Surface irrigation networks in Indonesia are damaged by several factors, and sedimentation is among the most severe challenges. Sand traps play a substantial role in improving irrigation system efficiency by reducing sedimentation. There are two periods in sand trap operation: the operational and maintenance periods. Pengasih is one of the irrigation schemes implemented in the Progo Opak Serang (POS) River Basin, which has a high level of erosion. This study aimed to propose an appropriate management strategy for the Pengasih sand trap as the first barrier in irrigation network sedimentation based on mathematical modeling. The HEC-RAS simulation software was used to simulate the sand trap hydraulic behaviour. The results show that the validated Manning’s coefficient was 0.025. The optimal transport parameters were Laursen for the potential function, Exner 5 for the sorting method, and Rubey for the fall velocity method. The recommended flushing timeframe is 315 min, with a discharge of 2 m3/s. We suggest that the sand trap flushing frequency be performed twice a year, and it can be performed at the end of March and October. This coincides with the end of the first and third planting seasons of the irrigation scheme.

Preparation for the modernization of the Kedung Putri Irrigation System (DI Kedung Putri) required a comprehensive assessment of the irrigation pillars, one of which was at the secondary level. To facilitate the assessment and development plan, a clustering was carried out using the k-medoids method, that used a representative data (called medoid) as the cluster center. Then, the decision making was conducted by using the Analytic Hierarchy Process (AHP) method. Performance assessment of 21 secondary channels was stated as the readiness index of irrigation modernization (IKMI). The assessment result showed that 9,52% included in good criteria, 71,43% included in fair criteria, and 19,05% included in poor criteria. Based on these results that DI Kedung Putri was not ready yet to be modernized. For this reason, it was necessary to conduct the system improvement in groups, namely by grouping based on similarities (clustering). The used method was k-medoids clustering using Rapid Miner 9.0 software. The clustering result showed that the optimal cluster number were 4 clusters, with the Davies Bouldin Index (DBI) value -1,959. The members of the 0, 1, 2 and 3 cluster were 6, 6, 8 and 1 secondary channels, respectively. Furthermore, the priority scale in clusters development was needed based on the performance of irrigation pillars on secondary channels. The results of AHP analysis showed that the order of priority development starts from cluster 0, followed by cluster 2, 1, and 3. The recommendations for the development of secondary channels incorporated in cluster, such as increasing water supply, routine infrastructure maintenance, technical assistance, and public campaigns in irrigation management. The secondary channel incorporated in cluster 3 had good performance on all pillars, so it only needed to maintain the existing operation and maintenance patterns.

Rainfall-runoff transformation is carried out when the series of discharge data is limited or unavailable. One of the components of rainfall-runoff transformation is unit hydrograph, which can be derived synthetically. The selection of the representative synthetic unit hydrograph is fundamental related to the results of the further calculation. This study compared three types of synthetic unit hydrograph, that were Gama I, Nakayasu and SCS. The study was conducted in Juana Watershed, which is located in Central Java Province and composed of 52 sub-watersheds. The calculation was carried out in the control point of Sentul Weir by using HEC-HMS version 4.2.1, in the case of January 2014 flood events. The results showed that the peak discharge from Gama I, Nakayasu, and SCS synthetic unit hydrograph were 80.78 m3/s, 85.32 m3/s, and 78.89 m3/s respectively. Those results then compared with the flood mark in Sentul Weir, which was estimated 76.53 m3/s. Therefore, the SCS method was determined as the representative synthetic unit hydrograph in Juana Watershed, refers to the minimum error value of 3.08%. Then the analysis of design flood hydrograph for the 52 sub-watersheds in Juana Watershed can be approached by using the SCS synthetic unit hydrograph method.

After New Yogyakarta International Airport (NYIA) opening, Kulon Progo continues to develop, one of which is The Bedah Menoreh route project which passes through the mountainous region. The development encourages agricultural land conversion, which impacts food security in Kulon Progo, especially in the mountainous region. This study aims to identify the conversion of agricultural land in the mountainous region of Kulon Progo Regency in 2005 – 2020 and analyze its impact on regional food security. The method used is a Normalized Difference Vegetation Index (NDVI) on Landsat Imagery using Machine Learning through Google Earth Engine (GEE) to identify land-use change and mathematical calculations in analyzing regional food security. The result of the supervised classification is a land cover map of the mountainous region of Kulon Progo Regency, which shows that every year the area of rice fields, in general, continues to decrease until 2020 the total area is 2,102.79 ha with a rate of agricultural land conversion -114.87 ha/year. It causes regional food security to be in a food-insecure condition, even though the availability of rice fields can be used for food self-sufficiency for up to 53 years. Other factors such as climate, rice seeds, soil, and water quality, in this case, are quite influential in rice production, not only productivity and agricultural land area.