Environmental sensitivity mapping for shoreline management planning

Environmental sensitivity mapping for shoreline management planning

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Tania Golingi
Head of Department, Environmental & Ecology Department, DHI Water & Environment, Malaysia
[email protected]

Annie Ong Hui Nee
Environmental Consultant/ GIS, Coastal & Marine Department, DHI Water & Environment, Malaysia
[email protected]

The requirement for shoreline management planning is recognised around the world and in particular in developing nations where development has resulted in mounting resource utilisation pressures along the countries’ shorelines and coastal areas. Integrated shoreline management planning must take into account the often conflicting goals of development or resource exploitation versus conservation of sensitive habitats and sustainable resource exploitation. A spatially anchored description of the existing environment and the issues faced along each discrete stretch of shoreline is thus the basis of shoreline management planning. Geospatial tools have been instrumental in informing shoreline management strategies due to the ability to integrate and synthesise information on sensitivities, vulnerabilities and opportunities along the coast. This article provides examples where such GIS methods have been used to produce environmental sensitivity mapping for the purposes of integrated shoreline management and discusses the data requirements and limitations of data availability and accuracy experienced. The examples given in this article include case studies from Malaysia, namely the Labuan and Melaka State Integrated Shoreline Management Plans, and on a more regional level, the Shoreline Management Strategy for Kenya.

Introduction
Shorelines constantly change due to waves, tides and sediment deposition and erosion. The ever changing coastlines are also highly influenced by human activity throughout the years. A large proportion of the world population living in the coastal areas depend on economic activities related to or dependant on the natural resources of the coastal zone and hence there is pressure to use the shorelines in such a way that human benefits can be maximised.

However, poorly managed coastal development puts stress on the natural environments through direct damage for example from dredging, land reclamation, sand mining for construction as well as through less direct pressures such as runoff from construction sites and removal of coastal habitat such as mangroves, which filter sediment and nutrients coming from the land. Therefore, the interaction between the various coastal processes and human activity is an important factor influencing the degradation of the coastal zone.

Shoreline management planning attempts to harmonise coastal development with the carrying capacity of the coastal zone through consideration of these interactive physical and ecological processes. Shoreline Management Plans (SMPs) aim to establish sustainable policies or strategies for the effective management of the shoreline. In Malaysia, they have primarily been large scale (e.g. at state-level) assessments of the risk associated with coastal processes and aims to reduce these risks to the human and natural environment. This has been carried out by dividing the coastline into discrete reaches, or ‘management units,’ for which objectives and management strategies are applied. The basis for the discretisation of the shoreline is a thorough understanding of the coastal processes at work. This is general is achieved through numerical modelling of the tidal currents, waves and sediment transport.

Representing another level of detail, the Shoreline Management Strategy for Kenya was a national-level strategy that aimed to identify and prioritise shoreline management issues. Again, this was carried out for discrete stretches of shoreline, however at a greater spatial scale as the first step towards shoreline management planning. Both these approaches, regardless of spatial resolution, relied upon mapping of shoreline and coastal uses, natural resources and the assessment of coastal processes at some level, whether facilitated through detailed modelling or site observations and expert judgements. The role of GIS as a tool for integration of all the various management parameters in shoreline management for these case stories are presented and discussed in the following.

ISMP in Malaysia
In Malaysia, the Integrated Shoreline Management Program (ISMP) carried out by the Department of Irrigation and Drainage is tailored along the principles of Integrated Coastal Zone Management (ICZM) to address the major issues and problems facing our shoreline.

The goal is to develop a management tool that harmonises all the activities in the coastal area to support a set of management objectives for the given area. ISMP in Malaysia is treated as a basis for the formulation of specific guidelines and policies for development activities or proposals in the coastal area.

With these objectives, ISMP in Malaysia has come to encompass detailed studies of natural resources distribution and status, socio-cultural, socioeconomic and landuse aspects, and the physical chemical environment, such as coastal water quality, coastal flooding, erosion and sedimentation. These are data intensive studies, which have generally been conducted over the course of at least two years.

The integration of all these varying factors can only come about based on geo-spatial mapping and overlays. The geodatabase is used as the basis for the analysis of strengths, weaknesses, opportunities and threats (SWOT analysis). From here SMP formulation heads more into the realm of subjective analysis where a diverse group of specialists representing various environmental components (hydraulic and morphological engineers, water quality, marine ecologists, planners and socioeconomists) sit together and propose out management objectives based on the situational analysis for each management unit. These are then validated by stakeholders including local community representatives, government agencies and NGOs. Finally, management strategies are developed to address the objectives identified for each stretch of shoreline.

The ISMP process was first carried out in South Pahang and has since been conducted in five states in Malaysia, including Malacca, Negeri Sembilan, Penang, Labuan and Sarawak. The Labuan and Melaka ISMPs were initiated in 2007 and completed in 2010. Based on Labuan and Malacca ISMP, management unit delineation depended more upon existing land uses. For instance, Malacca ISMP has delineated 51 management units out of the 70 km (approximately) shoreline and Labuan ISMP with 39 management units that cover slightly longer stretch of shoreline (89 km approximately). This is due to the more complex shoreline land uses in Malacca where development activities are concentrated along the coast.

Existing pressures for growth and higher land prices makes sea reclamation as a popular approach to urban development. In Labuan, coastal erosion and the failure of coastal structures have been a major issue addressed in the Labuan ISMP study.

Kenya
In Kenya, the National Environmental Management Agency (NEMA) took the initiative to develop a Shoreline Management Strategy (SMS) to address the need for integrated development guidelines to manage the shoreline within the broader context of Integrated Coastal Zone Management. In comparison to Malaysia, Kenya has the fortunate situation where a considerable body of geospatial data on the shoreline already existed through a national coastal mapping and coastal classification study which culminated in the production of the Environmental Sensitivity Atlas for the Coastal Area of Kenya (KENSEA, 2006). This geodatabase, encompassing geomorphologic data, socio-cultural and biological-ecological data formed the basis of the shoreline management strategy.

The knowledge and experience of government bodies, research institutions and other relevant agencies in Kenya were harnessed by NEMA to form a Shoreline Management Task Force to deliberate on and develop the Strategy with the geodatabase as a starting point. The development of shoreline management objectives and strategies was based on a systematic assessment and review of the database along discrete stretches of shoreline as defined by the Sediment Cell. The delineation of the sediment cells along the Kenyan shoreline was carried out through a review of the shoreline geomorphology, coastal classification (shoreline type) and aerial photographs along the shoreline.

Similarly to the Malaysian ISMPs, a SWOT analysis was carried out, however for the strategy this was done at the scale of the sediment cell rather than at the management unit resolution for the entire shoreline of Kenya. To demonstrate planning at the ISMP level however, an example SMP was done for one district, whereby Management Unit delineation and management objectives and strategies were formulated at a MU level.

Development of baseline conditions
Data Requirements: Sufficient information on the shoreline is required to gain an understanding of the shoreline characteristics and main issues affecting the shoreline. The information needed for sensitivity maps were obtained from existing, scientific publications, topographic maps, photographs and environmental data held by organisations such as government departments, universities and conservation agencies.

Relevant data include:

  • Remote sensing imagery – satellite and aerial photographs (orthographic or oblique)
  • Topographic maps
  • Bathymetric survey charts
  • Met ocean data – waves, currents, water levels and wind
  • Hydrological data
  • Land use
  • Cadastral information
  • Spatial plans
  • Tourism
  • Industries
  • Ports and harbours
  • Fisheries and aquaculture
  • Nearshore navigation
  • Inlet stability and navigation
  • Bottom sediment composition
  • Water quality and pollution
  • Marine habitats, communities and species (corals, seagrass, mangroves, soft-bottom, turtle landing beaches, shorebird habitats, etc.)
  • Terrestrial habitats
  • Sand mining and quarries

Determining processes: Data for certain physical parameters are generally limited in space and time, providing steady state snapshots of an otherwise changing environment. Numerical modelling is used as a tool to expand such information over the spatial and temporal dimensions. In ISMPs, numerical modelling is most often used to simulate physical and chemical processes based on the available data, therefore making it possible to anticipate these processes over time and space and with differing scenarios or conditions. The numerical models are used to obtain a detailed understanding of tide and ocean currents, nearshore wave conditions, water quality and riverine sediment plumes and littoral processes (see examples of modelling results for Labuan ISMP, 2010 in Figure 1 and Figure 2).


Figure 1: Predicted suspended sediment concentrations within Brunei Bay and Labuan Island from land based sources during typical flood (left) and high (right) tide for NE monsoon condition.

Figure 2: Sediment transport patterns with significant wave height of 2 meter.
Mapping: Mapping includes distribution of natural resources (habitat mapping); land use; socio-cultural features, threat and sensitivity mapping. The various components are described briefly below.

1. Ecology and environmental resources – Biological resources maps refers to terrestrial and marine habitats and sensitive locations such as corals, seagrass, mangroves, soft-bottom, marine parks, turtle landing sites, forest reserves, etc. It is important to map the coastal biological features as they will determine the management objectives for the affected section of the coastline. An example of distribution of key marine habitats and marine parks from Kenya SMS is shown in Figure 3.


Figure 3: Distribution of key marine habitats, species and protected areas in Malindi District, Kenya.
2. Shoreline geomorphology – In Malaysia, the National Coastal Erosion Study (1984-1986) categorized nine basic landforms that have been taken to describe the coasts of Malaysia as follows:

  • S – Straight shoreline
  • P – Protruding shoreline
  • B – Embayed shoreline
  • I – Irregular shoreline
  • R – River mouth or Estuary
  • Is – Island sheltered shoreline
  • H – Headland
  • D – Delta formation
  • Sp – Sand spit

3. Shoreline classifications –Shoreline in Malaysia ISMP are classified according to sediment type. Classes include sandy beach, rocky outcrops and rocks, coastal structure (seawall, revetment), mangroves and also water village areas. In Kenya SMS, the shoreline classification scheme has two categories; firstly, the primary coastal type which relates to the overall geomorphology or exposure of the coastline; and secondly, the component facies, which relates to the actual type of shoreline, i.e. sandy beach or rock cliffs (Table 1). Shoreline classification was carried out based on available shoreline classification carried out under the KENSEA project and modified to align with the classification scheme outlined in the Guidelines for the Study of Shoreline Change in the Western Indian Ocean Region. The shoreline classification was also carried out using the available aerial oblique photographs of the shoreline and information on coral reef distribution.


Table 1: Coastal classification scheme from the Western Indian Ocean Guidelines on Shoreline Change
4. Coastal erosion – The Labuan ISMP have the coastal erosion severity classified based on the NCES erosion category. Based on the erosion severity category given in Table 2, information such as land use, demographic and coastal resources are important to designate the appropriate erosion severity category for a particular subcell.


Table 2: Coastal erosion severity
The Kenya SMS a national-level strategy only identify sites with coastal erosion and marked as erosion hotspots based on the 2005 KENSEA aerial photo survey (see Figure 4).


Figure 4: Erosion hotspots along the coastline
Human Environment
Features and characteristics of the human environment include settlements and population densities along the coastline. Built up environment is spatially mapped out to assess the risks from coastal erosion, identify important economic zones or areas requiring protection such as fish landing areas, harbours, etc.

Management planning methodology
In shoreline management planning, the shoreline is divided into sediment cells and further detailed to Management Units (MUs) for which management strategies are selected based on the setting of management objectives.

Management units (MUs): A management unit (MU) boundary is determined by the geographical extent of natural coastal processes, gazetted conservation areas and human activities related to the coast.

Management objectives: The baseline studies highlighted a range of issues critical to the sustainable use of the shoreline through preservation, rehabilitation and development. These are expressed as generic management objectives to be targeted in each MU.

Management strategies: Management strategies are assigned for each MU to provide guidance towards planning and prioritising further studies and efforts in coastal zone management.

Define cells and subcells
Shoreline is divided into a series of cells and subcells define by their coastal morphology and geology. The main cells are defined as coastal stretches that do not interact which each other. The sub-cells are, however allowed to interact moderately which each other but must define coherent stretches of coastline. Sub-cell boundaries may therefore be defined by small coastal structures, rivers, small headland or if shoreline features changes. Example of sediment cells delineation with the overlays of shoreline classification and other coastal features is shown in Figure 4a.


Figure 4a: Cell and subcells, Labuan ISMP 2010.
Identification of management units
Cells are further divided into a series of management units based upon the map overlay of physical, biological and social characteristics of the shoreline. Baseline conditions to be considered in MU designation are outlined below:

  • Coastal characteristics (shoreline and sediment type)
  • Erosion threat and coastal protection requirements
  • Land use along the shoreline and immediate hinterland
  • Marine habitat types or marine protected areas

Examples of MU delineation based on coastal features are presented in Figure 5. The Malacca ISMP has designated MU5 as a unit based on the very narrow beach baked by terrestrial vegetation and the immediate MU6 as a different unit when the inshore features changes to housing.


Figure 5: Example of MU designation, Malacca ISMP 2009.
Setting of management objectives
The key features of importance or providing benefits to society that are found within each cell are listed in order of priority, followed by a list of issues or threats to these features or benefits in the cell. Specific objectives for the management of the features or benefits and the threats to these features are then listed (Table 3).


Table 3: Summary of features, threats and issues and management objectives for sediment cells 10-12 within the Malindi District, Kenya SMS 2010.
As for most decision making processes, prioritisation of issues is still subjective. The selection of management objectives for each management unit would thus normally be carried out with stakeholder consultation, especially to determine the local perception of each feature/benefit. During this process, GIS is important as a layperson tool with the overlays of key environmental features, issues and threat spatially to provide a clear picture to the stakeholders

Management strategy maps
Based on the critical issues identified along the coastline and the management objectives, a list of management strategies is formulated (Table 4 example from Kenya SMS). Management strategies that best fulfils the highest ranked objectives(s) are selected for each specific MU (Figure 6).


Table 4: Example of management strategies from Kenya SMS, 2010.

Figure 6: Management Strategies, Kenya SMS 2010.
It is noted that development of management objectives and strategies should be further refined as more information on coastal processes, proposed developments and general development objectives and policies is obtained.

Conclusion
The emphasis of this paper is the application of GIS technology as a decision support tool to assist in the formulation of management strategies in shoreline management planning.

Modelling of coastal phenomena are extremely valuable techniques for assessing the effectiveness and likely impacts of potential or proposed interventions. GIS has the ability to respond rapidly and flexibly to ad hoc ‘what if’ scenarios. The integration of modelling results in environmental sensitivity mapping would provide a valuable link for facilitating coastal decision-making and SMP policy formulation such that the expert evaluation and assessments of the modelling results can be more readily communicated or linked into the other SMP team members and the wider public.

In many cases, environmental sensitivity mapping is carried out for oil spill response. The level of sensitivity to the environment is quantified and following the level of the sensitivity, a management or response plan is drafted. This ESM approach is slightly different from the method applied in our Malaysia SMP experience. The GIS overlay of environmental sensitive features facilitates engineers and environmental scientists in the designation of management objectives and, subsequently, strategies. However, not all of the environmental sensitivity features are quantified and further classified based on their level of sensitivity. For instance, scoring systems could be applied on various marine life and habitats based upon their characteristics to sensitivities and the level of intervention. Future SMP studies should perhaps investigate this level of analysis in ESM.

The SMP formulation relied heavily upon the considerable body of existing data related to the physical, biological and land use features along the shoreline, in addition to the knowledge and experience of the engineer and environmental scientist. In particular the GIS datasets developed under the Environmental Sensitivity Atlas for the Coastal Area of Kenya (KENSEA) is an example of a comprehensive physical biological GIS datasets. The development of coastal resources maps and further calculated based on the environmental sensitivity index provide the key spatial baseline data used in the development of the Kenya Shoreline Management Strategy.

Data has become more and more elaborate or intricate – with for example morphological or water quality information expanded through numerical modelling, more information on consequences or impacts of various processes, interactions, etc. etc. All of this provides the opportunity for more sophisticated environmental and process-based spatial planning, and GIS provides the key tool to link and present such data. However, it is also the intention of this paper to highlight that whatever technologies and tools are available, whether it be used in the development of the data or the analysis and presentation of such data, how this increasingly detailed information is used must always fall back on the hands of the specialists involved, and we must be careful not to allow the tools to overwhelm the science.

REFERENCES

  • NEMA, 2010. Kenya Shoreline Management Strategy
  • DID Malaysia, 2010. Labuan ISMP
  • DID Malaysia, 2007. Malacca ISMP
  • GEUS, 2006. KENSEA: Environmental Sensitivity Atlas for Coastal Area of Kenya.
  • Application of GIS Technology for Coastal Zone Management: A Hydrographer Perspective, by Lt. Commander R. K. Bhardwaj
  • Improved Environmental Sensitivity Mapping (ESM) Tool for Sustainable Land-use Zoning in Aceh Selatan and Nias Island, by Carsten Huttche
  • Government of Kenya. 2009. State of the Coast Report: Towards Integrated Management of Coastal and Marine Resources in Kenya.
  • https://www.water.gov.my/