Judul: Economic Loss Estimation and Management Policy Alternatives of Siak River (Case Study: Rawang Air Putih Village, Siak Sub district, Siak Regency, Riau Province)
Abstrak: Guna memenuhi kebutuhan sehari-hari, masyarakat sekitar sangat bergantung dengan keberadaan Sungai Siak. Saat ini, Sungai Siak telah tercemar oleh limbah dari aktivitas industri yang terus meningkat. Tercemarnya Sungai Siak merugikan perekonomian masyarakat sekitar karena mereka perlu mengeluarkan biaya tambahan untuk mengakses air bersih dari sumber lain. Penelitian ini bertujuan untuk (1) menganalisa persepsi masyarakat Desa Rawang Air Putih terhadap pencemaran Sungai Siak, (2) mengestimasi nilai kerugian ekonomi masyarakat Desa Rawang Air Putih yang disebabkan oleh pencemaran Sungai Siak, (3) mengestimasi nilai kompensasi (Willingness to Accept/WTA) kerugian masyarakat Desa Rawang Air Putih, dan (4) merumuskan alternatif kebijakan pengelolaan Sungai Siak. Metode survei digunakan sebagai metode penelitian dalam penelitian ini. Data primer dan sekunder adalah dua jenis data digunakan dalam penelitian ini. Metode yang digunakan dalam pengambilan contoh adalah metode sensus dan purposive sampling. Metode analisis data menggunakan Skala Likert, Replacement Cost, Cost of Illness, Loss of Income, Contingent Valuation Method, dan Analytical Hierachy Process. Menurut hasil penelitian, responden di Desa Rawang Air Putih menyatakan bahwa Sungai Siak telah tercemar dan mengakibatkan kerugian ekonomi bagi masyarakat. Kerugian ekonomi yang ditanggung responden di Desa Rawang Air Putih rata-rata mencapai Rp 974.854/KK/tahun. Nilai dugaan rata-rata WTA kerugian responden dalam penelitian ini mencapai Rp 2.036.841/KK/tahun. Kompensasi yang diharapkan responden di Desa Rawang Air Putih yaitu kompensasi dalam bentuk dana, sumur bor, dan alat penyaring air. Berdasarkan hasil analisis AHP, pengawasan dan pemantauan sungai dipilih menjadi alternatif prioritas utama dalam kebijakan pengelolaan Sungai Siak. Alternatif kebijakan ini dipilih karena dapat mengurangi serta mencegah limbah yang dibuang ke Sungai Siak, In order to meet their daily needs, the surrounding community is very dependent on the existence of Siak River. Nowadays, the Siak River has been polluted by waste from industrial activity that tend to increase. The pollution of the Siak River causes economic losses for the surrounding community, because they have to incur additional costs to acces clean water from other sources. The purposes of this research are (1) to analyze the perception of Rawang Air Putih Village resident on the pollution of the Siak River (2) to estimate the economic loss of Rawang Air Putih Village resident (3) to estimate Willingness to Accept (WTA) due to economic loss of Rawang Air Putih Village resident (4) to formulate management policy alternatives of the Siak River. Survey method is used as the research method in this research. Two kinds of data are used in this research, primary and secondary data. The method used for sampling techniques are census and purposive sampling. Data are analyzed by Likert Scale, Replacement Cost, Cost of Illness, Loss of Income, Contingent Valuation Method, and Analytical Hierarchy Process. Based on the result, respondents of Rawang Air Putih Village stated that Siak River was polluted and lead to economic loss for the community. The average economic loss of respondents in the Rawang Air Putih village is around IDR 974,854/household/year. The estimated Willingness to Accept (WTA) in this study is IDR 2,036,841/household/year. Respondents in the Rawang Air Putih Village expect compensation in form of funds, drilled wells and water filter. AHP analysis showed that the main priority of
Keyword: Analytical Hierarchy Process (AHP), compensation, river pollution, Willingness to Accept (WTA)

Judul: Estimasi Nilai Kerugian Ekonomi Masyarakat Akibat Intrusi Air Laut (Studi Kasus: Desa Surya Bahari, Kabupaten Tangerang)
Abstrak: Intrusi air laut merupakan proses masuknya air laut ke dalam aliran air tanah daratan. Desa Surya Bahari merupakan salah satu desa di Kecamatan Pakuhaji, Kabupaten Tangerang yang terkena dampak intrusi air laut. Intrusi air laut telah menyebabkan kelangkaan air bersih di pemukiman masyarakat dan menurunnya produktivitas pertanian. Tujuan penelitian bertujuan untuk: 1) Mengidentifikasi karakteristik masyarakat dan usaha tani di Desa Surya Bahari 2) Mengestimasi besarnya nilai kerugian ekonomi masyarakat dan usaha tani yang diakibatkan oleh intrusi air laut 3) Mengestimasi kesediaan membayar masyarakat untuk memperbaiki sistem penyediaan air bersih di Desa Surya Bahari, dan 4) Mengkaji alternatif kebijakan yang tepat untuk mengurangi dampak intrusi air laut di Desa Surya Bahari. Metode penelitian yang digunakan adalah metode survei dan dianalisis dengan analisis deskriptif, replacement cost, change in productivity, dichotomus choice contingent valuation method (CVM) dan Analitycal Hierarchy Process (AHP). Berdasarkan hasil penelitian, 45% responden masyarakat Desa Surya Bahari adalah nelayan dengan rata-rata pendapatan Rp. 2.869.600 per bulan. Latar belakang pendidikan responden masyarakat Desa Surya Bahari didominasi dengan lulusan Sekolah Dasar. Mayoritas petani di Desa Surya Bahari merupakan petani penggarap non pemilik dengan rata-rata luas lahan sebesar 2,06 ha dan produktivitas lahan dibawah 4,7 ton/ha. Hasil dari penelitian menunjukkan bahwa total nilai kerugian ekonomi masyarakat Desa Surya Bahari akibat penurunan produktivitas pertanian dan pengeluaran biaya penggantian sumber air bersih adalah sebesar Rp. 5.096.863.340 / tahun. Estimasi nilai kesediaan membayar masyarakat sebesar Rp. 2.116,46/m3 menggunakan Metode Logit, dan Rp. 2.383/m3 menggunakan Metode Turnbull. Alternatif kebijakan yang disarankan untuk menjaga kelestarian air tanah adalah konservasi daerah resapan air dan pengawasan terhadap penggunaan air tanah., Sea water intrusion is the movement of saline water into the fresh water aquifer. Surya Bahari Village is one of the villages in Pakuhaji Sub-district, Tangerang Districts that was affected by seawater intrusion. Seawater intrusion has caused clean water scarcity in community settlements and affected the quality and productivity of agriculture in Surya Bahari Village. The aims of this study are to: 1) identify the characteristics of community and farmers in Surya Bahari Village 2) estimate the value of community and farmers economic losses due to seawater intrusion 3) estimate community’s willingness to pay to improve the water supply system in Surya Bahari Village 4) examine appropriate policy alternatives to reduce the impact of seawater intrusion in Surya Bahari Village. Survey method was used as research method and the results were analyzed with descriptive analysis, replacement cost, change in productivity, dichotomus choice contingent valuation method (CVM) and Analitycal Hierarchy Process (AHP). Based on research results, 45% of community in Surya Bahari Village is a fisherman with average income IDR 2,869,600 per month. Community education background was dominated by elementary school graduate. Majority of farmers in Surya Bahari Village are non-owner cultivators with average land area of 2.06 ha and land productivity below 4.7 tons/ha. The results of this study indicated that total value of community economic losses due to decreased agricultural productivity and expenditures on buying clean water was IDR 5,096,863,340 a year. The estimated value of community’s willingness to pay was IDR 2,116.46/m3 using logit method, and IDR 2,383/m3 using the
Keyword: Analitycal Hierarchy Process, Change in Productivity, Dichotomus Choice CVM, Replacement cost, Willingness to Pay

Judul: The Exploration of Discrete Logarithm over Finite Field GF(3m)
Abstrak: The security of many public~key algorithms is based on the problem of finding discrete logarithms. The generalized discrete logarithm problem is the following: given a finite cyclic group G of order n, a generator a of G, and an element fl E G, find the integer x, 0 ~ x ~ n - 1, such that 0: = fl. Algorithm for discrete logarithm problem focused on Menezes et al. (1997) that consist of exhaustive search algorithm, the baby-step giant-step algorithm, Pollard's rho algorithm, Pohlig-Hellman algorithm, and index-calculus algorithm. These algorithms are explorated to be used in discrete logarithm problem over finite field GF(3m ). The exploration also produces some algorithms, i.e. naif negative algorithm, baby-step mother-step algorithm, baby-step mother free-step algorithm, and baby-step free-step algorithm. All algorithms implemented using Maple 11. The Pohlig-Hellman and baby-step giant-step algorithms are efficient enough to be used in discrete logarithm problem over finite field GF(3m ) for m < 20.
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