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: Studi Perencanaan Pengelolaan DAS dengan Model Optimasi Penggunaan Lahan di Bagian Hulu DAS Mahakam
Abstrak: Land use which is not in accordance with the land capability, will cause land degradation. In Indonesia, there is progressive increase of critical land area size, every year, and this exerts an impact toward watershed damage. Objectives which are sought in the planning of watershed management often negate each other because from one point of view, there is a desire to maintain natural resources sustainability, and from other (economic) point of view, there is a desire to increase farmer's income. In order to obtain a model for planning sustainable watershed management, land use optiminazation was conducted and designed using the analysis of Linear Goals Programming (L GP) The study area had the size of 29 686 ha, comprising 3 subdistricts (namely Damai, Barong Tongkok and Melak) that were situated in the district of Kutai Barat, the province of East Kalimantan. The formulation of model for land use optimization was designed to achieve four targets, namely peak discharge. reduced rate of erosion (so that it is equal with or smaller than the targeted discharge and tolerable soil loss), ability of each farmer family to fulfill the need for food and rice, and ability of on farm income to create appropriate level of welfare. Research unit was homogeneous land unit. Data source for model input came from improvement of cropping pattern and alternative agrotechnology which was conducted by using simulation of CP factor. Data processing and analysis used the method of SCS, USLE and farm analysis. On the other hand, the completion of model used software General Algebraic Modeling System (GAMS) and Arcview 3,2. Land use with existing cropping pattern gave peak discharge of 116.39 m3/seconcj, erosion between 157-876 tonlha, production of upland rice 1.52 ton GKPlhalyear, and income Rp 3 268 636,-halyear. On the other hand, optimum land use pattern from the six scenarios model, showed better results as compared with the existing condition because ecologically, the land use could maintain the stability of peak discharge, and reduce erosion to the level below the targeted value. Although scenario model la and llla (with land use composition in the form of non irrigated rice field and dry land crop field) gave better result than those of existing conditions, but the occurring erosion were still higher than those in scenario model I, 11, Ill, and IV (with land use composition in the form of non irrigated rice field, dry land crop field, and estate field). This was because the priority for achieving erosion target in scenario la and llla was only up to the tolerable rate of soil erosion. Testing of scenario model I, 11, Ill, and IV showed that there was a tendency for increasing proportion of dry land crop field area size, but on the other hand, decreasing proportion of non irrigated rice field and estate field area size, if the target of achieving living standard is continuously increased. Spatially, recommendation that could be given for /and units of non irrigated rice field, dry land crop field and estate field is in the form of cropping pattern and agrotechnology LI *, L3b* ,
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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