# Introduction oastal zones are places where many people would like to visit, invest and enjoy, thus why human major projects have been developed, small islands areas, ecosystem services are among the major economic driving factors [1]- [3]. In many countries, cities are allocated along the coast [4] which are the most populated places in the world holding high population density (Kaneko et al., 2015). Historically coastal zones were most used before the invention and advancement of space and air transport development thus, navigation along ocean and rivers were the most transportation means [7] which influence the development of mega projects that we are witnessing nowadays in many countries; port and harbor development, towns [8] and entertainment like tourism development [9], etc. Due to these development projects, tremendous changes along the coast become vulnerable to flooding due to climate change impacts such as Sea Level Rise [9], [10]. Although coral and limestone Islands have natural protection along the shore, the continuous wave processes over a long time, sea-level rise, monsoon winds, and other human activities like tourism influence the dynamic process (Arthurton, 2004) of either accretion or retreat/erosion (Arthurton et al., 1999;Mahongo et al., 2011;Ngusaru, 2000;Nyandwi, 2010Nyandwi, , 2015)). On one side it could be considered are social and economic development [3] however, on another side, there are many impacts on ecology and environment [5], [16], [17] due to these anthropogenic. The shoreline of Small Island States has been originally changing over time like any other coast however when there is over interaction with human activities causes excess use of resources to interfere with the shoreline systems and processes [16], [18]. The general results in Urban West of Unguja Zanzibar shoreline, showing more accretion rather than retreat, the situation has been associated with major reclamation, especially at Darajani, Mnazi Mmoja, and Malindi port area extension, as well as beach nourishments at Mtoni due to the hotel and mariner development. Also, it has been revealed that five major types of mitigation and management measures that influence to reduce retreat are; mangroves, sea walls, groins, islets, inlets, and beach nourishment, even though the hard structural measures like groins and sea walls are helpful, they also exacerbate retreat in adjacent sides where there are luck such management practices. The experience shows that once the decision of construction of walls, jetties, and groins in urban areas should be at entire distributed along the shoreline or small part of urban forest mangroves buffer should be maintained as a control measure otherwise the adjacent sides will suffocate from severe erosion or retreat. This paper analyzes how human activities influence the transformation of shorelines and to what extent the longterm shoreline changes of Islands and urban areas have been reshaping coastline processes and management. The paper also considers how Geographical Information System on digital spatial analysis is important to detect, visualize shoreline position and also could be possibly used for coastal urban development, decision making, and management. The paper also considers a field survey and observation that was made by the author from August 2019 to January 2020 at Urban West of Unguja Island, Zanzibar. # II. # Methods and Study Area The area of the study is the Urban West Region of Unguja, Zanzibar. Zanzibar is one of two countries that form the United Republic of Tanzania which is also among the Small Island Developing States of the Western Indian Ocean [6]. Zanzibar is located on the eastern coast 40 km away from the east coast of Tanzania Mainland, West of the Indian Ocean. There are two major islands (Unguja and Pemba) and more than 50 other smaller islands and islets [6]. The northern tip of Unguja island which is the mother island is located at 5.72 0 Latitudes South and 39.30 0 East; with the Southernmost point at 6.48 0 South and 39.51 0 East. There is another Island of Pemba located at 4.870 0 South and 39.680 0 East, and the Southernmost point is located at 5.47 0 East (OCGS, 2018). Unguja is the larger of the two islands (having 1,666 km 2 ) and is some 35 kilometers from Mainland Tanzania, while Pemba (988 km 2 ) is located to the northeast (see also figure no. 3), around 55 kilometers from the Mainland [6]. The main objective of this paper is to analyze the coastal beach erosion vulnerability of Zanzibar, using GIS and RS applications, and find the relationship between the rate and trend of extreme beach erosion, extreme changing wind patterns, and sea-level rise, where the specific objectives are; 1. To analyze the rate and trends time series of coastal beach dynamic and shoreline changes between the 1880s to 2018, using GIS and RS application 2. To determine the relationship between extremely coastal beach erosion and extreme changing of wind pattern and sea-level rise 3. To determine the vulnerability of Zanzibar coastal zones in terms of population displacement, coastal squeeze and loss of associated ecosystem services, and the limit of land capacity. 4. To identify current best practices and possible motivating adaptation factors in building resilience and reducing the risk for coastal beach management. The Urban West of Unguja Town also known as Zanzibar Town/City, the region has three districts with more than 700,791 population until 2019 [20] based on 2018 population projection, with a density of more than 2600/km 2 [6]. The general characteristics of the coast are intertidal fringing coral-rich limestone of Pleistocene age (Arthurton et al., 1999), the shoreline of Urban West of Zanzibar City is a fringing reef, cliff coral, beaches and sandbanks, stream deltas, mangroves with mudflat and wetland. It has a warm and humid tropical climate with an average rainfall exceeding 1500mm/year and an average temperature of above 26 0 C, which is also influenced by Northern and Southern Monsoonal winds (Arthurton et al., 1999; The dataset used for spatial analysis is from the Guillain sketch plan survey map of 1846, and Baumann sketch plan survey map of 1892 1). All sketch maps, topographic maps, and images were carefully georeferenced with hours, minutes, and seconds (latitude and longitudes) using ArcGIS software whereby spatial analysis was made through demarcated along the study area. The study also involves ground truth observation carried out between August 2019 and January 2020 where photos, GPS coordinates, and video were collected to support the analysis. ) Shoreline spatial analysis carried out about 15km and 5km stretch of Urban Wes of Zanzibar City from Kilimani to Mtoni area, a mixed and integrated method using map and images for long term changes detection which is also used by [21]- [23], which is suitable to detect and analyze long time series of shoreline change when there is a limitation of data such as images of more than 100 years. It was used to analyze the shoreline position from 1846 to 2020 based on the distance of the shoreline stretch and area differences compared one dataset time shoreline position to another after being merged in both accreted or retreated. That means; dataset was carefully scanned, georeferenced, alienated, digitized, plotted, and merged, and then area measurement and geometry calculation were carried out to each spatial difference accreted or retread/eroded/reclaimed between two shoreline positions of executive years, then shoreline position was used to categorize the dynamism of changes of the area as such comparative for qualitative method has been used by [24], [25], as well as quantitative methods from dataset shoreline position differential in geometry calculation both length and area in meter square/kilometer square of each shoreline. # III. # Results and Discussion After carefully spatial analysis of mixed data, the results were categorized based on the availability of information collected, there was a dataset that only covers part of the Urban West shoreline only 5 km, and a dataset that covers 15 km shoreline. Also, results from analyses were performed based on the potential of the areas, length, and area of shorelines accretion and retreat as well. # a) Maisara, Malindi to Funguni shoreline changes between 1846 to 2020 This is an important area in Zanzibar where the capital city (Zanzibar City) is located, results showing there are tremendous changes of Malindi area due to extension of port and reclamation of Darajani creek and Mnazi Mmoja areas. Malindi port during 1846 observed having huge sand deposits at the shore (see figure 3 the year 1846) in a place known as 'Funguni' in Swahili which means the bank of sand deposit which developed north to the southwest along the shoreline, however at the inlet which is Darajani creek also known as 'Pwani ndogo' looked wide and extended to the southwest up to about 0.46 km square inland as seen in figure 1. In this year (1846) it could be seen a small Islet called Kisiwani within the inlets whereby the time was called 'Pwani Mbovu' (rotten sea) which is nowadays is known as Mnazi Mmoja area (figure 5 the year 1846). In figure 5 year 1892 the top north of Malindi area is observed there is development of 'ras' due to improvement of deposit and port extension and the expansion of the Stone Town city along the bank of the creek especially at Mbuyuni, Darajani, Kisiwandui, Mkunazini, Mchambawima, Kokoni and Mnazi Mmoja, these areas especially Mbuyuni and Kokoni were the areas with huge mangroves at this time, the analysis showing that the Kisiwani Islet at Mnzi Mmoja is already joined with Eastern part land of Mnazi Mmoja and Kikwajuni which form shoreline to change by creating new land area, due to the slowly reclamation and extension of the city, even though there was a slightly erosion and over floor of seawater, changes also is observed at top north of Malindi inside creek where there is high erosion forming an elbow shoreline shape probably due to the amount of water coming inside the creek bouncing along the bank of western part of the creek, from these changes also slowly result shoreline length reduction. In 1907 the passage of Creek at the north part at Funguni starts to narrow and the southern part of the inlet at Mnazi Mmoja as well. The result shows that by this time at Funguni and Malindi there is more development seaward especially in the Forodhani area (see figure no. 5 the year 1907). In between 1907 to 1987, there is a major change, a tremendous and major reclamation was done in this time, in figure 1, 2, and table 2 above, figure 3, 4, and 5 below are showing clearly the entire creek from Mnazi Mmoja, Darajani to Funguni at this time was reclaimed and transformed into other human development projects like; cities and other huge construction took place during this time. About 0.46 km square of the creek where it was called a rotten sea and 'Pwani ndogo' (figure 1 and 2 above) was reclaimed totally except a small portion which is now called Bwawani wetland. At the northwest of the area there is an extension seaward side up to several meters for Malindi port expansion (see figure 5 the year 2004 -2020), figure 3 and 4 are an example of changes before reclamation in 1920 and after 2020 respectively. However, at this time there was much sea wall development for protection along the entire shoreline of Zanzibar Stone Town to manage the shoreline and properties from wave destruction. Shallow and calm water of western side of Unguja Island together with barrier coral Islets at far north from Malindi port has been protecting the Island from direct strong waves and longshore bouncing, however, apart from this natural protection, the removal of Mpigaduri mangroves will highly affect the entire shore unless there will be other feasible adaptation measures. This development of mega projects although is said to be an advantage for land accretion also, the analysis shows there were challenges along the shoreline especially at the Funguni passage; in this area, there is extra erosion and inland water floor which extend several meters to Mpigaduri up to Mtoni shoreline that has also influence the development of mangroves (see also figure 5) although the increasing of mangroves is an advantage, it was also seeming like an attempt of increasing level of water at Malindi port in such a way that seafloor forced to change its direction to the southwest where there was a high and long impacts on this shoreline, two jetties are evidence (figure 5 Apart from human influences, some other factors have also influenced the changes of shoreline, there are natural processes as discussed by (Arthurton, 2004), even though there is no direct report of climate change impacts such as sea-level rise until the 1980s due to the limited availability of data sources in Zanzibar that could be also a reason for shoreline changes, some studies [26] showing falling of relative sea-level until 2000, it might be also a bit of good luck for the city to reduce severe impact from flooding of the shore. However, in recent years between 2000 to 2012 [1] shows there is a sign of rising in sea level that could be also possible related to shoreline changes [11], [27], thus why in some areas like Kilimani (will be explained later) have been facing such challenges which are associated to climate change impacts. # b) Shoreline changes Kilimani to Mtoni between 1846 to 2020 It was found that when the shoreline is longer than the previous one is an indication of having either too much retreat or huge accretion. The trend of the shoreline length in figure 6 shows that in the early 1900s (1846, 1892, and 1907) shoreline was longer and started to shorten up to the late 1980s, however, the tendency of stretched again is shown from the late 1980s to 2020, where this is correlated with accretion and retreat results obtained as shown in figure 8 which will be explained later. The figure shows four hotspots areas of changes, two have more accretion and two with more retreat of the shoreline. In Malindi hotspot which includes Darajani and Mnazi Mmoja (Zanzibar Town area) from 1846 to 2020, there is accretion as described earlier in this study, we could see the shoreline is longer and extended onshore several meters (see figure 7). The second hotspot that shows changes of accretion is the Mtoni area, this location has been accreted for the last decade in different years; 2010, 2004, 2016, 2017, 2019 to 2020. Kilimani and Migaduri are the other three and four hotspots respectively which their shoreline has seen to be longer and extended landward, for Mpigaduri hotspot which also involves Funguni and Kinazini; these areas according to spatial analysis are alternatives of wave movement to maintain a balance of Malindi and Darajani reclamation caused by port and city development which is adjacent to it. Likewise, Kilimani hotspot shoreline changes (figure no. 7 the year 1907 -2020 and from the year 2010, 2016, 2017, 2019, and 2020) show different stages of shoreline changes that have been caused by many factors; the development of sewer channels that interrupted coastal processes and causing seawater landward(inundate) and develop an inlet which did not exist before 2010 as shown in a map, although the area had a sandbank ridge in adjacent side of shoreline north westward there are walls thus why when seawater bounce is deflected and forced southeastward which found its way in loose white sand beach deposits which are easy to erode loose sandbank. The area also, because it is on the opposite side where coastal processes are likely to be little interrupted from Malindi Darajani reclamation which is opposite side but rather climate change impact could also a causal factor, other activities like sewer and stormwater drainage construction and channeling were very likely the cause erosion (retreat) where seawater found its way easily to weep out loose materials of sandbank beside the sewer channel before 2004 Kilimani area there were many human activities practices; agriculture like paddy cultivation, sports, and likes, sadly in 2010 the area changed totally when seawater invade the area and reach up to settled zones during high tide with no agricultural activities nor sports and even reduction of a crosswalk along the shore, changing the ecological system and new form of the inlet, mangroves, salt marsh, and tidal flat dominated the area, in figure 7 someone can see how Kilimani changed from 1907 to 2020, and from 2004 to 2020. # i. Area of land accretion and retreat of Urban West Unguja -Zanzibar Shoreline of Western Indian Ocean between 1846 to 2020. Accretion here is also meant deposits or land reclamation through natural and human influences through projects development or any other activities along the shoreline, the same way applies vise vasa to retreat. As we noticed earlier that one of the characteristics of the shoreline is that, when the stretch is long, it means either there is high erosional or deposition (retreat or accretion). It has been revealed in this study that, in 174 years the shoreline has been changed in different stages, for these years the geographical areas of Urban West sites experience more accretion rather than retreat, geographical, spatial analysis, and projections of the overall accretion and retreat in figure 8 and 9 shows for 174 years is 1527693.85 m 2 (1.53 km 2 ) and -936135.48 m 2 (-0.94 km) receptively. The average accretion of land from 1846 to 2020 is 8779.85m 2 /yr. (0.0088 km 2 /yr.) and retreat is -5380.09m 2 /yr. (-0.0054 km 2 /yr.) as shown in figure 8 above. A major accretion is observed during the early 1900s to late 1987 in which there was a major land transformation as shown in figure 9 below, as well as between 2010 to 2020. However, a land retreat is higher from 1987 to 2004. The process of accretion and retreat took place in a reversal from year to year, observed areas of high accretion up to 2020 are Malindi, Mtoni, Darajani, Mnazi Mmoja, and Funguni, and the areas of the high retreat are some parts of Kilimani, Mpigaduri, Mtoni and parts of Maisara shoreline. The accretion in urban cities is likely associated with the development and technological advancement in many cities especially developed countries [28] compared to the previous situation of a higher rate of erosion postulated by Bird (1984). However still developing countries, SIDS, and rural coastlines facing a higher rate of recession. # Conclusion There is a high impact of shoreline changes that are influenced by human activities rather than natural factors while also hard structural mitigation and management for properties are more practiced compared to other areas. Hard structural management always reduces sand deposits and seawater will find weaker and loose areas to retreat and inundate forming an inlet or canal landward when inlets are formed mangroves and other coastal vegetation will grow faster in a short period. A natural setting like small islands and islets acts as a barrier and should be considered in coastal urban development and Island states as management and protection measures. The extension of the city in shallow, long swash intermittent seafloor, closed shoreline coral and barrier reefs are likely to have low impacts if the reclamation will only consider natural setting and not exceeding coralline strip seaward side in consideration of mangrove site. Alternatively, the open and remote shorelines like small Islands and Islets are more likely to have high impacts when there is too much interruption from the human. Mangroves in urban areas are most important to slow the wave movement and balance especially when there is a major land transformation on the shoreline, thus when it comes to shoreline management through hard structural and engineering development at least a small portion of mangroves could be mitigated at these urban areas from the retreat and sever erosion as well as maintaining ecological and aesthetic value. ![(1: 10,000 Scale), Map of Zanzibar PWD No./44 M-8 of 1907 (1: 63,360 Scale), Hydrological Map of Zanzibar Map No. 3344 of United Nation of July 1987(1: 125,000 Scale), Aerial photographies field 2004 -2005 from the Department of Survey and Urban Planning under Smole II project, Landsat image data from SIO, NOAA, US Navy NGA, GEBO, CNES/Airbus 2020 google image 2019 copyright dataset (see also in table](image-2.png "") 1![Figure 1: Unguja Urban West plan of 1892 with its creek](image-3.png "Figure 1 :") 2131![Figure 2: Unguja Urban West map image of 2020](image-4.png "Figure 2 : 13 ()Figures 1") 3![Figure 3: Darajani Creek 1920 with shopping facilities](image-5.png "Figure 3 :") 43![Figure 4: Former Darajani Creek, now Darajani with shopping facilities 2020](image-6.png "Figure 4 :Figure 3") 5![Figure 3 and 4 show clearly how and to what extent shoreline has been shifting and even dropping its length from 1846 to 2020; Mpigaduri mangroves northeast of Malindi has been acting as a defensive mechanism for every reclamation that was made within nearly 2 centuries (174 years) from 1846 to 2020.Shallow and calm water of western side of Unguja Island together with barrier coral Islets at far north from Malindi port has been protecting the Island from direct strong waves and longshore bouncing, however, apart from this natural protection, the removal of Mpigaduri mangroves will highly affect the entire shore unless there will be other feasible adaptation measures. This development of mega projects although is said to be an advantage for land accretion also, the analysis shows there were challenges along the shoreline especially at the Funguni passage; in this area, there is extra erosion and inland water floor which extend several meters to Mpigaduri up to Mtoni shoreline that has also influence the development of mangroves (see also figure5) although the increasing of mangroves is an advantage, it was also seeming like an attempt of increasing level of water at Malindi port in such a way that seafloor forced to change its direction to the southwest where there was a high and long impacts on this shoreline, two jetties are evidence (figure5the year 2004 -2020) which were constructed offshore of Malindi and Funguni site to trap the sediments and protect the port from sediment accumulation to avoid the high cost of maintenance of dragging at later days.](image-7.png ")Figure 5 :") 6![Figure 6: Kilimani -Mtoni Zanzibar Urban West shoreline Zanzibar between 1846 to 2020](image-8.png "Figure 6 :") 7![Figure 7: Accretion and retreat of the shoreline of Urban West of changes between 1846 to 2020](image-9.png "Figure 7 :") 1Volume XXII Issue I Version IDatasetYearScaleAuthor/Publisher/OrganizationMap Plan1846Guillain 1846Map Plan18921:10,000Baumann 1892Topographic Map19071: 63,360Zanzibar PWD No./44 M-8 of 1907Topographic Map19871: 125,000United Nation No. 3344 of 1987Aerial Photograph2004Department of Survey, Zanzibar 2004-2005Landsat Image12/27/20102000ftGoogle Map 2020 datasatLandsat Image02/24/20162000ftGoogle Map 2020 datasatLandsat Image07/27/20172000ftGoogle Map 2020 datasatLandsat Image10/11/20182000ftGoogle Map 2020 datasatLandsat Image07/24/20192000ftGoogle Map 2020 datasatLandsat Image02/26/20202000ftGoogle Map 2020 datasat12( An Integrated GIS Method -The Influence of Human Activities on Shoreline Change in Western Indian Small Island States: A Two Centuries Analysis of Urban West Unguja -Zanzibar Shoreline © 2022 Global JournalsBAn Integrated GIS Method -The Influence of Human Activities on Shoreline Change in Western Indian Small Island States: A Two Centuries Analysis of Urban West Unguja -Zanzibar Shoreline ## Acknowledgement This work was performed to fulfill and meet the requirement of the Doctoral of Philosophy study of the Universiti Brunei Darussalam (UBD), the work and data are part of the study results. The authors would like to acknowledge the support from the Government of Brunei under UBD Graduate scholarship and the Department of Geography, Environment, and Development in the Faculty of Art and Social Science. The authors would also like to thank the Revolutionary Government of Zanzibar for providing images, maps, and other relevant information without forgetting the Zanzibar community for their special supports. * The Economics of Climate Change in Zanzibar PWatkiss July. 2012 * Reviving the Western Indian Ocean Economy: Actions for a Sustainable Future DObura 2017 * Tourism in Small Island Developing States (SIDS): Building a more sustainable future for the people Islands Aug. 2014 Madrid UNWTO * Impact of human interventions and coastal processes along the Nile Delta coast, Egypt during the past twenty-five years EMAli IAEl-Magd 10.1016/j.ejar.2016.01.002 Egypt. J. Aquat. Res 42 1 Mar. 2016 * Sustainable living with environmental risks NKaneko MKobayashi SYoshiura 10.1007/978-4-431-54804-1 Sustain. Living with Environ. Risks 2015 * the Revolutionary Government of Zanzibar the First Vice President' S Office Zanzibar Climate Change Strategy Rgoz 2014 * The Periplus of the Erythraean Sea: A Network Approach EHSeland 10.12773/arwh.2016.4.2.191 Asian Rev. World Hist 4 2 2016 * Coastal erosion induced by human activities: The case of two embayed beaches on the Moroccan coast MChaibi MSedrati J. Coast. Res 56 2009 * Tanzania Coastal Management Partnership: The Present State of Knowledge of Marine Sciences in Tanzania -Synthesis Report ANgusaru 5047 TCMP A 2000 * Coastal flooding and erosion under a changing climate: Implications at a low-lying coast (Ebro delta) VGrasses MGracia JGarcía-León JPLin-Ye Sierra 10.3390/w12020346 Water (Switzerland) 12 2 2020 * The Fringing Reef Coasts of Eastern Africa-Present Processes in Their Long-term Context RArthurton 10.4314/wiojms.v2i1.28424 West. Indian Ocean J. Mar. Sci 2 1 2003 * Wind Patterns of Coastal Tanzania: Their Variability and Trends SBMahongo JFrancis SEOsima West. Indian Ocean J. Mar. Sci 10 2 2011 * Late quaternary coastal stratigraphy on a platform-fringed tropical coast -A case study from Zanzibar, Tanzania RSArthurton AHBrampton CZKaaya SKMohamed J. Coast. Res 15 3 1999 * The Major Cause of Observed Erosion Surge on the Beaches North of Dar Es Salaam City NNyandwi Tanzania J. Sci 2010 * Reassessment of the nature of beach erosion north of Dar es Salaam, Tanzania NNyandwi December. 2015 * Beach erosion management in Small Island Developing States: Indian Ocean case studies Duvat 10.2495/CP090141 WIT Trans. Ecol. Environ 126 2009 * Practical measures to tackle climate change: coastal forest buffer zones and shoreline change in Zanzibar JMustelin 2009 Tanzania * Historical shoreline trend analysis and drivers of coastal change along the Ravenna coast OSytnik LRío NGreggio JBonetti NE * Adriatic 10.1007/s12665-018-7963-8 Environ. Earth Sci 77 23 0 2018 * Zanzibar in figures 2016 OCGS 2019 * ZANZIBAR STATISTICAL ABSTRACT 2016 OCGS 2017 * An integrated study of shoreline variability using GIS and ARGUS techniques PArmaroli YCiavola MBalouin Gatti J. Coast. Res 39 2006 * A Coastal GIS for Shoreline Monitoring and Management -Case Study in Malaysia RLi CWKeong ERamcharan BKjerfve DWillis Surv * L Inf. Syst 58 3 1998 * Quantitative analysis of urban expansion using RS and GIS, a case study in Lanzhou XLi LLiu XDong 10.1061/(ASCE)UP.1943-5444.0000078 J. Urban Plan. Dev 137 4 Jan. 2012 * Detecting urban growth using remote sensing and GIS techniques in Al Gharbiya governorate, Egypt AABelal FSMoghanm 10.1016/j.ejrs.2011.09.001 Egypt. J. Remote Sens. Sp. Sci 14 2 Dec. 2011 * Geospatial analysis of shoreline and land use/land cover changes through remote sensing and GIS techniques SSamanta SKPaul 10.1007/s40808-016-0180-0 Model. Earth Syst. Environ 2 3 2016 * Projections of Climate Change and Sea Level Rise for Zanzibar PWatkiss MBonjean May. 2012 22 * Obura Coral Reef Status Report for the Western Indian Ocean 2017. 2017 * The State of the World's Beaches ALuijendijk GHagenaars RRanasinghe FBaart GDonchyts SAarninkhof 10.1038/s41598-018-24630-6 Sci. Rep 8 1 2018