An Evaluation of Valuable Lands towards Landslide Susceptibility at Heritage Site, Sangiran, Central Java, Indonesia

Abstract

Sangiran Early Man Site is a world heritage located in a peri-urban area in Sragen Regency, Central Java, Indonesia. Due to its significance, this 59.21 km2 area is recognized as a valuable land. However, landslides persistently threaten its existence. The research intended to evaluate 1) the landslide susceptibility and 2) the vulnerability of the valuable lands in Sangiran Site. It applied the weights-of-evidence method to produce a landslide susceptibility map, which was further validated with field survey. The analysis output included five classes of susceptibility, namely, very low, low, moderate, high, and very high. The classification aimed to generate matrices containing indications of valuable lands in each class. The field survey found no landslides in very-low susceptible areas and several small ones in low susceptible areas. Landslides were found in valuable lands endangered with a moderate degree of landslides. Large but non-risky landslides were detected in highly susceptible areas, while large and risky ones were in very highly susceptible areas. Sangiran consists of 19 valuable lands that help to narrate geological and human evolution through fossils, scarcity, stratigraphy, and other unique features. For each land, a number is assigned to it to mark priority based its importance clues. Priority 13 was included in the low susceptibility class. While priorities 1, 5, 6, 7, 8, 12, 17, and 18 belonged to moderate susceptibility class, priorities 2, 3, 4, 9, 10, 11, 14, 15, 16, and 19 were classified into high susceptibility class. Therefore, Sangiran Site comprises heterogeneous characteristics that make its valuable lands the subjects of protection against landslide occurrences.