Rainfall thresholds that form the basis of the landslide warning systems now exist for a few areas in Indonesia. Based on analysis of historical data, threshold performance varies according to precipitation characteristics, and threshold exceed corresponds to a given probability of landslide occurrence. Early warnings of landslides and debris flows that include specific information about affected areas, probability of landslide and debris flow occurrence, and expected timing are technically feasible as illustrated by a case study made on Mt. Bawakaraeng, South Sulawesi, Indonesia. Records from 1997 to 2007 of rainfall data and history of landslides and debris flows were collected from the Ministry of Public Works of the government of Indonesia. The threshold, as defined by the lower boundary of the points representing landslides and debris-triggering rainfall events, is expressed by the equations = 41.85 before the large scale landslide on March 26, 2004 and = 37.71 after the large scale landslide, where is the rainfall intensity (mm/hr) and is the duration of rainfall (hr). According to empirical threshold analysis, the regression curve can be considered as a reliable rainfall intensityduration threshold for the study area, above which, landslide or debris flow event may occur.

ABSTRACT

Indonesia is one of the countries in the world that has experienced a negative economic impact due to the Covid-19 pandemic since early 2020. In overcoming this impact, the government has taken strategic steps by implementing the National Economic Recovery (PEN) program. One of the PEN programs implemented by the Ministry of Environment and Forestry is community economic development for peat farmer groups through the development of agroforestry food in 35 Social Forestry Business Groups (KUPS) in Pulang Pisau Regency, Central Kalimantan Province. It is one of the regencies known to have quite a large peatland area in Indonesia. This study aimed to analyze the risk management of the 35 KUPS PEN program in peatland.  A qualitative desk study methodology was used along with the fishbone model analysis. The results showed that various types of business activities had been developed by KUPS. In the management of social forestry businesses, various risks were identified starting from regional governance, institutional governance, and business governance. The PEN program implemented in 2020 showed a positive impact in improving the community's economy with a positive impact on ecology and socio-culture. This PEN activity has absorbed around 9,110 HOK (Working People's Day) local workers with 565 KUPS members. The implementation of this program can be replicated, especially for social forestry business groups in other areas.

The biogeophysical characteristics of watersheds have an important role as a determinant of the river discharge amount in the watershed. Various watershed problems such as flood and drought related to river discharge require data and information. The importance of this data and information will determine a better watershed management plan. The issue of flooding and drought are the important issues in Ralla sub watershed, Souht Sulawesi Province. This study aims to describe the biogeophysical characteristics and the discharge of Lompo Riaja Atas and Lompo Riaja Bawah Rivers in Ralla sub watershed, Lisu Watershed. This research was conducted in from November 2016 to August 2017. Primary data collection was done through river discharge and precipitation measurements during 34 days of observation. Secondary data obtained from government or related agencies such as geological data obtained from Geological map of the Ujung Pandang sheet 1982, the slope data from Aster DEM, land type from RePPProt 1987, land cover data from google earth image 2015. A quantitative descriptive method was used to analyze the data obtained. The results showed that the Lompo Riaja Atas and Lompo Riaja Bawah rivers have relatively similar discharge fluctuation, although they have a different amount of discharge. River discharge of both rivers is more influenced by rainfall compared to biogeophysical conditions such as geology, topography, soil type, watershed area, watershed shape, river length and order, gradient, flow pattern, flow density, and land cover.

ABSTRAKPermasalahan daerah aliran sungai (DAS) yang bersifat multisektor, multidisplin, multipihak, dan multidimensi adalah konsekuensi dari multifungsi DAS. Kompleksitas permasalahan ini menuntut suatu sistem dan pendekatan pengelolaan sesuai karakteristik dan tipologi DAS. Penelitian ini bertujuan untuk menganalisis karakteristik dan tipologi DAS Mapili Provinsi Sulawesi Barat. Penelitian ini dilakukan dengan metode survei, pengumpulan data sekunder dan data primer. Aplikasi dari geographic information system (GIS) dengan analisis tumpang susun peta dan skoring digunakan dalam penelitian ini. Hasil penelitian menunjukkan bahwa karakterisasi biogeofisik DAS Mapili yang meliputi meteorologi, morfologi, morfometri, hidrologi, kemampuan DAS dan karakterisasi sosial ekonomi, budaya dan kelembagaan mempengaruhi sistem penerapan pengelolaan DAS Mapili. Tipologi DAS Mapili diklasifikasikan menjadi 2 tipologi DAS, yaitu: tipologi II atau DAS yang memiliki jumlah penduduk tidak padat (97 jiwa/km 2 ) dengan curah hujan yang tinggi (>2500 mm/th); dan tipologi IV atau DAS yang memiliki jumlah penduduk padat (377 jiwa/km 2 ) dengan curah hujan yang rendah (<1500 mm/th). Kedua tipologi ini memiliki karakteristik permasalahan DAS yang berbeda. Tipolgi II umumnya berada pada daerah tengah dan hulu DAS Mapili, sedangkan tipologi IV berada pada daerah hilir DAS Mapili. Kata kunci: Karakteristik DAS, tipologi DAS, GIS, DAS Mapili ABSTRACT PENDAHULUANDaerah Aliran Sungai (DAS) merupakan suatu satuan ekosistem yang memiliki peranan penting bagi kehidupan (Halengkara et al., 2012). Secara umum DAS dapat dibagi menjadi tiga bagian yaitu DAS bagian hulu, DAS bagian tengah, dan DAS bagian hilir. DAS bagian hulu berdasarkan fungsi sebagai konservasi dikelola untuk mempertahankan kondisi lingkungan DAS agar tidak terdegradasi sedangkan DAS bagian tengah dan hilir didasarkan pada fungsi