Application of Remote Sensing and GIS for Flood Hazard Management: A Case Study from Sindh Province, Pakistan

American Journal of Geographic Information SystemAmerican Journal of Geographic Information System, Volume 2, Number 1, February 2013

Kabir Uddin, Deo Raj Gurung, Amarnath Giriraj, and Basanta Shrestha

“Floods are one of the most common hazards in the world, affecting people’s lives and livelihoods. Flood hazard mapping and flood shelters suitability analysis are vital elements in appropriate land use planning for flood-prone areas. This paper describes application of Remote Sensing (RS) and Geographical Information Systems (GIS) in identifying flood hazard zones and flood shelters and are therefore important tools for planners and decision makers. The purpose of this article is to describe a simple and efficient methodology to accurately delineate flood inundated areas, flood-hazard areas, and suitable areas for flood shelter to minimize flood impacts. Possible extent of flooding and suitable location flood shelter sites were modeled and mapped for Sindh Province in Pakistan, using the software ArcGIS model builder.

Flow diagram of flood shelter analysis

Flow diagram of flood shelter analysis

“The output was validated using inundation maps based on flood events that took place in 2010 in Pakistan. These were mapped using object-based image analysis (OBIA) implemented in eCognition software. The catastrophic flood of 2010 inundated a total area of 7579 km2, while the modeled result indicated the hazard area to be 6216 km2 out of 46138 km2. Discrepancies in modeled and mapped results are insignificant and acceptable considering the manual flood management interventions which are beyond the capability of models to represent. Thus, this method is robust enough to develop flood hazard zoning maps and map shelter sites for flood management. ”

A Study of Morphological Changes in the Coastal Areas and Offshore Islands of Bangladesh Using Remote Sensing

American Journal of Geographic Information SystemAmerican Journal of Geographic Information System, 2013; 2(1): 15-18

M. Shamsul Alam and Kabir Uddin

“Bangladesh is a country where 80 percent of the land is below 1 meters from the MSL. The small country with a huge population is already known to the outside world for her vulnerability to natural hazards. Among the impacts of climate change, the serious concern for Bangladesh is the relative sea level rise (RSLR). A 45-centimeter sea level rise in Bangladesh may dislocate about 35 million people from 20 coastal districts by 2050. In a worst-case scenario, Bangladesh could lose nearly 25 percent of its 1989 land area by around 2100. The process of erosion, deposition and accretion are common phenomenon in the deltaic country.

Morphological Changes in the Coastal Areas of Bangladesh, 1977-2010

Morphological Changes in the Coastal Areas of Bangladesh, 1977-2010

“This study based on remote sensing data tries to examine the erosion, accretion and net gain/loss of land in the Coastal Areas and Offshore Islands of Bangladesh and recommends measures to enhance the process of accretion to save millions from becoming environmental refugees.”

Town of Canmore Contracts Advanced Aerial LiDAR Survey to Assess Damage from Southern Alberta Floods

LiDAR Services International Inc.The Town of Canmore, Alberta contracted LiDAR Services International Inc., (LSI), a Calgary based airborne LiDAR mapping company to mobilize their advanced helicopter equipped laser mapping system to conduct an aerial LiDAR and imaging survey of 54 square kilometers of the Bow River valley in the Canmore area to assess damage as a result of the 2013 Alberta floods. The mountain town declared a state of local emergency on June 20 as over 220 millimeters of rain fell in 36 hours, nearly half of Canmore’s annual average rainfall on already saturated ground, coupled with a steep mountain watershed, resulted in a rapid increase in the size and flow of several rivers. The normally tranquil Cougar Creek raged, spilling over its banks, washing away roadways, a rail line, pathways and destroying swaths of green space and creek side homes.

“A tremendous amount of material has been swept off the mountain … rocks, dirt, soil, boulders and trees …into Cougar Creek and depositing the material in the Town of Canmore causing several homes to be destroyed and taking out the Trans-Canada Highway and a CP Rail line,” said Blair Birch, P. Eng., Municipal Engineer , Town of Canmore.

The flood initiated the need for the LiDAR survey … the Town contracts the collection of aerial ortho photos every five years, however, the flood created the immediate need for accurate, detailed topographic data that LiDAR can provide. “The LiDAR survey will capture where the water caused the greatest damage …where water courses were rerouted, how the hydrology of the watershed has been altered. The survey’s topographic data and imagery will assist in studying what happened and how to mitigate these events in the future,” said Birch. “We need to establish how much debris came down from the mountain and was deposited in the Town. The LiDAR will help to reestablish new watersheds and hydrological assessments and will also be helpful in applying for relief funds from federal and provincial governments.” “We used a Bell 206B helicopter to allow us to fly low and slow over the survey area in mountainous terrain to provide a very high accuracy data set of both LiDAR and imagery data,” said Tony Tubman, president, LSI. “We are very pleased to be able to respond to the Town of Canmore and its residents on such short notice in their time of need …there has been a lot of devastation as a result of the2013 Alberta flood …and we are happy to be a part of the relief effort.” LSI has expedited processing of the LiDAR and imagery data to get it to the Town of Canmore as soon as possible. Turning around the delivery of such huge volumes of collected data which normally takes several weeks to days is a testament to the commitment LSI has made to Canmore.

The aerial LiDAR survey deliverables include LiDAR point clouds classified to Ground, DTM Keypoints, Low Vegetation and High Vegetation classes; Bare Earth and Full Feature grids at 1 m spacing; Greyscale hillshades of Bare Earth and Full Feature surfaces at 1 m pixel resolution; and Ortho-mosaicked color digital imagery mapped at a 10 cm pixel resolution. The Town of Canmore has a full-time population of 17,000 but that can double during the winter ski and summer tourist seasons. TheTown attracts world-class athletes to its Nordic Centre. Officials are now conducting an overall assessment in the area to determine the full extent of the damage. With the local state of emergency in Canmore lifted, attention is turning toward ways to fix up Cougar Creek — the small but powerful stream that has breached its banks for the second time in two years – as well as several other stream courses entering Town.

[Source: LiDAR Services International Inc. press release]

Analysis of Tornado-Induced Tree Fall Using Aerial Photography from the Joplin, Missouri, and Tuscaloosa-Birmingham, Alabama, Tornadoes of 2011

djs_jam_52_5_COVER.inddJournal of Applied Meteorology and Climatology, Volume 52, Issue 5 (May 2013)

Christopher D. Karstens, William A. Gallus Jr., Bruce D. Lee, and Catherine A. Finley

“In this study, aerial imagery of tornado damage is used to digitize the falling direction of trees (i.e., tree fall) along the 22 May 2011 Joplin, Missouri, and 27 April 2011 Tuscaloosa–Birmingham, Alabama, tornado tracks. Normalized mean patterns of observed tree fall from each tornado’s peak-intensity period are subjectively compared with results from analytical vortex simulations of idealized tornado-induced tree fall to characterize mean properties of the near-surface flow as depicted by the model. A computationally efficient method of simulating tree fall is applied that uses a Gumbel distribution of critical tree-falling wind speeds on the basis of the enhanced Fujita scale. Results from these simulations suggest that both tornadoes had strong radial near-surface winds. A few distinct tree-fall patterns are identified at various locations along the Tuscaloosa–Birmingham tornado track. Concentrated bands of intense tree fall, collocated with and aligned parallel to the axis of underlying valley channels, extend well beyond the primary damage path. These damage patterns are hypothesized to be the result of flow acceleration caused by channeling within valleys. Another distinct pattern of tree fall, likely not linked to the underlying topography, may have been associated with a rear-flank downdraft (RFD) internal surge during the tornado’s intensification stage. Here, the wind field was strong enough to produce tornado-strength damage well beyond the visible funnel cloud. This made it difficult to distinguish between tornado- and RFD-related damage and thus illustrates an ambiguity in ascertaining tornado-damage-path width in some locations.”

The Steady-state Mosaic of Disturbance and Succession across an Old-growth Central Amazon Forest Landscape

PNAS-4.coverPNAS, 28 January 2013

Jeffrey Q. Chambers, Robinson I. Negron-Juarez, Daniel Magnabosco Marra, Alan Di Vittorio, Joerg Tews, Dar Roberts, Gabriel H. P. M. Ribeiro, Susan E. Trumbore, and Niro Higuchi

“Old-growth forest ecosystems comprise a mosaic of patches in different successional stages, with the fraction of the landscape in any particular state relatively constant over large temporal and spatial scales. The size distribution and return frequency of disturbance events, and subsequent recovery processes, determine to a large extent the spatial scale over which this old-growth steady state develops. Here, we characterize this mosaic for a Central Amazon forest by integrating field plot data, remote sensing disturbance probability distribution functions, and individual-based simulation modeling. Results demonstrate that a steady state of patches of varying successional age occurs over a relatively large spatial scale, with important implications for detecting temporal trends on plots that sample a small fraction of the landscape. Long highly significant stochastic runs averaging 1.0 Mg biomass⋅ha−1⋅y−1 were often punctuated by episodic disturbance events, resulting in a sawtooth time series of hectare-scale tree biomass. To maximize the detection of temporal trends for this Central Amazon site (e.g., driven by CO2 fertilization), plots larger than 10 ha would provide the greatest sensitivity. A model-based analysis of fractional mortality across all gap sizes demonstrated that 9.1–16.9% of tree mortality was missing from plot-based approaches, underscoring the need to combine plot and remote-sensing methods for estimating net landscape carbon balance. Old-growth tropical forests can exhibit complex large-scale structure driven by disturbance and recovery cycles, with ecosystem and community attributes of hectare-scale plots exhibiting continuous dynamic departures from a steady-state condition.”

Fusing Remote Sensing with Sparse Demographic Data for Synthetic Population Generation: An Algorithm and Application to Rural Afghanistan

International Journal of Geographical Information ScienceInternational Journal of Geographical Information Science, published online 19 November 2012

Seyed M. Mussavi Rizi, Maciej M. Łatek, and Armando Geller

“We develop a new algorithm for population synthesis that fuses remote-sensing data with partial and sparse demographic surveys. The algorithm addresses non-binding constraints and complex sampling designs by translating population synthesis into a computationally efficient procedure for constrained network growth. As a case, we synthesize the rural population of Afghanistan, validate the algorithm with in-sample and out-of-sample tests, examine the variability of algorithm outputs over k-nearest neighbor manifolds, and show the responsiveness of our algorithm to additional data as a constraint on marginal population counts.”

Aerial Surveys Give New Estimates for Orangutans in Sabah, Malaysia

PLoS Biology, 3(1): e3, 2004

Marc Ancrenaz, Olivier Gimenez, Laurentius Ambu, Karine Ancrenaz, Patrick Andau, Benoît Goossens, John Payne, Azri Sawang, Augustine Tuuga, and Isabelle Lackman-Ancrenaz

“Great apes are threatened with extinction, but precise information about the distribution and size of most populations is currently lacking. We conducted orangutan nest counts in the Malaysian state of Sabah (North Borneo), using a combination of ground and helicopter surveys, and provided a way to estimate the current distribution and size of the populations living throughout the entire state. We show that the number of nests detected during aerial surveys is directly related to the estimated true animal density and that a helicopter is an efficient tool to provide robust estimates of orangutan numbers.

Distribution and Size of the 16 Major Orangutan Populations Identified during the Surveys in Sabah, Malaysia, Borneo

Distribution and Size of the 16 Major Orangutan Populations Identified during the Surveys in Sabah, Malaysia, Borneo

“Our results reveal that with a total estimated population size of about 11,000 individuals, Sabah is one of the main strongholds for orangutans in North Borneo. More than 60% of orangutans living in the state occur outside protected areas, in production forests that have been through several rounds of logging extraction and are still exploited for timber. The role of exploited forests clearly merits further investigation for orangutan conservation in Sabah.”