Peat Ecosystem Inventory, as mentioned in the Regulation of the Minister of Environment and Forestry Article 1 Number P.14/Menlhk/Setjen/Kum.1/2/2017 concerning about the inventory procedures and peat ecosystem function determination, is defined as an activity to collect and obtain data and information about Peat Ecosystem Characteristics. While the Peat Ecosystem Function is the set of the peat elements needed to protect water availability, biodiversity, oxygen-producing carbon storage, climate balance, which is divided into the peat ecosystem protection function and peat ecosystem cultivation function. Peat Ecosystem Inventory is conducted using Transect Method (Observation Pathway Method) and observation of sample points based on the 13 characteristics of the peat ecosystem that has been determined by Minister of Environment and Forestry Regulation. Based on Ministerial Regulation Article 1 Number P.14/2017, the definition of Transect is an observation route both longitudinal and transverse by considering the hydrologic network pattern and relief of land surface, which is used in collecting sample in the field. While the definition of Observation Sample Point is the point location chosen for characteristic observation of the peat ecosystem, which represents the Peat Hydrological Unit. Based on Ministerial Regulation Article 4 Number P.14/2017, the data and information needed for Peat Ecosystem Inventory are: a. Indicative map of the national peat ecosystem distribution as contained in the Annex to Government Regulation Number 71/2014 concerning about protection and management of peat ecosystems as amended by Government Regulation Number 57/2016 concerning about amendments to government regulation number 71 of 2014 concerning Protection and Management of Peat Ecosystems; b. National map of peatland 1:250,000 from the Land Agricultural Resource Management Agency, Ministry of Agriculture; c. Map of River hydrology networks and altitude contours derived from the Earth Map 1:250,000; d. Land cover map derived from medium resolution remote sensing imagery; e. Digital Elevation Model (DEM) with 30 meters resolution generated from medium-resolution non-optical satellite imagery; f. Landscape maps (Landform) derived from land system maps (RePPProT); g. Watersheds map; h. Other legitimate sources in the geo-spatial mapping methodology according to the related-rules. The implementation of Inventory and Determination of Peat Ecosystem Functions is divided into 2 processes, those are: 1) the Inventory and Determination of National Peat Ecosystem Functions at a level of 1: 250,000 scale, 2) Inventory and Determination of Provincial and District/City Peat Ecosystem Functions at a level of 1: 50,000 scale. As referred in Article 5 section (2) of the Ministerial Regulation Number P.14/2017, the implementation of the Peat Ecosystem inventory is carried out by identifying the peat area based on the data and information as referred in Article 4. Based on the inventory of peat areas as referred in Article 5 section (2), the delineation of Peat Hydrological Units is carried out by observing: a. Boundary area around peatland which is located between 2 main rivers / order-1; b. Surface elevation pattern based on DTM / SRTM data with a resolution of 30 meters; c. Watershed boundary. If the characteristics above are not found, the delineation of the Hydrological Units is carried out using land system data. It is regulated in Article 5 section (4).