Using GIS in Wetland Managment

This blog was taken from a recent university study I conducted, using a case study on Cambodian wetland management to investigate using a Geographical Information System for management purposes. It therefore takes a more formal format than regular blogs but I didn’t alter it as I wanted to keep the research based tone.


Image Source: TYTO Wetlands


Wetlands are the classified as areas of land which are covered by water at least part of the year (DEE 2018). They can be considered transitional areas between the aquatic and marine, where the water table is frequently interacting with the surface. The floodplain is the alluvial plain of a river, the extent of which is often considered the maximum reach of flooding, they include wetlands as areas which are mostly wet throughout the year. Wetlands are ecologically significant and play a crucial role in providing ecosystem services or benefits to human populations on local and global scales. One key role is the regulation of water movement (Richardson 1994, Mitsch & Gosselink 1993). As such, wetlands provide flood control, increase groundwater recharge, reduce sediment load, contribute to carbon sequestering, reduce pollution by absorbing nutrients and provide habitats for plant and animal species. This is on top of benefits to industry such as providing nurseries for fish or supporting fertile soils for agriculture (DEE 2018, Datta & Gosh 2015). Therefore, the protection and management of these unique ecosystems is crucial to continue the economic, social and environmental benefits. This is particularly true with the growing pressures such as agriculture, rural and urban development and increased groundwater usage, which the Ramsar Wetland Convention estimates have contributed to the decline in the extent of global wetlands between 64-71% (Gardner et al. 2015).

The Ramsar Convention, an intergovernmental treaty, aims to counter this global trend of wetland loss and degradation through the designation of sites considered unique or important for conserving biological diversity. Once a set of criteria is met, sites can be designated as Wetlands of International Importance (Ramsar 2018). That Ramsar site is then required to be managed by that country with the express aim of conserving and ensuring its “wise use”, or the “maintenance of ecological character… within the context of sustainable development” (Ramsar 2010). Loosely there are two sets of criteria for classifying a site with a Ramsar status. One for unique wetlands and one for sites important in conserving biological diversity (Ramsar 1971).

Cambodia, a country of 181, 035 , has an estimated 20-30% of its total area as wetlands on which the country is both culturally and economically reliant (Sophal 2004). The Mekong River and its tributaries drive the hydrology of the area. Though the overall population density of Cambodia is relatively low for a southeast Asian country (89.3 people per square kilometre in 2016) the areas adjacent to the Mekong and Lake Tonle Sap are estimated at 500 people per square kilometre (Knoema 2018). Tonle Sap Lake, the heart of the system, is uniquely known for its pulsing flushes. From November to May the lake drains into the Mekong, shrinking substantially and then undergoes significant flooding during the monsoon season as water from the Mekong reverses the flow of the Tonle Sap river into the Lake. The Lake absorbs this influx of water, increasing in size anywhere between 4 to 6 times (Hoskin & Hopkins 1991), releasing slowly post flood (DeClerck et al. 2013). This flushing system results in momentous changes between wet and dry seasons on top of significant variations between wet and dry years. This variation has historically been difficult to predict and map (MacAlister & Mahaxay 2009).

cambodiaImage Source: Mekong Heritage Travel

This pulsing is the life support of the system, driving major biogeochemical cycles (Junk et al. 1989). Of the many communities which live and rely upon the system, an estimated 80% of the population rely on the production of wetlands resources (Quan et al. 2015). The pulses provide the necessary nutrients and water to sustain the productive freshwater and agricultural systems in the area (Davies et al. 2014, Flower & Fortnam 2015). When the Mekong inflows into the Lake an estimated 100 distinct species of migratory fish follow the waters to spawn in the Lake (Lovgren 2017), this increased activity is crucial to communities heavily reliant on fishing (MacAlister & Mahaxay 2009). Freshwater fisheries account for 82% of the total fishery production in Cambodia (Sithirith 2015). In general, communities within the floodplain are known to divide their time between rice cultivation and fishing (DeClerck et al. 2013). A sizable portion of the predominantly rural communities (80% of the total population) rely on subsistence farming, with the cycle of vulnerability of these people driven by high rates of poverty in combination with a country particularly susceptible to natural disasters, preventing producers reaching a state where they can sell large surplus’ (New Agriculturists 2018).

The Royal Government of Cambodia recently converted the “fishing lot” system or fishing territory allocation to open fishing on the Tonle Sap once again, a concern for fish conservationists. There are four Ramsar recognised wetland areas (sites), two of which are found within the vicinity of Tonle Sap. However, it has long been recognised that outside of these efforts the lack of coordination between various government agencies, the reliance on international aid, the neglect on the provincial level to maintain conservation efforts, the limited budget allocated to wetland protection, the issues with government regulation enforcement and the lack of information available on wetland management, are all significant barriers to the proper protection and management of wetland areas in Cambodia (Sophal 2004, Flower & Fortnam 2015). Particularly within the keeping of “wise use” for the prolonged benefits of ecosystem services.

The limitations to the Ramsar wetland sites of importance is in the criteria itself. Particularly when applied to a country such as Cambodia, where the reliance on wetlands and the associated ecosystem services is clear, but there is great uncertainty in relation to management of natural resources within the floodplain areas. Along with disorganised and segmented management, a lack of legal definition of wetland areas, defined by Cambodian Law, is preventing areas outside of the Ramsar status from obtaining appropriate protection and management (Sophal 2004, MacAlister & Mahaxay 2009).

Though flooding is vital to the systems overall function the Mekong River Commission estimates that the total damage to agriculture and infrastructure caused by flooding is 60-70 million USD annually (MRC 2018). The 2013 flood, the magnitude of which is not considered anywhere within the scale of a typical 1 in 100-year flood event for the region (MRC 2014), affected 1.8 million people across 20 provinces (Flower & Fortnam 2015). Floods with this level of impact have been increasing in severity and frequency. Previously major disruptive flood events would occur every 5 years, floods considered to have reached disaster level have occurred every 1-3 years since 1990 (Flower & Fortnam 2015). Climate change is expected to increase the magnitude, volume and duration of floods, particularly during the August-November flood pulse (ADB 2014, Keskinen et al. 2010). Cambodia was ranked eighth on a list of 193 countries, in terms of a Climate Change Vulnerability, an index rating the exposure, sensitivity and potential adaptability of countries. This vulnerability driven by the frequent exposure to droughts and floods as well as the countries reliance on agriculture and the lack of capacity for adaptation due to low incomes and limited support infrastructure (Maplecroft 2014, Flower & Forntam 2015). Water resources infrastructure development is predicted to change the flood regime (Xu et al. 2009, Grumbine & Xu 2011, Lauri et al. 2012, Flower & Fortnam 2015), with an estimated 126 hydropower projects currently under consideration between nations within the Mekong Basin (ADB 2014). This development is expected to “dampen” the flood pulse as well as shift spatial habitat patterns and interrupt migratory fish routes (Flower & Forntam 2015). This is coupled with the growing influence of expanding agricultural areas, increasing soil erosion driven by deforestation, in turn increasing sedimentation (Torell et al. 2004) which will influence the system’s capacity for storage of monsoon flood water (DeClerk et al. 2004).

Previous studies have been conducted into mapping and classifying wetland areas for management purposes, to ensure the continued sustainable use of their ecosystem services. In New Zealand, for example Ausseil et al. (2007) used a relatively simple digital terrain model with self-created landscape indicators to assign a score to a wetland based on the relative importance of each indicator. The City of Quebec used a Multi Criteria Analysis (MCA) method to access the ecological value of wetlands within its bounds (Lavoie et al. 2016). A method for wetland identification by Hunter et al. (2012) attempted to address the issues relating to poor mitigation site selection and the subsequent failure to recover full wetland function, by using a complex patchwork identification model coupled with an entropy based predictive model. Though effective, some of these techniques would be difficult to apply a location such as Cambodia, where the large flood plain area undergoes such drastic changes over the course of even just a year and there is limited data available. There is a need for a simple, cost effective method that can be easily adapted for site specific needs which can include the cultural and social reliance of areas, such as the floodplains of Cambodia, on the ecosystem functioning of wetlands.


The purpose of this report is to investigate the possible use of a simple Boolean Overlay (BO) through a Geographical Information System (GIS) in determining areas for mitigation, management and protection of wetlands. This is with the overall aim of determining the effectiveness of a simple method in accounting for the various forms of reliance on wetlands, as well as contributing to increasing the awareness of the importance of wetlands and the ecosystem services they provide.

With the current strains on resources, the lack of official government guidance, the vulnerability to natural disasters and climate change, as well as the heavy cultural and economical reliance on wetlands and the floodplain, the Kingdom of Cambodia is a suitable example study area to conduct a MCA to determine areas of the floodplain which could potentially provide the greatest benefit. The secondary purpose of this investigation is to evaluate whether an approach that considers the services provided by wetlands will differ to an approach that primarily considers vulnerability in light of future changes to the system.

This analysis has been separated into three parts:

Part 1: The Study Area – The Floodplain

The determination the extent of the floodplain in relation to the link between possible wetland areas and the comparison to established Ramsar sites.

Part 2: The Site-Specific Ecosystem Services

The identification of sites of wetland areas for priority management, based on specific ecosystem services provided.

Part 3: The Future Vulnerability

The identification of areas with the greatest vulnerability and how this knowledge could influence the identification of sites for possible wetland management. A comparison will then be conducted between these areas and those identified based on the ecosystem services provided.

Materials and Methods

Data and Software

It was decided that a model builder approach within ArcGIS would be an efficient method to prepare data for pre-processing before applying an MCA. Figure 1, Model Builder 1, shows the steps undertaken to prepare the data for analysis and the outputs necessary for Part 1. Model Builder 2, Figure 2, shows the steps taken for Parts 2 and 3 of the analysis. A list of the initial data sets (and sources) modified for the purposes of this analysis can be found in at the end.


A BO is the intersection of data layers that have been selected via binary methods, such as AND or OR. A simple BO form of an MCA was chosen due to its simplicity. This was partly the case because of limitations on data type, quality and detail. Rather than change site for this analysis it was considered part of the process to determine if a BO approach would be useful with such limitations on data. For example, ideally one of the criteria for selection would be based on the extent of a 1 in 100-year flood, however this data was not available for the region. BO is used in to create the proposed sites based on the binary separation of data created in Parts 1, 2 and 3. This output final layer was a result of the attempt to prioritise various ecosystem services and was then compared to an output map created from considering areas of varying future vulnerability.

Part 1: Study Area

As discussed in previously, Part 1 of this analysis was the identification of the specific study area for further steps of the analysis. There was no data available with predesignated areas classified as wetlands, as this has not been undertaken on the national government scale. Therefore, a floodplain area was determined to be sufficient for the purposes of this analysis. To determine the floodplain area, data was collated with land that has historically been subjected to inundation. Those areas which were hydrologically defined as being either non-perennial, intermittent or fluctuating, were all considered to be within the definition of a floodplain and therefore likely to contain areas of wetland.

A “typical” flood data set was obtained, to compare and validate this area allocated as floodplain. The 2013, September/November flood was chosen as the conditions of this flood have been shown to be within historical norms, with peak discharge ranging across the extent of the flood from average to below average (Adamson et al. 2014). This is in conjunction with limitations on data availability. A 2013 flood extent dataset was obtained and modified (e.g Clip tools) as shown in Figure 1, to obtain an estimation of the area affected by the flood that was not in the designated floodplain of this analysis.

Established Ramsar sites were pulled from data containing the natural protected areas of Cambodia. The area adjacent to Tonle Sap within this data set had no formal protection status allocated and was in fact designated as “multi-use” and therefore would be of no further assistance in this analysis and in fact further confirmed the need to conduct an investigation such as this one.

All datasets were clipped to only include areas within the administrative bounds of Cambodia. Population data was associated with certain layers when necessary, using the Add Field tool. The floodplain layer created in this part would then become the bounds of the study area for the rest of the analysis.

Part 2: Ecosystem Services

To include the benefits of ecosystem services in consideration for site selections for wetland management, key services within the context of the Cambodian floodplains needed to be identified. Arguably, as discussed in previously, flood protection is clearly an dominant ecosystem service for Cambodia. Therefore, to represent this reliance on flood protection within the floodplain the following aspects were investigated.

Regions reliant on agriculture

As discussed previously, subsistence farming is an integral part of the culture in Cambodia which has historically in this form been vulnerable to flooding. Therefore, areas that were designated for agricultural land use were identified and accessed. Around 90% of the agricultural production of the entire country is rice (New Agriculturists 2018). Hence, for a more in-depth analysis, the percentage of land cover by rice was found at the smallest administration level that data was available for (communes).

Regions (by commune) reliant on fish farming

It is estimated that 80% of the human consumed protein in Cambodia is sourced from freshwater fish (Arias et al. 2013). Data representing communes reliant on fish farming was also included, which was based on the results of the 2013 Census.

Regions with higher poverty rates

A study in 2014 (Davies et al. 2014), found that the incidences and risks associated with water borne diseases increases with flooding in Cambodia and are related to the inaccessibility of health service as well as inability, without access to power, for people to treat water. It is estimated that a loss of around 1,200 riels (equivalent of 30 cents US) per day of income would plunge 3 million Cambodians back into poverty, which would double the rate of poverty in Cambodia (World Bank 2014). Considering this, poverty rates per commune was considered a useful method for demonstrating the reliance on flood protection within the floodplain as it could be considered that those areas of higher poverty rates would likely be more susceptible to flooding.

After an initial assessment of the results from parts 2a, b and c, the following criteria was established in order to create a proposed area for wetland protection within the floodplain of Cambodia:

  • Communes which have more than 75% of the land use as predominately for rice farming
  • Communes deemed dependent on fish farming
  • Communes where more than 30% of the population are below the national poverty line

By binary selection and then exporting from the layers established in Model Builder 2 the criteria above were individually segregated. Then through the use of the Union tool (BO “AND” method) the combination of these three criteria were used to create an entirely new layer of the proposed area for wetland protection and management.

Part 3: Future Vulnerability

Cambodia is considered a Kingdom relatively vulnerable to climate change, as discussed previously. Data was available from the Economy and Environment Program for Southeast Asia, a program administrated by WorldFish (World Fish 2013), that visualised the vulnerability of areas in Cambodia to climate change. The data represented the level of exposure to climate variability and sensitivity to climatic stresses, as well as relative adaptability through an index value from 0 to 1, 1 being the highest vulnerability rating.

Another key future vulnerability of the system is the expected influence on the flood pulse system of growing hydrological development. To represent this, one predicted change to the system was spatially applied to show the area that would be affected by this change. Expected changes to the Mekong are that the wet season on the river system will lower by 40-50cm (Lauri et al. 2012). This was found to relate to a horizontal shift of around 500m, creating a reduction across the system in the floodplain area that is annually flooded (Arias et al. 2013). A Buffer tool was used to apply this reduction of 500m to the floodplain area to find the remaining area that would be affected.

Model Builder 1
Figure 1: Model Builder 1, the model and steps taken for pre-processing data and for Part 1 of the analysis.
Model Builder 2.jpg
Figure 2: Model Builder 2, the model and steps taken for pre-processing data and for Parts 2 and 3 of the analysis.

Results and Discussion

Part 1: Study Area

The result of Part 1 of this analysis are shown in Map 1. It is clear, as expected, that the areas designated as the floodplain, the study area for this analysis, are those adjacent to Lake Tonle Sap and other major water bodies of Cambodia. As can be seen in Map 1, all those areas defined as Ramsar sites are within the floodplain. These only account for 3% of this total area of floodplain. In comparison the floodplain itself is a total of 13% of the surface area of the country. The 2013 flood extent was also compared to this floodplain. 24% of the area affected by this “typical” flood was outside the areas classified as regularly inundated; the floodplain.

Map 1.jpg
Map 1


Map 2.jpg
Map 2

Part 2: Ecosystem Services

As can be seen in Map 2, accessing agricultural areas based on land use appears to have given a substantial underestimation, that does not match what is known about the prevalence of subsistence farming. The areas allocated for agricultural use are also predominantly isolated from the adjacent areas of the lake, also outside expectations in terms what has previously been discussed as the cultural/social trends within the floodplain. Map 3 however shows some clear patterns in terms of a separation between communes and the reliance on rice farming and fishing. Approximately 25% of the floodplain area contains communes with greater than 75% by area of rice farming and 23% of the floodplain contains areas that are classified, based on the 2013 Census as being dependent on fish farming. Map 4 indicates that 11% of the floodplain area has 30% or more of its population living below the national poverty line.

The resultant area found through the combination all the three criteria given in he Methodology section was approximately 50% of the total floodplain area, as shown in Map 5.

Map 3.jpg
Map 3
Map 4.jpg
Map 4
Map 5.jpg
Map 5

Part 3: Future Vulnerability

Map 6 shows the result of the combination of the two vulnerabilities under consideration. Of the total floodplain area of Cambodia, approximately 27% has a climate change vulnerability rating of greater than 0.5. This is classified as a “high” level of vulnerability to climate change, as given by the Economy and Environment Program, Southeast Asia by Worldfish (Worldfish 2013). The area found to be affected by a 500m horizontal reduction in the floodplain was approximately 32% of the total floodplain area.

Map 6.jpg
Map 6


A simple visual inspection of Map 1 indicates that, for the purposes of this study, it was justified to only consider the floodplain extent and not the extent of the 2013 flood. The flood data appears incomplete in certain areas and where it is complete however, the data set serves to validate the determined floodplain area. It may be a slight underestimation of the potential flood area but was deemed suitable for the purposes of this analysis. The inability to consider the results from Map 2 as part of the final site selection for the potential area for wetland protection, highlights the issues in data reliability. The assumption is for the rest of the analysis is that with such a transient system the data available would still be sufficient to represent patterns, particularly on a large, preliminary scale.

The areas found to be reliant on fish farming and rice cultivation in this analysis are, to a certain extent, within expectations based on previous studies. Perhaps the difficulties in mapping and recording such a transient system has led to a possible slight underestimation of these two factors. It was estimated in 2004 that 84% of cultivated land was rice crops (Yu & Fan 2009), and it is commonly understood that those who live within the floodplain are self-reliant on a combination of fishing and rice farming. The area of the floodplain (27%) found to have a climate change vulnerability index greater than 5 was smaller than expected, considering that the overall country rating for Cambodia has regularly been given as above 7 over the last decade. The area found to be affected by a 500m horizontal reduction in floodplain was 7,531 , which is approximately 4% of the total land surface of Cambodia. This 32% reduction of floodplain is greater than that estimated by Arias et al. (2013), of 22% of the seasonal floodplain.

Despite these relatively small deviations from expected patterns, the BO has shown to be useful, particularly as a cost effective and simplified method for a broad form of site identification. The results of Map 5, if nothing else, stress the importance of the floodplain areas surrounding Tonle Sap and qualitatively highlight the extent of the reliance of the floodplain communities on the wetland system. Though the final proposed area for possible protection was a sizable portion of the study area, this analysis has shown the usefulness of the method in a preliminary assessment in site identification. It is popular opinion that to overcome some of the governmental barriers in designating wetland areas for management and protection, a deviation from the top down approach is necessary. Specifically, that more community participation is necessary, coupled with an improvement to the general understanding of wetland functions (Sophal 2004, Sithirith 2015). The method could be an effective support tool in identifying which communes and communities could become a focus within management strategies for wetland protection.

It is clear from comparing Maps 5 and 6 that the two approaches for identifying wetlands areas for priority management will give differing results. Though there are some similarities in areas adjacent to the southwest of Tonle Sap, which could be considered important for protection and management if considering both ecosystem services as well as relative future vulnerability.

Limitations to this method include the need for on the ground, community engagement to confirm the feasibility of sites selected for management. Further analysis could be conducted into potential applications of this method in establishing buffer zones around wetland areas as protections from agriculture fields and communities, particularly considering the results found applying reductions to wetland areas from hydrological influences. Depending on data availability, potential next steps could be to apply a weighted analysis and compare the level of detail and area that would result.


The purpose of this study was to investigate the potential for a simple method such as a BO in providing guidance for site selection for wetland management. This study was successful in establishing the feasibility of this method, particularly when applied to creating criteria based upon the site-specific ecosystem benefits of wetlands and the potential vulnerabilities of the system. A clear takeaway from this analysis is that the allocated Ramsar wetlands are a small fraction of the area that could potentially be prioritised for management, when considering wetlands of “importance”. Under the Ramsar Convention the “wise use” of wetlands includes not only the long-term maintenance but also “human well-being” and the “alleviation of poverty”. Within these definitions, and the results of this analysis implies that there is a need to closely examine how wetland areas are related to wellbeing and the alleviation of poverty, within a specific site or within the context of a country’s social, economic and environmental reliance on wetlands.


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Arias, M, Cochrane, T, Norton, D, Kileen, T & Khon, P 2013. ‘The Flood Pulse as the Underlying Driver of Vegetation in the Largest Wetland and Fishery of the Mekong Basin’. Ambio vol42 pp864-874. Available from:

Ausseil, A, Dymond, E, Shepard, D & James, D 2007. Rapid Mapping and Prioritisation of Wetland Sites in the Manawatu-Wanganui Region, New Zealand’. Environmental Management vol 39 pp316-325. Available from:

Datta, D & Gosh, P 2015. ‘Evaluating sustainability of community endeavours in an Indian floodplain wetland using multi‐criteria decision analysis.’ Singapore Journal of Tropical Geography vol 36 pp38-56. Available from: https://onlinelibrary-wiley

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DeClerck, F, Kosal, M & Johnstone, G 2013. ‘CGIAR: Preventing Cardiac Arrest for Cambodia’s Heart’. CGIAR. Available from:

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Flower, B & Fortnam, M 2015. ‘Urbanising Disaster Risk’.Available from:

Gardner, R.C., Barchiesi, S., Beltrame, C., Finlayson, C.M., Galewski, T., Harrison, I., Paganini, M., Perennou, C., Pritchard, D.E., Rosenqvist, A., and Walpole, M. 2015. State of the World’s Wetlands and their Services to People: A compilation of recent analyses. Ramsar Briefing Note no. 7. Gland, Switzerland: Ramsar Convention Secretariat. Available from:

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Junk, W. J., P. B. Bayley, and R. E. Sparks. 1989. The flood pulse concept in river- floodplain systems. In Proceedings of the International Large River Symposium (LARS), ed. by D. P. Dodge, pp. 110–127. Canadian Special Publication of Fisheries and Aquatic Sciences, Ottawa, Canada.

Keskinen, M, Kummu, M, Kakonen M & Varis, O 2010. ‘Mekong at the Crossroads: Next Steps for Impact Assessment of Large Dams’. Ambio vol 41 pp319-324. Available from:

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Lovgren, S 2017. “Enourmous fish make one of the world’s largest migrations’. National Geographic Website. Available from:

MacAlister, C & Mahaxay, M 2009. ‘Mapping wetlands in the Lower Mekong Basin for wetland resource and conservation management using Landsat ETM images and field survey data.’ Journal of Environmental Management. Vol 90 pp2130-2137. Available from:

Maplecroft 2014. ‘Climate Change and lack of food security: Climate Change and Risk Atlas.” Available from:

Mitsch, W & Gosselink, J 1993. ‘The value of wetlands: importance of scale and landscape setting.’ Ecological Economics, vol 35 pp25-33. Available from:

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A Case of the Sweats: an argument to address the urban heat island effect


For this blog I would like to discuss and present a case for the need for the heat island effect to be addressed. So firstly how exactly does the #urbanheatislandeffect (UHI) work and why should we even consider being concerned? Watch this video below to get an idea of the UHI, with the example of Western Sydney:

So this concept has actually been around for a while now but I believe that considering how much we know and have researched and studied into this field it is surprising the lack of actual change has occurred. So for this blog I will:

  • Discuss the implications of UHI effect for the future
  • Present the strategies we have now to address it and what are the benefits 
  • Consider what barriers need to be overcome to address the issue
  • Use the principles of #ecologicalengineering to suggest a way forward

Implications of the UHI effect

Diagram from here

“If you can’t stand the heat, get out of the kitchen.”

Harry S. Truman

The only problem of course with this quote is the implication that if we can’t handle the pressure we should leave it for someone else; a classic way to neglect future generations, an attitude that I think we need to squeeze out of society.

A recent study (only one of many examples) in Hong Kong showed that the city had a rise in urban mean temperature of 0.169 degrees centigrade per decade for the last four decades. Even here in Australia it has been found by the Melbourne City Council that the average temperatures within the CBD are up to 4 degrees higher than surrounding suburbs.

This phenomenon can be clearly seen as an issue when combined with one of the worlds deadliest natural disasters, in fact this disaster can be held responsible for up to 70, 000 deaths in Europe during the 2003 episode. This natural disaster is known as a #heatwave.

heat wave.jpg
Image taken from an article about scientists being able to better predict heat waves in the future

The pre-existing UHI effect means that cities are more vulnerable to heat waves than surrounding rural areas. Why is this exactly?

So the UHI effect is a localised phenomenon, it creates a permanent temperature anomaly, spatially concentrated. Read this excellent study which looks into the physics details about how this effect works. Whereas heat waves are more large scale, temporal high pressure systems producing an anomaly increasing the air temperature for rural and urban regions. We do have some idea of how the interactions between these effects can lead to intensified heat. Also read section two of this paper to get a better idea of how urban environments impact the balance of energy.

Breaking the problem down further there are two main reasons I believe are sufficient enough to catalyse a movement to deal with the  increased heat in urban areas. These refer to our base case, the “business as usual” scenario:

  1. We know that 50% of the worlds population lives in cities and this is widely known to be increasing, by 2050 it is expected that 66% of the worlds population will be living in cities
  2. We also know that climate change will result in an increase in frequency and severity of heat wave events
  3. We know that heat waves cause more deaths than floods, hurricanes and tornadoes combined. 

The image below highlights the changes that we have already been able to quantify in Australia. In Melbourne, 2013 there was approximately 200 heat related deaths and the predictions are for this to double by 2030. It is a well known fact that, even in Australia, the more vulnerable (the elderly, people with pre-existing medical conditions and the poor) suffer the most from extreme weather conditions. Globally this is also the case, often poorer countries are located in the tropics and Nicolas Herold, a fellow at the Climate Change Research Centre at the University of New South Wales said that he and his fellow researches found that the increase in extreme heat measurements has been more pronounced in poorer countries:

“We expected it to be a lot worse since the [low-income] countries are near the equator but the difference of more than double is quite shocking”.

business as usual

There are other consequences of increasing UHI effect combined with heat waves, I found highlighted nicely in an article I read, that I also think should be considered:

  • The increase in energy consumption and chemicals released by cooling equipment
  • In some places, the increase in power outages
  • Higher concentrations of air pollutants
  • Promotes the creation of ground level ozone which has been known to lead to health issues and intensify numerous breathing problems
  • Higher temperatures of storm water (due to the heating of urban surfaces) which reduces the amount of dissolved oxygen in the water of nearby bodies

What we can do and the benefits

There has been extensive research into methods of combating the UHI effect in order to reduce the severity of the impact of heat wave events on the urban environment. I would like to break them down into 3 areas, one of which I will discuss. The second is to change the colour scheme of our built environments, as is being done in Western Sydney (image below, read here for more on this project and here  and here for more on decreasing albedo).  The third is the modification, planning and the design of cities to increase air flow, an interesting case I found of this is in Stuttgart in Germany, which you can read about here.

Urban heat island effectWestern Sydney’s project for paler roads, watch the video on their website for more.


From an article on the rise of the forest city, with more and more vertical forest towers being created, with the benefits if reducing heating and cooling needs, increasing biodiversity, improving air and noise pollution as well as decreasing the UHI effect.

I read an exciting study published this year, the results of which suggests that:

“…tree dominated greenspace offers the greatest heat stress release when it is most needed.”

A study (discussed in the previously mentioned article) conducted of Glasgow predicted that an increase of 20% in greenspace could eliminated between a third and a half of the cities expected UHI effect in 2050!

In many European cities there has been a push towards rooftop gardens. There are also other creative solutions such as greenscaping into vertical gardens such as in the image to the left, in places such as Bangalore and Beijing.

Just having a surface covered shade can reduce its surface temperature by 11-25 degrees but I think that the most impressive part about greenspaces as a mitigation technique for UHI is the broad range of benefits associated:

  • Other ecosystem services  – reduced surface runoff and modification of micro climates
  • Increased biodiversity
  • Aesthetically pleasing
  • Reduction in energy costs (shading from trees means nearby buildings require less cooling)
  • Improve air quality
  • Storm water management and improve water quality
  • Can reduce noise
  • Decrease stress on water resources

It is quite exciting to think about all of the positives to come out of one relatively small change, which I think will also improve the #livability of our cities, something that seems to be particularly a cultural movement in Australia, to aim for enhanced “livability”.

Who is involved

This is a business case though so I must also address stakeholders and the economic side, as I have clearly highlighted many environmental and indeed ecological benefits. The wider community clearly has much to benefit from a solution like this, not only does it make our neighbourhoods more aesthetically pleasing but also as I have mentioned earlier the health benefits are measurable when it comes time for heat waves. The reduction in energy consumption within buildings introduces big company owners or government agencies who are spending the money to keep their buildings cool. On a wider scale I think it is also important to include future generations as stakeholders as by following “business as usual” current generations are leaving the more severe consequences to be dealt with in the future. I think that local, state and federal government also have parts to play with different levels of the problem. On a grander scale the Federal government have an environmental responsibility (also a global responsibility) and on a local scale the other benefits such as the reduction in noise, for example, are the kind of issues that should be considered anyway.

Arguably it is a good option economically as well. A 5-city study conducted in the US found that when quantified, the benefits of the planting the extra trees amounted to $1.50-$3 per dollar invested!

Something from me

I believe that the way forward isn’t necessarily only to use these methods, I think we are still at the stage where we can consider alternatives that may also assist in mitigating the UHI effect, though clearly greenspacing is such an elegant solution. To come up with these alternative solutions, we should be considering the design principles for ecological engineering (please see my first blog post to be more familiar with these).

I would like to point out the the second principles, design for site specific context,  this I think highlights the limitations with the use of greenspaces. In Australia water is more of a limiting resource in comparison to Europe, where vertical forests have the ability to flourish, though a city like Perth does have a lot more open space to be able to have standard greenspaces.

There are studies that have shown that the effectiveness of greenspaces is “…subjective to effective geometry and width…”. This limitation of required area could cause a problem for cities that are quite dense, and ironically some of those cities have a greater need for these systems.

I combined my knowledge of the principles of ecological engineering, and thought why aren’t we utilising what we already know about the natural world? After all the reason we are having this issue in the first place is because the design of our cities inadvertently alters the natural order.  The way I see it is that the UHI effect isn’t just a result of many anthropogenic mishaps but also a representation of our lack of ability to incorporate ourselves with the natural environment.

survey of North American trees found that plants protect their ability to photosynthesise by maintaining a leaf  temperature of about 21 degrees, no matter the external environment. Plants use several mechanisms to do this, such as changing the angle of their leaves relative to the sun. This made me question why our built environments aren’t also flexible to adapt to an environment that changes so rapidly over short periods of  time? Why aren’t we creating design consistent with ecological principles, to mimic our natural environment (the second design principle).

And so I have chosen to pitch to you my suggestion in a Vlog, for possible ways we could mimic our natural environment to address UHI effect, please enjoy below:

The article about Fred and his kind.

Evaporation on its own can decrease peak summer temperatures by 1-5 degrees Celcius.  The maintenance and initial planting costs associated with greenspaces were estimated in a study on 5 US cities and their urban forestry programs to be 15-65 US dollars a year per tree. Imagine if we could come up with an idea like this one, a once off alteration to manufacturing and building our cities that could assist in decreasing the UHI effect. As soon as I had the idea I realised the limitations and that it too would have to be considered for each site separately (second principle). But I think that where we are falling short is the first principle, solutions that mimic nature. What other cooling mechanisms in the natural world could we mimic? Post any ideas for this below, I would love to hear them. I think it is important for us to consider alternative solutions in order for us to make positive change seem more desirable, possibly in this case, financially.

Maybe there are many other applications for this, possibly in water transport, I would love to know what you all think? Will ideas such as this one fit into the design principles for ecological engineering? Please post ideas/limitations or other comments below.

References for images used in video:

I Beg of Y’all: Drink from my Wetland

From what I am starting to understand about this magical concept of ecological engineering is that we need to integrate what we know or can learn about natural processes and the environment into what we already have and know about ourselves. The potential significance of what “we” or humans can learn from the natural world is clear, look at birds, then planes, the connections already exist, we just need to utilise them more, for our own benefit.

By some sort of accident, I found myself looking and thinking about the most efficient and complex ecosystems. I had studied zoology as one of my Undergraduate majors, so I thought back to what impressed me in the natural world back then. I came up with wetlands, a functioning ecosystem on a very efficient level. Wetlands are some of the most productive ecosystems on the planet, it has been estimated that even though wetlands are only 5-8% of the earths land surface, they account for 20-30% of the earths soil pool for carbon.

So how to incorporate an already existing efficient ecosystem function into the great cities of the world? I figured this could be important, as it is expected that 70% of the world’s population will live in urban centres by 2025.

I read an article discussing the future of “green cities”, something I found easy to get excited about. Literal green cities; an obvious step in the right direction but this article argued a valid point:

“…giving buildings a biological hairdo does not a green city make.”

image 1 vlog
sustainable “green city”

A city must focus on the integration of many systems to be truly utilising ecological principles, towards a “sustainable city”.

What are the Issues?

Let’s put some perspective on this first. The issue I thought could be addressed was the already costly system of getting potable, or safe drinking water, to where we want it but in a more ecological minded and cost effective way. Currently we are adding the cost for bringing clean water in, to the costs of then removing this water after use; we are effectively paying twice for our water usage. This is a very basic way to look at the current system in most of our cities. There are also costs associated with dealing with storm water, which can in some cases be linked directly to poor design of infrastructure, a growing concern with climate change and urban densification looming.

A clever man I came across during my research said something that stuck with me:

“…if more people take advantage of things like grey water systems and green roofs then our demand for water (and its disposal) may drop to the point that our infrastructure may no longer be completely necessary. Reservoirs, aqueducts and huge pipelines guiding water to major cities could wind up as over-built, archaic achievements of a different age”.

The Magic of Wetlands

image 2 vlog.png
Image from Natural Explorer and text

So how do these incredible systems work and what functions are the ones we can benefit from? A simple breakdown of wetland functions can be found in the above image. Also a little definition for in the box to the right. text 1 vlog 1

To find out more, or if don’t want to take my word for it, follow this link for the functions of wetlands on a local and global scale. And watch this home grown Aussie video made by the Department of Environment and Heritage, the Queensland Government.

We Can Make Wetlands

What I found interesting was the potential for wetlands for water purification. This is by no means a new idea, to use wetlands as a treatment process for our waste water.

First again some facts:

·         Globally, two million tons of sewage, industrial and agricultural waste is discharged into the world’s waterways

·         At least 1.8 million children under five years-old die every year from water related disease, or one every 20 seconds.

·         Wastewater treatment facilities in the United States process approximately 34 billion gallons of wastewater every day.

·         Only 1% of drinking water in many cities of western countries is used for actual drinking

·         In Australia we use 341, 000 Litres of water each year

These facts can be found here and here. text 2 vlog 1

In Australia, we have already used man made constructed wetlands to influence hydrology, decrease erosion and provide shade and reduce light availability for algal photosynthesis on our farms. See here to find out about Queensland’s Wetland plan for improving farm water runoff quality by addressing these aspects.

Through constructed wetlands the processes for the purification for waste water are as followed:

·         Phytoremediation- which is really a big word for using plants to remove contaminants in water. The plants take up the bad stuff through their roots, studies have showed that deeper root trees are also effective, as they can reach the contaminants at a deeper level. The other magic at this level is that the plants can also influence soil structure and characteristics by releasing organic substances that can alter chemical composition.

·         Microbiological Mineralisation – fancy talk for the activity of bacteria to encourage mineral formation

·         Filtration by gravel and gravity

A study conducted by Griffith University, Queensland, pointed out that in Australia very little of our sewage effluent is reused or recycled, that we tend to purify our water to then release it back into rivers and oceans. Our current disinfection processes with chlorine is not only expensive but also produces unnecessary by-products. The need is already there for a system that can remove pathogens whilst taking back nutrients and water from our waste water, it also has to be “environmentally sustainable, socially accepted and cost effective.”

A man I came a across a couple of times looking for information on sustainable cities was Jeff Speck, a city planner with a nice voice for these kind of things. He spoke about the use of wetlands to purify waste water and said that once the water has flowed through some of these wetland filtration systems:

“…the water is about as high-quality as potable water, but just to be safe, there is an additional mechanical filtration system that uses UV to blast out any remaining pollutants. The water can then be reused to water landscapes or sent back to households for toilets.”

Read more about Jeff and his work.

Tell Me How!?

I found a rather thorough study, published as far back as 1998 in the Netherlands, which considered the “Opportunities and Limitations” of the use of wetlands for waste water treatment. Check out my side box for the six steps to the purification process discussed in this study.text 3 vlog 1

The study found that one of their constructed wetlands in Holland received sewage from a total of 800 people and could remove 99% of the bacterial pollution, 80-90% of COD and BOD (see my lovely section to the left below) but only 30-40% of the nitrogen and phosphorus necessary. The facility was used for 10 years for the treatment of a recreational facility.

text 4 vlog 1See the diagrams below to get an understanding of how wetlands deal with phosphorus (right) and nitrogen (left):

Another study recently in Italy, 2005, compared the effectiveness of two methods of wetland waste water treatment systems.

1.. There is surface flow constructed wetlands, see the diagram below. All the action for these types occur in the upper layers and therefore can be a breeding ground for mosquitoes.

image 6 vlog 1
Surface Flow Constructed Wetland

2. The other type is subsurface flow, the one I consider more practical due to the potential for these to not be a health hazard or unpleasant (sometimes wetlands smell, I know) for the public to be near. Of this type, there are another two types that have been studied, also shown in the diagrams below. The first diagram (on the left), the vertical flow, rely on a controlled source of energy but take 2/3 of the space of the horizontal flow, (diagram on right), which has fluid circulating horizontally naturally. Both of these, so subsurface flow in general, require on average 80% less space than the surface flow.

Show Me Where?!

An intuitive natural progression from here is to bring these efficient systems into our cities, incorporating an entire natural ecosystem into our day to day lives or at least into the fabric of the city. Turns out this also isn’t a new idea, in fact one impressive lady from Morocco caught my eye through TED talks. Watch the video, it’s only a few minutes long I promise!

Aziza Chaauni, an architect presents a wonderful plan to reinvigorate and transform the Fez river and so the Medina (the old town area, which is actually a World Heritage Site) of Fez from

This:                                                                                                                 To something like this:

Her grand plan also included the use of a constructive wetland within the Medina area, in conjunction with the river as a self-filtering system for the area; much needed as originally the river was so polluted they had to cover it with concrete and you couldn’t drink from the running fountains that used to provide people with drinking water. The process is still ongoing but in an interview in 2014, Aziza said that there has already been improvement, particularly downstream from the Medina, where there has been noticeable changes in biodiversity. Also attitudes have changed from viewing the river as a river, not a sewer; craftsmen have stopped polluting the river (watch the video for more, but this was a central issue to the problem in the first place).

Read more here if you would like to find more information about the transformation of the Fez River.

For a quick summary of my favourite case study, and perhaps the most impressive application I could find of the use of constructed wetlands, please enjoy this vlog posted on YouTube.

Once you have watched the Vlog I am sure you will want to see an actual clear diagram of the Flowlands project found below.

image 12 blog 1.jpg

The proposed plan for the Gowanus River as explained in the video above. See here to zoom in on the image.


Now What?

I have already referred to the benefits of something like this for Australia and other western countries, to decrease costs of our water treatment and to also contribute to a more ecologically minded society but I also think that the possibilities for parts of the developing world are equally advantageous.

For instance, and I only think of Mumbai as I have spent time there recently, but in India less than half of its domestic waste water is treated. If there was a way to get this constructed wetland system to be so effective as to have the end result as potable water, the possibilities are exciting! A report from the General Pollution Board in March 2015 estimated that sewage generation from urban areas is estimated at around 62,000 million litres per day (MLD) whereas the total treatment capacity available is only 23,277 MLD. Also partially or untreated sewage is the largest contributing source for the decline of surface or groundwater quality, it contributes  to 70% of the pollution to streams or water bodies of India.

In Mumbai in 2016 the government was considering a new 6.39 kilometre sewage pipeline as part of a $300 million Mumbai Sewage Disposal Project. Imagine if this large amount of money went towards a design such as Flowlands that could benefit the community is so many other ways and was in line with ecological design principles. The system could be self sustaining, in that it could provide a certain area with water as well as treat the water coming out as waste. A small notch in a larger problem for somewhere like Mumbai but the benefits of these designs being space conscience is crucial for a city as dense and complex and Mumbai.

The clear benefits here of integrating ecological principles into engineering design are not only environmental but economical and, as with Aziza’s plan for the Fez, can be social too.It can also integrate an aspect of humanitarian engineering for the benefit of the people long term as well, to possibly assist in increasing peoples standard of living.





The Principles of Ecological Engineering

I would like, in these blogs, to investigate the principles of ecological engineering and what they can mean for the future of engineering or to me, as an engineering student. The principles I will be using as a base for these investigations are as below, found in an article by Bergen et al, Design Principles for Ecological Engineering. It is a great read and I have found these principles as an excellent guide to interpreting the value of engineering projects.

  1. Design consistent with ecological principles
  2. Design for site specific context
  3. Maintain the independence of functional requirements
  4. Design for efficiency in energy and information
  5. Acknowledge the values and purposes that motivate design

The first point is the importance to take advantage of, mimic and include natural systems into our engineering design. To read more about these principles read here.