Unit hydrograph is a very practical tool in runoff prediction which has been used since decades ago and to date it remains useful. Unit hydrograph method is applied in Way Kuala Garuntang, an ungauged catchment in Lampung Province, Indonesia. To derive an observed unit hydrograph it requires rainfall and water level data with fine time scale which are obtained from automatic gauges. Observed unit hydrograph has an advantage that it is possible to derive it for various time steps including those with time step less than an hour. In order to get a more accurate unit hydrograph, it is necessary to derive a unit hydrograph with small time step for a small catchment such as those used in this study. The study area includes Way Kuala Garuntang and its tributaries, i.e. Way Simpur, Way Awi with areas are 60.52 km 2 , 3.691 km 2 , and 9.846 km 2 respectively. The results of this study highlight the importance of time step selection on unit hydrograph, which are shown to have a significant impact on the resulting unit hydrograph's variables such as peak discharge and time to peak.

Abstract. Significant land use changes due to rapid development, a central issue in Bandar Lampung and high rainfall intensity are the main triggers for frequent flooding. This study was carried out to define design rainfall intensity based on analysis of hourly temporal rainfall pattern for calculating design discharge, predict the impact of land use changes on flood peaks, and predict the impact of infiltration well on flood peak reduction. The results showed that rainfall distribution pattern for storm duration of 4 h are 40, 35, 20 and 5% for the first, second, third and fourth hour, respectively. Analysis on land use changes underlined that if 30% of the catchment area is maintained for green land then flood peaks can be decreased. However, with city development, land conversions are intended for settlements, industries and trading areas which will increase flood peaks significantly. Application of infiltration well in the catchment can reduce surface runoff depends on the density and dimension of the well. The results suggest that using infiltration well with diameters between 0.8 to 1.4 m which are applied each in every 4000 m2 of land area will reduce flood peaks from 6.9 to 12.6%. While the application of infiltration well with density of 500 m2 will reduce flood peaks from 55.21 to 99.8%. Commitment and relevant government policies and community participation will encourage to undertake flood reduction measures.

There is direct relation between global warming and precipitation. Air capacity of water increase by 7% to increasing of 1°C of air temperature, causing more water vapor content in the air. This research aims to investigate how IDF Curve and Unit Hydrograph can be used as signature of characteristic changing of Way Kuala Garuntang Watershed. The study area is Way Kuala Garuntang watershed and rainfall data source is from automatic rainfall recorder of Stasiun BMKG Maritim Panjang, ARR Tipping bucket installed at Way Kuala Garuntang watershed, and 4 manual raingauges. From the research can be concluded that IDF Curve can be used as signature of characteristic changing of Way Kuala Garuntang watershed mainly the changing of rainfall intensity in various of return period. Meanwhile, due to average of IUH of 5 flood events in 1 year data serie, and significant differences of Qp between IUH and SUH, the Unit Hydrograph was not suitable as signature of characteristic changing of Way Kuala Garuntang watershed.

Optimization of agricultural land is an effort to mprove and increase land support capacity, in such a way become more productive farmland. The Local Government of Pringsewu Regency planned to develop irrigation network by utilizing Way Wayah river. This study aims to design irrigation area in Way Wayah and to analyse water availability of Way Wayah river and water need of the planned irrigation area. Irrigation network design includes analysis of determining the location of the weir, so that it can be estimated the area of designed paddy field, the catchment area as well as the availability of water resources. Analysis includes spatial analysis using Geographical Information System, hydrologic analysis for water availability and Penman method for irrigation water need. The results show that (1) the planned weir will be located in Giri Tunggal with catchment area of 7,238.9 ha, the area of total paddy rice fields (existing and planned paddy rice fields) is 960.46 ha; (2) The need for water are 6196.88 m3 ha-1 season-1 and 6556.96 m3 ha-1 season-1 for planting seasons 1 and 2 respectively. Water availability is sufficient during preparation and planting periods

Kegiatan pengabdian ini dilaksanakan di Desa Sumberejo, Kecamatan Kotagajan, Kabupaten Lampung Tengah dengan mitra sasaran Perkumpulan Petani Pemakai Air (P3A). Kegiatan ini dilatarbelakangi oleh studi kalibrasi pintu air di Daerah Irigasi Punggur Utara yang mendapati koefisien debit pintu air irigasi yang kurang lazim dan ternyata diakibatkan oleh kondisi jaringan irigasi. Kegiatan ini bertujuan untuk memberdayakan P3A Desa Sumberejo yang terletak di BPU 15 Daerah Irigasi Punggur Utara. Metode kegiatan berupa peningkatan pengetahuan tentang Operasi dan Pemeliharaan Jaringan Irigasi oleh P3A dan pemberdayaan P3A melalui perbaikan ringan dan perawatan jaringan irigasi. Hasil dari kegiatan ini adalah meningkatnya pengetahuan dan kesadaran anggota P3A tentang tugas dan peran mereka dalam Operasi dan Pemeliharaan jaringan irigasi. Sebagai wujud pemahaman dan kesadaran,  anggota P3A segera melakukan  perbaikan saluran tepat di bawah pintu irigasi yang sebelumnya dibobok agar air pembagian air irigasi dapat dilakukan dengan adil, pembersihan sampah-sampah di saluran irigasi maupun perawatan saluran lainnya. Simpulan dari kegiatan ini adalah pentingnya peningkatan pengetahuan, pemahaman maupun peran P3A dalam operasi dan pemeliharaan jaringan irigasi agar kinerja jaringan irigasi meningkat     Kata kunci: Operasi dan Pemeliharaan, Jaringan Irigasi, P3A