Infiltration which occurs on slope has a specific behavior that can be parameterized. One of the reasons is because the slope generates less ponding on the sloping soil surface. This condition affects infiltration rate and surface runoff proportion of water from any kind of rainfall distribution in time. Since surface runoff tends to be higher, erosion rate is also to be higher on slope. The slope steepness is the most important parameter of a slope. In this study, the effect of slope steepness on infiltration capacity and erosion rate of Mount Merapi bare slope material were tested in a laboratory using rainfall simulator. Three values of slope steepness of 36%, 47%, and 58% were used. The rainfall intensity was set constant and was found has rate of 116,312 mm/hour. The infiltration rate was measured by volumetric balance principle and the erosion rates were measured by collecting the eroded grains at the downstream end tank. Infiltration rate was evaluated by using Horton method and the average erosion were analyzed from the eroded grain data for each test. After fitting the recorded infiltration rate data to the Horton equation, the infiltration capacity was obtained. The results were the relationship between slope steepness and the affected the infiltration capacity and erosion for each test. Infiltration capacity is found to increase and the decrease with the increase of slope steepness while erosion rate is found to increase on the steeper slope. The increase of erosion range is between 15% to 33% for each 1o increase of slope steepness. In addition, polynomial and exponential equations were developed to express the relationship between slope steepness and infiltration capacity and also the erosion rate.

The short-duration-rainfall monitoring techniques have become important recently due to the high demand for disaster risk miti­gation. Such techniques produce important information on the rainfall intensity during heavy rainfall in the form of snake line. At the same time, use of X-Band Multi-Parameter Radar (XMP Radar) in rainfall monitoring has increased significantly be­cause of its capacity to cover wide area. An assessment on the snake line performance that was developed based on XMP Radar and ground rainfall monitoring instrument (i.e. Automatic Rainfall Recorder or ARR) has been applied to Mt. Merapi area, Java, Indonesia. Selected rainfall data of November-December 2018 were examined. The assessment used a single pixel of radar data at the location of the ARR. The result shows that rainfall data obtained from XMP Radar are lower than those from ARR. The computed snake line obtained from XMP Radar differs from that from ARR data. The XMP Radar underestimates the warning level by about two level out of four.

Indonesia’s flash floods have increased significantly since the flash flood in Bohorok, North Sumatra, in 2003 and Jember, East Java, in 2006. Such flash floods have caused negative impacts, loss of human life and damage to vital infrastructures such as houses, roads, bridges, or other public facilities. Understanding the factors driving flash floods and their mechanism at the outset is essential in mitigating the negative impacts mentioned above. This paper presents the results of the analysis of the flash flood characteristics of several hydraulic parameters under conditions just before the flash flood incident, including the intensity of the rainfall, the time of concentration, and the time lag of the occurrence. As the object of the study, a flash flood event was selected in Batu City, Upper Brantas River, which occurred on November 4, 2021. The results show that the lag time of the flash flood occurrence at 40 minutes magnitude at Bulukerto Village of Batu City, the application of Kirpich for the time of concentration equation performed better than the Ventura and Watt & Chow equations. Further assessment of precursory characteristics for other similar small catchment and hydro-meteorological conditions is still the subject of beneficial study or research.

Untuk dapat memenuhi target pemenuhan akses air minum untuk masyarakat, Pemerintah melalui Kementerian Pekerjaan Umum telah mencanangkan Program Penyediaan Air Minum dan Sanitasi Berbasis Masyarakat bagi daerah yang belum terlayani oleh PDAM. Dari program ini, lahirlah kelompok masyarakat pengelola SPAM Pedesaan (SPAMDes). Pengelolaan jaringan SPAMDes tergantung pada kemandirian pengelola, dukungan masyrakat pengguna air, dan pendampingan Pemerintah. Karena kondisi ini, sistem pengelolaan SPAMDes di setiap kelompok pengelola sangat bervariasi. Pola pendampingan Pemerintah untuk mewujudkan keberlanjutan SPAM berbasis masyarakt perlu memperhatikan karakteristik masing- masing kelompok pengelola. Kegiatan pengabdian ini bertujuan untuk mengkaji sistem pengelolaan SPAMDes yang ada di Dusun Plugon, Kabupaten Kulon Progo. Kegiatan pengabdian ini dilakukan melalui wawancara dan survey kuesioner kepada pengguna dan kelompok pengelola. Berdasarkan hasil kajian, diketahui bahwa kelompok pengelola SPAMDes telah melayani kebutuhan air warga dengan baik, tetapi perlu adanya prosedur yang jelas untuk kelancaran penyelenggaraan pelayanan air, terutama dalam hal perawatan dan penanganan kebocoran. Hasil kegiatan pengabdian ini diharapkan dapat menjadi masukan bagi Pemerintah yang melakukan pendampingan kelompok Pengelola SPAMDes.

Dalam rangka memenuhi kebutuhan air minum masyarakat di Provinsi Yogyakarta, pengelolaan sarana air minum di daerah-daerah yang tidak terlayani PDAM diserahkan kepada masyarakat. Peran serta masyarakat dalam pengelolaan penyediaan air minum diwujudkan dalam bentuk kelompok-kelompok masyarakat yang tergabung dalam Pamaskarta (Paguyuban Air Minum Masyarakat Yogyakarta). Secara mandiri, Pamaskarta mengatur distribusi air minum dari dan untuk komunitas. Salah satu kendala yang dihadapi oleh kelompok pengelola SPAMDesa dalam mengontrol kualitas dan kuantitas penyediaan dan pendistribusian air bersih adalah sistem pengelolaannya yang masih tradisional serta minimnya pendampingan dari Pemerintah. Kegiatan pengabdian ini bertujuan untuk mengkaji kondisi jaringan sistem pengelolaan SPAMDes yang ada di Dusun Kaliapak, Kabupaten Kulon Progo. Kegiatan pengabdian ini dilakukan melalui wawancara dan survey kuesioner kepada pengguna dan kelompok pengelola. Berdasarkan hasil kajian, diketahui bahwa kondisi jaringan SPAMDes tergolong cukup baik dan mampu melayani kebutuhan air. Akan tetapi, kualitas air masih belum terkontrol dengan baik. Selain itu, debit air juga belum cukup mampu memenuhi pelayanan air secara 24 jam. Hasil kegiatan pengabdian ini diharapkan dapat menjadi langkah awal menuju pengelolaan SPAMDes yang berkelanjutan serta sebagai masukan bagi Pemerintah yang melakukan pendampingan kelompok Pengelola SPAMDes.

Debris flow is a natural phenomenon that can cause some damage and fatalities. Debris flow from Mount Merapi frequently happens through the Putih River, so it is necessary to do research. Anticipating the occurrence of debris flows can be done with predictions to reduce the number of casualties and material losses. This research used a simulation method based on Ashida, Takashi, and Mizuyama equation that applied the Nakayasu synthetic unit hydrograph through modeling on SIMLAR V2.1 application by modifying the hyetograph pattern and the rain intensity value. The test result contained flood area, velocity, volume, flow height, and the value of degradation and aggradation that happened in each simulated pattern. The velocity value in simulation with rain intensity of 56.8 mm and one peak hyetograph is 1.36 m/s, and in simulation with rain intensity of 56.8 mm and two peak hyetograph is 1.42 m/s. It means the parameter increases by 4.4%. Based on the results, it can be concluded that the hyetograph pattern is very influential on the impact of lava floods. The increase in the hydrograph value is also directly proportional to the increase in flow velocity. The value of rain intensity and rain pattern also affects the number of areas affected by the lava flood. The increasing value of the intensity and pattern of rain is also directly proportional to the increase in the area affected by flooding.

No abstract

Pengelolan SPAMDes Tirtosari masih memperhitungkan biaya operasional dan harga pokok produksi berdasarkan perkiraan dan kesepakatan bersama, belum mempertimbangan biaya produksi. Metode full costing untuk memperhitungkan harga pokok produksi, kemudian digunakan metode cost plus pricing dan rumus berdasarkan Permendagri Nomor 71 Tahun 2016 untuk menentukan harga jual air. Dari hasil analisis, biaya operasional terbesar terjadi pada tahun 2018 yaitu sebesar Rp. 64.273.209. Selain itu diperoleh nilai harga jual air per m 3 yang lebih tinggi dibandingkan harga pokok produksinya. Seperti pada tahun 2022, harga pokok produksi yang dihasilkan sebesar Rp. 1.899 dan harga jual yang dihasilkan sebesar Rp. 2.713. Hasil perhitungan harga jual air per m 3 yang mengacu pada metode cost plus pricing dan Permendagri Nomor 71 Tahun 2016 dengan menambahkan nilai laba pada perhitungannya juga menunjukkan nilai yang lebih besar dibanding harga pokok produksi air yang telah dihitung sebelumnya yaitu berkisar antara Rp. 3.940 -Rp. 9.158. Jika perusahaan menetapkan harga jual air sesuai hasil perhitungan, maka perusahaan sudah mampu untuk menutupi biaya operasional air serta mendapatkan laba.