Riverbank erosion is a natural process, but often human activities can have a significant impact on the rates of morphological change. This paper aims to assess bank erosion problems in the Vientiane-Nong Khai section of the Mekong River, where the Mekong borders Thailand and Lao PDR. The study provides new and more accurate information about recent riverbank movement rates. The bank movement rates are quantified using two Hydrographic Atlases dated 1961 and 1992, derived originally from aerial photos and a field survey, and SPOT5 satellite images acquired on 4 December 2004 and 28 April 2005 with a resolution of 2.5 m in natural colours. Bank erosion and accretion rates on the left (Lao PDR) and right (Thailand) banks of the Mekong are analysed for two time periods: 1961-1992 and 1992-2005, respectively. The quantified average bank erosion rates were found to be slow, ranging from 0.8 to 1.0 m/a for the first and second analysis period, respectively. These average annual erosion rates are only 0.1% of the channel width, which is very low on a global scale. However, erosion rates were much higher for the islands in the river, 2.4 and 4.8 m/a for the two time periods. The quantified accretion for the main banks was 0.4 m/a during 1961-1992 and 0.7 m/a during 1992-2005, which for the islands increased from 0.6 to 6.4 m/a from the first to the second period. r
Aim: Deforestation is rapidly altering Southeast Asian landscapes, resulting in some of the highest rates of habitat loss worldwide. Among the many species facing declines in this region, clouded leopards rank notably for their ambassadorial potential 1640 | MACDONALD et AL.
Rates of biodiversity loss in Southeast Asia are among the highest in the world, and the Indo-Burma and South-Central China Biodiversity Hotspots rank among the world’s most threatened. Developing robust multi-species conservation models is critical for stemming biodiversity loss both here and globally. We used a large and geographically extensive remote-camera survey and multi-scale, multivariate optimization species distribution modelling to investigate the factors driving biodiversity across these two adjoining biodiversity hotspots. Four major findings emerged from the work. (i) We identified clear spatial patterns of species richness, with two main biodiverse centres in the Thai-Malay Peninsula and in the mountainous region of Southwest China. (ii) Carnivores in particular, and large ungulates to a lesser degree, were the strongest indicators of species richness. (iii) Climate had the largest effect on biodiversity, followed by protected status and human footprint. (iv) Gap analysis between the biodiversity model and the current system of protected areas revealed that the majority of areas supporting the highest predicted biodiversity are not protected. Our results highlighted several key locations that should be prioritized for expanding the protected area network to maximize conservation effectiveness. We demonstrated the importance of switching from single-species to multi-species approaches to highlight areas of high priority for biodiversity conservation. In addition, since these areas mostly occur over multiple countries, we also advocate for a paradigmatic focus on transboundary conservation planning.
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