Bendungan direncanakan dibangun untuk dimanfaatkan dalam memenuhi kebutuhan di bidang sumber daya air. Disamping manfaat yang terkandung di dalamnya, akan terdapat bahaya besar bila ada ketidakmampuan struktur bendungan dalam menahan banjir yang masuk ke dalam waduk. Pemilihan metode yang tepat untuk memperkirakan besaran banjir rencana merupakan bagian dari keamanan bendungan. Permasalahan yang terjadi di Indonesia adalah pencatatan data pada pos duga air tidak tersedia. Salah satu metode perhitungan kehilangan air (losses) pada pemodelan banjir adalah NRCS-CN. Kelebihan metode ini dapat digunakan untuk wilayah yang tidak memiliki data hidrograf banjir maupun tinggi muka air waduk, tetapi tersedia data pencatatan hujan. Dalam penentuan nilai CN, Indonesia belum memiliki peta HSG (Hydrologic Soil Group) sehingga perlu dibuat peta tanah seperti HWSD. Penelitian dilakukan dengan penentuan CN menggunakan peta tanah (HWSD), tataguna lahan (BAPPEDA). Kehilangan air dilakukan dengan model HEC-HMS. Penelitian  dilakukan di DAS Brantas Hulu dengan titik outlet Bendungan Sutami. Simulasi dilakukan dengan kalibrasi tinggi muka air. Kelompok HSG yang didapat dari peta HWSD pada DAS Brantas Hulu adalah D (lempung), B (tanah liat berlanau), dan A (pasir bertanah liat). Penentuan HSG dari peta tanah HWSD dengan metode kehilangan air NRCS-CN dan hidrograf satuan NRCS menghasilkan kalibrasi terbaik didapatkan dari RMSE dan beda tinggi pada AMC II dan λ=0,2 untuk bulan Maret 2007 (RMSE=0.55) serta AMC II dan λ=0,05 bulan Desember 2007 (RMSE=0.65).

The rainfall-runoff model is commonly used in flood discharge computation. One of the most frequently employed methods to estimate the flood discharge in the ungauged basin is NRCS-CN. This study is aimed to determine the CN value with/without soil drainage capacity from the soil information in SPT Indonesia. The location used is Pataruman watershed by calibrating the simulation discharge results with the observed discharge. Soil conditions in the Pataruman watershed show that the soil texture has a fine texture (HSG D), a slightly fine texture (HSG C), and a slightly coarse texture (HSG A). The average composite CN in the Pataruman watershed without soil drainage capacity was 85.58 while soil drainage capacity was 81.01. The results of the analysis show that with/without taking into account the soil drainage capacity in the Pataruman watershed there is no significant difference in discharge with a relation coefficient of 0.734 (without soil drainage capacity) and 0.732 (with soil drainage capacity). CN calculations with/without soil drainage capacity are recommended for small watersheds.

Drought is one of the disasters that has a major impact on food security. Tasikmalaya is a developing area where it is prone to drought. The communities have the right to obtain and utilize groundwater and also have a role to participate and play an active role in the implementation of groundwater conservation activities. The purpose of this community service is to support groundwater conservation with biopore infiltration holes (LRB) which can help control runoff and reduce organic waste. For this reason, the use of LRB was conducted at RW 03 Winayajaya Housing, Sambongjaya Village, Mangkubumi District, Tasikmalaya City, by making 20 pieces of LRB spread evenly. The enthusiasm of the community from installing LRB is various, some are supportive, and some are not. Three of the 20 houses that were planned to be installed LRB refused to install LRB. Five of the 20 houses have large stone land, making it difficult to install LRBs. Fifteen out of 20 houses were successfully installed LRB with the distribution in all RTs in RW 03. This service concludes that the community's awareness of groundwater conservation is not fully visible from the entire RW 03, this can be seen from the yards available in each house as well as the residents' desire to participate in the use of LRB.

Hydrologic Soil Group (HSG) for each region is different depending on soil conditions. It is one of the key elements in the NRCS-CN determination to account for the rain-runoff relationship. But unfortunately in Indonesia there is no map of HSG. Adidarma (2013) has conducted the research about HSG determination by using hydrogeology map. However, the map has a long process of pedotransfer and HSG parameter approach is still generally and qualitative. Furthermore, Ramadan (2017) has done research of HSG determination with HWSD map; the map is a global map which depth of information type of soil is less profound. Related to those problems, the researcher will conduct the determination of HSG in accordance with the condition of land in Indonesia by using Land Map Unit (SPT) Indonesia. HSG will be overlay with the transparent of land in Pataruman Water Catchment Area (WCA) until obtained the value of NRCS-CN and then the discharge plan will be calculated and will be calibrated with debit recording in Bendung Pataruman.

Dams are planned and built to be used for water resources activities. Besides the benefits, there were a great danger if the inability of the dam structure to holding the flood is available. The choice of the right method for the magnitude of the plan flood is part of the dam security. Problems that occurred in Indonesia former record data from AWLR is not available. One method of losses flood modeling is NRCS-CN. Moreover, this method can be used for areas without flood hydrograph or reservoir water leveldata, however rainfall record data is available. In CN's determination, Indonesia does not have a HSG (Hydrologic Soil Group) map that needs to be made from another soil map like HWSD. The research was conducted using CN method using land map (HWSD), land use (BAPPEDA). Losses were carried out with HEC-HMS model. The study was conducted in the Upper Brantas basin withSutai Dam outlet. The simulation was done by calibrating the water level. HSG groups obtained from HWSD maps in Upper Brantas basin are A (loamy sand), B (loam), and D (clay). Determination of HSG from HWSD soil map with NRCS-CN loss method and NRCS UH resulted the best calibration of AMC II and ? = 0.2 in March 2007 (RMSE = 0,55) and AMC II and ? = 0.05 December 2007 (RMSE = 0.65).