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Images, UC QuakeStudies

An aerial photograph of a residential area in Avonside. The photograph has been captioned by BeckerFraserPhotos, "The dominant road in this picture is Avondale Road which crosses the River Avon. To the left of this photograph is all zoned red apart from a small piece on the other side of the river. On the right-hand side of Avondale Road, some streets are zoned green although the streets closest to the river are red-zoned".

Videos, UC QuakeStudies

A compilation video of footage about the 4 September 2010 earthquake. The video includes footage of the damage to the central city, members of the police guarding cordons, residents at a Civil Defence Emergency Centre, a fire on Worcester Street, and aerial footage of New Brighton, the central city, and Homebush. It also includes an interview with local resident Quentin Garlick, and a press conference with Mayor Bob Parker outside the Christchurch Art Gallery.

Images, UC QuakeStudies

An aerial photograph captioned by BeckerFraserPhotos, "A view looking north-west over the central city towards Hagley Park. Hereford Street can be seen in the foreground, as well as Worcester Street running towards the the Christ Church Cathedral. The empty site of the Press Building and Warners hotel can also be seen".

Research papers, University of Canterbury Library

Land cover change information in urban areas supports decision makers in dealing with public policy planning and resource management. Remote sensing has been demonstrated as an efficient and accurate way to monitor land cover change over large extents. The Canterbury Earthquake Sequence (CES) caused massive damage in Christchurch, New Zealand and resulted in significant land cover change over a short time period. This study combined two types of remote sensing data, aerial imagery (RGB) and LiDAR, as the basis for quantifying land cover change in Christchurch between 2011 – 2015, a period corresponding to the five years immediately following the 22 February 2011 earthquake, which was part of the CES. An object based image analysis (OBIA) approach was adopted to classify the aerial imagery and LiDAR data into seven land cover types (bare land, building, grass, shadow, tree and water). The OBIA approach consisted of two steps, image segmentation and object classification. For the first step, this study used multi-level segmentation to better segment objects. For the second step, the random forest (RF) classifier was used to assign a land cover type to each object defined by the segmentation. Overall classification accuracies for 2011 and 2015 were 94.0% and 94.32%, respectively. Based on the classification result, land cover changes between 2011 and 2015 were then analysed. Significant increases were found in road and tree cover, while the land cover types that decreased were bare land, grass, roof, water. To better understand the reasons for those changes, land cover transitions were calculated. Canopy growth, seasonal differences and forest plantation establishment were the main reasons for tree cover increase. Redevelopment after the earthquake was the main reason for road area growth. By comparing the spatial distribution of these transitions, this study also identified Halswell and Wigram as the fastest developing suburbs in Christchurch. These results provided quantitative information for the effects of CES, with respect to land cover change. They allow for a better understanding for the current land cover status of Christchurch. Among those land cover changes, the significant increase in tree cover aroused particularly interest as urban forests benefit citizens via ecosystem services, including health, social, economic, and environmental benefits. Therefore, this study firstly calculated the percentages of tree cover in Christchurch’s fifteen wards in order to provide a general idea of tree cover change in the city extent. Following this, an automatic individual tree detection and crown delineation (ITCD) was undertaken to determine the feasibility of automated tree counting. The accuracies of the proposed approach ranged between 56.47% and 92.11% in thirty different sample plots, with an overall accuracy of 75.60%. Such varied accuracies were later found to be caused by the fixed tree detection window size and misclassifications from the land cover classification that affected the boundary of the CHM. Due to the large variability in accuracy, tree counting was not undertaken city-wide for both time periods. However, directions for further study for ITCD in Christchurch could be exploring ITCD approaches with variable window size or optimizing the classification approach to focus more on producing highly accurate CHMs.