Introduction
This study summarizes land-use/land cover (LULC) changes occurring in Delaware between 1984 and 1992. It is, in part, a follow-up to AES Bulletin 483, Land Use Transitions in Delaware, 1974-1984, published September, 1989, by Mackenzie. Complete results from this prior study are available in hardcopy.
The present analysis was undertaken by the Spatial Analysis Lab without external funding, and without any contractual commitments to statistical accuracy. Data inconsistences between the 1984 and 1992 LULC layers, and corrections of some of these inconsistencies, are discussed below.
An analysis of LULC changes between 1992 and 1997 has been completed by the Office of State Planning. The 1992 and 1997 data were developed from equivalent imagery sources using a consistent classification scheme, and have only minor registration errors.
1984 and 1992 Data
We are distributing the data used in this analysis in both a
UTM-18N
(NAD83) projection (based on GRS80 spheroid), and unprojected lat-lon
decimal degrees. All data are Arc Export (.E00) format, WinZipped.
The change analysis was performed on the UTM data. The unprojected lat-lon
decimal-degree data are mainly provided for use with ArcView, since ArcView
is incapable of reconciling any other format to a specified View projection.
The lat-lon files were processed by Jian Chen, UD Research Data Management
Service.
| UTM-18N (NAD83) | Unprojected (Lat-Lon decimal degrees) |
| New Castle Co. 1984 LULC (556K) | New Castle Co. 1984 LULC (679K) |
| New Castle Co. 1992 LULC (3.94M) | New Castle Co. 1992 LULC (3.44M) |
| New Castle Co. 1997 LULC (10.8M) | New Castle Co 1997 LULC (10.5M) |
| Kent Co. 1984 LULC (560K) | Kent Co. 1984 LULC (646K) |
| Kent Co. 1992 LULC (5.56M) | Kent Co. 1992 LULC (4.79M) |
| Kent Co. 1997 LULC (14.0M) | Kent Co. 1997 LULC (14.0M) |
| Sussex Co. 1984 LULC (1.00M) | Sussex Co. 1984 LULC (1.21M) |
| Sussex Co. 1992 LULC (8.40M) | Sussex Co. 1992 LULC (7.49M) |
| Sussex Co. 1997 LULC (19.2M) | Sussex Co. 1997 LULC (18.6M) |
The 1984 LULC series was developed by Earthsat Corp. under contract with the Delaware Dept. of Agriculture at resolution consistent with Landsat MSS satellite imagery (79-meter pixel size), using a modified 2-digit Anderson LULC classification scheme, with a 15-acre minimum mapping unit. The original data were in Delaware State Plane Projection, NAD 1927, in feet, based on Clarke 1866 spheroid.
The classification codes for the 1984 LULC series are:
10: undifferentiated urban 11: single family/duplex residential 12: multiple unit residential 13: mobile home residential 14: other residential 15: commercial/service/institutional 16: industrial 17: transportation/communication/utility 18: water-related recreation 19: other recreation 21: agriculture--confined feeding operation 22: other agriculture 30: brushland 41: deciduous forest 42: coniferous forest 43: mixed forest 50: wetland 61: river/canal/estuary/bay/ocean 62: pond/lake/reservoir 71: beach 72: other barren 80: other open/urbanThe 1992 and 1997 LULC series was developed by Earth Data (formerly PhotoScience) under contract with the State of Delaware. LULC polygons were digitized on 1-meter resolution digital orthophotos using a different modification of the Anderson LULC classification scheme, with a 4-acre minimum mapping unit. The original data were in Delaware State Plane Projection, NAD 1983, in meters, based on the GRS80 spheroid.
The classification codes for the 1992 and 1997 LULC series are:
110: RESIDENTIAL 111: single-family dwellings 112: multi-family dwellings 114: mobile-home parks 120: COMMERCIAL 121: retail sales/wholesale/professional services 122: vehicle-related activities 123: junk/salvage yards 125: warehouses 129: other commercial 130: INDUSTRIAL 140: TRANSPORTATION/COMMUNICATION 141: highways 142: parking lots 143: railroads 144: airports 145: communication 146: marinas/docks 150: UTILITIES 160: MIXED URBAN/BUILT-UP 170: OTHER URBAN 180: INSTITUTIONAL/GOVERNMENT 190: RECREATION 200: AGRICULTURE 211: cropland 212: pastures 213: idle fields 215: truck crops 220: orchard/nursery/horticulture 230: confined feeding operations 240: farmsteads/farm buildings 290: other agriculture 300: BRUSHLAND/RANGELAND 310: herbaceous rangeland 320: shrub/brush rangeland 330: mixed rangeland 400: FOREST 410: deciduous forest 420: coniferous forest 430: mixed forest 440: clear-cut forest 500: WATER 510: streams/canals 520: lakes/ponds 530: reservoirs 540: bays/coves 600: WETLAND (including forested wetlands) 700: BARREN 720: beaches 730: inland sandy areas 750: extraction areas 760: transitional/filled/graded areas
There are various inconsistencies between these data sources.
Both series were re-projected to UTM Zone 18 (meters) in ArcInfo, and then imported to GRASS for analysis. All maps were rasterized at 30-meter resolution. Wetland cells in the 1992 maps which were assigned to any forest category in the 1984 maps were re-assigned to that same forest category for 1992. The map series for both years were then reclassified to the following simplified scheme:
1: residential 2: commercial/industrial/infrastructure 3: recreation 4: agriculture 5: brushland 6: deciduous forest 7: coniferous forest 8: mixed forest 9: water 10: wetland 11: barren/beachAnalysis
A graphical frequency analysis of LULC categories in the two series was performed for each county, as well as for the northern and southern halves of New Castle County. The thumbnail .GIF images below access full-screen side-by-side LULC mappings for 1984 and 1992. Accompanying histograms are included to indicate aggregate acreages in each LULC category in the two mappings, and acreage changes occurring over the 8-year interval between them. These images are intended to provide a general idea of where the major transitions occurred in each county. (Use right mouse-click to save images to your disk.)
The following tables summarize acreage estimates in each aggregated category. NOTE: These are preliminary numbers only. Some percent change figures reflect significant classification inconsistencies. Acreage totals do not match mainly because of inconsistent treatment of water features.
These numbers indicate continuing rapid rates of conversion of agricultural and forest lands to residential and other urban uses in all three counties.
AGGREGATE LAND-USE/LAND COVER CHANGES, 1984 AND 1992 DELAWARE, BY COUNTY (PRELIMINARY ESTIMATES)
NEW CASTLE COUNTY--BELOW THE C&D CANAL:
1984 acres 1992 acres Change Pct. Chg.
1 residential 2,847
9,146 6,300 221%
2 comml/indl
596 1,847 1,251
210%
3 recreation
83 38
(45) -54%
4 agriculture 70,409
68,737 (1,671) -2%
5 brushland 1,806
1,526 (280) -16%
6 decid forest 26,085
21,667 (4,418) -17%
7 conif forest 432
291 (141) -33%
8 mixed forest 1,167
1,317 150
13%
[ all forest 27,684
23,274 (4,410) -16% ]
9 water
980 4,027 3,047
311%
10 wetland 17,069
12,535 (4,535) -27%
11 beach/barren 114
931 817
718%
(TOTALS) 121,587
122,061
NEW CASTLE COUNTY--ALL:
1984 acres 1992 acres Change Pct. Chg.
1 residential 41,845
55,506 13,661 33%
2 comml/indl 21,063
33,712 12,649 60%
3 recreation 5,482
5,788 306
6%
4 agriculture 105,812
88,617 (17,195) -16%
5 brushland 13,098
6,293 (6,805) -52%
6 decid forest 59,776
53,458 (6,318) -11%
7 conif forest 884
783 (101) -11%
8 mixed forest 1,506
2,719 1,213
81%
[ all forest 62,166
56,960 (5,206) -8% ]
9 water
2,531 7,534
5,003 198%
10 wetland 21,975
15,052 (6,923) -32%
11 beach/barren 1,239
6,725 5,486 443%
ALL NEW CASTLE CO 275,211 276,187
KENT COUNTY
1984 acres 1992 acres Change Pct. Chg.
1 residential 16,857
25,210 8,353
50%
2 comml/indl 9,119
11,735 2,616
29%
3 recreation
997 1,234
237 24%
4 agriculture 195,070
193,380 (1,690) -1%
5 brushland 3,914
2,085 (1,829) -47%
6 decid forest 99,432
59,061 (40,371) -41%
7 conif forest 2,162
14,306 12,144 562%
8 mixed forest 4,850
20,375 15,525 320%
[ all forest 106,444
93,742 (12,702) -12% ]
9 water
5,980 8,493
2,513 42%
10 wetland 44,203
43,377 (826)
-2%
11 beach/barren
0 3,366 3,366
--
ALL KENT CO. 382,584
382,622
SUSSEX COUNTY
1984 acres 1992 acres Change Pct. Chg.
1 residential 22,295
40,092 17,797
80%
2 comml/indl 6,862
13,909 7,047
103%
3 recreation 1,566
1,789 223
14%
4 agriculture 298,227
278,481 (19,746) -7%
5 brushland 26,857
14,578 (12,279) -46%
6 decid forest 55,616
24,822 (30,794) -55%
7 conif forest 63,865
49,514 (14,351) -22%
8 mixed forest 92,593
120,739 28,146
30%
[ all forest 212,074
195,075 (16,999) -8% ]
9 water
22,853 30,248 7,395
32%
10 wetland 29,898
42,855 12,957
43%
11 beach/barren 2,445
7,050 4,605
188%
ALL SUSSEX COUNTY 623,078 624,078
DELAWARE
1984 acres 1992 acres Change Pct. Chg.
1 residential 80,996
120,808 39,812
49%
2 comml/indl 37,044
59,356 22,312
60%
3 recreation 8,045
8,811 766
10%
4 agriculture 599,109
560,479 (38,630) -6%
5 brushland 43,870
22,957 (20,913) -48%
6 decid forest 214,824 137,342
(77,482) -36%
7 conif forest 66,911
64,603 (2,308) -3%
8 mixed forest 98,949
143,833 44,884
45%
[ all forest 380,684
345,778 (34,906) -9% ]
9 water
31,363 46,275 14,912
48%
10 wetland 96,077
101,284 5,207
5%
11 beach/barren 3,684
17,141 13,457 365%
ALL DELAWARE 1,280,872 1,282,887