Priority Determination of Maintenance Sediment Control Bengawan River Basin, Indonesia

. The volume of sedimentation in the Bengawan Solo river is 592,936.05 m 3 per year. Several check dams have been built to overcome the sedimentation problem. However, this check dam building has experienced a decrease in performance due to sedimentation. Therefore, the research in this thesis aims to determine the priority of maintenance and repair of sediment control buildings (check dams). Determining priorities due to lack of budget for buildings processed by the government. Use guidelines for classifying check dam damage and building maintenance. Determining maintenance priorities based on the condition of the building using the analytical hierarchical process method. The location of the case study is a check dam building on the Bengawan Solo River and the results of the analysis show that the one with maintenance and repair priorities is the ploso check dam with severe damage (42.5%) and the maintenance carried out is rehabilitative (performance <60%).


Introduction
Check dam building is a building whose function is to slow down sediment movement and gradually reduce sediment volume [1] [2].According to data from BBWS, the Bengawan Solo River has a sediment transport volume of 592,936 m 3 per year [3].Where the main damage to the check dam building is the sedimentation rate which is increasing day by day [4] [5] [6].When the check dam building experiences continuous sedimentation, the performance life of the check dam will decrease continuously [7] [8].From here, it is necessary to maintain and repair the check dam building to maintain its performance to function optimally.With a limited budget, it is not possible to maintain and repair the entire existing check dam building so that a priority scale is needed to be efficient [9] [10].To determine the priority scale, an inventory of the check dam building is carried out to determine the condition of the check dam building.With the standards set in this study using the Sabo dam operation and maintenance guidelines Pd 02-2018-A [11], 2 factors were made, namely technical factors and nontechnical factors.Because these two factors are the scope of inspection contained in the operation and maintenance manual for the Sabo dam.After an assessment of the condition of the check dam building is carried out, it will be seen how the condition of the damage experienced by the check dam can be carried out and a priority scale can be carried out to maintain and repair the check dam building.Using the Sabo dam operation and maintenance guidelines Pd 02-2018-A, 2 factors were made, namely technical factors and non-technical factors.Because these two factors are the scope of inspection contained in the operation and maintenance manual for the Sabo dam [11].After an assessment of the condition of the check dam building is carried out, it will be seen how the condition of the damage experienced by the check dam can be carried out and a priority scale can be carried out to maintain and repair the check dam building.

Material and method
Data collection in this study obtained primary data from the results of field inspections and secondary data obtained from BBWS Bengawan solo.Sabo dam operation and maintenance guidelines Pd 02-2018-A, which is a reference in conducting this research.Beginning with an inventory of the sediment control structures located on the Bengawan Solo River.After carrying out an inventory, an assessment of the condition of the building is carried out, this activity is carried out with the standard assessment of the Sabo dam operation and maintenance guidelines Pd 02-2018-A with the aim of getting the percentage of damage to sediment control buildings.when the percentage of damage is carried out, classification is carried out to identify damage to sediment control structures based on the Pd 02-2018-A guidelines.the use of the analytical hierarchy process method is carried out after obtaining the percentage of damage and performance of the sediment control building to determine the highest cause and priority of the sediment control building for maintenance [9] [12] [13].Followed by using statistical methods to obtain a model of maintenance costs and components in sediment control buildings that affect maintenance costs.

Location Study
Data obtained from the Bengawan Solo River Basin is in the Provinces of Central Java and East Java, at 110°18 East Longitude to 112° 5 East Longitude and 6° 9 South Latitude to 8°08 South Latitude.The Bengawan Solo River is the largest river on the island of Java, flowing in a watershed (DAS) with an area of ±16,100 km 2 .The Bengawan Solo area consists of 3 provinces, namely the Special Region of Yogyakarta, Central Java and East Java.With 20 districts and 3 cities.The Bengawan Solo River has a total area of 20,125 km 2 .

Sediment Control
There are 2 types of sediment control with their respective functions, namely: 1. Closed Check Dam is built using concrete material.
Closed type check dams can function effectively to control debris flow if the containment area is not filled with sediment [7].2. The open-type check dam functions to restrain the flow of debris through the catch in the opening due to large and long materials that lock together during a flood or debris flow [7].

Assessment condition
To carry out an assessment of the condition of the building, a predetermined scale is needed based on the operation and maintenance guidelines for the Sabo dam Pd 02-2018-A.with the assessment of the condition of the sediment control building, the following criteria are met [11] [14]: Score 1: The condition of the part of the building under consideration is heavily damaged but still identifiable.Score 2: The condition of the part of the building being inspected is moderately damaged, still recognizable, but not operating properly.Score 3: The condition of the inspected building is moderately damaged, can be identified and is still operating normally.Score 4: The state of the structure with minor damage, recognizable and in normal operation.Score 5: The condition of the parts of the building that are seen are in good condition and are still operating very well.
In the sediment control damage analysis, the following parameters are used as a reference for maintenance [11] [14]: 1. Good condition, if the damage is less than 10% in the initial construction condition.2. Minor damage, if the damage is from 10% to less than 20% of the original construction condition.3. Moderate damage, if the damage is from 20% to less than 40% of the original construction condition.4. Severely damaged condition, if the level of damage is greater than or equal to 40% of the original construction condition.

Analysis
After assessing the condition of the building on the conditions that cause damage to the sediment control building.calculated using the following formula below: The results obtained by the above formula are the classification of damage to sediment control buildings and maintenance that can be carried out based on the performance of sediment control buildings.1 is a classification of damage to sediment control structures and will be used to determine performance and maintenance that can be carried out.After determining the percentage of damage to the sediment control building (Table 2), data testing was carried out on the priority of maintaining the sediment control building using the analytical hierarchy process method with the help of the expert choice 11 application [8] [9] [10].Figure 5 shows statistical method tests data that is normally distributed or not.The test performed is the normality test of the data, using the Kolmogorov-Smirnov test with the criteria if the value is asymp.Sig (p) >, then the data distribution is normally distributed, the guidelines for normality decision making using the Kolmogorov-Smirnov test in SPSS 16.0 are [15]: 1. Sig value or significance or probability value < 0.05 the data distribution is not normal, 2. Sig value or significance or probability value > 0.05 the data distribution is normal.
And the linearity test, the test for the analysis requirements is the regression linearity test (Table 3).
Linearity test is used whether the variable variance has a relationship or not.

Discussion
The assessment of the condition of the building with the classification of damage there are 12 moderately damaged conditions and 8 heavily damaged conditions.Maintenance that can be carried out based on the percentage of sediment control building performance is that 13 check dam buildings are carried out corrective maintenance and 7 check dam buildings are carried out rehabilitative maintenance.The analytical hierarchy process method is carried out to obtain priority for sediment control (check dams) for maintenance.the data information obtained is damage due to sedimentation conditions in the Sabo dam with a weight of 0.158 as the highest weight and the sediment control building (check dam) ploso getting the highest weight of 0.67.By obtaining information about the performance of sediment control buildings, the data normality test method was used which resulted in the Smirnov-kolmogorov test with an Asymp.Sig value of 0.200 which indicates that the probability is > 0.05 and indicates that the data is normal [15].Regression linearity method, this method is carried out to determine how much influence the components in the sediment control building have on maintenance costs.The information obtained is the length of the crestdam as a component that is very influential on maintenance costs with a probability value of 0.052 approaching a value of 0.05.
The condition of damage that is the highest cause is the condition of sedimentation in the sabo dam which is something that needs to be considered.the highest priority for maintenance and repairs on sediment control buildings (check dams) is ploso with the status of damaged conditions with a percentage of 42.5% heavily damaged.maintenance carried out is rehabilitative maintenance because the performance of the check dam ploso building has a percentage of 57.5%.The component that affects maintenance costs is the length of the crest dam.For the future period, the method in this research can be used and the variables for the assessment of building condition can be developed again, the determination of maintenance costs can be expanded again with components that are not found in this study.

Fig 4 .
Fig 4. Weight of Assessment of Sediment Control vs Conditions (Multicriteria)

Table 1 .
Check dam condition

Table 2
Maintenance Type