meters. Almost all the storms passing through the Gulf of Maine require 12 hours or more to do so. This increase in surge levels of 15 centimeters will, in effect, increase the number of damaging storms which impact the coast by a factor of 21/2.

I wish to make it clear that the projects will not influence our climate regimes, and thereby increase the number of storms, but will increase the storm surge levels which we have experienced in the past.

For example, Stone & Webster Engineering Co. as part of a previous Federal flood insurance study determined that a coastal surge level of exceedance probability 13.3 percent or a storm as most of us would know as a 72 return storm caused unexpected beach erosion and damage to manmade coastal structures. This was the threshold storm. Storms of higher or greater than 13.3 percent probability cause insignificant erosion or damage. Those of lower exceedance probability caused even more significant erosional damage. If 15 centimeters of tidal height are added to historical coastal storm surge levels, a coastal storm of 45 percent in exceedance probability or 2.2 year return storm will become the threshold storm which causes significant beach erosion and coastal damage.

From 1940 to 1979, the Gulf of Maine experienced only 11 storms of 13.3 percent exceedance probability, 30 storms of 45 percent exceedance probability. If the tidal power projects had been completed in 1940, Maine, New Hampshire, and Massachusetts would have been impacted by 30 storms causing significant damage rather than 11. În addition, the magnitude of storm damage expectancy will increase. With an increase of the tidal amplitude of 15 centimeters, a 100-year storm of today will cause storm surge levels equivalent to a 300-year storm. A 50-year storm will be equivalent to a 200-year storm, and a 25-year storm will be equivalent to a 100-year storm. All of us in New England are familiar with the February 1978, northeast storm and the damage which it caused. This storm is taken by most as the storm of record and the 100-year storm. From 1940 to 1979, only one storm of this magnitude occurred. If the tidal power projects had been completed prior to 1943, storms of this magnitude or greater would have occurred.

These are facts on coastal storm surges certainly to be significant. Certainly warrants our attention as it translates into significant beach erosion, millions of dollars of damage to manmade coastal structures and facilities and probably increased deposition of sand and mud in harbors and some navigation channels.

I would like to go now into a consideration of the effects of storms on beaches and beach retreats which Dr. Larsen, I think, has already mentioned very briefly.

Geologists seem to be split into two camps as to whether beach recession rates are caused mostly by coastal storm wave erosion or sea level rise. I happen to be that camp that believes that coastal storms are the major controlling variable. Bruce Nelson, in a fairly lengthy master's thesis in 1979 determined that sea level rise in Maine can account for 9 to 12 centimeters of annual beach recession on many of our beaches. But the beaches are exceeding at a far greater rate at about 30 centimeters per year. Nelson as well as myself would attribute this to coastal storm erosion. I do not believe that the increased tidal amplitude alone

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will cause any more erosion on the New England coastal beaches than is otherwise being experienced.

Increased recession rates, however, will be experienced because increased storm surge levels will allow wave energy to be expanded higher, the beach profile allowing for deeper penetration of erosion. If we are correct in our assumption that coastal storms are the major controlling variable, beach recession, and the relationship between the amount of beach recession and storm energy linear, then the amount of recession which will be experienced by our major beaches because of the tidal power projects will be about 60 centimeters per year. This relationship is probably too simple to be reality, but we are looking at a situation where recession rates will increase probably from 111⁄2 to 21⁄2 times the present rates. The recession rates actually experienced may even be higher as recent investigations by the Maine geological survey and the EPA hint that sea level rise rates may be increasing in much greater rate than in the immediate past.

Now, I would like to simply direct my comments to some possible effects on coastal navigation. It is fairly well known now by geologists that much of the sediment that is deposited in shallow estuaries, lagoons, and coastal embayments is derived from the ocean, especially in New England.

Detmar Schnitker, nicely documented how important coastal storms are in eroding near and off-shore bottom sediments and transporting elevated concentrations of suspended sediment into coastal embayments along Maine. Much of the mud making up our tidal flats is derived from the ocean bottom. It has been observed that coastal storm erosion of barrier beaches and spits leads to increased deposition of sand in lagoons and estuaries behind the barriers. We should expect, therefore, that the tidal projects will increase the deposition in our harbors, mooring basins, and some navigation channels.

In light of my previous testimony on beach recession, those harbor and channel areas which have been dredged in coarse-grained or sandy back barrier embayments will experience more frequent shoaling. Areas such as Gloucester Harbor, Hampton Harbor, Wells, Camp Ellis in the Saco River and the Scarborough River, for example, will require more frequent dredging than in the past.

The 30-centimeter increase in tidal range projected as an effect of the power project will allow coastal storm waves to erode off-shore bottom areas never before effected, as well as allowing an increased expenditure of energy on the bottom areas which have been effected. This increased erosion capability coupled with the increased storm surge penetration will result in greater amounts of suspended sediment being delivered to sheltered navigation waters dredged into fine grain, subtidal and intertidal flats.

Some harbors and navigation channels will be unaffected as the preliminary assessment indicates that flushing rates will increase in estuaries, transporting more suspended sediment seaward than it is now presently the case. Deposition of fine grained sediments in well stratified estuaries, however, should increase. In some instances, deposition in these types of estuaries will be in areas where deposition does not now occur as the salt wedge will penetrate further landward due to the increase tidal range. Consequently, some harbor areas such

as Portsmouth, Portland, Royal River, and Winterport which is in the Penobscot River which are well stratified and historically have had fine grain material dredged from their waterways should require dredging more often in different areas than in the past.

It is not possible to be at all quantitative in determining the amount of increased deposition that will occur in these areas. Our research data base in this area is not as sizable as the beach recession base.

Suffice it to say, that if the tidal power projects are to be reality, this problem will have to be studied much more closely. Thank you, Mr. Chairman.

Senator MITCHELL. Thank you, Mr. Timson. Your remarks and Dr. Topinka's remarks lead me to conclude from the testimony we have had today that there are really two separate questions here in evaluating the impact of this project. The first is what effect will the construction of the dam have at Minas Basin on the tides, the second question is what effect will the increased tide, or the change in the tides, have on the coast?

Dr. Greenberg has indicated that at least from his standpoint the first question has effectively been answered, and while it would be useful to have an additional independent verification to confirm his conclusions, he said he would be surprised if it produced any different results.

It seems to me that based on the testimony you gentlemen have given that the second question has not been definitively answered, that is, you have reached some tentative conclusions, but I gather, particularly listening to you, Mr. Timson, that you have reviewed the existing research on the subject rather than having conducted directly independent research in the area.

I would ask Dr. Larsen, Dr. Topinka, and Mr. Timson to comment on this and to tell me whether my conclusion is correct or incorrect. If it is correct, would you specify the areas where you feel more research is necessary to arrive at a more definitive answer?

Dr. LARSEN. Yes. You are correct in what you say. When we began the State planning study, we interviewed a number of theoretical physical oceanographers to ask them their opinion of the adequacy of the Greenberg model, and I would say they were-whereas there were questions about certain details here and there, no one questioned the results. Some comments of this type are contained within the State planning report that will be submitted soon.

These people were all so confident in the results of the study. Rather than do any kind of review which was detailed-review which is out of our field of expertise, we decided to accept the Canadian projections politically that also seemed easier and then set off to determine, OK, if the tides are going to change this much, what is the impact on the coast of Maine, what changes can we expect in the components of the environment which are dependent on the tidal range, geology, biology, and to some extent socioeconomic aspects?

Where we go from here. I can probably talk all day. We won't. There are a number of items listed in the State planning report. I just briefly listed three of four here which in the interest of time I did not go into. There seem to be two sorts of time scales for the kinds of things that can be done to provide the interest we need. We do have

scientific expertise in the region and we also in many cases have a data base so some questions can be answered in a very short time period, a year or two. Other aspects are much more complex and would take 5 years, 7 years of very interactive work among a number of investigators or organizations.

Part of our concern indeed is that the 3-year precommitment study does not allow enough lead-time to answer some of the environmental questions, so we are concerned that the environmental work begin just as soon as possible. It could be in the best interest of everyone concerned, and we also think it would be scientifically more efficient to have cooperative programs with the Canadians so we don't plow over the same ground again, as Mr. Baker suggested.

The two or three things I would like to put out today as suggested areas of research is how significant are the projected changes in estuarine flushing rates. An estuarine flushing model is now operative at the Bigelow Laboratory. Information on floor rates, volume, tidal ranges of the various estuaries is also available. This model could be run for each Gulf of Maine estuary with an output field checked and results interpreted, in perhaps 18 months. This would give us an answer of do we need to worry about changes in estuarine flushing as being especially bad or especially good for the coast of Maine.

Some insight into the significance of the increased tidal current velocity can be gained by examining long-term tidal cycles. There are a number of tidal cycles that we can look at, and tidal current may vary by as much as 5 percent over some of these cycles. And some fishery biologists believe that the cycles and fishery landings are related to the changes in tidal currents which affect other things like surface water temperature, productivity, as others have said today. These long-term tidal records, temperature, and current statistics all exist. And with a small group of experts, we probably analyze these and see if indeed, if a 5-percent change in tidal currents has some manifestation in a biological component such as fisheries landing, then maybe we should be concerned about the 10-percent increase. The expectation would be the increase in tidal currents would increase fisheries productivity, however.

Another exercise that could be done rather quickly is for a detail case study of one or more coastal communities. Get together a group of people, a geologist, biologist, hydrologist, waste water engineer, real estate appraiser, just a butcher, baker, candlestick maker-type approach and walk a length of shore and just see in the different people's opinions what would be altered by this change of tidal regime, and then we can put a dollar value on it which would be fairly accurate for that length of coast and use that as an estimate to project some either dollar value of increased damage due to the storm associated with a higher tidal rate or suggest some mitigative measures which could offset some of the effects. A very important area, but one that is more complex is interaction of tidal mixing primary productivity and fisheries landing, for instance. A lot of progress has been made in recent years and a lot is being done. In fact, there's a lot of cooperation between Canadian and American institutions on this subject.

But these are complex problems that would take a longer time and certainly much more financial commitment to get answers. And even

then, I am afraid there would be those that would not be satisfied because whenever you are dealing with complex biological systems, there will always be a great deal of uncertainty with any predictions that result.

Senator MITCHELL. Thank you, Dr. Larsen. Doctor Topinka, would you comment briefly that?

Dr. TOPINKA. I can say I agree very much with what my colleague has just stated. And I would like to reemphasize in a coastal zone that I think the areas that need to be addressed to the greatest degree have to do with changes in intertidal areas. How much is going to be-how much just due to the change of inundation patterns, this what appears to be this minute 6 inch change in mean high water. What is it actually going to do? What is the change on a lowering of low water by 6 inches? What is that going to do? How much area will that affect in particular types of habitats.

We have estimations, for instances, that on the order of 4,200 acres of the terrestrial border would now be sort of claimed by the sea, claimed by new mean high water level. Well, how is this distributed? Would it be mainly in terms of salt marsh? How much beach area will that affect? Where will those areas be? And what will that-what will the consequences be to the biological population that inhabit those areas? These are all relative to just the changes in inundation patterns. Perhaps of greater significance and this was touched on by my colleagues has to do with the ways in which that change in tidal regime is translated into changes in tidal current velocities. Tidal currents are a very important part of the energy source that derives many biological systems. We need to understand in what regions the biological productivity would be changed by a 10-percent change in tidal range. We need to know this because we are talking about not just a small area. We are talking about the entire coast of Maine, virtually the entire Gulf of Maine.

Senator MITCHELL. Thank you, Dr. Topinka. Mr. Timson.

Mr. TIMSON. In general, I would agree with your conclusion and what Drs. Larsen and Topinka said. I think this study has taken the next step beyond the Greenberg model which said it'll have these effects in the Gulf of Maine, and this study has it.

What, then, are the areas which are going to be impacted along the Maine Coast? We have identified, I think, some of those areas within my own interest on beaches, for instance. I think that it is a safe conclusion to say that beaches are going to be affected significantly. It now becomes a matter of defining how much damage will be done to property and how much change will take place because of the project. That would take several years to undertake. I think you would have to go look at it beach by beach. You would have to now recalculate the 100-year flood storm in order to determine future damage and things of that nature.

When it comes to the effects of sedimentation on navigation, I am not comfortable in saying the impacts are significant. I think there will be an impact, but it has not been defined as yet. We don't have enough information to determine whether these will be negligible, moderate, or significant.