Spatial and temporal distribution of estimated surface runoff caused by land use/land cover changes in the upstream Citarum watershed, West Java, Indonesia

In Indonesia, flooding is one of the natural hazards that often occurs during the rainy season. Surface runoff coefficient values are an essential indicator of the supply of regional water resources. The smaller the surface runoff value, the greater the water storage in the ground, and the smaller surface was running water. This study analyses the spatial and temporal distribution of the estimated surface runoff caused by land use/land cover changes in the upstream Citarum watershed. The study area is located in the upstream Citarum watershed, West Java, Indonesia. The site has a long history of flooding and various complex environmental problems. The geographic Information System method was used as a tool in analyzing the spatially and temporally. The research result shows that there has been a change in land cover in several periods of the year in the Citarum upstream watershed. The occurrence of the LULC phenomenon positively affects the surface runoff coefficient. The increasing area of Built land and plantation in the Citarum upstream watershed will further increase the surface runoff coefficient and, in the end, will potentially increase the surface runoff and contribute to flooding in the Bandung basin. This study results can be used to provide input in determining the direction and policies for watershed management, taking into account the varying characteristics of each subwatershed.

Evaluation of land cover changes and secondary ecological succession of typical agroforestry landscapes in Phu Yen Province

The study of land cover changes as well as landscape succession has theoretical and practical significance. Determining the characteristics, causes, and trends of the changes and succession of a landscape allows for assessing the natural and human characteristics of the territory. On this basis, appropriate solutions and policies in resource management, socioeconomic development, and environmental protection are available for each locality. Applying and integrating remote sensing data with field investigations and surveys improves the accuracy and reliability of research results. From the establishment of a land cover change map based on land cover map data collected in 2010, 2015, and 2020, variations in the land cover types of Phu Yen Province were observed. In the period 2010–2015, the area of natural forests and grasslands, shrubs, and bare lands decreased rapidly, whereas the covered areas of intentionally planted forests, industrial trees, and crops increased significantly. The secondary ecological succession of the agroforestry landscape of Phu Yen Province in the last 50–60 years occurred under the strong influence of human activities. Under the impact of chemical warfare and policies and farming practices of the local people, several evergreen broad-leaved tropical forest landscape units have undergone four to six stages of succession, with the interweaving of the economic development policy of Phu Yen Province and farming practices of the local people, making the structure and length of each period and succession very different.