Over preco chrbaty stracali elevation ale peaky narastali pre M2 a E

Editor:
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D p.23 llt should be LLC

D resolve Main - main, ...

Dr. Whittekar:
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D Graber 53 is the same as US Coast and GeodSurvey, 1955, changed to Graber 

D Fisher in press was be updated to:
Fisher, P. F., Wood, J., Cheng, T., 2005. Fuzziness and Ambiguity in Multi-scale 
Analysis of Landscape Morphometry. In: Petry, F.E., Robinson, V.B., Cobb, M.A. (Eds.),
Fuzzy Modeling with Spatial Information for Geographic Problems. Springer, NY, pp. 209-232.

D NOAA 2004  see Havholm #5.

D Figure 4a,c fixed units (deg, m2)

D Figures 6,7 caption changed to:
...area change for the active dune sub-region with elevation z > 6 m and no vegetation.
...Overlay of active dune surfaces (sub-regions without vegetation where elevation z > 6 m),...

Dr. Havholm
-----------

Figure 10 was included with additional information about the location and
impacts

M,R #1. Title was changed to: 
     GIS Modeling and Analysis of the Coastal Sand Dune Field Evolution:
     Jockey's Ridge, North Carolina

M #2. Abstract TODO

D p.4 #3. the relevant section was modified as follows:
For each month of the year, the eighteen-year average of the mean monthly wind speed 
exceeded 4.5 m/s critical velocity needed to move the sand.  In addition, 
the annual wind rose for 1982-1999 indicates that stronger winds (7-20 m/s) 
from the north and northeast are more frequent (USACE FRF, 2004), resulting 
in greater sand transport to the south and southwest. This conclusion is also 
supported by the sand transport rose for 1980-1991 in Fig. 1 by Havholm et al., 2004.

D p.5 #4. Modified sentence
... GIS database with multitemporal data layers representing topography 
and its properties (slope, curvature, peaks, etc.) was established. 

D p.6 #5. The NOAA reference to Historical Charts Archive was changed as follows,
so no a,b was needed for NOAA references:
NOAA Office of Coast Survey, 2004. Historical Map & Chart Collection. 
Online document, http://historicals.ncd.noaa.gov/historicals/histmap.asp

D p.7 #6. The sentence was simplified as follows:
The vertical accuracy of the data is 0.06 m for spot elevations and the
horizontal accuracy 0.30 m.

D p.9 #7. The sentence "Similar values ..." was removed - it was not needed.

D p.10 #8. see also #18  Section 3.3 Topographic analysis
  was modified to explain the 6m threshold:
  the first sentence was changed to:
  Topographic analysis was used to identify the features defining the dune's location 
  and geometry: peaks, slip faces, active crests, windward side ridges, 
  and active dune areas (Fig. 4).

  In the subsection "Peaks" the reference should be to Fig. 5A

  A subsection was added for the active dune area derivation:
  3.3.4 Active dune area
  Visual analysis of contours, generated from the DEMs at 0.3 m (1 ft) interval and displayed
  along with elevation and slope maps, was used to identify a threshold elevation 
  that defines the active dune area. Topography below this threshold flattens and 
  includes only small, mostly stable vegetated features. Elevation surface 
  above the threshold has typical dune geometry and bare sand.
  For all models (1974 - 2001) this threshold elevation was found to be 6 m (18 ft). 
  For the 1999 model, the elevation threshold had to be combined with land cover
  derived from the 1998 aerial photography to eliminate trees and buildings.
  Map algebra was then used to compute the active dune models as subregions with elevation
  z > 6 m that were used for computation of volume and area in Fig. 6B and 
  for dune surface overlays in Fig. 7. 

H p.11 #9. There is subtle shading as in a, c, d, I may re-do it to make it more visisble

D p.11 #10. Subsection Dune ridges was modified as follows (this also answers #27)

  ... an alternative method based on the density of slope lines 
  (lines in the direction of surface gradient, perpendicular to contours) generated 
  uphill from each grid cell was used (Mitasova et al., 1996). This approach is an inverse 
  version of the flow accumulation algorithm commonly used for extraction of streams
  (e.g., Tarboton, 1997) where slope lines are traced downhill from each cell
  and cells with slope line density (flow accumulation) exceeding a given threshold
  define the stream network. To extract ridges, slope lines  
  were generated uphill using a D-infinite (vector-grid) 
  algorithm (Mitasova et al., 1996) to avoid artificial patterns produced by 
  the standard D-8 methods on smooth surfaces typical for dunes.  
  The ridges were then extracted as grid cells that had the number of slope lines 
  passing through them (slope line accumulation) > 600 (Fig. 4C). 
  The average slope of the windward side of the dunes was then computed 
  by manually defining representative windward profiles 
  along these ridges, extracting slope values along the profiles from the slope
  maps and computing the average value for each dune (Fig 4C insert).

M p.11 #11. find and add the references here, otherwise leave as is.

D p.11 #12. yes, it should be Fig. 6A

D p.11 #13. The first paragraph of section 3.4 Quantification of the dune
change was rewritten as follows:
  ...
    Jockey's Ridge, as a complex dune field that includes individual dunes with
  different heights and morphologies, has a spatialy and temporaly variable migration,
  growth, and deflation rates (Fig. 6). To quantify its evolution, 
  an approach based on topographic analysis of
  elevation surfaces that involves extraction of dune features and
  measurement of the change in their location was used (Fisher et al. 2005)
  High resolution digital elevation models (DEMs) and GIS tools make
  such analysis feasible and effective.

D p.12 #14. The sentence was removed because it did not fit well with the rest
of the text and the described method was not used in this paper.

D p.12 #15. Fisher et al. reference was fixed, as the book chapter was
pulished in 2005

D p.13 #16. the sentence was modified as suggested
 To quantify the rate of lateral dune migration, the shortest distance between
two consecutive locations of windward side ridges, as defined by slope line
densities (Fig. 4C), was measured.

D p.13 #17 To clarify, the sentence was modified as follows:

Change in the shape and size of crests and ridges contributed to uncertainty in the
measurements; therefore, each distance was measured six times and an average
value was computed. The standard deviations of these averages did not
exceed 3 m. 

D p.13 #18 The 6m threshold is explained in methods, see #8, the sentence was
further modified as follows

Volume change was computed as a difference in volumes estimated 
for the active dune sub-regions (see section on Topographic analysis).
Similarly, area change was computed as a difference in areas defined
by the same active dune sub-regions.

D p.13 #19 The misplaced reference to Fig. 7 was fixed:

... confirms prevailing southern migration of the entire dune field (Fig. 7)
accompanied by dune deflation.

D p.13 #20 sand transport rose

Apparently, the overall direction of dune migration to the SW is not dictated
by the long-term mean wind orientation (winds from the SE).  Rather, as shown
by the sand transport rose presented by Havholm et al. (2004), 
it is is the higher frequency of stronger winds 
from NE (see also USACE FRF, 2004) that lead to the prevailing SW direction of 
the potential sand trasport. 

D p.14 #21 USACOE changed to USACE FRF

D p.14 #22 South dune was removed from the third sentence in this paragraph
to avoid repetition.

D p.15 #23 paragraph modified to correctly reflect the figure 5b as follows:
(we are very grateful to Dr. Havholm for catching this mistake - for
explanation, this paragraph was written before the horizontal shift
in data due to different datums was fixed, we checked the rest of
the results to make sure that they reflect the corrected data). 

The horizontal dune movement was reflected in the main peak migration in the
southeast direction between 1953 and 1995, with an eastward turn between
1995 and 1998, then becoming more south-southeast direction
in the following years, with the exception of 2001-2002 time interval,
when the peak moved westward (Fig. 5B).  The peak migrated 
225 m over 50 yr period.

D p.15 #24 The paragraph was reformulated to more accurately
describe the horizontal migration rates

Between 1974 and 2004, the prevailing movement of slip faces was in the S/SW
direction at average annual rates between 2.8 m for the west dune and
6.3 m for the fastest moving east dune. The ridges moved in
a S/SE direction.  As expected, the lower east and south dunes were moving
faster than the higher main dune (Fig. 7A), reaching the rates of migration 
over 10 m/yr for the time interval 1998 - 1999.

D. p.16 #25 the sentence was modified to describe the evolution of the angle
between the windward side ridges and the crests;

The angle between the windward side ridges and dune crests,
measured clockwise from the ridge line,
was relatively stable for the main and west dunes, 
ranging between 110 - 120°. For the east dune, this angle changed gradually
from 100 in 1974 to 130° in 2001.

D p.17 #26 the sentence was modified as follows

Elevation on the windward side ridges never increased, except for a very short
period between 1998 and 1999, indicating that the dune ridges have been
steadily losing elevation at least since 1974.
add ref to figure 8d if it is redone for 1974-2001

D p.17 #27 the description of slope measurement was added to methods section
(see #10):

M p.19 #28 I think that this paragraph covers the possibility that it was 
anthropogenic.

M p.20 #29 Wright photos - we can take them out or use different ones,
that show more sand than one could see now.

D p.21 #30  The following sentence was added:

As the sand supply is reduced, transformation of the dunes 
into parabolic shape begins to take place, a process that has been 
documented for numerous locations (Havholm et al., 2004),
including the False Cape dunes in Virginia (Hennigar, 1977).

should we mention here that the dune field is being transformed
from a dune field with a dominant main dune to system of a sand hills
with similar elevation at 20m???

D p.21 #31 nothing needed for this one

D References were fixed and the following two were added:
============

Tarboton, D. G., (1997), "A New Method for the Determination of Flow
Directions and Contributing Areas in Grid Digital Elevation Models,"
Water Resources Research, 33(2): 309-319.

Hennigar, H.F., 1977. Evolution of coastal sand dunes: Currituck spit, VA/NC.
In: Coastal Processes an Resulting Forms of Sediment Accumulation,
Currituck Spit VA/NC, Virginia Institute of Marine Science SRAMSOE No. 143,
pp. 403-422

M Table 1  Margery please finish this to ensure proper formatting:
=========

Adjust formatting as suggested by editor (horiz. lines need to be inserted), 
Dr havholm suggested to add annual rates - it makes the table little too
busy (she has actually computed the rates in her review)
my comment:
The fact that the East dune is growing casts doubts at the 
theory of crescent - > parabolic - > stabilization sequency, although
it is most likely due to installed fences (I need to write George
when did they install them)

Figure Captions
===============

D Figures

D Figure 4 units on the legend were fixed for slope and added
for slope line density (square m), the 2001 year was added.
Shading in 4b was slightly enhanced  and show that it is draped 
over topography. Insert was added to 4C to illustrate computation
of average windward slope.

D Figure 6 caption was modified to include more information
about the migration measurements

D Figure 7 was re-organized, more info was added to the caption and 
colors were changed on insets.

D Figure 8 legend was repeated for A, B

D Figure 10 Map showing the location of management actions was added,
as well as a view from the east close to ground highlighting the change
in he main dune between 1974 when the park was established and 2001.

several BW figures were lightened


Authors changes
===============
1. East dune peak elevation change added in Table 1 and section 
4.2 Peak change. We did not analyze the east dune peak elevation 
in the original manuscript and we missed the fact that it has grown
over the past 6 years (this was suggested by the hang gliding instructor
at our recent visit there.). Any references to peak elevation decline 
were changed to main peak elevation decline

Changes after it was emailed to Margery
=======================================

Rename 3.3.3 to Windward side dune ridges

Tasks for modeling:

1. why the dune has grown so large in this particular place and time
and can we generalize to guide land use management in other aeas?

2. can the dune grow if the source area is kept clear of vegetation?

r.sum source area for main dune=45000ft x 400sft=18mil cft=60000 cubic yards?
                                  13700m

the dune might have grown after the fencing in 30s as described by Hennigar 77
for dunes to the north?