You don't need to slog around in Xtra- Tufs to see how Homer's coastline has changed. This week, Kachemak Bay Research Reserve delivered to the city of Homer a draft report of "Homer Coastal Changes," an analysis of aerial photographs from 1951 to 2003 showing how the coast has eroded over the past 52 years. The report was produced under a state Coastal Impact Assessment grant.

Carey Meyer, director of Public Works for the city of Homer, said the final report is due later this month. The aerial photograph analysis also is being incorporated into the city's Geographic Information System. Visitors can now see a PowerPoint slide show with highlights of that report at the Alaska Islands and Ocean Visitor Center.

Oceanographer Scott Pegau and research analyst Steve Baird produced "Homer Coast Changes" using aerial photographs of Homer from 1951, 1961, 1968, 1975, 1996 and 2003. Photographs from 1984 will be added later. Some photographs lack fine resolution, while in more recent photographs, "You can look in the back of a pickup and see how many buoys are there," Pegau said.

Pegau and Baird adjusted digitally scanned images so they all had the same scale and projection, a process called rectifying. They used reference points like buildings and road intersections, although that presented problems.

"So many roads that existed in 1961 didn't exist in 1996," Pegau said. "As they smooth the roads out, we lose the corners we were using for reference."

The researchers looked at changes in the bluff edge from west of Overlook Park below the Baycrest Hill Turnout to just east of Miller's Landing at Kachemak Drive. The coastline -- where the beach meets the sea -- varied in photographs because of the tides, and was also less distinct. In some cases the bluff edge appears to increase because vegetation sloughs off the edge and revegetates below the old bluff line.

"There's no new beach," Pegau said.

West of the Homer Spit, the bluff eroded at an overall rate of 2.64 feet a year. East of the Spit, the bluff eroded at 1.98 feet a year. Common wisdom had it that the coastline from Mud Bay at the base of the Homer Spit to Miller's Landing at the end of Kachemak Drive didn't erode as much. That proved to be false, Pegau said.

While the 1964 Alaska Earthquake caused land to drop from 4 to 6 feet, from 1961-68 erosion slowed down, speeding up in 1968-75, Pegau noted.

"It took a little while for the toe of the bluff to eat away," he said.

The most extreme erosion is at Overlook Park, Pegau said. The bluff eroded at an overall rate of 4.95 feet a year, or 257 feet in 52 years, with a maximum rate of 20.46 feet a year. The bluff below Lampert Lake on Kachemak Drive eroded most slowly, at an overall rate of .132 feet a year, or 6.8 feet overall, with a maximum rate of 2.97 feet.

Munson Point, the area along Ocean Drive Loop where the new seawall was built, eroded at a rate of 5.61 feet a year, or 291 feet in 52 years, at a maximum rate of 9.51 feet a year. Part of Munson Point was excavated for gravel during World War II to build the Homer Airport. The report shows the coastline both inside and outside of the gravel pit.

Areas with a southwest orientation generally eroded the most, Pegau said. Those areas take the prevailing southwesterly storms head on. One oddity is that the western tip of Munson Point hasn't had a high erosion rate, while the beach east of it has eroded at a higher rate. Removing gravel probably caused most of the erosion along that area, Pegau said.

He noted the analysis looks at general trends and that some individual lots might experience erosion at different rates. The city's GIS system shows information like parcel lot lines and ownership. Pegau and Baird didn't analyze causes of erosion, only changes in the bluff edge.

Although the study focuses on bluff erosion, the aerial photographs also show how Homer has changed over the years. A 1951 aerial photograph of Bishop's Beach shows Ohlson Lane intersecting the south end of Main Street and continuing down to the beach. Today, Ohlson Lane and Main Street end at the bluff edge. The aerial photograph also shows cabins on land now underwater.

"There's a lot of potential to look a historic patterns," Baird said. "But we were just looking at the bluff edge."

Meyer said the study came about from the recommendations of the Beach Policy Task Force. The task force suggested doing an ecological profile of the shoreline.

"What are our beach resources and how to protect them?" Meyer said the task force asked.

"Homer's Coastal Changes" is one part of a three-part study to analyze the city's coastline. KBRR also is mapping salt marshes and doing a physical habitat map. Baird and Pegau have walked every mile of Homer's beaches -- and most of about 320 miles of the Kachemak Bay coastline.

Meyer said he was surprised at how consistent erosion has been since 1951. He also found the changes at the end of the Spit to be fascinating. Probably the most dramatic change is the construction of the Homer Harbor -- nonexistent in 1951.

"It's really an interesting look at the end of the Spit," he said. "There's been an amazing change from the human perspective."

Meyer said with the KBRR analysis added to the city's GIS, the city's planning capabilities will be improved.

"It's becoming an incredibly powerful tool for the city to plan whatever we're going to do," he said. "Having aerial photographs of the community back to 1951 will be of value. That information will help solve problems and gain some insight."

After the budget is finished in December, Meyer said he would present the report to the Homer City Council.

It will be available at the Homer Public Library and the Planning Department, and eventually be accessible on the city's Web site. The city plans to have available for sale a map showing the changes in coastline for all the years analyzed.

Michael Armstrong can be reached at michael.armstrong@homernews.com.