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


  • Salim Hamad Bakar
  • Shafi Noor Islam



Human activities, shoreline changes, Accretion, Retreat, Urban management, Zanzibar


Purpose: Urban areas have a high impact on shoreline changes that are more influenced by human activities rather than natural factors, together with hard structural mitigation and management, which are more practiced compared to other areas. This paper describes shoreline changes of small islands specifically; the shoreline of Urban West of Unguja Island in Zanzibar United Republic of Tanzania. This island has been changed for 174 years in different stages due to human activities including; reclamation of Darajani creek, port expansion at Malindi, Mtoni beach nourishment, sewer and stormwater channeling at Kilimani, construction of walls, groins, jetties, etc.  

Methodology: The study uses an integrated method to analyze and detect changes using a sketch plan survey map of 1846 and 1892, a topographic map of 1907 and 1987, an aerial photo of 2004, Landsat images, and google images of 2019 and 2020. These maps were carefully georeferenced with latitude and longitudes, digitized using ArcGIS and demarcated along the study area supported with ground truth observation to analyze the coastal shoreline changes.

Findings: The results show that the area experiences more accretion rather than retreat, integrated analysis and projections of the overall accretion and retreat for 174 years is 1,527,693.85 m2 (1.53 km2) and -936,135.48 m2 ( -0.94 km) receptively. The average accretion of land from 1846 to 2020 is 8,779.85m2/yr. (0.0088 km2/yr.) and retreat is -5,380.09m2/yr. (-0.0054 km2/yr.). A major accretion was observed and detected during the early 1900s to late 1987 which were major land transformation while other minor development activities were between 2010 to 2020. Sea walls, groins, beach nourishment, mangroves, barrier islands, and islets are major management practices of the shoreline which show a positive impact.

Recommendations: The study finds it more appropriate to use multi datasets as an integrated method to analyze long-term coastal shoreline changes especially when there is limited data.           

Author Biographies

Salim Hamad Bakar

Department of Geography, Environment, and Development, Faculty of Art and Social Science, University Brunei Darussalam.

Shafi Noor Islam

Department of Geography, Environment, and Development, Faculty of Art and Social Science, University Brunei Darussalam.


P. Watkiss et al., “The Economics of Climate Change in Zanzibar,” no. July, pp. 1–36, 2012.

D. Obura, Reviving the Western Indian Ocean Economy: Actions for a Sustainable Future. 2017.

UNWTO, “Tourism in Small Island Developing States (SIDS): Building a more sustainable future for the people Islands,” Madrid, p. 5, Aug. 2014.

E. M. Ali and I. A. El-Magd, “Impact of human interventions and coastal processes along the Nile Delta coast, Egypt during the past twenty-five years,” Egypt. J. Aquat. Res., vol. 42, no. 1, pp. 1–10, Mar. 2016, DOI: 10.1016/j.ejar.2016.01.002.

N. Kaneko, M. Kobayashi, and S. Yoshiura, “Sustainable living with environmental risks,” Sustain. Living with Environ. Risks, pp. 1–286, 2015, DOI: 10.1007/978-4-431-54804-1.

E. H. Seland, “The Periplus of the Erythraean Sea: A Network Approach,” Asian Rev. World Hist., vol. 4, no. 2, pp. 191–205, 2016, DOI: 10.12773/arwh.2016.4.2.191.

M. Chaibi and M. Sedrati, “Coastal erosion induced by human activities: The case of two embayed beaches on the Moroccan coast,” J. Coast. Res., no. SPEC. ISSUE 56, pp. 1184–1188, 2009.

A. Ngusaru et al., “Tanzania Coastal Management Partnership: The Present State of Knowledge of Marine Sciences in Tanzania - Synthesis Report,” 5047 TCMP A, 2000.

A. Grases, V. Gracia, M. García-León, J. Lin-Ye, and J. P. Sierra, “Coastal flooding and erosion under a changing climate: Implications at a low-lying coast (Ebro delta),” Water (Switzerland), vol. 12, no. 2, 2020, DOI: 10.3390/w12020346.

R. Arthurton, “The Fringing Reef Coasts of Eastern Africa—Present Processes in Their Long-term Context,” West. Indian Ocean J. Mar. Sci., vol. 2, no. 1, pp. 1–13, 2003, DOI: 10.4314/wiojms.v2i1.28424.

R. S. Arthurton, A. H. Brampton, C. Z. Kaaya, and S. K. Mohamed, “Late quaternary coastal stratigraphy on a platform-fringed tropical coast - A case study from Zanzibar, Tanzania,” J. Coast. Res., vol. 15, no. 3, pp. 635–644, 1999.

S. B. Mahongo and J. Francis, “Wind Patterns of Coastal Tanzania: Their Variability and Trends,” West. Indian Ocean J. Mar. Sci., no. June 2017, 2011.

V. Duvat, “Beach erosion management in Small Island Developing States: Indian Ocean case studies,” WIT Trans. Ecol. Environ., vol. 126, pp. 149–160, 2009, DOI: 10.2495/CP090141.

J. Mustelin et al., Practical measures to tackle climate change: coastal forest buffer zones and shoreline change in Zanzibar, Tanzania, no. 13. 2009.

O. Sytnik, L. Del Río, N. Greggio, and J. Bonetti, “Historical shoreline trend analysis and drivers of coastal change along the Ravenna coast, NE Adriatic,” Environ. Earth Sci., vol. 77, no. 23, p. 0, 2018, DOI: 10.1007/s12665-018-7963-8.

RGoZ, “the Revolutionary Government of Zanzibar the First Vice President ’ S Office Zanzibar Climate Change Strategy,” 2014.


OCGS, “Zanzibar in figures 2016,” 2019.


P. Watkiss, M. Bonjean, and Y. W. Shaghude, “The Economics of Climate Change in Zanzibar 1 . Current Weather Data for Zanzibar and the Effects of Climate Variability and Extremes,” Zanzibar City, 2012.

C. Armaroli, P. Ciavola, Y. Balouin, and M. Gatti, “An integrated study of shoreline variability using GIS and ARGUS techniques,” J. Coast. Res., no. 39 SPEC. ISSUE, pp. 473–477, 2006.

R. Li, C. W. Keong, E. Ramcharan, B. Kjerfve, and D. Willis, “A Coastal GIS for Shoreline Monitoring and Management - Case Study in Malaysia,” Surv. L. Inf. Syst., vol. 58, no. 3, pp. 157–166, 1998.

X. Li, L. Liu, and X. Dong, “Quantitative analysis of urban expansion using RS and GIS, a case study in Lanzhou,” J. Urban Plan. Dev., vol. 137, no. 4, pp. 459–469, Jan. 2012, doi: 10.1061/(ASCE)UP.1943-5444.0000078.

A. A. Belal and F. S. Moghanm, “Detecting urban growth using remote sensing and GIS techniques in Al Gharbiya governorate, Egypt,” Egypt. J. Remote Sens. Sp. Sci., vol. 14, no. 2, pp. 73–79, Dec. 2011, doi: 10.1016/j.ejrs.2011.09.001.

S. Samanta and S. K. Paul, “Geospatial analysis of shoreline and land use/land cover changes through remote sensing and GIS techniques,” Model. Earth Syst. Environ., vol. 2, no. 3, pp. 1–8, 2016, DOI: 10.1007/s40808-016-0180-0.

P. Watkiss and M. Bonjean, “Projections of Climate Change and Sea Level Rise for Zanzibar,” no. May, p. 22, 2012.

D. Obura et al., Coral Reef Status Report for the Western Indian Ocean (2017). 2017.

A. Luijendijk, G. Hagenaars, R. Ranasinghe, F. Baart, G. Donchyts, and S. Aarninkhof, “The State of the World’s Beaches,” Sci. Rep., vol. 8, no. 1, pp. 1–11, 2018, doi: 10.1038/s41598-018-24630-6.

E. C. . Bird, Coast: An Introduction to Coastal Geomorphology, 3rd eds. United Kingdom: Blackwell, 1984.




How to Cite

Bakar, S. H. ., & Islam, S. N. . (2022). 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. American Journal of Environment Studies, 5(1), 9 - 26.