Thi-Thanh-Hiên Pham

Assessment of land‐cover changes related to shrimp aquaculture using remote sensing data: a case study in the Giao Thuy District, Vietnam

Shrimp culture is a sector of aquaculture that has a high potential for poverty alleviation and rural development in Vietnam. However, the development of this activity induces changes that potentially have negative impacts on the environment, one of which is wetland deterioration. This paper describes the use of a proposed change detection methodology in the assessment of mangrove forest alterations caused by aquaculture development, as well as the effectiveness of the measures taken to mitigate deforestation in the district of Giao Thuy, Vietnam, between 1986, 1992 and 2001. Geometric and radiometric corrections were applied to Landsat images prior to identifying changes through comparison of unsupervised classifications. Changes were afterwards validated using a thresholding method based on Tasselled Cap feature image differencing and a rule‐based feature selection matrix. The matrix is used to identify the feature that is most efficient at detecting the presence of change between given land‐cover classes. The proposed approach aims to minimize commission errors in the post‐classification change detection process. The results suggest that 63% of mangrove areas apparent in 1986 had been replaced by shrimp ponds in 2001. Between 1986 and 1992, 440 ha of adult mangrove trees had disappeared, whereas the mangrove extent increased by 441 ha between 1992 and 2001. This recovery is attributed to reforestation projects and conservation efforts that promoted natural regeneration.

The conversion of agricultural land in the peri-urban areas of Hanoi (Vietnam): patterns in space and time

Rapid urbanization is accelerating the loss of agricultural land in Hanoi (Vietnam), raising concerns about food provision for inner citizens and livelihoods of peri-urban farmers. Understanding how this loss is linked with urban expansion is important to predict impacts of urbanization on peri-urban agriculture. In this paper, we examine the conversion of agricultural land to built-up land in Hanoi by using Landsat images (1993, 2000 and 2007). About one-third of the agricultural land was converted to built-up areas. Agricultural patches tend to be more fragmented and to have irregular shapes. Areal loss, fragmentation and edge irregularity of agricultural land appear to be related to the change from rural status into urban status. Such tendencies of the conversion correspond to urban growth patterns in Hanoi (infill, expansion and linear branches). This study calls for immediate measures to protect agricultural land and accelerate the creation of the green belt in Hanoi.

Using Landsat Thematic Mapper records to map land cover change and the impacts of reforestation programmes in the borderlands of southeast Yunnan, China: 1990–2010

Abstract At the beginning of the new millennium, after a severe drought and destructive floods along the Yangtze River, the Chinese government implemented two large ecological rehabilitation and reforestation projects: the Natural Forest Protection Programme and the Sloping Land Conversion Programme. Using Landsat data from a decade before, during and after the inception of these programmes, we analyze their impacts along with other policies on land use, land cover change (LULCC) in southwest China. Our goal is to quantify the predominant land cover changes in four borderland counties, home to tens of thousands of ethnic minority individuals. We do this in three time stages (1990, 2000 and 2010). We use support vector machines as well as a transition matrix to monitor the land cover changes. The land cover classifications resulted in an overall accuracy and Kappa coefficient for forested area and cropland of respectively 91% (2% confidence interval) and 0.87. Our results suggest that the total forested area observed increased 3% over this 20-year period, while cropland decreased slightly (0.1%). However, these changes varied over specific time periods: forested area decreased between 1990 and 2000 and then increased between 2000 and 2010. In contrast, cropland increased and then decreased. These results suggest the important impacts of reforestation programmes that have accelerated a land cover transition in this region. We also found large changes in LULC occurring around fast growing urban areas, with changes in these peri-urban zones occurring faster to the east than west. This suggests that differences in socioeconomic conditions and specific local and regional policies have influenced the rates of forest, cropland and urban net changes, disturbances and net transitions. While it appears that a combination of economic growth and forest protection in this region over the past 20 years has been fairly successful, threats like drought, other extreme weather events and land degradation remain.

Applying a Systematic Review to Land Use Land Cover Change in Northern Upland Vietnam: The Missing Case of the Borderlands

As Vietnam embraces the market economy, and a number of state policies promote reforestation and rural market integration, land use and land cover (LULC) changes are occurring in the countrys northern uplands in increasingly complex and fragmented ways. Yet understandings of the degree and consequences of LULC changes in this diverse agro-ecological region are incomplete. We conduct a systematic literature review of research reported in academic articles tracing and analysing LULC change in Vietnams northern regions. We find that these studies have tended to take place away from the most mountainous, northern borderlands. The studies nonetheless highlight a diversity of land use land cover changes caused by numerous causes, making the distinction of overall trends difficult. To complement and extend this body of research, we introduce recent LULC change research we have completed in the mountainous border districts of Lao Cai province, on the Sino-Vietnamese border. The heterogeneity of causes of LULC change in both the review articles and our case study points to the importance of adapting land use policies to local agro-ecological and socio-economic conditions and ethnic diversity, taking into account state–farmer relations, household livelihood decision-making, and policy implementation at the commune and district levels.

Spatial Logic and the Distribution of Open and Green Public Spaces in Hanoi: Planning in a Dense and Rapidly Changing City

Abstract Vietnam recently started to recognise the multiple benefits brought by open and green spaces to urban population and environment. In this paper, we analyse the provision of open and green spaces (parks, public gardens and lakeshores) in Hanoi. Using a model proposed by Talen (2010), we examine the spatial evolution of these spaces between 2000 and 2010, their level of proximity to residential units, and the extent to which their distribution matches social needs (defined in terms of population density). We find that while the absolute number and surface area of parks and public gardens has increased significantly in Hanoi, these new public spaces are mainly built on the city’s newly urbanised periphery. As a result, in 2010, only 15% of Hanoi’s residential blocks had access to a park or public garden within a reasonable walking (1000m) or biking distance (2500m). Moreover, the city’s densest residential areas have only access to relatively small gardens and parks, resulting in overcrowding. Lakeshores, however, represent an opportunity to enhance access to open and green spaces in Hanoi due to their spatial distribution. We conclude by advocating for the integration of spatial measures of proximity and needs into Hanoi’s public space planning policy framework.