Classification of potential landslides using the Shuttle Radar Topography Mission imagery in the Tulis Watershed, Indonesia

Tulis is one of the watersheds in the Mrica Reservoir Catchment Area in Indonesia. The Tulis Watershed has an area of 12,750 ha, which is dominated by hilly areas with areas below alluvial-colluvial. This study aimed to map the potential distribution of the landslides in the Tulis Watershed. As the Tulis Watershed has the potential for landslides, this study was conducted by using Shuttle Radar Topography Mission (SRTM) imagery year 2016. This study considered five aspects that affect landslides, namely: geological type, soil regolith depth, fault, slope, and soil texture. Areas in the Tulis Watershed were classified into five levels of landslide potential The following landslide classes and the area they cover were predicted after applying the formula: very low (0%), low (48%, 6,126 ha), moderate (51%, 6,548 ha), high (0.5%, 63 ha), and very high (0.1%, 13 ha). From the results of the level of potential landslides, several prevention and mitigation measures are recommended according to the level. For shallow landslide levels, it is recommended that relocation centers should be set up. In contrast, for those areas with very high landslide potential, it is necessary to mitigate and install Early Warning System (EWS) tools and prepare the community for adaptation

The Effects of Spatiotemporal Changes in Land Degradation on Ecosystem Services Values in Sanjiang Plain, China

Sanjiang Plain has undergone dramatic land degradation since the 1950s, which has caused negative effects on ecosystems services and sustainability. In this study, we used trajectory analysis as well as the Lorenz curve, Gini coefficient and relative land use suitability index (R) to analyze spatiotemporal changes of land degradation from 1954 to 2013 and to make a preliminary estimation of the role of human activities in observed environmental changes using a five-stage LULC data. This study also explored the effect of land degradation on the values and structure of ecosystem services. Our results indicated that more than 70% of marsh area originally present in the study area has been lost, whereas less than 30% was preserved. Dry farmland and paddy increased rapidly at the expense of marsh, forest and grassland. Land use structure became more unsuitable during the past 60 years. Compared with natural factors, human activities played a dominant role (89.67%) in these changes. This dramatic land degradation caused the significant loss of ecosystem services values and the changes in the structure of ecosystem services. These results confirmed the effectiveness of combining temporal trajectory analysis, the Lorenz curve/Gini coefficient and the R index in analyzing spatiotemporal changes in progressive land degradation. Also, these findings highlight the necessity of separating dry farmland from paddy when studying land degradation changes and the effects on ecosystem services in regions where dry farmland has often been converted to paddy