The world is facing the most severe refugee crisis in history with an average of 28,300 people per day and every 20 min forced to flee their homes due to war, violence, or persecution for their race, religion, ethnicity or political opinion, and the number is growing every day [1
]. The Rohingya people are one of the most stateless and widely persecuted minorities in the world, facing an ethnic cleansing by the Buddhist majority in Myanmar [2
], forcing them to flee in search of relative safety in the neighboring country of Bangladesh. Since the early nineties, the Rohingya have continued to flee in large numbers (in Figure 1
) from the Rakhine state of Myanmar across the border, mostly to the Teknaf region of Bangladesh, with memories of gruesome violence, loss of loved ones, and destruction of homes and entire villages [4
]. The latest wave of violence, however, has triggered the largest Rohingya influxes; 688,000 refugees are estimated to have crossed from the Rakhine state into Teknaf since 25 August 2017 [6
]. The majority of this population settled in makeshift camps, replacing forested hills surrounding the two existing refugee camps located in Kutupalong and Nayapara in Teknaf [7
]. In addition to settling in overcrowded existing camps, refugees have settled in spontaneous sites in more outlying and remote areas with little access to services and infrastructure [6
]. Such unprecedented speed and scale of the refugee influx and associated makeshift camps expansion has already resulted in the degradation of protected forest and destruction of critical wildlife habitat, with widespread ecological and environmental damage in the region. Various estimates suggest that approximately 4000 acres of forested hills in the study area have been cleared to erect makeshift camps since August 2017 [7
]. The forestland located in the study area provides, however, a critical home for both forest-dwelling and wetland species, and a sizeable number of bird species [12
]. It provides an important environment for a vast array of plants, including a number of medicinal plants that are used by the local communities [13
], as well as being a source of substantial carbon storage [15
]. Additionally, this environment contains a sanctuary for wild Asian elephants, nesting sites for many shore birds, and provides food and shelter for monkeys, snakes, bats, and other wild animals [16
]. The protected forest, with its wildlife habitat and other natural capital in the study area, is being destroyed and degraded at an alarming rate mainly due to clear-cutting for agriculture, ranching and development, and logging for timber. However, degradation due to rapid conversion for refugee camps and makeshift settlements is the greatest catalyst of environmental destruction occurring at a large scale in recent times [18
Empirical studies suggest that deforestation driven by anthropogenic activities can have multiple negative impacts on the environment including loss of wildlife habitat [19
], soil erosion and desertification [20
], water cycle disruption, loss of traditional livelihoods, and increased ecological risks from forest fragmentation. Changes in forest cover further affect the capacity of forest biomass to store carbon, disturbing local climate by modulating the diurnal temperature variation, and thus increasing risks of global climate change [21
]. Hence, periodical forest cover change and drivers of such change must be monitored and documented to support policies and management practices to protect, conserve, and sustainably use resources while maintaining ecosystem functions and forests biodiversity [22
]. Remotely sensed satellite observation data are widely used to monitor local [24
], regional to global land cover change and vegetation health monitoring [25
] due to their high spatial resolution and temporal frequencies and open availability on the internet. Satellite remote sensing may also be used for terrestrial carbon quantification and monitoring of climate variability, using, for example, NASA’s MOD17 algorithm [26
] and data from the advanced very high resolution radiometer (AVHRR) [28
The monitoring of refugee camp expansion and the resultant degradation of the environment and forest cover change using earth observation data such as aerial photography, LiDAR, and high-resolution satellite imagery (i.e., Quick bird, IKONOS) has been seen quite often in practice [29
]. Different methodologies with varying degrees of resources, costs, accuracy, expertise and technology have been applied in tracking refugee camps and assessing environmental impacts on the camps’ surroundings. For example, Lodhi et al. (1998) [33
] monitored land cover changes and environmental impacts using Landsat imagery with unsupervised classification in the Siran Valley in northern Pakistan resulting from an influx of Afghan refugees in the early 1990s. Spröhnle et al. (2016) [32
] observed the impacts of internally displaced person (IDP) camps on wood resources in Zalingei, Darfur using high resolution satellite imagery between 2003 and 2008. Their research found that increasing IDP camps caused a considerable decrease in woody vegetation surrounding the camp area. Langer et al. (2015) [34
] monitored the long-term environmental impacts, including deforestation, of refugee camps using Landsat data in Lukole, Tanzania. The authors observed that the development of camps caused significant degradation of the natural vegetation surrounding the camps area.
Although there exists a widespread consensus that deforestation currently taking place in the Teknaf region of Bangladesh is largely driven by refugee settlement expansion and related infrastructure development, to date, no study has been carried out to quantify the actual rate of forest degradation resulting from camp expansions in the area. Hence, to fill this knowledge gap, this study aims to quantify settlement expansion coupled with forest cover destruction using Sentinel-2A and -2B imagery between pre-influx and post-influx of Rohingya refugees in 2017 in the Teknaf area—situated in the southernmost tip of Bangladesh. Sentinel-2A and -2B imagery has a high spatial resolution of 10 m (blue, red, green and near-infrared bands) and is openly and freely available on the internet and updated frequently. Such high-resolution data is optimal for conducting large area vegetation, land cover, and environmental change monitoring.
In this study, we utilized a RF model based on a developed dataset of 16 explanatory variables and high resolution multispectral satellite imagery from Sentinel-2A and -2B to classify two time-step land cover maps to observe the growth of refugee settlements and associated forest loss in the Teknaf region of Bangladesh. The land cover maps of two time-steps with three broad land categories derived from the RF model show promising results which are echoed by the high overall classification accuracy. The findings also highlight that by using expert knowledge and an iterative analysis process, the production of a satisfactory land cover map with a desirable outcome is possible. Although RF models do not require separate validation, we employed independent cross validation in GIS using high resolution QuickBird images and Google Earth for the pre-influx periods (i.e., 2016) land cover maps. However, for the land cover map of 2017, we had to rely on a true color composite Sentinel-2B image and ground-truth training samples since high resolution Google Earth imagery for the area was unavailable after January 2016. Even with the increasing availability of sophisticated data analysis tools and improved spatial and spectral resolution of remotely sensed data, monitoring forest cover change remains challenging. This is especially true for tropical areas, as they are constrained by multiple factors including persistent cloud cover, high rainfall and temperature variability, and the spatial and spectral resolution of imagery with low availability of useable optical imagery during the rainy season (especially during the monsoon), all of which present a challenge for interannual analysis and timely detection of newly changed areas. Our analysis may have been improved if we able to use satellite imagery for dates closer to the major refugee influx event, i.e., between the months of September and August of 2017 and onward; however, persistent cloud cover over the study area restricted us to dry season (i.e., December) image analysis. There are multiple spontaneous refugee camps within and outside of the study area, some of which are in host communities and others consisting of refugees residing in temporary shelters. In addition, a large quantity of refugee camps were identified during our field visit as settlements in more remote forested locations, which are not detectable using moderate resolution imagery due to tree shade. Further, some areas in the north and northeast sections of the study area were classified as forest which should be homestead vegetation. Hence, our results may have suffered from these limitations. However, the trend documented here shows that the area has been experiencing a radical land cover change with forest degradation due to the sudden expansion of refugee camps and their associated activities. Such an unprecedented mass exodus of refugees puts extreme pressure on the social, economic, and ecological fabric of the entire nation, which is already afflicted by overpopulation and poverty, coupled with increasing frequency of climatic and environmental hazards. The area where the greatest concentration of Rohingya refugees are settling in makeshift camps is a highly sensitive ecological region, containing a protected forest for endangered animals. The magnitude and rate of the recent influx has created enormous pressure on the natural resources and has already substantially altered the local landscape. With the large influxes of refugee entrants, there is a huge demand for firewood, which is increasing daily. The new arrivals demand 750,000 kg of fuelwood every day [53
], and meeting this need is putting extreme pressure on cutting protected forests and social forestry trees [11
]. Although various estimates suggest refugees have been the cause of the stripping away of 4000 acres of forestland [7
], our analysis using satellite imagery estimates approximate 5650 acres of forested land surrounding three resettlement camps were lost since December 2016. If the current pattern of refugee camp expansion persists and the volume of forest clearing continues, we fear that the area will soon become a barren land and the hilly forest will cease to exist. In addition, the wiping out of vegetative cover and the herbaceous layer from the hills, along with rampant hill-cutting, may trigger landslides during the monsoon season, which may cost the lives of many refugees and result in further environmental degradation (Figure 8
). Wildlife in the area has also been affected by the encroachment. The most dramatic impact is a loss of habitat for thousands of species—the diverse array of animals and plants that live in the forest. Due to space shortage in the area, many refugees have been camping two to three kilometers in the deep forests, blocking an elephant corridor. Such expansion into the forested land causes not only ecological damage but also puts the lives of Rohingya refugees at further risk from wildlife encounters, as six refugees have already been trampled to death and numbers injured by wild elephants as of January 2018. As the refugee camps continue to grow in size and number, there will be further ecological and socioeconomic impacts. Many refugee camps have expanded into forested areas or along mountainous regions and are built next to other built-up areas which will additionally impact preexisting communities.
Although local Bangladeshi people are being sympathetic to the plight of the Rohingya refugees, the continued influx, however, has fueled concerns among the local populace who fear that the refugees will drastically alter the landscape of the coastal district and population configuration in the region. Along with our field investigation, various reports indicate the price of daily essential commodities including rice, vegetables, and oils among others have soared since the crisis erupted. Local transportation costs have climbed, making conditions more difficult for daily wagers, and many fear losing their jobs, as the refugees are willing to do the same work for lower wages. In addition, if the refugee crisis continues and is not solved immediately, it may adversely impact the tourism industry in the region, as the forest and sandy beaches are the main attractions and mass tourist destinations of the nation [54
]. There is also a potential risk of a rise in local and international terrorism activities as these vulnerable peoples can be an easy target of vested groups [55
]. This will put the county in further danger of home grown terrorism which may destabilize the whole region as well. In addition, the area may see the proliferation of a synthetic drug called “Yaba”, which is imported from Myanmar through the border by Rohingya refugees, intensifying the risk of human trafficking and prostitution. There is also fear of an increase in the incidence and transmission of infectious diseases that may spread out in the region, such as water-borne pathogens, as crucial groundwater supplies are depleted and contaminated [56
The consistent, methodical and escalating pattern of killings, torture, rape, and arson against the Rohingya minority group, who were previously living in a denial state over the last decades, is a clear indication of ethnic cleansing and an act of genocide committed by Myanmar [3
]. The latest evidence presented by Médecins Sans Frontières (MSF) shows that nearly 9000 Rohingya have been killed [57
] and 354 villages burned in the northern Rakhine State [58
] since violence erupted in August 2017 at the hands of the local militants and the Burmese army, intensifying the uncertainty of the fate of these minority groups. The mass influx of refugees to Teknaf within such a short period of time has made this region of Bangladesh the world’s fastest growing refugee crisis in recent history. In addition to the humanitarian crisis that has ensued, an environmental catastrophe is occurring in the area. Hence the government of Bangladesh should take immediate and concrete measures to relocate the refugees or repatriate them using diplomatic channels with Myanmar and broader, international platforms by including the United Nations, ASEAN, OIC, SARC and other appropriate parties [59
]. While repatriating them to the hand of Myanmar, all parties should be included to ensure their safety in their return to their home by guaranteeing citizenship and equal access to all civic facilities that other citizens enjoy in the country. If refugees remain in Bangladesh, they must be relocated to other safe places immediately and alternative fuel sources provided for the Rohingya so that the forest and its resources are preserved. In addition, the data results from this study may be used to project future growth of refugee camps, reduce deforestation and environmental impacts, and help plan more organized and stable living conditions for the Rohingya refugees through special protection, conservation, and sustainable practices of landscape, wildlife, and importance of tourism.
An unprecedented influx of Rohingya refugees into southeastern Bangladesh is putting the ecologically fragile region on the brink of an environmental disaster. Based on remote sensing data and a nonparametric land cover classification technique such as RF, this study documented land cover change and forest cover degradation resulting from Rohingya refugee settlement expansion between pre-august and post-august influxes of August 2017. Employing RF as an image classification approach for this study with a cross-validation technique, we obtained a high overall classification accuracy of 94.53% and 95.14% for 2016 and 2017 land cover maps, respectively, with overall kappa statistics of 0.93 and 0.94. The producer and user accuracy for forest cover ranged between 92.98–98.21% and 96.49–92.98%, respectively. Our land cover maps produced from this study, the evidence obtained from ground observations, photos and high-resolution spatial videos, and the analysis of various online studies, suggests that refugees are destroying the forest ecosystems by the rampant and swift clearing of the forested hills. As many as seven reserve forests, totaling about 5650 acres, have been damaged from the erection of makeshift shelters, burning of firewood, and anthropogenic activities relating to subsistence needs of the refugees. As a result, lands that were formerly vegetated and forested are now converted to refugee camps as populations urgently seek shelter and safety in an area unequipped and unprepared to deal with the crisis. Remote sensing data and RF land cover classification proved efficient and valuable in quantifying the effects of refugee camps and associated human activities on the surrounding environment, providing evidence of the negative correlation between camp expansion and adverse impacts on the natural surroundings. The results indicated that environmental destruction—namely loss of forested land and other vegetation that housed endangered animals, biodiversity and ecosystems and their services—has occurred at an alarming rate in the last five months (i.e., August 2017 to December 2017). Such degradation of these critical ecological resources might trigger multiplicative impacts on the environment, biodiversity, wildlife habitat and overall socioeconomic health of the entire region. If no measures are taken now or in the near future to protect the vegetation cover, forests, and overall local environment, there will be long-term and irreparable damage that may cause larger problems for the country as well. Given the speed, number of migrants, and spontaneous nature of the recent refugee influx, the government of Bangladesh and the Bangladeshi people are unprepared to accommodate the swelling refugee populations, lacking the means to effectively plan camp structures and limit environmental impacts. Hence the resulting geographical information and thematic map with employed methodology produced from this study may provide a useful tool for policymakers and concerned authorities to assess the environmental impacts of large scale refugee movements and concentrations in the context of effective crisis management. In addition, the environmental effects of forced mass migrations should be studied and documented so that nations—and the world—may better prepare and ameliorate the adverse outcomes of the ever-increasing phenomena of refugee camps and temporary settlements in the world.