25 JUNI 2018 - AMSTERDAM ANALYSIS OF SUBSIDENCE IN CITY PARKS IN AMSTERDAM A CASE STUDY FOR FOUR DIFFERENT PARKS BENTHE TIMMERMANS - 11037016 UNIVERSITY OF AMSTERDAM Dr. H. Seijmonsbergen WORDS: 5147 Benthe Timmermans – Bachelor Thesis, 2018 Abstract City Parks are imPortant green areas for cities. They proVide cooler microclimates, recreation areas, imProVe biodiversity and buffer surface runoff. HoweVer, the Parks in Amsterdam exPerience long- term subsidence due to the natural consolidation ProPerty of Peat and clay. Subsidence leads to runoff and causes higher groundwater tables. This may negatiVely affect vegetation and water storage caPacity. The aim of this research is to obtain insight in the sPatial distribution of subsidence in four city parks: the VondelPark, FleVopark, OosterPark and SarPhatiPark. Subsidence will be related to both lithology and trees, because recent studies haVe ProVen they both influence subsidence. To ProVide a subsidence maP, eleVation maPs of the Netherlands will be used (Algemeen Hoogtebestand Nederland). The subsidence statistics that are obtained are comPared with the geological maP of Amsterdam and tree distribution. The research concludes that all the four parks show differential subsidence. The SarphatiPark has the highest aVerage of subsidence and the lowest minimum hotspot of subsidence. Whereas, the FleVopark shows different spatial distribution, the subsidence is on average aboVe zero. It is concluded that Patterns in subsidence cannot directly be related to lithology for the four parks. Furthermore, there is no significant relation with tree heights. Although, natural subsidence will continue in city Parks in Amsterdam, Variation within Parks exists, and will require further research to coVer a full exPlanation. - 1 - Benthe Timmermans – Bachelor Thesis, 2018 Content Content ........................................................................................................................................................... 2 List of abbreviations ....................................................................................................................................... 3 1. Introduction ................................................................................................................................................ 4 1.1 Background ........................................................................................................................................... 4 1.2 Research aim & questions ...................................................................................................................... 5 2. Methods and Data ...................................................................................................................................... 7 2.1 Study area ............................................................................................................................................. 7 2.2 Data ...................................................................................................................................................... 7 2.3 Methods ................................................................................................................................................ 8 2.3.1 AHN & ZEB-REVO data .................................................................................................................... 8 2.3.2 GeoTOP data .................................................................................................................................. 8 2.3.3 Trees file ........................................................................................................................................ 9 3. Results ...................................................................................................................................................... 10 3.1 Height change map ............................................................................................................................. 10 3.2 Lithology oF the parks .......................................................................................................................... 12 3.3 Tree correlation ................................................................................................................................... 13 3.3.1 Tree height ................................................................................................................................... 13 3.3.2. Tree sPecies ................................................................................................................................ 13 4. Discussion ................................................................................................................................................. 14 4.1 Interpretation oF the results ................................................................................................................. 14 4.2 Methodological discussion ................................................................................................................... 15 4.3 Further research .................................................................................................................................. 15 5. Conclusion ................................................................................................................................................ 17 Acknowledgements ...................................................................................................................................... 18 Literature list ................................................................................................................................................ 19 Appendices ................................................................................................................................................... 22 Appendix A: Height change map oF diFFerent parks ..................................................................................... 22 Appendix B: ZEB-REVO data ....................................................................................................................... 26 Appendix C: Lithology occurrence .............................................................................................................. 27 Appendix D: Tree height ............................................................................................................................ 28 Appendix E: Tree species ............................................................................................................................ 29 Appendix F: Matlab Code ........................................................................................................................... 30 - 2 - Benthe Timmermans – Bachelor Thesis, 2018 List of abbreviations AHN Algemeen Hoogtebestand Nederland DEM Digital EleVation Model DTM Digital Terrain Model GeoTOP Geologisch toplagen GIS GeograPhical Information System IDW Inverse Distance Weighting LiDAR Light detection and ranging NaN Not a Number NAP Normaal Amsterdams Peil RD Rijksdriehoeks STD Standard Deviation ZEB-REVO GeoSLAM ZEB-REVO RT (hand-held LiDAR system) - 3 - Benthe Timmermans – Bachelor Thesis, 2018 1. Introduction 1.1 Background Nowadays, more than 80% of the PoPulation in northern EuroPe is liVing in urban areas, and this number is exPected to be around 90% in 2030 (Antrop, 2004). This urbanization is an issue, because cities may exPerience an urban heat island, where air temPerature is higher than in rural areas (Valsson & Bharat, 2009; Mentens et al., 2006). Furthermore, one of the major problems of urbanization is that it interrupts the natural hydrological cycle, since urban areas rePlace vegetation (Mentens et al., 2006; Bulkeley, 2013). Vegetation has imPortant functions such as better infiltration, water storage functions, evaPoratiVe cooling, shading and rainfall intercePtion and can therefore partly absorb problems that arise with urbanisation (Gill, et al., 2007; Whitford et al., 2001). Vegetated areas such as Parks can function as water sponges, since they reduce surface water runoff (Gill et al, 2007; RainProof, n.d.; Bolund & Hunhammer, 1999). As an illustration, Vegetated areas haVe only 10- 15% runoff whereas urban areas can exPerience runoff to 60% of the precipitation (Bolund & Hunhammer, 1999). This reduction of runoff is imPortant, since the Netherlands exPects an increase of 10-15% in heaVy precipitation due to climate change (Frich et al., 2002; Houghton, 2009). MoreoVer, parks proVide cooler microclimates which counter the urban heat island effect (Zhang et al., 2012). Lastly, parks are important for biodiVersity of a city and proVide recreation areas (SaVard, et al., 2000, KurPershoek & Ligtelijn, 2001). HoweVer, green urban spaces can exPerience subsidence that results in different Problems. Amsterdam is an area where this subsidence is occurring, which is caused by the fact that Amsterdam is located in a Peaty area (Van Trik & Ahrens, n.d.). Peat has a ProPerty to lower over time due to secondary consolidation (Barden, 1968; Gans, 2011). Therefore, all parts in Amsterdam are raised with sand or suPPorted with Poles, howeVer this raising is not executed for all urban parks (Gans, 2011; Grontmij, 2011). Subsequently, many Parks inside the ring road of Amsterdam lie around 2 meters lower than surrounding areas (Gans, 2011) (fig. 1 & fig, 2). Therefore, the water table in these Parks will rise, since water of the surrounding areas will flow to the