Pemanfaatan hujan berbasis rumah tangga untuk mengatasi bahaya kekeringan di Kabupaten Gunungkidul Yogyakarta

WINARNO, Prof. Dr. Ir. Sunjoto, Dip.HE.,DEA

2010 | Tesis | S2 Teknik Sipil

Kekeringan adalah peristiwa terjadinya periode kekurangan air, pada saat ini sering melanda daerah-daerah, khususnya pada musim kemarau. Kabupaten Gunungkidul sering mengalami bencana kekeringan, sehingga ketersediaan air bersih menjadi masalah utama. Penduduk memanfaatkan air hujan dan sumber air lainnya (air sungai, telaga, mata air dan goa-luweng) untuk memenuhi kebutuhan air. Namun saat musim kemarau tiba masalah akan timbul karena volume curah hujan sangat sedikit dan banyak sumber air mengalami kekeringan. Penelitian dilaksanakan dengan tujuan mengkaji potensi air hujan untuk memenuhi kebutuhan air rumah tangga, menentukan ukuran bak penampung air hujan (PAH) yang efektif dan mencari alternatif sumber air untuk mengatasi kekurangan air rumah tangga pada musim kemarau. Penelitian dilakukan dengan mengumpulkan data sekunder dan data primer. Data sekunder meliputi data curah hujan harian, data penduduk dan data sumber air. Data primer diperoleh dengan pengambilan sampel menggunakan kuesioner yang meliputi data luas atap rumah, jumlah anggota keluarga, kebutuhan air rumah tangga pada musim penghujan dan kemarau. Pengolahan dan analisa data curah hujan dilakukan dengan menggunakan program Microsoft Excel bertujuan untuk mengetahui potensi hujan. Kuesioner dianalisa dengan menggunakan metode tabulasi, bertujuan untuk mengetahui potensi atap dan kebutuhan air per kapita musim penghujan dan kemarau. Pemilihan alternatif sumber air bertujuan untuk mengatasi kekurangan air rumah tangga pada musim kemarau. Berdasarkan analisis data hujan, rata-rata curah hujan tahunan di Kabupaten Gunungkidul berkisar antara 1.257 s/d 2.456 mm/thn. Besarnya Potensi hujan rumah tangga di fisiografi Baturagung berkisar 66.963 s/d 113.307 l/thn, Basin Wonosari antara 70.759 s/d 107.875 l/thn dan Karst Pegunungan Sewu antara 63.808 s/d 90.693 l/thn. Berdasarkan hasil analisis kuesioner, besarnya konsumsi air per kapita di fisiografi Baturagung musim penghujan sebesar 77,9 l/kpt/hr dan kemarau sebesar 52,8 l/kpt/hr, di fisiografi Basin Wonosari 67,2 dan 59,9 l/kpt/hr dan di fisiografi Karst Pegunungan Sewu 57,5 dan 45,5 l/kpt/hr. Pada fisiografi Baturagung dibutuhkan bak penampung air hujan (PAH) berkisar antara 12 s/d 37 m3, di fisiografi Basin Wonosari antara 18 s/d 37 m3 dan di fisiografi Karst Pegunungan Sewu berkisar antara 9 s/d 32 m3. Besarnya potensi hujan rumah tangga sebagian desa yang ada di Kabupaten Gunungkidul lebih kecil dari rata-rata kebutuhan air tahunan. Untuk mengatasi defisit air skala rumah tangga di fisiografi Baturagung dapat dilakukan dengan cara penambahan luas atap rumah, pembuatan sumur gali dan pemanfaatan air sungai atau pembuatan sumur gali (disesuakan dengan potensi sumber air dan kondisi alamnya). Pada fisiografi Basin Wonosari dengan pembuatan sumur gali dan di fisiografi Karst Pegunungan Sewu dengan penambahan luas atap rumah

An extreme event of lack of water that is usually defined as drought, occurred more often in Gunungkidul Regency especially in dry season. Fresh water availability is the major problem in Gunungkidul Regency. The people use rainfall water and other water resource e.g. river, ponds, spring and sinkhole to fulfill their water need. However, there is a problem during dry season. The rainfall intensity is very low and the water resource is going to be dry. The objectives of the research are to study rain water potency in order to fulfill domestic water need, to determine the effective dimension of rain water reservoir (Penampung Air Hujan-PAH), and to find the alternative water resource in order to cope with a lack of water during dry season. Secondary and primary data were employed in this research. Secondary data includes daily rainfall data, population data, and water resources data. Sampling method by using questionnaire was used to gain primary data. It includes roof area, household members, and household water need in dry and rainy season. Microsoft Excel Program was used to process and to analyze the rainfall data. It is applied in order to analyze rainfall potency. Cross tabulation methodology was used to analyze the questionnaire. The aims of this methodology are to identify roof area potency and water need per capita during dry and rainy season. The selection of water resource alternative is intended to cope with the lack of household water resource during dry season. The average yearly rainfall in Gunungkidul Regency ranges from 1,275 mm/ year to 2,456 mm/year. Household rainfall water potency in Baturagung Physiography, Wonosari Basin, and Karst Sewu Mountain ranges from 66,963 l/year to 113,307 l/year, 70,759 l/year to 107,875 l/year, and 63,808 l/year to 90,693 l/year respectively. Meanwhile, based on the questionnaire analysis, the amount of water consumption per capita in Baturagung Physiography, Wonosari Basin, Karst Sewu Mountain during rainy season is 77.9 l/capita/day, 67.2 l/capita/day, and 57.5 l/capita/day respectively. Whereas, the amount of water consumption per capita during dry season is 52.8 l/capita/day, 59.9 l/capita/day, and 45.5 l/capita/day for Baturagung Physiography, Wonosari Basin, Karst Sewu Mountain respectively. Therefore, Baturagung Physiography, Wonosari Basin, and Karst Sewu Mountain require rainwater reservoir ranging from 12 m3 to 37 m3, 18 m3 to 37 m3 and 9 m3 to 32 m3 respectively. The amount of household rain water potency in a part of villages in Gunungkidul Regency is less than the average yearly water demand. The deficit of household water demand in Baturagung Physiography could be managed by increasing the area of house roof, making digging well (depend on the water resource potency and natural condition), and by using river water for domestic use. Whereas, making digging well and widening house roof could be applied in Wonosari Basin, and Karst Sewu Mountainous area respectively

Kata Kunci : Bahaya kekeringan,Hujan,Rumah tangga