Industrialised Peat Extraction Scoping Project. Technical Report & Results. from. University College Cork. November 2010

Transcription

1 Industrialised Peat Extraction Scoping Project Cataloguing of exposed peat soil areas identified on Peatlands of Ireland Mapped from Landsat Imagery (PIMLI) Technical Report & Results from University College Cork November 2010 Fiona Cawkwell, Rory Scarrott and Ned Dwyer

2 Contents List of Acronyms 3 List of Figures 3 List of Tables 3 Executive Summary 5 1. Introduction 6 2. Processing Tasks Local Authority boundaries pre-processing to remove artefacts Processing the PIMLI cloudmask Processing the PIMLI image date file Processing the PIMLI Obtaining a national vector shapefile of exposed peat soil 13 area polygons Creating a national reference file of exposed peat soil 14 locations Extracting and naming exposed peat soil areas over 50ha 16 in area 3. Results County and Local Authority summaries County maps and tables County Carlow County Cavan County Clare County Cork County Donegal County Dublin County Galway County Kerry County Kildare County Kilkenny County Laois County Leitrim County Limerick County Longford County Louth County Mayo County Meath County Monaghan County Offaly County Roscommon County Sligo County Tipperary North Tipperary Local Authority Area County Tipperary South Tipperary Local Authority Area County Waterford County Westmeath County Wexford County Wicklow Outputs summary References 184 2

3 List of acronyms EPA FIE GIS ING LA MIDA OSI PIMLI SRTM UCC Environmental Protection Agency Friends of the Irish Environment Geographical Information System Irish national Grid Local Authority Marine Irish Digital Atlas Ordnance Survey Ireland Peatlands of Ireland Mapped from Landsat Imagery Shuttle Radar Topography Mission University College Cork List of Figures Figure 1: Overall workflow of the project 8 Figure 2: Initial steps in pre-processing the EPA Local Authorities 10 shapefile Figure 3: Final steps in pre-processing the EPA Local Authorities 10 shapefile Figure 4: Missing local authority boundaries (Co. Tipperary), and the 11 distribution of boundary mismatch artefacts in the EPA Local Authorities of the Republic of Ireland shapefile Figure 5: The largest (5.4ha) sliver located between Carlow and Wicklow 12 Figure 6: Obtaining the area under cloud from the PIMLI cloud mask 13 Figure 7: Obtaining the area left from unmapped by the PIMLI map in 13 each Local Authority Figure 8: Obtaining an area-attribute polygon shapefile of all exposed peat 14 soil areas in the Republic of Ireland, as designated by the PIMLI Figure 9: Obtaining a shapefile of inter-la exposed peat soil areas, and 15 the point locations of all exposed peat soil areas nationally for all LAs Figure 10: Obtaining a shapefile of inter-la exposed peat soil areas, and 17 the point locations of all exposed peat soil areas nationally for all LAs List of Tables Table 1: County and Local Authority summaries of total area and area lost 18 due to data quality issues Table 2: County and Local Authority summaries of exposed peat soil areas 19 Report compiled by Mr. R. Scarrott, Coastal & Marine Resources Centre, University College Cork All enquiries relating to this project to be addressed to : Dr. Fiona Cawkwell, Department of Geography, Tel University College Cork, Fax Cork, Ireland. f.cawkwell@ucc.ie 3

4 Acknowledgements Friends of the Irish Environment would like to thank the Geography Department and the Coastal Marine Research Centre of University College Cork for their extensive work in producing the Peatlands of Ireland Mapped from Landsat Imagery (PIMLI) Reports and GIS products, all of which are available directly from our website or on request. We would also like to acknowledge the assistance of the Department of the Environment, Local Government and Heritage and the Comhar, the National Sustainable Development Council for their part in funding this work. project. Comhshaol, Oidhreacht agus Rialtas Áitúil Environment, Heritage and Local Government 4

5 Executive summary The Peatlands of Ireland Mapped from Landsat Imagery (PIMLI) dataset was processed to produce per-local authority summaries (statistics and maps) of exposed peat soil areas, for all county areas within the Republic of Ireland. A number of ancillary datasets were used to support this work, including Local Authority boundaries and the Bord na Móna bog works database. Data quality issues arising from the PIMLI (including percent identified cloud cover and the area left un-imaged) were accounted for in the local authority summaries. All data processing was undertaken using ArcGIS and ArcCatalog 9.3 software, and Microsoft Excel Included in this report are the county level summary figures for all exposed peat soil areas identified in the PIMLI. Details of their locations (in both Irish National Grid coordinates and latitude/longitude), any information available on their ownership, and their area are given for each exposed peat soil area. Furthermore, each exposed peat soil area covering an extent greater than 50ha in total has been given a named designation (derived from its Bord na Móna name, the name of its electoral district, a nearby highland area name, or nearby watercourse name), along with its association within groups of peat complexes (clusters of exposed peat soil areas near a pronounced landscape feature, or within a designated cluster of Bord na Móna peat extraction works). This report is accompanied by: 1) An excel workbook summarising the overall national area and information quality figures, and per-county summary figures for exposed peat soil areas over 50ha. 2) A suite of 4 GIS layer products, derived from the PIMLI map with explanatory metadata, sufficient to satisfy the requirements of the INSPIRE directive. These products are a. A national shapefile of all areas of exposed peat soil extracted from the PIMLI. Each segment is attributed with a unique National Identification Number and their area calculated. b. A point shapefile giving the centroids of every exposed peat soil region identified in the PIMLI. These have the unique National Identification Number, along with co-ordinates in the Irish National Grid and Geographic projections. c. A polygon shapefile of all exposed peat soil areas that straddle two Local Authority boundaries. d. A polygon shapefile of all regions of exposed peat soil over 50ha in size (both entirely within Local Authorities, and across Local Authority borders). Each region has been named according to a welldefined hierarchical structure, is assigned membership of an exposed peat soil complex, and has a unique number identifying it (that is different to the National Identification Number for all peat soil regions). 5

6 1. Introduction In 2009 University College Cork (UCC) was commissioned by Friends of the Irish Environment (FIE) to produce a national scale map of the Peatlands of Ireland Mapped from Landsat Imagery (PIMLI) acquired during the period (see Cawkwell, Dwyer and Scarrott, 2010, for details). The PIMLI is a raster-based image product comprised of pixels designated as exposed peatland, possible vegetated peatland or non-peatland. The PIMLI exhibited a high producer s accuracy (97.14%) with respect to the identification of exposed peat soils or peatlands. However, to be of maximum benefit to FIE, as well as to County Councils and regulatory bodies, the raster dataset needed to be converted to a vector dataset comprised of polygons representing the exposed peat areas, thereby allowing the data to be integrated with other vector datasets such as water bodies, for further spatial analysis. Furthermore, these exposed peat polygons needed to be catalogued on a county-by-county basis, with features such as their area calculated, and position recorded. The work entailed the following processing steps: 1) Vectorisation of raster dataset 2) Calculation of area of each individual exposed peatland polygon 3) For each county in the Irish Republic, creation of a summary spreadsheet containing: a. The central point location of every exposed peat soil area b. The area of every exposed peat soil area, subdivided into classes of <10ha, 10-30ha, 30-50ha and >50ha c. The name of a nearby townland, village or natural feature for all exposed peat soil areas >50ha 4) For each county in the Irish Republic, creation of a map containing all exposed peat soil areas, colour coded by size. The work was undertaken in UCC by Rory Scarrott, an expert in the Geographical Information System (GIS) tasks required to complete the necessary steps, and overseen by Dr. Fiona Cawkwell and Dr. Ned Dwyer. 6

7 2. Processing Tasks The overall workflow of the project to catalogue areas of exposed peatland for each Local Authority (LA) is summarised in figure 1. The date ascribed to the peatland boundary was determined from the raw Landsat imagery, and the extent affected by data loss (due to cloud cover or lack of imagery) calculated. The area of each LA was derived and the total area of exposed peat soil as evident in the PIMLI computed, in addition to that of individual contiguous regions of exposed peat soil. Discrete regions within each LA were mapped and located with a central identifying co-ordinate, with those above 50ha in area given a unique name. Areas of exposed peat soil that straddled Local Authority boundaries were highlighted, but prior to doing so the boundary shapefile defining LA boundaries had to be cleaned to remove artefacts that prevented further processing. All processing steps were undertaken using ArcGIS and ArcCatalog 9.3 software, with the exception of summary table compilation which was completed in Microsoft Excel Final map edits involved the use of Microsoft paint and Picasa Photo editor for optimal quality. A number of different datasets were used for this work, with many in the Irish National Grid projection, TM65 datum; namely the PIMLI, PIMLI cloud mask, PIMLI image date file, LA boundaries, Electoral districts, rivers database (from the Environmental Protection Agency), and the Bord na Móna bog works database. Elevation was derived from the Shuttle Radar Topography Mission (SRTM) raster dataset which was only available in geographic co-ordinates on the WGS84 datum. 7

8 Figure 1: Overall workflow of the project, showing the input datasets (yellow), the primary processing steps (blue), and the outputs which were then summarised in maps and tables provided in this report (green) 8

9 2.1. Local Authority boundaries pre-processing to remove artefacts The most accurate freely available dataset depicting LA boundaries, was the Local Authorities for Republic of Ireland map provided by the Environmental Protection Agency (EPA) via the Marine Irish Digital Atlas (MIDA) website. This dataset was produced in 2004 by the EPA, Ordnance Survey Ireland (OSI) and Compass Informatics Ltd., and was derived from an Electoral District dataset. On inspection it was realised that this dataset would need to be pre-processed (figures 2 and 3), to account for a number of artefacts (figures 4 and 5), namely that North and South Tipperary were defined as a single entity and, more significantly, there were a number of boundary mis-matches. A shapefile of the South Tipperary boundary was obtained with the kind permission of South Tipperary County Council. Checks confirmed that the shapefile shared a common boundary with that of the EPA LA dataset, which enabled the North Tipperary extent to be derived from the difference between the two datasets. The original County Tipperary element of the EPA shapefile was then replaced with the two Local Authorities, and the attribute table updated. This process is described in figure 2. The metadata for the boundary dataset indicated that the map was intended for boundary extent depiction only, but did indicate that there was a Slight boundary mismatch on Dublin City Council boundary. However further investigation revealed similar mismatches extending across much of the country (see figure 4). A total of 2623 boundary mismatches were identified, with an average area of 0.04ha (443m 2 ) and a standard deviation of 0.3ha (2604m 2 ). The largest boundary mismatch had a total area of 5.4ha, as shown in figure 5. To remove the boundary mismatch artefacts, the slivers of no data were converted into polygons and merged with the updated LA shapefile. Slivers were assigned to alternating Las along the boundary until all boundaries matched exactly, as described by the workflow in figure 3 and illustrated in figures 4 and 5. This updated LA shapefile was then used in all further steps requiring decisions on boundaries and areas. 9

10 Figure 2: Initial steps in pre-processing the EPA Local Authorities shapefile, Figure 3: Final steps in pre-processing the EPA Local Authorities shapefile including creation of separate North and South Tipperary local authority areas. to remove inter-local authority slivers of no data. 10

11 Figure 4: Missing local authority boundaries (Co. Tipperary), and the distribution of boundary mismatch artefacts in the EPA Local Authorities of the Republic of Ireland shapefile used in this project. 11

12 Figure 5: The largest (5.4ha) sliver located between Carlow and Wicklow Processing the PIMLI Cloudmask The main processing steps to obtain the figures for local authority areas that were unmapped in the PIMLI due to cloud cover, are outlined in figure 6. The process involved converting the raster cloud mask to a feature dataset (without generalising the lines), and merging the cloud polygons, whilst deleting the non-cloud polygons. The cloud area per LA was calculated, and the per-local authority cloud masks themselves were used in compiling the county summary maps. 12

13 2.3. Processing the PIMLI Image Date file The main processing steps to obtain the figures for local authority areas that were unmapped due to an image being unavailable during the construction of PIMLI, are outlined in figure 7. The split function in ArcGIS was used to subset the image into different date (and no image date) segments within each LA, enabling the magnitude of information loss to be associated with the per-la database. Figure 6: Obtaining the area under cloud from the PIMLI cloud mask Figure 7: Obtaining the area left from unmapped by the PIMLI map in each Local Authority area, due to a lack of available imagery Processing the PIMLI Obtaining a national vector shapefile of exposed peat soil area polygons The raster PIMLI (with pixel values of 1 = no peatland, 2 = suspected peat vegetation, and 3 = exposed peat soil) was converted to a vector polygon shapefile (lines were not generalised during the conversion). All polygons representing no peat, and suspected vegetated peatland were removed. The area of every exposed peat soil polygon was calculated, and each region given its own unique number identification. The process is summarised in figure 8. 13

14 Figure 8: Obtaining an area-attribute polygon shapefile of all exposed peat soil areas in the Republic of Ireland, as designated by the PIMLI Creating a national reference file of exposed peat soil locations A select by location query was run on the exposed peat soil polygon shapefile, seeking polygons whose boundaries intersected those of the updated LA shapefile. The search result was then extracted and saved as a new dataset of peatland regions which were not solely within a single LA. The centroid of each peat soil polygon was identified and designated the central identifier location point in Irish National Grid (ING) co-ordinates (which are comparable to most OSI maps). The centroid identifiers were also transformed into Geographic latitude/longitude co-ordinates based on the WGS84 datum, as described by figure 9. The final output was a database and shapefile of point locations for each exposed peat soil region in the Republic of Ireland in two commonly used co-ordinate systems. 14

15 Figure 9: Obtaining a shapefile of inter-la exposed peat soil areas, and the point locations of all exposed peat soil areas nationally for all LAs 15

16 Extracting and naming exposed peat soil areas over 50ha in area A select by attributes query was run on the exposed peat soil polygon shapefile, seeking polygons with an area greater than 50ha. This new dataset was then subset into LA regions, cutting larger inter-la exposed peat soil areas into separate fragments, and assigning each to different jurisdictions. With this in mind, a second ID number had to be assigned to this set of exposed peat soil segments. It must be noted that the national ID number described in section , and the >50ha ID number assigned here are NOT the same. The exposed peat soil polygons were named according to a well-defined hierarchy of data relevance (see figure 10) as follows: 1: The peatland was preferentially assigned the Bord na Móna bog name if it had one. In the case where a single Bord na Móna bog corresponded to more than one exposed peat soil region, the numbers 01, 02 etc. were appended onto the end of the name. For clarity however, all exposed peat soil areas were given a number suffix regardless of whether they were part of a cluster. Furthermore, if a single exposed peat soil area straddled an inter-la boundary, the segments were given the required name and number of the bog, and letters (a,b,c etc.) after the number in lower case. Finally the exposed peat soil name was suffixed with the Local Authority code in upper case, for example Glenlough01aWH corresponds to the Bord na Móna bog complex called Glenlough, it is segment number 1 and straddles a LA border, but this entry in the database corresponds to the part within Westmeath (the Longford entry reads Glenlough01bLD indicating that it is the Longford component of the same entity). 2: Exposed peat soil areas over 50ha which did not correspond to an official Bord na Móna site were referred to using the Electoral District name in which they were found. In cases where more than one exposed peat soil region existed within an electoral district, the numbers 01 and 02 were appended onto the end of the name for clarification, but again all exposed peat soil areas were given a number suffix regardless of whether they were part of a cluster. Furthermore, if a single exposed peat soil area straddled an inter-la boundary, the fragments were given the required name of the Electoral District, and lower-case letters (a, b, c etc.) were appended after the number to indicate that it was a fragment of a trans-boundary exposed peat soil area. Finally the exposed peat soil name was suffixed with the Local Authority code in upper case, for example Knockarrow01WH. The named exposed peat soil areas were then aggregated into clusters known as complexes. This was done based on a number of preferential factors: 1: Those bogs that were part of a Bord na Móna scheme, were assigned to a complex bearing the same name as the works program. 2: If the exposed peat soil area was not part of a Bord na Móna works program, it was first assigned a name based on the local area of high ground. A 90m resolution digital elevation model was classified into 100m altitudinal zones to provide a simple highland map of Ireland which was cross-referenced 16

17 with hillwalking field guides to identify the names of highland areas. This name was then assigned to any exposed peat soil areas lying within it (e.g. Wicklow Mountains Complex). 3: Lastly, those exposed peat soil areas that were not part of the Bord na Móna works program and did not lie on a highland area were aggregated into complexes adopting the names of a nearby watercourse. The EPA river database found on MIDA (mida.ucc.ie) was used for this purpose with the nearest watercourses visually located, and the complex of exposed peat soil areas then adopted the appropriate name (e.g. Owenacharra River). The named exposed peat soil polygons were then linked with their centre point location identifiers and the final polygon shapefile was updated to allow complete cross-referencing. This shapefile was used to compile the necessary maps, whilst the database attribute files allowed for information to be extracted on each exposed peat soil area, tabulated and presented in the results section. Figure 10: Obtaining a shapefile of inter-la exposed peat soil areas, and the point locations of all exposed peat soil areas nationally for all LAs 17

18 3. Results 3.1. County and Local Authority Summaries Table 1 shows the per-local Authority summaries on data quality within the PIMLI and table 2 the per-local Authority figures on exposed peat soil areas, including a breakdown of the total exposed peat soil areas within each area category (under 10ha, between 10-30ha, between 30-50ha, and over 50ha). Each LA code is also presented, derived from the codes affixed to car registration plates where possible, but in some cases (the Dublin local authorities), the code is an abbreviation of the LA name. Per-county figures can be derived from summing the component LA values. Table 1: County and Local Authority summaries of total area and area lost due to data quality issues 18

19 Table 2: County and Local Authority summaries of exposed peat soil areas 19

20 3.2. County Maps & Tables Maps and tables generated for each county are presented, listed in alphabetical order. A table summarising regions of exposed peatlands greater then 50ha in size, with their Unique County Number (UCN), name, associated exposed peat complex, area and the coordinates of the centroid point (the IDs in this table relate to the locators in map (iv), not the other maps). Map (i) The point location of all exposed peat soil areas greater than 10ha in size found entirely within the county, or straddling its boundary. The national point database contains the locations of all exposed peat soil areas, but for clarity of display purposes, those below 10ha were removed. The numbers on the map link with the National Identification Number (NIN) in the accompanying excel sheet database. All are available in the product GIS layer file for further examination in a GIS. Map (ii) A map of those peat soil areas within the county boundaries, graded by size. Map (iii) A map of those exposed peat soil areas that straddle the county (and component local authority) boundaries. Map (iv) A map of exposed peat soil areas over 50ha in extent (or component fragment if the peat soil area crossed the county boundary) and its Unique County Number (UCN) designation. The unique number designation links the exposed peat soil area to its description in the table, and to the appropriate within county description in the accompanying excel sheet. All are available in the product GIS layer file for further examination in a GIS. Map (v) A map showing the image dates (or areas where no data was available from the PIMLI due to lack of an available Landsat image), of the county area. 20

21 County Carlow Table associated with Map (iv) 21

22 22

23 23

24 24

25 25

26 26

27 County Cavan Table associated with Map (iv) 27

28 28

29 29

30 30

31 31

32 32

33 County Clare Table associated with Map (iv) 33

34 34

35 35

36 36

37 37

38 38

39 County Cork Table associated with Map (iv) 39

40 40

41 41

42 42

43 43

44 44

45 County Donegal Table associated with Map (iv) 45

46 46

47 47

48 48

49 49

50 50

51 County Dublin Table associated with Map (iv) 51

52 52

53 53

54 54

55 55

56 56

57 County Galway Table associated with Map (iv) 57

58 58

59 59

60 60

61 61

62 62

63 County Kerry Table associated with Map (iv) 63

64 64

65 65

66 66

67 67

68 68

69 County Kildare Table associated with Map (iv) 69

70 70

71 71

72 72

73 73

74 74

75 County Kilkenny Table associated with Map (iv) 75

76 76

77 77

78 78

79 79

80 80

81 County Laois Table associated with Map (iv) 81

82 82

83 83

84 84

85 85

86 86

87 County Leitrim Table associated with Map (iv) 87

88 88

89 89

90 90

91 91

92 92

93 County Limerick Table associated with Map (iv) 93

94 94

95 95

96 96

97 97

98 98

99 County Longford Table associated with Map (iv) 99

100 100

101 101

102 102

103 103

104 104

105 County Louth Table associated with Map (iv) 105

106 106

107 107

108 108

109 109

110 110

111 County Mayo Table associated with Map (iv) 111

112 112

113 113

114 114

115 115

116 116

117 County Meath Table associated with Map (iv) 117

118 118

119 119

120 120

121 121

122 122

123 County Monaghan Table associated with Map (iv) 123

124 124

125 125

126 126

127 127

128 128

129 Table associated with Map (iv) County Offaly 129

130 Table associated with Map (iv) 130

131 131

132 132

133 133

134 134

135 135

136 County Roscommon Table associated with Map (iv) 136

137 137

138 138

139 139

140 140

141 141

142 County Sligo Table associated with Map (iv) 142

143 143

144 144

145 145

146 146

147 147

148 County Tipperary North Tipperary Local Authority Area Table associated with Map (iv) 148

149 149

150 150

151 151

152 152

153 153

154 County Tipperary South Tipperary Local Authority Area Table associated with Map (iv) 154

155 155

156 156

157 157

158 158

159 159

160 County Waterford Table associated with Map (iv) 160

161 161

162 162

163 163

164 164

165 165

166 Table associated with Map (iv) County Westmeath 166

167 167

168 168

169 169

170 170

171 171

172 County Wexford Table associated with Map (iv) 172

173 173

174 174

175 175

176 176

177 177

178 County Wicklow Table associated with Map (iv) 178

179 179

180 180

181 181

182 182

183 183

184 4. Outputs Summary Summary maps for all 26 counties of the Republic of Ireland have been generated. These are accompanied by summary figures describing the extent of exposed peat soil within each Local Authority s jurisdictional area. Four GIS layers were generated to accompany the PIMLI product set. These are: o A national shapefile of all areas of exposed peat soil extracted from the PIMLI. Each segment is attributed with a unique National Identification Number and their area calculated. o A point shapefile giving the centroids of every exposed peat soil region identified in the PIMLI. These have the unique National Identification Number, along with co-ordinates in the Irish National Grid and Geographic projections. o A polygon shapefile of all exposed peat soil areas that straddle two Local Authority boundaries. o A polygon shapefile of all regions of exposed peat soil over 50ha in size (both entirely within LAs, and across LA borders). Each region has been named according to a well-defined hierarchical structure, is assigned membership of an exposed peat soil complex, and has a unique number identifying it (that is different to the National Identification Number for all peat soil regions). The agreement has been made that these four shapefiles comprise the final GIS products of the project. Their metadata has been compiled to a level that is compatible with standards set under the INSPIRE directive and are referenced to this technical report. Finally, an artefact was found to be present in the cloud mask accompanying the PIMLI. This issue has now been corrected for the purposes of this project. 5. References Cawkwell, F., Dwyer, N. and Scarrott, R. (2010) Final report on the use of remote sensing to evaluate the potential of identifying exposed and vegetated peatlands in the Republic of Ireland, unpublished project report, 35pp. Also available at: peatland_scoping_project.pdf 184