Judul: The development of sustainable water resources of way betung watershed, Bandar Lampung city
Abstrak: Way Betung watershed is one of the most potential watersheds as water supplier in Lampung Province and the most potential water resources for Bandar Lampung City particularly for potable water provided by regional water supplier company (PDAM). The ever increasing population and economic activities in Bandar Lampung City resulted in the increasing need of clean water. However, over time, the conditions of Way Betung watershed as water resources supplier have been declined. Therefore, to improve or to restore the conditions of Way Betung watershed, the forest and land rehabilitations programs are necessary. Thus research was aimed: (a) to study the impact of land use change in Way Betung watershed on its potential as water resources supplier of Bandar Lampung City, (b) to study the economic value of Way Betung water resources (c) to formulate sustainable water resources development plan of Way Betung watershed. The impact of land use change on the Way Betung water resources was analyzed by a regression method, and the annual economic value of water resources was analyzed by Willingness to Pay (WTP) method. The development plan of sustainable water resources of Way Betung watershed was arranged in five scenarios. To determine the best scenario, the simulations of the erosion level by the USLE method and the runoff volume by the SCS method were performed. The results showed that the land use change of Way Betung watershed (1991-2006) resulted in the increasing of the annual run off coefficient, the maximum daily discharge (Q max), and the decreasing of the daily minimum discharge (Q min), as well as the increasing of the river discharge fluctuation. The total annual economic value of water resources of Way Betung watershed was Rp101.1 billion/year and the total willingness to pay value for the rehabilitation of Way Betung watershed was Rp1.5 billion/year, which were derived from PDAM sector, tourism, water mineral companies, households and paddy field farmers in the upstream watershed. The best development of sustainable water resources of Way Betung watershed was the scenario-4 (the forest as much as 30% of watershed areas + alley cropping on mixed farms). Scenario-4 will reduce the erosion to lower than the tolerable soil loss (TSL), will decrease the fluctuation of monthly run off from 64.7 to 30.9, and the forest rehabilitation will be achieved in the best time (10 years with a scheme-B). Therefore, economically the water users community are willing to pay the rehabilitation costs (WTP) and socially it is accepted by the society.
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Judul: Nilai air dan manfaat bagi masyarakat serta PLTA Way Besai pada beberapa skenario perubahan penggunaan lahan di Kecamatan Sumberjaya, Kabupaten Lampung Barat, Provinsi Lampung
Abstrak: Forest conversion to other land use systems will affect to water supply, both in quantity as well as in quality due to environment services function. Communities use water as an important daily needs, farmers use as an agriculture input and hydropower company uses as an input in producing electricity. In the other side, communities need agricultural land as source of income. Valuing water as source of household need, agriculture input, particularly to produce rice and coffee and source of electricity production at current condition is one of the aim of this study. In the other part, communities’ income based on the land use change scenario had also been quantified to know land use composition in Sumberjaya which provide the maximum communities and Hydropower income. Amount of 150 samples (respondents) in three villages, Simpang Sari (downstream), Sukajaya (middle stream) and Tribudi Sukur (upstream) had been interviewed related to willingness to pay of water and income from agricultural (rice and coffee). GenRiver model used to generate water discharge at five land use scenarios, scenario 1 (13% monoculture coffee), scenario 2 (61% coffee-based agroforestry), scenario 3 (23% forest), scenario 4 (30% forest) and scenario 5 (84% forest). Water dischage is an important component of Hydropower to produce electricity and generate income. Average of willingness to pay of water in Sumberjaya is amounted to Rp. 503.30 per m3. Total water value is Rp 608.629.000.000 per year in Sumberjaya, coffee is Rp. 236,121,720,331.00 per year or equal with Rp 6,223,556.15 per hectare per year and electricity production by Hydropower is Rp 359.106.730.000 per year. Value of water to produce electricity by Hydropower is the highest component (59%) from total water value in Sumberjaya then followed by coffee which is 39%. Land use change scenario in Sumberjaya indicate that scenario 2 which consists of coffee-based agroforestry 33,062 hectare (61%), simple shade coffee 7,046 hectare (13%), forest and paddy field each of them 5.420 hectare (10%), horticulture and settlement each of them 1.626 hectare (3%) give the highest income for communities, even though the total income of HYDROPOWER Way Besai income was decreased, but not significant different. Total income for communities in scenario 2 is Rp 339,095,140,000.00 per year or equal to Rp 3,490,787.94 per household and total income of Hydropower Way Besai Rp 352,252,000,000.00 per year. Due to maintain water resources sustainability, integrated management between communities, particularly coffee and rice farmer with Hydropower and local government is needed. Keeping 10% of remnant forest and applying coffee-based on agroforestry system in Sumberjaya area should be the main point of policy.
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Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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