance fundamental understanding of sandhill wetland/water ecohydrology and endeavor to ensure their proper management and protection amidst increasing groundwater demands, ever-expanding development, and a changing climate.Water level elevations and/or geochemistry were compared for 12 wetlands, five ponds, two lakes, and 12 monitor wells (10 constructed in limestone, two in surficial sand) in west-central Florida. Hydrograph and regression analyses indicate widely ranging water levels for most features and wells that are similar in elevation and very highly correlated with each other (0.84<R2<0.99). Water geochemistry varies from rainwater to water in contact with limestone as a function of feature depth relative to the depth of the rainwater-limestone water mixing zone. Results suggest sandhill wetland/water features are surface water expressions of the underlying regional aquifer hydrology, distinguishing them from isolated features elsewhere and establishing them as a groundwater endmember along the hydrologic continuum.

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