Pengaruh Alokasi Air Daerah Irigasi Asin Atas Terhadap Pola Tanam Daerah Irigasi Asin Bawah di Kabupaten Ponorogo

Al Fassah, Julian Ady (2026) Pengaruh Alokasi Air Daerah Irigasi Asin Atas Terhadap Pola Tanam Daerah Irigasi Asin Bawah di Kabupaten Ponorogo. Diploma thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Daerah Irigasi (DI) Asin merupakan sistem irigasi bertingkat yang menghubungkan DI Asin Atas dengan DI Asin Bawah, sehingga ketersediaan air di wilayah hilir dipengaruhi oleh pelepasan Telaga Ngebel, pemanfaatan air di wilayah hulu, sumber air lokal, kehilangan air selama pengaliran, dan return flow. Penelitian ini bertujuan menganalisis kondisi ketersediaan air DI Asin Bawah, pengaruh alokasi air DI Asin Atas terhadap tingkat kecukupan air, serta pemenuhan kebutuhan air pada kondisi defisit dengan skenario pompa. Analisis menggunakan data klimatologi, curah hujan, outflow Telaga Ngebel, debit sumber lokal, debit intake Bendung Bollu, dan realisasi pola tanam. Evapotranspirasi dihitung menggunakan metode Penman Modifikasi, curah hujan wilayah dengan Poligon Thiessen, debit andalan dengan metode Weibull, serta kebutuhan air irigasi berdasarkan KP-01. Ketersediaan dan kebutuhan air dianalisis setiap periode 10 harian melalui water balance dan Faktor K, sedangkan return flow dianalisis secara bertingkat dari setiap Sub DI menuju Bendung Bollu. Hasil analisis menunjukkan debit tersedia di Ponorogo sebesar 492–873 L/detik pada MT I, 717–939 L/detik pada MT II, dan 696–868 L/detik pada MT III. Faktor K rata-rata sebesar 0,723 dengan nilai minimum 0,326 dan maksimum 1,000; dari 36 periode terdapat 19 periode berkategori tinggi, 5 sedang, dan 12 rendah. Tanpa kontribusi sumur pantek, air permukaan hanya mampu mendukung intensitas tanam 106,99% dari target 299%. Pemenuhan defisit maksimum memerlukan 268 unit pompa berdebit 5,99 L/detik per unit. Dengan investasi awal Rp12.566.520.000, titik impas tercapai pada akhir MT II saat panen Agustus, dengan arus kas kumulatif Rp9.568.580.811. Hasil penelitian menunjukkan bahwa pengelolaan alokasi air hulu, pemanfaatan return flow, dan pengoperasian pompa sesuai periode defisit diperlukan untuk mendukung keberlanjutan pola tanam DI Asin Bawah.
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The Asin Irrigation Area is a cascade irrigation system connecting the Asin Atas and Asin Bawah Irrigation Areas; therefore, downstream water availability is influenced by Ngebel Lake releases, upstream water use, local sources, conveyance losses, and return flow. This study aims to analyze water availability in the Asin Bawah Irrigation Area, the effect of upstream water allocation on water adequacy, and the fulfillment of irrigation demand under deficit conditions using a pumping scenario. The analysis used climatological data, rainfall, Ngebel Lake outflow, local-source discharge, Bollu Weir intake discharge, and existing cropping-pattern data. Evapotranspiration was estimated using the Modified Penman method, regional rainfall using the Thiessen Polygon method, dependable discharge using the Weibull method, and irrigation water requirements according to KP-01. Water availability and demand were evaluated for each ten-day period using water-balance analysis and the K Factor, while return flow was analyzed sequentially from each irrigation sub-area toward Bollu Weir. Available discharge in Ponorogo ranges from 492–873 L/s during MT I, 717–939 L/s during MT II, and 696–868 L/s during MT III. The average K Factor is 0.723, with a minimum of 0.326 and a maximum of 1.000; of 36 periods, 19 are classified as high, 5 as moderate, and 12 as low. Without shallow-well contributions, surface water alone can support only 106.99% cropping intensity compared with the 299% target. Meeting the maximum deficit requires 268 pumps with an operating discharge of 5.99 L/s per unit. With an initial investment of IDR 12,566,520,000, the break-even point is reached at the end of MT II during the August harvest, with a cumulative cash flow of IDR 9,568,580,811. The results indicate that coordinated upstream allocation, return-flow utilization, and period-based pumping are required to support downstream cropping sustainability.

Item Type:	Thesis (Diploma)
Uncontrolled Keywords:	alokasi air, sistem irigasi bertingkat, return flow, Faktor K, pola tanam, sumur pantek, water allocation, cascade irrigation system, K Factor, cropping pattern, shallow wells
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC812 Irrigation
Divisions:	Faculty of Vocational > 22301-Civil Infrastructure Engineering (D4)
Depositing User:	Julian Ady Al Fassah
Date Deposited:	08 Aug 2026 04:04
Last Modified:	08 Aug 2026 04:04
URI:	http://repository.its.ac.id/id/eprint/144260

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