Journal of Hydrology: Regional Studies (2017) 36–37 Contents lists available at ScienceDirect Journal of Hydrology: Regional Studies journal homepage: www.elsevier.com/locate/ejrh Peer Review Report Peer review report on “Sea level rise and coastal groundwater inundation and shoaling at select sites in California, USA” Original Submission 1.1 Recommendation Minor Revision Comments to Author: Review of manuscript titled “Sea level rise and coastal groundwater inundation and shoaling at selected sites in California” by: Daniel J Hoover, Kingsley O Odigie, Peter W Swarzenski, and Patrick Bernard The subject manuscript describes projected effects of sea level rise in three coastal areas of California The intended outlet is an on-line journal “Journal of Hydrology: Regional Studies” The subject area is of concern to State and local resource managers in coastal California and elsewhere The manuscript presents a simplified and brief analyses of the project effects of sea level rise in three coastal areas of California that are representative of the larger California coastline In its current version the manuscript is very simplistic and over generalizes the impacts of sea level rise on the basis of three coastal study areas Comments are provided as marginal notations on the manuscript and summarized below: Editorial comments: There are numerous place names that are discussed in the text and not shown in any figures Only an individual with significant knowledge of coastal California would know where these places are They need to be shown on apropiate figures for the manuscript to be meaningful for most readers Fig does not have a scale The area extent of the Malibu aquifer is listed in Table as 1.27 km2, but is actually 3.4 km2 Technical Comments: The technical analyses in the manuscript is very simplified Although not incorrect, there are significant limitations in the approach, some of these limitations are discussed in the manuscript, which is good A more sever technical limitation is the hydrogeologic simplification that does not recognize the presence of unconfined saline aquifers along the California coast that overlie confined aquifers freshwater aquifers pumped for water supply The “perched” aquifers (they are not truly perched) have very shallow water levels and would contribute to high groundwater levels in coastal areas that are dismissed in this manuscript This simplification has led to statements throughout the manuscript (such as Lines 557-558) that dismiss groundwater emergence due to sealevel rise as having limited impact because of deeper depths to groundwater These perched systems are not commonly monitored because the water is not potable but they are present Two examples are the Oxnard area (http://pubs.usgs.gov/fs/1996/0125/report.pdf) and in the East Bay Plain of San Francisco Bay (http://pubs.usgs.gov/wri/wrir024259/ca0443text.pdf) This issues needs to be properly addressed in the manuscript DOI of the original article:http://dx.doi.org/10.1016/j.ejrh.2015.12.055 2214-5818/$ – see front matter http://dx.doi.org/10.1016/j.ejrh.2016.11.022 Peer Review Report / Journal of Hydrology: Regional Studies (2017) 36–37 37 The Arcadia and possibly the Stinson Beach study areas are only smaller parts of larger coastal aquifers I not believe the study areas for these two sites conform to any management unit used for water resource or other management purposes This leads the reader to the conclusion that large parts of these areas are impacted by sealevel rise and rising groundwater levels As such the manuscript greatly overstates the case for impacts of sealevel rise, especially since the discussion in the text is in terms of percentages, rather than actual area Only the Malibu area is a complete aquifer or hydrogeological unit The potential impacts described in the manuscript need to be put in context The data from the hydrograph from well C-1 in the Malibu area is misinterpreted (line 444-446) See comment in text The manuscript is suitable for publication in the intended outlet but will need some revision prior to acceptance for publication The manuscript does present interesting information that readers should find useful Thanks for the opportunity to review Specific comments: Line 50 (Abstract): delete “isolated” or perhaps change to coastal Lines 59-65 (Introduction): Move “recent increases have been attributed primarily to global warming and associated melting of polar ice caps (Refs)tă o the end of the paragraph after the Cayan reference You might want to change “global warming” to “global climate change” to be USGS politically correct Lines 66-68: Is this correct as stated The meaning is that sealevel has risen globally everywhere except Californnia? If not your intent you may need to clarify Lines 94-96: Most of this is likely the result of decreased precipitation, changes in snowmelt and runoff ect For this paper is it possible to separate the fraction of the decrease attributable to sealevel rise Likely not, but I thought I would ask Lines 123-125: There should be significant differences between WL rises directly associated with rising sealevel and with water level rises associated with groundwater rises or inundation (other than simply water logging of the coastal area) It might be relevant to discuss some of those differences described by the other studies referenced Line 176: Santa Clara groundwater basin not shown on Fig Line 179-180: The phrase “human development” is very vague Does that refer to commercial, residential, agricultural land use, or all of the above? Clarify Lines 204-205: The groundwater levels below sealevel are possibly for deeper aquifers that are pumped for water supply Coast aquifers in California commonly have perched water level aquifers that are well-connected hydraulicly to surface water and to the ocean, these would be susceptible to sealevel rise and GW inundation Lines 222-223: Groundwater in the Malibu area is not pumped for public supply This should be made clear in this paragraph as the way the information is presented on would think that it is Line 253: Fig shows precipitation not areas of the state vulnerable to m of sealevel rise as stated ă Line 288-289: delete “which would produce a planar groundwater surface.and combine sentences Lines 341-344: Have you estimated infiltration from precipitation in this area and compared it with on-site wastewater treatment system discharges? You should check that calculation and verify the water budget Line 427-430: This conclusion seems incorrect If the data not reflect the worst case scenario, how can they produce a conservative estimate It would seem they underestimate the potential seawater rise GW inundation? Line 432-434: This is a misinterpretation of the data The tidal signal in C-1 is damped by WL in the lagoon under closed berm conditions present at the time C-1 is measuring a much different hydrologic setting than the other wells Line 443: The wet area to the west in a natural feature There is an artificial wetland constructed in the area for stormwater capture, but this is not it Line 486: replace “chronically low” with “lowered” Lines 488-491: Nice statement This should be included in the abstract Line 494: delete “abundant” Line 501-505: Not a true statement as the aquifers pumped for water supply (such as the Oxnard aquifer) in the area are overlain by shallower unconfined aquifers In the Oxnard area this aquifer is commonly referred to as the “perched aquifer”, although not truly perched in most areas it is unconfined and highly saline Similar aquifers are present all along the Californai coast Line 508: actually recharge from the septic systems does create the aquifers, but they cause increased water levels in those shallow aquifers Please claify Line 513: consider replacing “potentially contaminated” with something on the order of “high nitrate or bacterial concentrations associated with septic discharges” Lines 506 and 521: Consider replacing the phrases “Coastal beach communities” and “Coastal lagoon communities” with “Coastal beach development” and “Coastal lagoon development” Line 576-577: replace “population pressure” with “increasing population” Fig 2A The wells are difficult to distinguish from the control points in the figure, suggest using different colors Anonymous ... level aquifers that are well-connected hydraulicly to surface water and to the ocean, these would be susceptible to sealevel rise and GW inundation Lines 22 2 -22 3: Groundwater in the Malibu area... produce a conservative estimate It would seem they underestimate the potential seawater rise GW inundation? Line 4 32- 434: This is a misinterpretation of the data The tidal signal in C-1 is damped... clear in this paragraph as the way the information is presented on would think that it is Line 25 3: Fig shows precipitation not areas of the state vulnerable to m of sealevel rise as stated ă Line