scholarly journals Applications of Open-Access Remotely Sensed Data for Flood Modelling and Mapping in Developing Regions

Hydrology ◽  
2018 ◽  
Vol 5 (3) ◽  
pp. 39 ◽  
Author(s):  
Iguniwari Thomas Ekeu-wei ◽  
George Alan Blackburn
Keyword(s):  
Open Access ◽  
Frequency Estimation ◽  
Management Strategies ◽  
Flood Management ◽  
Remotely Sensed ◽  
Flood Frequency ◽  
Remotely Sensed Data ◽  
Developing Regions ◽  
Flood Modelling ◽  
Radar Images

Flood modelling and mapping typically entail flood frequency estimation, hydrodynamic modelling and inundation mapping, which require specific datasets that are often unavailable in developing regions due to financial, logistical, technical and organizational challenges. This review discusses fluvial (river) flood modelling and mapping processes and outlines the data requirements of these techniques. This paper explores how open-access remotely sensed and other geospatial datasets can supplement ground-based data and high-resolution commercial satellite imagery in data sparse regions of developing countries. The merits, demerits and uncertainties associated with the application of these datasets, including radar altimetry, digital elevation models, optical and radar images, are discussed. Nigeria, located within the Niger river basin of West Africa is a typical data-sparse country, and it is used as a case study in this review to evaluate the significance of open-access datasets for local and transboundary flood analysis. Hence, this review highlights the vital contribution that open access remotely sensed data can make to flood modelling and mapping and to support flood management strategies in developing regions.

scholarly journals An era of Sentinels in flood management: Potential of Sentinel-1, -2, and -3 satellites for effective flood management

2021 ◽  
Vol 13 (1) ◽  
pp. 1616-1642
Author(s):  
Sai Kiran Kuntla
Keyword(s):  
Optical Sensors ◽  
Management Strategies ◽  
Flood Management ◽  
Flood Frequency ◽  
Economic Damage ◽  
Earth Observations ◽  
The Earth ◽  
The People ◽  
Technical Specifications ◽  
Sentinel 2

Abstract The repetitive and destructive nature of floods across the globe causes significant economic damage, loss of human lives, and leaves the people living in flood-prone areas with fear and insecurity. With enough literature projecting an increase in flood frequency, severity, and magnitude in the future, there is a clear need for effective flood management strategies and timely implementation. The earth observatory satellites of the European Space Agency’s Sentinel series, Sentinel-1, Sentinel-2, and Sentinel-3, have a great potential to combat these disastrous floods by their peerless surveillance capabilities that could assist in various phases of flood management. In this article, the technical specifications and operations of the microwave synthetic aperture radar (SAR) onboard Sentinel-1, optical sensors onboard Sentinel-2 (Multispectral Instrument) and Sentinel-3 (Ocean and Land Color Instrument), and SAR altimeter onboard Sentinel-3 are described. Moreover, the observational capabilities of these three satellites and how these observations can meet the needs of researchers and flood disaster managers are discussed in detail. Furthermore, we reviewed how these satellites carrying a range of technologies that provide a broad spectrum of earth observations stand out among their predecessors and have bought a step-change in flood monitoring, understanding, and management to mitigate their adverse effects. Finally, the study is concluded by highlighting the revolution this fleet of Sentinel satellites has brought in the flood management studies and applications.

scholarly journals Application of random forest classification and remotely sensed data in geological mapping on the Jebel Meloussi area (Tunisia)

2021 ◽  
Vol 14 (21) ◽  
Author(s):  
Gáspár Albert ◽  
Seif Ammar
Keyword(s):  
Random Forest ◽  
Remotely Sensed ◽  
Geological Mapping ◽  
Vegetation Coverage ◽  
Remotely Sensed Data ◽  
Random Forest Classification ◽  
Radar Images ◽  
Forest Classification ◽  
Geological Map ◽  
Sentinel 2

Abstract Remotely sensed data such as satellite photos and radar images can be used to produce geological maps on arid regions, where the vegetation coverage does not have a significant effect. In central Tunisia, the Jebel Meloussi area has unique geological features and characteristic morphology (i.e. flat areas with dune fields in contrast with hills of folded and eroded stratigraphic sequences), which makes it an ideal area for testing new methods of automatic terrain classification. For this, data from the Sentinel 2 satellite sensor and the SRTM-based MERIT DEM (digital elevation model) were used in the present study. Using R scripts and the random forest classification method, modelling was performed on four lithological variables—derived from the different bands of the Sentinel 2 images—and two morphometric parameters for the area of the 1:50,000 geological map sheet no. 103. The four lithological variables were chosen to highlight the iron-bearing minerals since the spectral parameters of the Sentinel 2 sensors are especially useful for this purpose. The training areas of the classification were selected on the geological map. The results of the modelling identified Eocene and Cretaceous evaporite-bearing sedimentary series (such as the Jebs and the Bouhedma Formations) with the highest producer accuracy (> 60% of the predicted pixels match with the map). The pyritic argillites of the Sidi Khalif Formation were also recognized with the same accuracy, and the Quaternary sebhkas and dunes were also well predicted. The study concludes that the classification-based geological map is useful for field geologist prior to field surveys.

scholarly journals Local Perception of Drivers of Land-Use and Land-Cover Change Dynamics across Dedza District, Central Malawi Region

2019 ◽  
Vol 11 (3) ◽  
pp. 832 ◽  
Author(s):  
Maggie G. Munthali ◽  
Nerhene Davis ◽  
Abiodun M. Adeola ◽  
Joel O. Botai ◽  
Jonathan M. Kamwi ◽  
...  
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Land Management ◽  
Agricultural Land ◽  
Management Strategies ◽  
Rural Livelihoods ◽  
Remotely Sensed ◽  
Remotely Sensed Data ◽  
Barren Land ◽  
Lulc Changes

Research on Land Use and Land Cover (LULC) dynamics, and an understanding of the drivers responsible for these changes, are very crucial for modelling future LULC changes and the formulation of sustainable and robust land-management strategies and policy decisions. This study adopted a mixed method consisting of remote sensing and Geographic Information System (GIS)-based analysis, focus-group discussions, key informant interviews, and semi-structured interviews covering 586 households to assess LULC dynamics and associated LULC change drivers across the Dedza district, a central region of Malawi. GIS-based analysis of remotely sensed data revealed that barren land and built-up areas extensively increased at the expense of agricultural and forest land between 1991 and 2015. Analysis of the household-survey results revealed that the perceptions of respondents tended to validate the observed patterns during the remotely sensed data-analysis phase of the research, with 57.3% (n = 586) of the respondents reporting a decline in agricultural land use, and 87.4% (n = 586) observing a decline in forest areas in the district. Furthermore, firewood collection, charcoal production, population growth, and poverty were identified as the key drivers of these observed LULC changes in the study area. Undoubtedly, education has emerged as a significant factor influencing respondents’ perceptions of these drivers of LULC changes. However, unsustainable LULC changes observed in this study have negative implications on rural livelihoods and natural-resource management. Owing to the critical role that LULC dynamics play to rural livelihoods and the ecosystem, this study recommends further research to establish the consequences of these changes. The present study and future research will support decision makers and planners in the design of tenable and coherent land-management strategies.

scholarly journals Bottom-Up Assessment of Climate Risk and the Robustness of Proposed Flood Management Strategies in the American River, CA

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 907
Author(s):  
Kara DiFrancesco ◽  
Alix Gitelman ◽  
David Purkey
Keyword(s):  
Climate Change ◽  
Decision Making ◽  
Cost Effectiveness ◽  
Management Strategies ◽  
Flood Management ◽  
Flood Frequency ◽  
Bottom Up ◽  
American River ◽  
The Face ◽  
System Robustness

The hydrologic nonstationarity and uncertainty associated with climate change requires new decision-making methods to incorporate climate change impacts into flood frequency and flood risk analyses. To aid decision-making under climate change, we developed a bottom-up approach for assessing the performance of flood management systems under climate uncertainty and nonstationarity. The developed bottom-up approach was applied to the American River, CA, USA flood management system by first identifying the sensitivity and vulnerability of the system to different climates. To do this, we developed a climate response surface by calculating and plotting Expected Annual Damages (EAD, $/year) under different flood regimes. Next, we determined a range of plausible future climate change and flood frequency scenarios by applying Bayesian statistical methods to projected future flows derived from a Variable Infiltration Capacity (VIC) model forced with Global Circulation Model (GCM) output. We measured system robustness as the portion of plausible future scenarios under which the current flood system could meet its performance goal. Using this approach, we then evaluated the robustness of four proposed management strategies in the 2012 Central Valley Flood Protection Plan in terms of both flood risk and cost-effectiveness, to assess the performance of the strategies in the face of climate risks. Results indicated that the high sensitivity of the expected damages to changes in flood regimes makes the system extremely vulnerable to a large portion of the plausible range of future flood conditions. The management strategy that includes a combination of nature-based flood management actions along with engineered structures yields the greatest potential to increase system robustness in terms of maintaining EAD below an acceptable risk threshold. However, this strategy still leaves the system vulnerable to a wide range of plausible future conditions. As flood frequency regimes increase in intensity from the current conditions, the cost-effectiveness of the management strategies increases, to a point, before decreasing. This bottom up analysis demonstrated a viable decision-making approach for water managers in the face of uncertain and changing future conditions. Neglecting to use such an approach and omitting climate considerations from water resource planning could lead to strategies that do not perform as expected or which actually lead to mal-adaptations, increasing vulnerability to climate change.

Land-use change and floods: what do we need most, research or management?

2002 ◽  
Vol 45 (8) ◽  
pp. 183-190 ◽  
Author(s):  
Arne Tollan
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Flood Risk ◽  
Human Impacts ◽  
Management Strategies ◽  
Flood Management ◽  
Flood Damage ◽  
Flood Frequency ◽  
Small Scale ◽  
Infiltration Capacity

Land-cover change (urbanisation, deforestation, and cultivation) results in increased flood frequency and severity. Mechanisms include reduced infiltration capacity, lower soil porosity, loss of vegetation, and forest clearing, meaning lower evapotranspiration. Major research challenges lie in quantification of effects in terms of flood characteristics under various conditions, ascertaining the combined effects of gradual changes over long time periods, and developing model tools suitable for land-use management. Large floods during the 1990s gave a new focus on these problems. Reference is made to the Norwegian HYDRA research programme on human impacts on floods and flood damage. The paper concludes that land-use change effects on floods are most pronounced at small scale and for frequent flood magnitudes. Model simulations of effects of land-use change can now be used to reduce flood risk. Modern flood management strategies have abandoned the position that dams and dikes are the only answers to mitigating flood disasters. Today, the strategic approach is more often: do not keep the water away from the people, keep people away from the water. Flood management strategies should include flood warnings, efficient communication, risk awareness, civil protection and flood preparedness routines, effective land-use policies, flood risk mapping, … as well as structural measures.

scholarly journals Evaluation of Hydrological Data Collection Challenges and Flood Estimation Uncertainties in Nigeria

2018 ◽  
Vol 8 (2) ◽  
pp. 44 ◽  
Author(s):  
Iguniwari Thomas Ekeu-wei
Keyword(s):  
Data Collection ◽  
River Basin ◽  
Water Resource Management ◽  
New Technologies ◽  
Flood Management ◽  
Flood Frequency ◽  
Anthropogenic Factors ◽  
Developing Regions ◽  
Hydrological Data ◽  
Flood Impact

In recent years, flooding has become a recurring problem in many regions including Nigeria, owing to changing climatic conditions, as well as anthropogenic factors such as poor land use management and urbanization that aggravate flood impact. To effectively manage and mitigate flood impact, hydrological data is required, and in many developing regions gauging stations are established, and gauge readers recruited and trained to collect and transmit such data to designated hydrological or water resource management agencies. This study focuses on understanding the challenges associated with hydrological data collection in Nigeria, using the Ogun-Osun River as a typical case, while analytically assessing how these challenges result in uncertainties that propagate unto flood frequency estimates that are used to inform flood management decisions. The findings reveal that (i) capacity and institutional gaps; lack of maintenance of hydrological infrastructure and surrounding landscape; poor data management architecture; and floods events that destroy hydrological equipment and inundate roads thereby restricting access to collected data during peak floods, are some of the challenges associated with hydrological data collection in developing regions; (ii) these conditions result in gaps in and shortened length of annual maximum hydrological time series required for flood frequency estimation, consequently leading to under or overestimation of low and high flood quantiles such as 1-in-2year and 1-in-100year floods, to levels of 0.67 m and 0.9 m respectively for the Ogun Osun River Basin. The need for improved data collation, management and adaptation of new technologies such as radar or sonar by the Ogun-Osun River Basin Development Authority is recommended in this study, to ensure sustainable and improved hydrological data collection, management, transferability and usability for flood management.

Using remotely sensed data to support flood modelling

2006 ◽  
Vol 159 (1) ◽  
pp. 35-43 ◽  
Author(s):  
S. Néelz ◽  
G. Pender ◽  
I. Villanueva ◽  
M. Wilson ◽  
N. G. Wright ◽  
...  
Keyword(s):  
Remotely Sensed ◽  
Remotely Sensed Data ◽  
Flood Modelling

Institutional Repositories in Swaziland: An Exploratory Study

Mousaion ◽  
2019 ◽  
Vol 36 (2) ◽  
Author(s):  
Ncamsile Nombulelo Dlamini ◽  
Maritha Snyman
Keyword(s):  
Open Access ◽  
Exploratory Study ◽  
Management Strategies ◽  
Current Status ◽  
Academic Institutions ◽  
African Countries ◽  
Institutional Repositories ◽  
Limited Knowledge ◽  
Advocacy Strategies ◽  
Awareness Level

The purpose of this paper is to assess the current status of institutional repositories (IRs) in Swaziland’s academic institutions. The factors under discussion are the number of IRs in Swaziland, their usage, the level of awareness of these IRs, and the challenges that prevent the implementation of IRs in Swaziland’s academic institutions. A webometric approach, interviews and semi-structured questionnaires completed by IR managers or librarians working for the Swaziland’s academic institutions were used to collect data for this study. Responses were received from 11 respondents. The findings indicated that there is one IR in Swaziland that is accessible to the institution’s community via the intranet. This IR was, at the time when this study took place, not registered in any of the international registries of repositories, such as the Registry of Open Access Repositories (ROAR) and the Directory of Open Access Repositories (OpenDOAR). Currently, this IR faces problems of insufficient content, a low level of IR awareness, limited knowledge of effective and appropriate IR advocacy strategies and limited knowledge of effective IR implementation and management strategies. Based on the findings and information gained from a literature review of IRs, the paper recommends strategies to academic institutions in Swaziland that may enable them to increase their number of IRs, the awareness level of IRs and consequently the use of IRs. The findings and recommendations may also benefit other African countries in similar situations.  

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