The Delta Works

Holland's Delta Works has been on Geoff's list of things to see for a long time, so we headed down to Neeltjie Jans to see the works with friends of ours Justin and Bronwen Cross who now live in Rotterdam.

The Engineers: Justin and Geoff

On a cruise around the storm surge barriers

Upon setting up the building site, this skeleton of a Mammoth was excavated and now welcomes visitors to the centre 

They grow them big in the Netherlands..

Approximately half of the Netherlands lies below sea level and the sea has been kept at bay by a series of dykes for centuries.  In 1953 very high sea levels combined with a severe storm resulted in a number of dykes being breached and causing catastrophic flooding with 18,000 people dead and tens of thousands of head of livestock drowned.  In response the Delta Works project was launched to protect the low lying areas from flooding from the sea.  A series of new dykes and dams were proposed and built (the dams becoming fresh as water drained into them).  The government started this in the northern and inner areas which were 'simpler' to construct, hoping that by the time that they needed to build the more south easterly dykes and dam walls that closed the huge combined Rhine, Meuse and Scheldt Estuary that they would have gained the necessary experience and skills to tackle these difficult tasks.  All went according to plan until they started building the final dam wall in the Oosterschelde area.  By then the 1970's and huge protests broke out over the closing of the estuary - both from the environmental groups and from the local fisheries industry who grew and harvested shellfish from the estuary. The government was forced to go back to the drawing board and they came up with a series of storm surge barriers that would be closed if the sea level was expected to rise more than the spring high tide.  This compromise allowed the Oosterschelde to remain open to the sea and tides and at the same time protect the low lying areas from flooding in severe conditions.  It was one of the first times in the world that the impact on the environment became such an important issue, dividing the country, and where the preservation of the natural ecosystem influenced the approach taken to this engineering problem.

The storm surge barrier viewed from the water. It comprises of  three sections made up of 64 buttresses.

Windmills everywhere!

The design of the barriers involved compacting the seabed, then laying a rock mattress over it both to found the barrier on and to prevent erosion around the barrier. At Neeltjie Jans they cast the complicated and enormous concrete buttresses in a bunded dry dock area which was flooded once all 64 (plus one spare) buttresses were complete. The buttresses were then floated and towed out to the correct position where they were lowered to a tolerance of less than 10mm (often having to contend with tides! Huge concrete beams span between the buttresses holding a road and the service ducts.  They then built up the foundation material around the buttresses and hung the big storm surge barriers between the buttresses.  These are lowered to close the sea out when very high tides are predicted, which is approximately twice a year. The project has resulted in a reduction in the flood risk from 1 in 80 to 1 in 4000 years.  The project was completed in 1986.

Neeltje Jans is the artificial island that was built on a sandbank in the estuary to accommodate all the building infrastructure required for building the storm surge barriers.   It is now the site of the information centre, museum and visitor activities.  

The spare buttress now lies dormant in the flooded old construction area. It was designed such that if any of the other buttresses was lost or failed it could be used instead and not delay the project. It is now used for recreation. Spelunking trips course through its cavernous interior and climbing walls pickle its exterior. 

Looking across one of the barrier gates. The dark grey structure on the left is the heavily reinforced gate, the white pylons are the hydraulic rams that force it down and pull it up again. 

A model of the storm surge system from a front elevation.

We spent a full day at Neeltjie Jans and really enjoyed learning about the project.  Apart from the museum and the information centre, there is a section of the barrier that is open to the public and you can walk in under the road and out onto one of the pillars and see how it works.  We were there as the tide was coming in and it was amazing to see how fast the water was flowing in through the gaps between the pillars.  By modern standards the barrier could not claim to have "no impact on the natural ecosystem" and we're pretty sure they would need a more complicated solution now days, but it was pretty ground breaking for the 1970's/80's. 

The storm surge barriers from the shore.

The tide racing through at 4m/s. Note the enormous standing wave - though too shallow to be able to surf...?

We enjoyed the exhibition covering the events of the 1953 flood, through the planning and construction of the dams of the Delta works to the final section on the storm surge barriers and how they came about and were constructed.  There was also a movie shown summarising the events and highlighting Dutch humour.  We enjoyed the ferry ride which took us past some of the sites of the Delta Works, exploring the aquarium that they have there, experiencing the strength of hurricane force winds in the hurricane generator and doing the water slides.

One of the amazing hydraulic kids displays. This kid really enjoyed himself!

What happens when you merge Geoff and Lucy at high speed...? Gucy du Toit?

The Delta Works is a fascinating set up and well worth a visit if you're in the Netherlands.

You knew it was coming...

Plitvicka Jezera National Park - the Lakes

Plitvicka Jezra National Park  is the oldest national park in Croatia and was proclaimed a UNESCO World Heritage Site in 1979,  The park is pretty impressive. It is covered in a lush old forest of beech and fir and has a series of lakes running through it.  These lakes are formed by a build up of tavertine barriers in the ancient river. Tavertine, as we learnt at the Krka National Park, forms when particles of calcium are precipitated out of water and are trapped in biological growth such as algae and mosses where it forms hard barriers. 

The classic view of Plitvicka.

The travertine waterfalls start as small cascades which get covered in vegetation which traps the precipitate which forms travertine.

Everything underwater gets coated in travertine and doesn't decompose.

Any part of the fallen trees that aren't submerged in the water quickly start decomposing and are colonised with vegetation.

The main difference between Krka and Plitvicka is the large scale of Plitvicka  which includes 16 large lakes and the tranquilness of an extensive old forest.  We loved walking the board walks along the lakes and waterfalls, and on the kilometres of trails through the forests.

The highest lake is one of the largest in the park.

Around some of the lakes are lovely meadows full of flowers.

A waterfall peeping out of the forest.

Lovely and tranquil scenery.

We loved the low cascade waterfalls best.

It was great to explore the lakes with Neville and Diny.

As with many of the national parks that we went to, your entrance fee includes transport within the park, so it is worth making a full day or two of it as you can explore a lot of the park with their bus services that run between the two entrances and the highest lake and the ferry services that run across some of the lakes. We also found it easiest to explore from early in the morning while it was still relatively cool, nap under a shady tree over midday and then explore again in the afternoon and evening.

Geoff in his favourite place.

Happy Geoff.

One of the amazing things about travertine waterfalls is that the travertine is being built all the time and so the waterfall moves outwards leaving overhangs and caves behind the falling water.

We wanted a jumping photo of this waterfall.   The problem was that we were on a rickety wooden walkway only 1,5m wide and involved Lucy lying on the over hanging edge trying to fit Geoff's frame and the waterfall onto the screen.

The rickety wooden walkways.

The forest in this part of the country is really lovely.

The largest waterfall is supposedly 70m high.

The park supports a fair amount of wildlife.  The lakes are full of every sized trout that you could imaging (from a couple of species), and we enjoyed seeing ducks, herons, forest frogs,  both land and water snakes and a freshwater lobster.  We were not lucky enough to see the bears or wolves or any of the raptors for which the park is known.

The overhanging branches make lovely walkways along the clear turquoise water.

We were impressed with the good quality of the paths and the interesting water that they provided.

The colour of the water was just surreal.

Looking across to one of the bigger cascades.

One of the walks we did took us away from the lakes and through some of the most beautiful forest that we'd walked in.

Looking down on some of the lakes from above.  Each lake is separated by a collection of waterfalls.

Apart from the Travertine and Limestone that forms most of waterfalls, there is also a considerable amount of Dolomite.  There were some interesting caves that we explored (and many more that we didn't) that were formed from one or more of the above rock types. We really enjoyed this added dimension to our trip.

One of the caves formed in the Limestone. (Neville and Diny)

Looking up a 'sinkhole' or doline from near the water level.

We couldn't get enough of the beautiful blue water.

Plitvicka - what a lovely place to play.

Tired after a long walk.

And of course there are stunning evenings.

Paklenica National Park

There was a sense of sadness at returning the yacht after an amazing 12 day cruising trip.  It had been a highlight of our travels, however we then had five days of road tripping with Neville and Diny (Lucy's folks) ahead of us.  Zadar was hot, the road was hot, everything was hot- but at least we had air conditioning in the car. 

The coastal landscape north of Zadar is wild and harsh. We never expected to find lush forests and cool streams...

As we left the City, Neville commented on how barren the coastal mountains looked, Geoff mentioned that this impression is superficial as there are reportedly substantial forests with beautiful gorges running through them. So, as we passed signs to the Paklenica National Park, Neville suggested we pop in to see what it was about.  From the hot coastline we entered a deep gorge where we learnt that the park offered flowing rivers, deep forests, caving and was the best centre of sport and big wall climbing in Dalmatia, if not in the whole of Croatia. Geoff was intrigued and as a group we decided to come back to spend the following day exploring the park.

The access to the climbing is really easy. We didn't have our climbing kit with us though so could only look!

This 650m face is one of the main climbing attractions to the park and hosts one a European big wall speed climbing competitions annually in May. Most of the routes are bolted.

The park had excellent trails with a great compromise between limestone viewpoints and the deep forest.

Accommodation was easy to find in Starigrad and we enjoyed one of the most beautiful sunsets of the trip as the sun transformed to a vivid red globe on the horizon. There was a vibrant nightlife and we explored the bustling markets after dinner before retiring for the night.

Up at sparrows we raced through to the park and were having breakfast in the gorge by 7am watching a poor donkey being loaded with goods headed to the mountain refugio. Our tactic was simple - get there early and gain altitude before it got hot. However even by 9am it was already above 30deg and we were on the sunny slope climbing a steep path to the cave. Neville had opted to stay low down as he hadn't been feeling strong, but we took regular breaks on the hill and we noticed a figure charging up behind us. Neville "Tank" Norton at full speed - clearly he had decided he wasn't so tired after all!

The park has had an interesting history. Shortly after the formation of Yugoslavia it was closed to the public for 5 years as the government developed a system of underground bunkers to serve as a refuge in times of war. Presently these are being redeveloped into visitor facilities. 

Lucy in forest with a view to the big wall.

The cave system is only 135m long, but it comprises an enormous dolomite cavern with huge limestone features including fins, terraced pools and rose crystals in addition to the columns, stalactites and stalactites. These features have effectively subdivided the huge cavern into three distinct zones.  Access is with a guide only and the caves are lit by solar powered lights. The reduced lighting created a very strong contrast of light and shadow which we felt enhanced the cave experience even more. Our guide was a charming young lady with a masters in natural science who explained a lot of the geological phenomena we saw. Geoff couldn't help but envy her day job - hiking 1.5hrs up to a stunning cave system to guide tourists for 3hrs then home! The best part about the caves was that they were a consistent 10 deg C in contrast to the 35 deg C outside!  We didn't want our tour to end!

Photographs never really do justice to caves. We had the system all to ourselves and loved it!

As we sat outside the cave, Diny pointed out to Geoff on a map board that if he continued up above the Cave he would be able to summit the nearby peak and do a solid loop back to meet the others at the refugio. The guide confirmed this would be tough in the heat but was manageable in 3 hours at a brisk pace. With the gauntlet now down Geoff wasn't going to say no and after checking he had enough water and the emergency rescue phone number he set off. His hot ascent was compounded by the direct sun, and reflections from the white limestone. Additionally stopping was difficult due to the mosquitos. However he summitted and raved about the wildly beautiful limestone and alpine terrain and forest he had all to himself when we met up again. No doubt the icy swim in the river back at the refugio was a welcome relief.

From the summit of a peak you can see the jagged limestone and  forested valleys below.

Panorama from the summit

A well deserved swim

The afternoon was spent exploring the extraordinary forests of the park, and swimming in the fresh streams. Paklenika National Park is well worth a visit and we were very glad we had made the effort.

Leaping Lucy at the refugio and mountain hut at the head of the valley.

Croatia Sailing - its a wrap!

Our 2 weeks sailing was fantastic!  Our boat was well suited to us and sailed well.  Our Crew learnt quickly and we were a pretty slick operation by half-way though.  It was sad to say goodbye to everyone at the end of the charter.

The staff at Meridijan.hr sailing were really helpful and quick to go the extra mile for us.  We would recommend them to anyone looking for a sailing holiday in Croatia.  

Thank you Bracera!