Rudolph's criticisms of our manuscript stem from a misunderstanding of the design of our study and a motivation to defend the Bogue Banks, North Carolina, monitoring program. Before we address the criticisms, it is important to make clear that Bogue Banks is only used as an example in Theuerkauf and Rodriguez (2012) because it is close to the study area (Onslow Beach, North Carolina) and has a similar morphology as the northern end of Onslow Beach, and pre- and post-storm monitoring using beach profiles were conducted there. The intention was not to single out the Carteret County beach management program as being subpar or as an example of a choice of survey design that is worse than any other beach-monitoring program. We did not perform a comprehensive examination of beach management efforts and cannot comment on how management of Bogue Banks measures up to other programs around the world; that is way beyond the scope of our study. We stand by our statement: “The large spread of volumetric change measurements from profile surveys in our study suggests that survey design [the survey design employed on Bogue Banks to calculate the volume of beach eroded from hurricane Ophelia] is not suitable for making measurements of beach volumetric changes for beach research and management” (Theuerkauf and Rodriguez, 2012, p.716). We appreciate this opportunity to reiterate some aspects of our study that were ignored or not understood by Rudolph.

The intent of our paper was not to look at dune morphology or nearshore bathymetry; however, our results are also applicable to those coastal areas at time scales ≤1 year. Dunes are morphologically complex areas, much more so than a foreshore with beach cusps (Houser and Mathew, 2011), and volume changes based on beach profiles spaced >1 km apart will likely perform even worse in the dunes than on a beach with widely spaced beach cusps. It is important to note that light detection and ranging (LIDAR) methods work well in the dunes, and extracting the bare earth topography from point clouds is straightforward (Houser and Hamilton, 2009; Houser, Hapke, and Hamilton, 2008; Woolard and Colby, 2002). We did not image the dunes well in our study because those areas were peripheral to where the laser scanner was set up. Nearshore areas will also not be quantified well with widely spaced profiles because of morphological complexity associated with longshore bars (Wright and Short, 1984). Our study concludes that complex morphology is not quantified well with widely spaced beach profiles over short timescales, and that point is also very applicable to dunes and nearshore areas. The foredunes and nearshore areas are generally the most dynamic in terms of erosion during storms; thus, the post-Ophelia monitoring on Bogue Banks likely quantified the erosion there the worst.

Rudolph's argument that we did not thoroughly address the accuracy and repeatability of using terrestrial laser scanning to measure beach topography indicates that he does not understand the design of our study. We state in the methods section (Theuerkauf and Rodriguez, 2012, pp.709–710) that “The volumetric changes are not reported with an error estimate because here we define the ‘true’ morphology of the beach as being equal to the [digital elevation models] DEMs. The DEMs are the benchmark that the volumetric change based on the beach profiles is measured against.” We define beach morphology as being equal to the DEMs that we show in the manuscript and derive the beach profiles from those DEMs. The volume changes we used to compare the profiles against are precisely the true volume changes because of the study design. We used high-resolution DEMs to represent the different beach morphologies that commonly exist on sandy open-ocean coastlines worldwide and critically examine the ability of the beach profile method to quantify volume change when transects are spaced 150 m apart. The focus of our study was to explore the amount of volume change beach profiles might miss; it was not a critical examination of survey accuracies for various methods one can employ to map topography and bathymetry along a coastline (including terrestrial laser scanning data) as Rudolph implies in his discussion. Given the purpose of our study, which is made clear in the Introduction—“The purpose of this study is to quantify the performance of beach profiles in measuring volumetric change with respect to variable beach morphology and morphodynamics” (Theuerkauf and Rodriguez, 2012, p. 708)—our methodology and consideration of error was appropriate.

Rudolph argues that widely spaced—>1 km spacing—two-dimensional data (beach profiles) are appropriate (accurate) for calculating volume changes along a beach at short time periods despite the evidence presented in Theuerkauf and Rodriguez (2012) and other studies to the contrary (e.g., Pietro, O'Neal, and Puleo, 2008). He asserts that we are premature in our statement that LIDAR is a superior method to beach profiles; however, results from our study expand upon the findings of many other workers who have examined the utility of LIDAR in measuring beach changes (Gares, Wang, and White, 2006; Mitasova et al., 2004; Sallenger et al., 2003; White and Wang, 2003). Airborne LIDAR, terrestrial laser scanning, and multibeam bathymetry are superior tools over two-dimensional beach profiles spaced >1 km apart on which to base calculations of volume change, especially when volume change needs to be quantified over a short time period. Only a very small area of the beach is actually being mapped with widely spaced beach profiles, and vertical and horizontal errors are also associated with these topographic data. Those errors are not included in Theuerkauf and Rodriguez (2012) because, with our design, the beach profiles exactly represent the beach where they are located; the profiles were created from the DEMs.

We never stated in Theuerkauf and Rodriguez (2012) that the same laser-scanning methods we used to derive the DEMs should be applied for beach monitoring, as Rudolph continually argues in his discussion. Furthermore, we never claimed that local governments were “negligent” by not employing a full-coverage system to quantify the erosion associated with Ophelia; rather, we argue that the >1-km spacing used in the beach profiling design likely missed a large portion of the volume change. In addition to active remote sensing methods, profiles spaced closer than 1 km would likely have greatly improved the volume change estimate. We could have more thoroughly summarized the long-term monitoring program at Bogue Banks, but that was peripheral to the topic of our study, which focused on beach changes that occurred over short time periods. Because FEMA has no specific guidelines for documenting volume change, it is up to local governments and coastal engineering firms to design the most appropriate monitoring scheme, taking into account how close to the true volume change they determine it is appropriate to quantify. For example, if ±50% of the true volume change is the target, then widely spaced profiles might achieve that goal. The typical profile spacing used on Bogue Banks is ∼300 m, which was the spacing for the pre-Ophelia surveys. Every fifth transect was occupied in the post-Ophelia survey, likely because of logistical constraints; thus, poststorm profiles were spaced between 1 and 2.25 km (Carteret County Shore Protection Office, 2012). Perhaps FEMA guidelines do need to be developed to ensure tax dollars are spent in the most responsible manner and coastal areas are being restored properly. The ultimate goal of our paper was “to help beach managers, engineers, and researchers assess the morphologic conditions under which beach profiles can and cannot be used to effectively measure volumetric change” (Theuerkauf and Rodriguez, 2012, p.708).

The comprehensive monitoring program on Bogue Banks is touted by Rudolph as being successful because he has collected widely spaced beach profiles from the same transects year after year. The best monitoring programs are continually assessed and evaluated to ensure management needs are properly served. Incorporating new technologies into monitoring programs or simply using old technologies, like beach profiles, more effectively will help coastal communities better manage the shoreline and prepare for future challenges associated with climate change, development, and dwindling sand resources. To argue that monitoring designs should be static because changing the methodology would affect data quality and that an ideal three-dimensional mapping tool does not exist is short-sighted.