OR/16/006 Mainstreaming opportunities context
| Colm J Jordan, Tom Dijkstra and Stephen Grebby. 2016. Risk information services for Disaster Risk Management (DRM) in the Caribbean: mainstreaming opportunities. British Geological Survey Internal Report, OR/16/006. |
EO Information Products Delivered
Numerous data layers were incorporated into eleven map-based EO information products that were delivered through the implementation of three Services for disaster risk management in the Caribbean region. These Services are summarised in Table 1. Services 1 and 2 deliver key information — including landslide inventories, land use/land cover maps, elevation data and information on rivers and streams — for input to landslide and flood hazard assessments undertaken within the WB-led CHARIM project (van Westen, 2014)[1]. Service 3 delivers elevation information for input to flood hazard assessments for Belize, also undertaken within the CHARIM project. More detailed descriptions of the Services and their associated EO information products are provided in the following sub-sections along with associated Service Readiness information published in Jordan & Grebby (2014)[2] with Operational Documentation published in Jordan et al (2015)[3] and a Service Utility review published in Grebby et al (2015)[4].
| Service number | Service description | Service coverage |
| 1 | Land use/land cover mapping | St. Lucia Grenada St. Vincent and the Grenadines |
| 2 | Hazard mapping to support landslide risk assessment | St. Lucia Grenada |
| 3 | Digital Elevation Model | Belize |
Service 1: Land use/land cover mapping
The objective of Service 1 was to generate land use/land cover maps (including water features and road basic networks) for St. Lucia, Grenada, and St. Vincent and the Grenadines by exploiting recent high-resolution or very high-resolution optical satellite imagery. The mapping was undertaken using a combination of Pleiades (spatial resolution of 0.5 m panchromatic and 2 m multispectral) and RapidEye (5 m) satellite imagery, acquired from the relevant providers through the ESA Third Party Mission (TPM) scheme.
Service 1 demonstrates the ability to produce high-resolution land use/land cover maps remotely from EO data using a largely automated processing method. The primarily benefits of this approach are increased cost and time effectiveness in comparison to traditional field based mapping, and the ability to overcome terrain accessibility issues that commonly restrict field surveys in tropical environments and rugged terrain. The maps delivered by this Service provide a more contemporary snapshot of land cover/land use than the existing maps produced by The Nature Conservancy Mesoamerica and Caribbean Region project (Helmer et al., 2007[5]; 2008[6]), while also providing an order of magnitude increase in spatial resolution (2 m compared to 30 m). More detailed and recent land use/land cover information has been beneficial to the CHARIM project because it was used to better understand the factors controlling landslides and consequently improve the landslide susceptibility modelling. Beyond hazard risk, EO-derived land use/land cover information delivered by this Service has a wide spectrum of uses. For example, such information can be used for planning purposes, asset management and conservation. Given its semi-automated nature, the mapping approached implemented in this Service can be readily applied to monitor change over time.
Prior to delivery, the land use/land cover information products were quality checked and subject to an initial validation (Jordan et al 2015)[3]. Quality checking generally comprised evaluating whether the products satisfied the specified user requirements with regards to the minimum coverage of the areas of interest (AOIs) and thematic accuracy. The thematic accuracy of the land use/land cover maps was determined using the conventional remote sensing approach of deriving confusion matrices (Congalton, 1991)[7]. Specifically, the land use/land cover class identities of a sample of validation pixels in the map were compare with their ‘true’ land use/land cover class to compute the overall accuracy (i.e., the percentage of validation pixels correctly classified). The thematic accuracies were then further corroborated with the aid of observations made in the field during a 10-day visit to the region in October 2014. This involved visiting numerous randomly selected locations on the ground to cross-check the actual land use/land cover type with that on the map.
Ahead of delivery, the land use/land cover data was released to the CHARIM project partners at ITC for initial validation. This initial validation involved evaluating the suitability of the define land use/land cover classes for hazard assessment and checking for significant misclassifications or artefacts in the maps.
The EO information products delivered through Service 1 are described in Figures 1–3.
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Service 2: Hazard mapping to support landslide risk assessment
The objective of Service 2 was to generate ground-truthed landslide inventories and digital elevation models (DEMs) for St. Lucia and Grenada. The landslide mapping was undertaken using a combination of multi-temporal, pan-sharpened Pleiades (spatial resolution of 0.5 m) and RapidEye (5 m) satellite imagery, acquired from the relevant providers through the ESA TPM scheme. The DEMs were generated using ASTER stereo satellite imagery (30 m) in conjunction with ancillary elevation data (e.g., airborne LiDAR, contour heights, SRTM DEM).
Service 2 demonstrates the ability to utilise very-high resolution, multi-temporal optical satellite imagery for landslide inventory mapping. Implementation of this Service has led to the delivery of annual landslide inventories for St. Lucia for the period 2010–2014 and a single inventory for Grenada (also covering the same period). Mapping landslides remotely from satellite imagery is again far more time and cost effective than traditional field-based mapping, and it provides a means of readily accessing the inhospitable terrain in which landslides typically occur. The very-high resolution Pleiades satellite imagery offers advantages over satellite imagery with a more moderate spatial resolution (e.g., Landsat) because it enables small landslides (<100 m2) to be mapped in detail. Furthermore, the very-high resolution imagery provides sufficient detail to allow the generation of geomorphological maps that can be attributed with information such as the likely nature of deformation and a timeline of event progression. This Service also provides a practical means of monitoring landslide activity on an annual basis, which helps gain a better understanding of the landscape response to trigger events (e.g., hurricanes). Information on trigger event response, spatial distribution, magnitude-frequency, type of movement that can be obtained through this Service is very valuable for the development of landslide susceptibility maps and landslide risk assessments. Accordingly, the landslide inventories delivered in Service 2 comprised crucial information that was input to the landslide susceptibility modelling under the CHARIM project. Service 2 also delivered accurate national-scale 30 m DEMs generated from optical satellite imagery. This Service therefore demonstrates a cheaper, alternative approach to generating DEMs at this scale over large areas in comparison to ground-based GPS or airborne LiDAR surveys. The DEMs and derived information (e.g., slope, relief) are essential to both the landslide and flood risk assessments undertaken within the CHARIM project. The generation of 1 m DEMs was planned, but issues acquiring cloud-free Pleiades stereo satellite imagery during the Atlantic hurricane season meant that this could not be completed within the timeframe.
The landslide inventories were ground-truthed prior to delivery, by visiting the locations of potential landslides identified on the satellite imagery during a 10-day field trip to the region. Subsequently, the inventories were updated to remove any false positives that were confirmed during ground-truthing. The DEMs were validated by computing their vertical accuracies using GPS control points (St. Lucia) and high-resolution airborne LiDAR data (Grenada).
The EO information products delivered through Service 2 are described in Figures 4–9.
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Service 3: Digital Elevation Model
The objective of Service 3 was to deliver a national-scale DEM for Belize and as a demonstration, a high-precision DEM (for an area 100 km2) to support risk/hazard mapping. The national-scale 30 m DEM was generated using ASTER stereo imagery, while a higher resolution 20 m DEM covering 40% of the country was derived using SPOT-5 stereo satellite imagery. Pleaides tri-stereo (also refer to as triplet) satellite imagery, obtained through the ESA TPM scheme, was used to generate the high- precision 1 m DEM demonstration product.
This Service demonstrates the ability to generate both national and local-scale DEMs from optical satellite imagery with different spatial resolutions. In the absence of any other suitable elevation data, the 20 m and 30 m DEMs can be used as the basis for modelling flood risk at national-scale across Belize as part of the CHARIM project. Moreover, the precise DEM demonstration product derived from the very-high resolution Pleiades tri-stereo imagery can be used to more accurately model flood risk on a local-scale. With the ability to generate contemporary elevation data with a similar quality to airborne LiDAR, this approach represents a viable alternative to DEM production when airborne surveys are too costly or logistically challenging. Beyond flood risk modelling, high resolution DEMs such as this are important for infrastructure planning and resource management.
The DEMs delivered by this Service were quality checked for data gaps and artefacts, and rectified where necessary. In the absence of ancillary GPS or other control data, the national-scale 30 m DEM was validated using the higher resolution 20 m SPOT-derived DEM acquired from Airbus Defence & Space. The DEM was validated by computing the vertical accuracy using a subset of 32 000 randomly chosen elevation values from the 20 m DEM.
Due to issues acquiring cloud-free Pleiades tri-stereo satellite imagery during the Atlantic hurricane season, it was not possible to generate the 100 km2 high precision DEM until relatively recently. For this reason — in addition to the lack of any suitable GPS or other control data — it has only been possible to undertake a preliminary validation of the high precision DEM to date. As for the national-scale DEM, this involved computing the vertical accuracy using 32 000 randomly chosen elevation values from the 20 m DEM.
The EO information products delivered through Service 2 are described in Figures 10–12.
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Current user requirements
The EO products and Services delivered by this project address the issue of disaster risk management in the Caribbean region. Specifically, the Services deliver data products that are fundamental in helping to improve understanding of the risk posed by natural (geo-) hazards that frequently affect each country (Jordan et al, 2015)[3] (Table 2).
style="vertical-align:top;"|| Belize | Saint Lucia | St. Vincent and the Grenadines | Grenada | |
| Coastline | 386 km | 158 km | 84 km | 121 km |
| Terrain | Flat, swampy coastal plain; low mountains in south. Max. elevation 1160 m | Volcanic and mountainous with some broad, fertile valleys. Max. elevation: 950 m | Volcanic, mountainous. Max. elevation: 1234 m | Volcanic in origin with central mountains. Max elevation: 840 m |
| Natural hazards | Frequent, devastating hurricanes (June to November) and coastal flooding (especially in south). | Hurricanes and volcanic activity, debris flows, flash floods. | Hurricanes; Soufriere volcano on the island of Saint Vincent is a constant threat. Flash floods and landslides | Lies on edge of hurricane belt; hurricane season lasts from June to November. Flash floods and landslides. |
| Hazard characteristics | Hurricanes and tropical storms are the principal hazards, causing severe losses from wind damage and flooding due to storm surge and heavy rainfall. Hurricanes Keith (2000), and Iris(2001) caused some of the worst damage ever, reaching 45% (US$280 million) and 25% of GDP,respectively. | Saint Lucia’s mountainous topography coupled with its volcanic geology means that it experiences landslides, particularly in the aftermath of heavy rains. Much of the island’s housing is distributed along steep slopes and poorly engineered and constructed housing is particularly at risk. Additionally, the island periodically experiences earthquakes of generally lower magnitudes. Also storm surge and flash floods are among the other risks regularly faced by the island. | Landslides, particularly on the larger islands, are a significant hazard and the risk is increased during the seasonal rains. Coastal flooding is a major concern particularly relating to storm surge and high wave action. The Grenadines are more susceptible to drought. The active volcano La Soufriere, located on the north end of St. Vincent is another risk factor, posing threats from shallow earthquake and eruption events. Since 1900, St. Vincent has been hit by 8 named storms, the strongest being Hurricane Allen (Category 4), which passed between St. Lucia and St. Vincent in 1980. The 1939 eruption of the volcano Kick‐‘em‐Jenny located some 100 km reports South of Grenada, generated a 2‐meter high tsunami. | The country was heavily affected by Hurricane Ivan in 2004, and Hurricane Emily in 2005. There are two active volcanoes in Grenada, Mount St. Catherine in the centre of the island and the submarine volcano kick‐‘em‐Jenny is located 8 km north of the island and has led to tsunami in the past. Flood risk in Grenada is largely associated with storm surge in low lying coastal areas. Flash flooding from mountain streams coupled with storm surge events are the primary causes of flood events and effects are generally limited to communities located in the coastal margins along stream passages. Landslides are a common event in Grenada, with much of the impact experienced along the roadway network. |
The user requirements were determined by WB and the WB CHARIM project, and then used to define the Services in the SOW. In some cases, these initial requirements were refined slightly following subsequent discussions with the WB team (i.e., the WB TTL and CHARIM project) and BGS-stakeholder discussions in workshops held in the Caribbean and in the Netherlands (Jordan et al 2015)[3]. Overall, the Services are designed to support flood/landslide hazard mapping by providing essential data that is currently missing or inadequate due to limitations with the current practices. Specifically, the primary requirement is information on land cover/land use, water bodies (e.g., streams, rivers, lakes), landslides and elevation (i.e., DEMs). Acceptance of the Services by the users is therefore dependent on successfully demonstrating the capability to deliver EO products that provide information on these elements that is currently missing, or new information that represents a significant improvement over what already exists (e.g., in terms of accuracy, detail, time period). Further acceptance by the local users could also be dependent on them recognising the benefit of the EO products in applications beyond disaster risk management.
Service 1 provides comprehensive information on the main land use/land cover types, surface water bodies, basic road network and building footprints for St. Lucia, Grenada and St. Vincent and the Grenadines. Overall, the delivered EO products meet the requirements outlined in the SOW, and provide enhanced information that is considerably more detailed and up-to-date than already exists (Table 3). Although this can be implemented as an entirely stand-alone Service for land use/land cover mapping from optical satellite imagery, some aspects were augmented using ancillary baseline information (e.g., existing land use/land cover maps) in order to produce more accurate and consistent data for input to the risk assessment undertaken within the CHARIM project.
Service 2 delivered detailed landslides inventories and national-scale DEMs for St. Lucia and Grenada. The EO products fully meet the requirements, additionally providing yearly landslide inventories for St. Lucia. Although existing landslide inventories are available (see Table 3), the inventories delivered by Service 2 better capture the state of recent activity. Similarly, elevation data also exists, but is outdated, has a low spatial resolution or provides only partial coverage of the countries. Service 2 addresses this by generating DEMs with full coverage and the desired spatial resolution. The landslide inventory mapping aspect of this Service is stand-alone, as it was undertaken using information derived from the optical satellite imagery. However, as defined in the SOW, the mapping was ground-truthed using in-situ field observations. The generation of DEMs from optical satellite imagery can be implemented as a stand-alone process, but in this case was augmented with the existing elevation data to maximise the accuracy of the data for use in subsequent risk assessments.
Service 3 provides a national-scale DEM for Belize, in addition to a higher resolution regional DEM and a local-scale high-precision DEM. In contrast to Service 2, this Service is implemented as a stand-alone service for generating DEMs solely from optical satellite imagery. The resulting DEMs provide more accurate and higher resolution elevation information than currently available, therefore permitting enhanced flood risk modelling at national- and local-scale.
The EO information products delivered by the three Services are fundamental in assessing the flood and/or landslide risk in the four countries. However, these products must be used in conjunction with additional information (e.g., geology, soils, rainfall data) in order to robustly assess risk. Although beyond the scope of this project, optical satellite imagery and other types of EO data (e.g., radar) can be used to provide much of this additional information.
Current practices
There is a range of skills and experience amongst the local users, ranging from little or no use of geospatial data, to complex use and understanding (e.g., the University of West Indies). Table 3 lists the geospatial information currently being utilised by WB and local users through a variety of risk/hazard-related projects and initiatives in the Caribbean region. In general, flood and landslide hazard assessments to date have relied upon making the best use of any existing relevant geospatial data. However, much of this data is incomplete, generalised or somewhat outdated – with the historical data likely to have been produced through conventional means such as field surveys. Table 3 also highlights how the current project has utilised EO satellite data to help overcome limitations associated with the current practices and the availability of essential information.
In Grenada, risk mapping and GIS capability is managed predominantly by the Ministry for Agriculture, but progress is limited and digital data is relatively scarce. A vulnerability assessment of school buildings as shelters in the event of natural hazards has been completed (https://www.oas.org/CDMP/document/schools/vulnasst/gre.htm), but this did not consider landslides. Nonetheless, flooding due to torrential rain was considered, with the vulnerability assessment based on very generalised topographical and land use/land cover information gained through local field surveys. To date, a comprehensive multi- hazard map has not been prepared. The WB is implementing a Disaster Vulnerability Reduction Programme. Component 2 (Disaster and Climate Risk Reduction) of the Disaster Vulnerability Reduction Project which would consist of new construction and rehabilitation of existing infrastructure in order to reduce their vulnerability to natural hazards and climate change. Included within the activities are consultancy services to undertake soil investigation mitigation measures for landslip sites in several sites. In 2006, a landslide hazard map was produced by the Caribbean Development Bank/Caribbean Disaster Emergency Response Agency. This involved producing a landslide inventory based on limited field work confined locations accessible from the road network. This inventory was used in conjunction with a DEM-derivatives derived from a contour map and low quality (i.e., outdated and generalised) soil and geology maps (see Table 3) to model landslide susceptibility. Recently, an enhanced airborne LiDAR DEM has become available, but this does not provide full national coverage. A national flood hazard assessment was also undertaken by the Caribbean Development Bank in 2006, but this did not involve rigorous hydrologic/hydraulic analysis and its reliability will be hindered by the use of outdated and generalised input data (e.g., land use/land cover, soil map) that was likely mapped through field surveys.
| Geospatial information | Grenada | St Vincent and the Grenadines |
Saint Lucia | Belize |
| DEM | 10m raster DEM (source unknown) and partial LiDAR coverage | 5 m raster DEM (higher parts are not covered). There are LiDAR data, but the format is incorrect so they cannot be analysed | 50m raster maps and contours with 2.5 m intervals | ASTER (30 m) and SRTM (90 m). Higher resolution DEM urgently required for flood risk modelling. |
| 30 m DEM, full coverage | 30 m DEM, full coverage | National DEM at 30 m, 40% of territory at 20 m and 100 km2 at 1 m | ||
| Land use/land cover | USDA 30 m raster map from Landsat data from ca. 2000. | Polygon map exists with 11 land use classes (ca. 2000) | 1:50 000 raster maps. Vegetation information is in vector format | Not applicable |
| Derived from 2 m satellite data | Derived from 2 m satellite data | Derived from 2 m satellite data | ||
| Landslide inventory and hazard map | 1988: OAS study for selected towns. 2006: CDB/CDERA limited landslide inventory, not available digitally | Landslide footprints are available from 1987, but there is no detailed information. | Inventory for 1987 (USDA) and 2006 (CDB/CDERA). 2010 inventory produced from satellite imagery | Not applicable |
| Landslide inventory at 1:20 000 | Landslide inventory at 1:20 000 with key areas (< 50%) at 1:10 000 | |||
| Elements-at-risk | Non-attributed building footprints | Not available | Building footprints available for country-occupancy/structural type unavailable | Not available |
| Building footprints captured on 2 m land use/land cover map | Building footprints captured on 2 m land use/land cover map | Building footprints captured on 2 m land use/land cover map | ||
| Geological map | A very general one is available, made by USGS | A very general one is available, made by USGS | Vector map is available | Not applicable |
| Soil map | A 1959 soils report exists, but map not available | General soil map from USAID from 1990 | Vector map is available | General map has been scanned by ITC |
| Discharge data | Continuous stream flow data do not exist | None available | None available | None available |
| Geotechnical data | None available to date | None available | None available | Not applicable |
| Rainfall data | 50 stations, non-continuous data available from Land Use Division, Ministry of Agriculture, Lands, Forestry & Fisheries | None obtained thus far, but rainfall stations do exist | Hourly rainfall data for 24 stations | Missing |
| Socio-economic data | Missing | Missing | Missing | Missing |
In Saint Vincent and the Grenadines, progress in preparation of hazard maps is also limited. To date, risk mapping has largely focussed on volcanic risks and some coastal vulnerability analyses. A landslide inventory and susceptibility map exists (produced in 1987), but this was based on generalised and somewhat outdated input data (e.g., geology, elevation, land use/land cover) and therefore will not accurately reflect the current state. Similarly, past flood hazard assessments have been hindered by coarse DEMs derived from contour maps. In recent years higher resolution elevation data (e.g., airborne LiDAR) has become available from an unknown source, although the data is currently in a format that is usable. Basic GIS-ready maps of roads, contours, rivers, coastlines, agricultural & urban land use have been prepared — primarily available through the Ministry of Planning and the National Emergency Management Organisation (NEMO). The WB is implementing a Regional Disaster Vulnerability Reduction Programme. Components include identification and creation of required baseline data for hazard assessment; development of institutional systems for the collection, sharing and management of geospatial data among national agencies and with regional institutions; training and education in applications integrating geospatial data systems, hazard and risk assessment to support decision making within various sectors and mainstream the use of these tools as a standard practice in development planning.
In Saint Lucia, landslide inventories were produced in 1987 and 2006 through field reconnaissance. However, fieldwork was confined to areas accessible from the roadside and so the inventories do not provide an accurate reflection of the spatial distribution of landslide activity. Subsequently, the Caribbean Development Bank/Caribbean Disaster Emergency Response Agency produced a landslide susceptibility map from the 2006 inventory, but this was again based on low quality (i.e., outdated and generalised) soil and geology maps and elevation data. A 2010 landslide inventory is available, although this appears to have been generated through automated classification of bare ground on satellite imagery. Accordingly, the inventory contains many false-positive landslides owing to a lack of expert knowledge and interpretation. A landslide hazard map was produced in 2012, but this predominantly relates to debris flows and there is also some concern about the source and integrity of much of the input data. A national flood hazard assessment was also undertaken by the Caribbean Development Bank in 2006, but this did not involve rigorous hydrologic/hydraulic analysis and its accuracy will be hampered by outdated and generalised input data. The WB is implementing a Disaster Vulnerability Reduction Programme. Component 2 (Technical Assistance, Regional Collaboration Platforms for Hazard and Risk Evaluation, Geospatial Data Management, and Applications for Improved Decision-Making) would finance: a series of capacity-building, knowledge-building and technical assistance interventions at the national and regional levels to support disaster risk management and climate change adaptation. There are specific areas that have been identified and proposed as high priorities for intervention. At the national level, activities would include, inter alia: i) enhancement of national hydro-meteorological monitoring networks; ii) development of an integrated watershed management plan for flood mitigation; iii) technical assistance for the establishment of maintenance monitoring systems for bridges and public buildings that would integrate natural hazards and extreme events considerations; iv) establishment of geo-spatial data sharing and management platform and related training activities; and v) climate change adaptation public education and awareness campaigns. The GeoNode platform for Saint Lucia is accessible here: https://sling.gosl.gov.lc.
In Belize, a multi-hazard risk study was undertaken in 1999 for several districts as part of a support activity for NEMO. This study focusses on landslides, volcanic and storm hazards amongst others. This assessment appears to have been based largely on historical data, local reports of the occurrence of such events and basic GIS data. Although a nationwide flood hazard map based on hydrological modelling does not appear to exist, several local- or regional studies have focussed on the susceptibility of the road network flood and coastal flooding. Nevertheless, flood hazard mapping in Belize is hindered by the absence of a detailed and accurate DEM. Previous studies have restricted to using a coarse DEM generated from a 1:50 000-scale contour map with 20 m contour intervals. Belize is participating in the Central American Probabilistic Risk Assessment (CAPRA) platform, but the initiative remains modest in Belize.
References
- ↑ 1.0 1.1 van Westen, C J. (2014). Preliminary Assessment Report: CHARIM Caribbean Handbook on Risk Information management. ITC, University of Twente.
- ↑ Jordan C J and Grebby, S. (2014). Risk Information Services for Disaster Risk management (DRM) in the Caribbean: Service Readiness Document. British Geological Survey Open Report, OR/14/064. 31pp. https://nora.nerc.ac.uk/511674/
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Jordan C J, Grebby S, Dijkstra T, Dashwood, C and Cigna, F. (2015). Risk Information Services for Disaster Risk management (DRM) in the Caribbean: Operational Documentation. British Geological Survey Open Report, OR/15/001. 31pp. https://nora.nerc.ac.uk/511672/
- ↑ Grebby S, Jordan, C J and Dijkstra, T. (2015). Risk Information Services for Disaster Risk management (DRM) in the Caribbean: Service Utility Document. British Geological Survey Open Report, OR/15/061. 44pp.
- ↑ Helmer, E H, Schill, S, Pedreror, D H, Kennaway, T, Cushing, W M, Coan, MnJ, Wood, E C, Ruzycki, T, and Tieszen, L L. (2007). Forest formation and land cover map series-Caribbean Islands. U.S. Geological Survey/Earth Resources Observation and Science (EROS), Land Cover Applications and Global Change, International Land Cover and Biodiversity, Caribbean Land Cover Analyses.
- ↑ Helmer, E H, Kennaway, T A, Pedreros, D H, Clark, M L, Marcano-Vega, H, Tieszen, L L, Ruzycki, T R, Schill, S R, and Carrington, C M. (2008). Land cover and forest formation distribution for St. Kitts, Nevis, St. Eustatius, Grenada and Barbados from Decision Trees classification of cloud-cleared satellite imagery. Caribbean Journal of Science, 44, 175–189.
- ↑ Congalton, R G. (1991). A review of assessing the accuracy of classifications of remotely sensed data. Remote Sensing of Environment, 37, 35–46.