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Case Studies

Siem Reap River - Cambodia

Siem Reap River flows through Siem Reap Province, in North-West Cambodia, and runs downstream from Siem Reap into the Tonle Sap Lake about 30km away.  Along the river, although efforts were made to keep it clean near the main population and tourist section, the remaining 29km was not cared for; local residents often disposed of their household trash along the riverbanks, which would later be lost to the river during heavy rain. 

A group of concerned citizens learned about the Global Alert mobile app, where they can report trash hotspots in waterways, and decided to use the app to take photos and geotag the locations of trash hotspots.  The initial nine hotspot locations reported, were documented to contain thousands of kilograms of trash.  The reported trash included household litter, commercial trash, plastics and styrofoam.


Nusa Penida - Bali, Indonesia

The two photos below illustrate the volume and type of trash found in the landfill adjacent to the riverbed.  The last picture is of the riverbed itself, which when full, acts as a transport mechanism for the waste to flow directly into the ocean. 

Location: From Toyapakeh to Sampalan, Nusa Penida, Bali

Testimonial: “As a result of using the Global Alert Platform, I have been able to host some important meetings with local businesses, The Nusa Penida Conservation Department, The Coral Triangle Centre [NGO], The Nusa Penida "Eco-Club" at the local high school, The Nusa Penida Youth Forum, local business owners and marine tourism operators, and the "Camat" of Nusa Penida, or the district head i.e. the highest governing official on the island.   Through consultation with all of these groups, using data compiled at the trash hot spots, and with discussions about reasons for the trash source, we are now working on the following initiatives:


1. The 9km shoreline on the north of the island is the number 1 trash "hot-spot", or area most at risk of allowing trash to enter the ocean.  Local communities discard their waste on the beach where it is swept away.  When asked why, they insist there is no alternative.  Data from this "hot-spot" has been uploaded to community-managed online platform "Global Alert” and socialisation techniques are being discussed, such as plays.

2. The waste collection service currently services only 2km of this shoreline, but should service all 9km.  The trucks have the time to extend their route but not the budget.  We are determining the budget and also payment mechanisms.  Once we are aware of the cost and discover a means of sustainably sourcing funds for the trash collection service expansion, we will provide trash bins to all north shore households and educate them in how to prepare their waste for collection.

3. On Wednesday March 23rd, a trash cleanup was arranged with members from the Nusa Penida Youth Forum and the Eco-Club.  Identifying the types of trash collected and where they are located will help the student groups come up with socialisation techniques such as plays to perform for the local communities, explaining why dumping trash is so bad for the environment and economy.  Footage of these and similar efforts will be shared with the local and international media to highlight the cause.

4. The teacher in charge of the Eco-Club is in conversation with a former Head of Customary Performance and Arts (Kepala Adat), to develop entertainment to be performed in the temples at various ceremonies, island-wide.  The performances will explain the social, economic and environmental effects of trash dumping.

5. A social media campaign under the banner #PenidaTanpaSampah" ("Penida Without Litter") will collate photos and information about waste management so that we can form a visual database to track ideas and progress.

Key points: The Global Alert Platform provides a way to visualize and support advocacy of litter reduction and waterway/coastal health.  Reporting on the platform allows users to share successes, while also alerting local authorities or other community stakeholders to the importance of clean-up, and long term prevention with education and improved landfill management and recycling capacities.

Sustainable Seas Trust - South Africa

Sustainable Seas Trust is now using Global Alert for the development of the African Marine Waste Action Consortium, a project to significantly reduce litter in coastal Africa and promote education.  Sustainable Seas Trust is working closely with Dr. Sylvia Earle and her Mission Blue team to expand the Hope Spots in South Africa, and to integrate waste and pollution management into existing Hope Spots, minimizing land-based impacts in protected areas.  The goal of this partnership is to replicate these best practices in other African countries. 

Hope Spots are special places that are critical to the health of the ocean - Earth‘s blue heart.  Some of these Hope Spots are already formally protected, while others still need defined protection.  About 12% of the land around the world is now under some form of protection (as national parks, world heritage sites, monuments, etc.), while less than 4% of the ocean is protected in any way.  Mission Blue is committed to changing this, with networks of marine protected areas which maintain healthy biodiversity, provide a carbon sink, generate life-giving oxygen, preserve critical habitat and allow low-impact activities like ecotourism to thrive. 

Sustainable Seas Trust has made the South African Hope Spots people orientated; they are community based and people driven by giving everyone an opportunity to care for their own marine environment. One of the obvious first steps is to get rid of marine debris, particularly plastic waste.  


The Global Alert platform helped guide cleanup efforts with community mapping and reporting, while the Sustainable Seas Trust and its partners initiated coastal cleanup efforts.  Estimates from one of the cleanups are as follows:

Hope Spots

False Bay

Hermanus in Cape Whale Coast


Plettenberg Bay

Algoa Bay Hope Spot, Swartkops Estuary


Weight (kg)







Sustainable Seas Trust will use the information collected to expand the dataset on African Waste that it is building.  We believe the Global Alert platform will help the Sustainable Seas Trust to bring greater awareness and improvements in our coastal management of Hope Spots and protected areas vis-a-vis trash and pollution minimization in those areas. 

Hope Spot Description 

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