Mass Movement

Tunisia - Technical Advsiory Mission

At the request of, and in coordination with the National Civil Protection Office of Tunisia, UN-SPIDER is conducting a Technical Advisory Mission to Tunisia from 4 to 6 March 2020 to identify the needs of the country to fully take advantage of space-based information for disaster management. In order to discuss the use of space-based information for risk and disaster management to subsequently make recommendations on improvements, the expert team meets with key disaster management authorities in the country.

The mission is conducted with the support of experts from the Algerian Space Agency (ASAL); the Romanian Space Agency (ROSA); the United Nations Economic Commission for Africa (UNECA); the National Observatory of Athens (NOA); and an expert on the Copernicus Emergency Management Service. The mission team is also benefiting from the support of the Chief of Space Applications of the United Nations Office for Outer Space Affairs.

As part of the mission, the team of experts will visit several institutions including the National Office of Civil Protection; the Directorate General for Forests of the Ministry of Agriculture; the Faculty of Sciences of Tunis, University of Tunis El Manar; the National Agronomic Institute of Tunisia; the National Institute of Meteorology; as well as at the Ministry of Local Affairs and Environment. Meetings will also be conducted with representatives of the National Cartographic and Remote Sensing Centre of Tunisia and other organizations. In addition, the TAM team will meet the United Nations Country Team in Tunisia, which supports disaster management efforts in the country.

During the TAM, a workshop with over 20 participants from nine institutions will take place in order to present the UN-SPIDER programme to Tunisian counterparts involved in disaster management, and encourage inter-institutional cooperation and sharing of geospatial information among them.

UN-SPIDER aims at ensuring all countries have the capacity to use all types of space-based information to support risk and disaster management efforts. To make sure that all interested stakeholders can benefit from this information in the most effective way possible, UN-SPIDER provides Technical Advisory Support to Member States through missions such as this one.

The Algerian Space Agency (ASAL), the Romanian Space Agency (ROSA) and the National Observatory of Athens (NOA) are UN-SPIDER Regional Support Office.

Dates: 

Wed, 04/03/2020 to Fri, 06/03/2020

Host Institution: 

National Office for Civil Protection (ONPC), Ministry of the Interior of Tunisia

Country/Region: 

Mission Team: 

  • Alexandru Badea, Romanian Space Agency (ROSA)
  • Kamel Tichouiti, Algerian Space Agency (ASAL)
  • Alexia Tsouni, National Observatory of Athens (NOA)
  • Francoise Villette, Expert on Earth observation and disaster management, and on Copernicus EMS
  • Luc St-Pierre, United Nations Office for Outer Space Affairs (UNOOSA)
  • Coen Bussink, UN-SPIDER (Head of Delegation)
  • Radu Botez, UN-SPIDER

Mission Profile: 

Three-day mission with a stakeholder workshop that brough together 21 participants from 13 Tunisian institutions, in addition to the mission team.

AttachmentSize
PDF icon Tunisia TAM - Data sources booklet969.11 KB

Recommended Practice: Mudslides and Associated Flood Detection Using Sentinel-1 Data

English

Teaser Recommended Practice: 

Floods and landslides are the first and fourth most frequent disasters around the world (Petley, 2012). There are several examples of downstream flooding caused by massive mudslides where rapid mapping is an indispensable tool for supporting disaster management activities by civil protection authorities.

Since July 2014, the Copernicus programme of the European Union has been providing free-of-charge access to Sentinel-1 radar data coveirng the entire world. This allows for the exploration of new applications to strengthen hazard monitoring and disaster mitigation activities.

This UN-SPIDER Recommended Practice emphasizes the use of SAR data during and after a disaster crisis, since optimum atmospheric conditions for optical satellite images are not always available. In the example provided here, it is used to map the mudflow following the dam collapse that occured on 25 January 2019 at Brumadinho, Brazil.

Flowchart Recommended Practices: 

Logo 2: 

Objective: 

The aim is to identify the area affected by mudslide and associated floods using the backscattering information from "magnitude" SAR data. This step-by-step procedure applies a ratio-change detection technique and principal component analysis using SAR images before and after the dam collapsed.

Disaster Cycle Phase: 

  • Recovery & Reconstruction
  • Relief & Response

Main Hazards: 

  • Mass Movement

Test Site: 

Minas Gerais located in Brumadinho, Brazil

Context: 

This Recommended Practice was developed by a visiting scientist from the Autonomous University of Mexico State (UAEM) who beneiftted from the support provided by the National Council of Science and Technology (CONACYT-Mexico). This method was applied for a massive mudflow that occurred 25 January 2019 in Brumadinho, Brazil, where a dam collapsed in the Minas Gerais mining complex triggering a mudslide and causing the death of 232 people. A large volume of sludge flooded at least 12 km downstream, burying mining infrastructure and nearby workers' houses.

Applicability: 

This UN-SPIDER Recommended Practice can be applied to all SAR images with dual polarization (HH, VV, HV, and VH) or full polarization (HH, VV, HV, and VH). Single polarization is not recommended to use in this practice since the digital treatment technique needs two polarizations as a minimum requirement.

The methodology can be applied over massive mudslides and associated floods, also when large areas of sludge-water are involved. It is essential to mention that the proposed method is focused on extracting the most significant amount of backscattering information linked to the surficial roughness of the mudslide using the magnitude information of SAR image. To achieve this task, we use change detection techniques (Log- Ratio) and principal component analysis (PCA).

The applicability of PCA to detect massive mudslides (and associated floods) lies in applying digital treatment using the magnitude values of SAR images acquired on different dates. PCA implies a data regrouping, where towards the first "out band components" the variance is maximized, which means that the more significant pixel information is keeping; while towards the last "out band component," all noise or redundant information is separated. This method is highly recommended when the flooded areas cannot be detected by the traditional change detection analysis due to soil moisture conditions, differences between water bodies or by the large volume of sediments transported during a flood.

Recommended Practice: Exposure Mapping

English

Teaser Recommended Practice: 

Mapping the extent of a natural hazard (e.g., assessing areas with a high risk) or disaster is a first step in disaster risk management and emergency response. Subsequently, exposure mapping enables the estimation of the impact of hazards or disasters, for example, regarding the number of affected inhabitants or infrastructure. The following practice shows the use of Quantum GIS to analyze a disaster extent map in combination with auxiliary data such as population or land cover data.

Flowchart Recommended Practices: 

Related Software: 

Objective: 

The objective of this practice is to estimate the exposure of a natural hazard or disaster. As an example, the number of inhabitants affected by a flood event is estimated. The joint use of the flood mask, created by the Recommended Practice: Flood Mapping, and the WorldPop data set constitutes a viable solution to quickly estimate the impact of the flood regarding the population. The proposed methodology is a universal practice which combines a simple approach based on open-source software and free of charge data together with a beforehand created map covering the extend of a natural hazard or disaster.

Disaster Cycle Phase: 

  • Mitigation
  • Preparedness
  • Recovery & Reconstruction
  • Relief & Response

Main Hazards: 

  • Drought
  • Earthquake
  • Extreme Temperature
  • Forest Fire
  • Flood
  • Insect Infestation
  • Mass Movement
  • Pollution
  • Severe Storm
  • Tsunami
  • Volcanic Eruption

Test Site: 

Malawi

Context: 

The practice was applied in the context of the flood event in Malawi in January 2015. Since December 2014, heavy rains affected Malawi causing rivers to overflow. The flooded area in this analysis covered a part of the Nsanje district around Chiromo.

Applicability: 

This practice can be applied globally. Besides of the beforehand created hazard or disaster extent map, the practice does not need specific near real-time data as it is based on population, land cover, or other auxiliary geodata archives. The WorldPop data set provides population data for Africa, Asia as well as Central and South America with a spatial resolution of 100 meters. The Landcover30 data base provides global landcover data with a spatial resolution of about 30 meters.

ERS-1,2

Disaster Cycle Phase: 

  • Preparedness

Space Technology/Product and Application: 

  • EO/RS
  • Risk Map

Field of Application: 

  • Disaster Type
  • Mass Movement

Satellite: 

Undefined

Detailed rockslide mapping in northern Norway with small baseline and persistent scatterer interferometric SAR time series methods

Rockslides have a high socioeconomic and environmental importance in many countries. Norway is particularly susceptible to large rockslides due to its many fjords and steep mountains. One of the most dangerous hazards related with rock slope failures are tsunamis that can lead to large loss of life. It is therefore very important to systematically identify potential unstable rock slopes. Traditional landslide monitoring techniques are expensive and time consuming.

External Contact Person: 

T.R. Lauknes

Email: 

Tom-Rune.Lauknes [at] norut.no
Undefined

Bibliographic reference: 

Lauknes, T. R., Shanker, A. P., Dehls, J. F., Zebker, H. A., Henderson, I. H. C., & Larsen, Y. (2010). Detailed rockslide mapping in northern Norway with small baseline and persistent scatterer interferometric SAR time series methods. Remote Sensing of Environment114(9), 2097-2109.

SPOT-5

Disaster Cycle Phase: 

  • Relief & Response

Space Technology/Product and Application: 

  • EO/RS
  • Landslide Hazard Assessment
  • Landslide Monitoring

Field of Application: 

  • Disaster Type
  • Mass Movement

Satellite: 

Undefined

Comparison between automated and manual mapping of typhoon triggered landslides from SPOT-5 imagery

Two large tropical cyclones struck Taiwan in the summer of 2004 and landslides triggered by these events caused not only casualties and housing damage but also produced large volumes of sediment that entered rivers and reservoirs. For reservoir and watershed management it is important to quickly identify the location and areal extent of new landslides for coordinating

External Contact Person: 

K. Chang

Email: 

ktchang [at] ntu.edu.tw
Undefined

Bibliographic reference: 

Borghuis, A. M., Chang, K., & Lee, H. Y. (2007). Comparison between automated and manual mapping of typhoon‐triggered landslides from SPOT‐5 imagery. International Journal of Remote Sensing28(8), 1843-1856.

IRS-1D

Disaster Cycle Phase: 

  • Mitigation

Space Technology/Product and Application: 

  • EO/RS
  • Landslide Hazard Assessment

Field of Application: 

  • Disaster Type
  • Mass Movement
Undefined

Geospatial technology in landslide mitigation - A case study in Nilgiris District

Landslides constitute one of the major natural catastrophes, which account for considerable loss of life and damage to communication routes, human settlements, agricultural and forestland. Most of the terrain in mountainous areas have been subjected to slope failures under the influence of variety of terrain factors and figured by events such as extreme rainfall or earthquake. In India, landslides are occurring frequently in Himalayan region in North and Western Ghats in South.

External Contact Person: 

Email: 

Undefined

Bibliographic reference: 

VIDHYA, D. GEOSPATIAL TECHNOLOGY IN LANDSLIDE MITIGATION–A CASE STUDY IN NILGIRIS DISTRICT.

IKONOS, Quickbird

Disaster Cycle Phase: 

  • Mitigation

Space Technology/Product and Application: 

  • EO/RS
  • Landslide Hazard Assessment

Field of Application: 

  • Disaster Type
  • Mass Movement

Satellite: 

Undefined

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