Judul: Penilaian Kerusakan dan Model Pengelolaan Hulu Daerah Aliran Sungai Deli Provinsi Sumatera Utara
Abstrak: The Deli Watershed (DAS) is designated as a watershed whose carrying capacity needs to be restored based on the Decree of the Minister of Forestry of the Republic of Indonesia Number: SK. 328/Menhut-II/2009 concerning Determination of Priority Watersheds in the Framework of Medium-Term Development 2010-2014. This status is supported by watershed conditions prone to environmental damage, such as erosion, landslides, floods, droughts, and critical land and sedimentation. One of the reasons the status of the Deli Watershed has not changed since it was first established is the lack of green vegetation (forest) in the Deli Watershed, which is only 2,610.96 ha (6.68%) of the total watershed area. Meanwhile, the forest area ideally is 30% of the entire watershed area as regulated in the Law of the Republic of Indonesia Number 41 of 1999 concerning Forestry. The environmental degradation in the Deli Watershed is determined by the condition of its upstream, which functions as a conservation area. Good environmental conditions do not support the function of the upstream Deli Watershed as a water regulator, so this area is experiencing various problems, including soil erosion/slides, critical land, and decreased soil nutrient content. These environmental problems result in economic losses for the community as resource users and the government as policymakers. Based on this explanation, this study aimed to 1) identify the factors causing the damage to the upstream Deli Watershed; 2) estimate the value of the economic loss from the damage to the upstream Deli Watershed; and 3) analyze the institutional management of the upstream Deli Watershed. The methods used in this research were Root Cause Analysis (RCA), Geographic Information System (GIS), Universal Soil Loss Equation (USLE), replacement cost, content analysis, and actor analysis using primary and secondary data. The results of the root cause analysis stated that limited ownership of the land area, business capital, and skills of farmers was the core problems of environmental damage in the upstream Deli Watershed. The solution is by developing additional income/livelihood of the community through guidance and counseling by relevant government and local government agencies. The calculation of economic losses due to damage to soil fertility in the upstream Deli Watershed was IDR 2,179,828,456/ha/year. This nominal represents the replacement cost of soil macronutrients (N, P, K) lost due to 267.93 tons/ha/year erosion on Ultisol soil types. This calculation used the nutrient content of chicken manure as a substitute for the lost soil nutrient content. The institutional analysis of the upstream Deli Watershed management consists of a content analysis of statutory regulations and an actor analysis involving five groups of formal actors (central government, provincial government, district government, non-structural institutions, and resource users). The existing regulations have been implemented according to their substance by the managing actors. However, environmental degradation still occurs due to the ineffective performance of actors in managing the upstream Deli Watershed. Institutions with a working area covering the upstream Deli Watershed have not been actively involved in preparing the Deli Watershed management plan. Furthermore, the institution as a coordination forum has not been able to oversee all stakeholders managing the Deli Watershed. Therefore,
Keyword: actor, economic loss, management, regulation, root cause

Judul: Model skema pembayaran jasa lingkungan dalam pengelolaan daerah aliran sungai (studi kasus di sub DAS Citanduy Hulu dan sub DAS Ciseel)
Abstrak: This study suggests an alternative solution to solve degradation in Subwatershed Citanduy Hulu and Sub-watershed Ciseel using Payment Environmental Services (PES) model. It is an instrument of economic policy based on economic incentives. PES is established between the owner or manager of the land on the upstream with water users both for commercial and non commercial purposes on the middle as well as the downstream. Conditions and characteristics of the watershed are different from one to another, therefore in order to apply PES an appropriate model is required. The purpose of this study is to design a PES model in Sub-watershed Citanduy Hulu and Sub-watershed Ciseel, includes an analysis of the typology of the watershed, watershed characteristics analysis, economic valuation and institutional analysis. The typology of watershed is used to determine which regions are eligible for the implementation of PES. Soil Water Assessment Tool (SWAT) is applied to determine such regions. The analysis showed that there are 7 (seven) Subwatershed in the area of Citanduy watershed, namely: Sub-watershed Citanduy Hulu, Cijolang, Cimuntur, Ciseel, Cikawung, Citanduy Tengah and Citanduy Hilir. Among those sub-watersheds, only Sub-watershed Citanduy Hulu and Subwatershed Ciseel are qualified because of their potential for environmental services, environmental service providers, resource management, and institutional environment. The watershed characteristics is used as the basis for determining the scope of the PES model. From SWAT analysis results in flow of water in the upstream Sub-watershed Citanduy Hulu, which is about 11,4% is the flow of surface (surface flow) and 88.6% lateral and groundwater flow, while in the middle-end of about 5,5% is the surface flow and 94,5% lateral and ground water flow. This condition shows that from the aspect of availability of Sub-watershed Citanduy Hulu currently still in safe condition, both the dry and rainy season. Nevertheless, in order of quantity, quality and continuity of water can remain assured, it is need to rehabilitate the land cover with the erosion rate is relatively moderate and severe area of 1.574 Ha and maintain existing wetland and gardens. For Sub-watershed Ciseel water flow composition in the upper and middledownstream almost equal, is about 46% came from surface flow and 54% of the lateral and groundwater flow. This condition shows that from the aspect of availability of Sub-watershed Ciseel still depends on the season, it is necessary to rehabilitation and conservation of land cover with moderate and severe area of 1.402 Ha and improve wetland and gardens conditions. This indicates that the water catchment area in each unit of land significant role in providing groundwater recharge...dst
Keyword: Critical watershed, typology of watershed, watershed characterististic, econimic valuation, institutional, and payment of environmental services scheme

Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf