Study of Irrigation Water Supply Efficiency to Support the Productivity of Farmers (Case Study at Kobisonta North Seram Central Maluku District)

The need of water is a major media of irrigation in order to support the effectiveness of agricultural business which is manifested as the supporting of food provision. The purpose of this study is to analyze the amount of discharge in each channel and the efficiency in Kobisonta irrigation area, Seti North Seramsubdistrict, Central Maluku district with area of 3,150 ha. The study was conducted on secondary channels Kobisonta includes BKS7, BKS8, BKS9, Kobisonta Secondary Channel includes BKS10, BKS11, BKS12 and Seti Secondary Line includes BS1, BS2 and BS3 The water debit requirement in the rice field and the efficiency in the irrigation area of Kobisonta was analyzed by using the incoming debit - discharge method based on flow velocity measurement. Providing irrigation water for efficiently is not simple because many factors affect the way and the process, besides that if the water supply and irrigation on the channel is inefficient, then it can reduce or decrease agricultural productivity. From the result of actual debit analysis on channel BS3, BKS9, BKS11, and BKS12, they are able to meet therequirement of irrigation water thoroughly in irrigation area. In BS1, BS2, BKS8 and BKS10 channels, actual discharge has not been able to meet the irrigation water needs in its irrigation area. The efficiency of irrigation channels in Kobisonta Irrigation Area varies by channel. According to the efficiency standard by the Directorate General of Irrigation, the secondary Saluaran in Irrigation Area is categorized as efficient where for BKS7 is 90%, BKS8 is 97% and BS2 is 91%.


INTRODUCTION
Irrigation is an effort to supply and regulate water with the purpose of agriculture supporting that can include surface water irrigation, underground water irrigation, pump irrigation and local irrigation. Kobisonta is located in East Seram District Seti, Central Maluku district with a population of 14,923. It is one of the rice production centers. The construction of Kobi weir which is located in the village of Kobisonta, North Seram District Seti, Central Maluku District which in this case, has a water catchment area of 145.4 km2, is expected to meet the water needs for irrigated rice fields of 3,150 ha. So here, researchers use the object of research located in one of the villages located in the Central Maluku District. In supporting the water needs in the agricultural sector with irrigation system, indeed there will be some problems that arise. One of them is the loss of water that occurs in each channel on the way to the rice field. This study is conducted can give contribution in completing the existing irrigation network study information, by focusing more on the efficiency and effectiveness of irrigation network operating system on the level of service of primary channel, secondary and tertiary channels to water requirements in rice crops.

II. LITERATURE REVIEW The meaning of Irrigation
Irrigation is a watering activity on an agricultural land that aims to create moist conditions in the root of the plant to meet the water needs for plant growth. According to Basri, 1987 irrigation is the provision of water in plants to meet the water needs for its growth. According to Karta Saputro, 1994 irrigation is an activity of supply and regulation of water to meet the interests of Agriculture by utilizing water from surface water and soil. According to Suharjono, 1994 irrigation is a number of water that is generally taken from rivers or weirs that flowed through the irrigation system to maintain balance the amount of water in the soil.

Irrigation Network
The irrigation network is the unity of the canals and structures necessary for the regulation of irrigation water from the provision, collection, distribution, delivery and use. There are two kinds of irrigation networks: 1. The main irrigation network: irrigation network that is located in an irrigation system, starting from main building, main / mainline, secondary channel, and tapping building and its complementary building. a. Main / primary channel b. Secondary irrigation channels 2. Tertiary Irrigation Network: a network that serves as a water service infrastructure within a tertiary grid consisting of a carrier channel called a tertiary channel, a dividing channel called a Quaternary channel, and a drainage channel and auxiliary channels.

Irrigation Efficiency
Irrigation efficiency shows the use of water that is the ratio between the amount of water used and the amount of water given expressed in percent (%).

Water Discharge
The amount of liquid that flowing through a cross-section of flow per one unit of time is called flow discharge (Q).

Water Loss
Water loss is generally divided into 2 categories, among others: 1. Loss of physical consequences where water loss occurs due to water seepage in the channel and percolation at farm level (paddy field); and 2. Operational loss occurs due to exhaust and excess water discharges during channel operation and waste of water used by farmers.  The determination of effective rainfall is based on monthly rainfall that is using R80, which means 20% probability is unavailable. The amount of effective rainfall for rice plants is 70% of the minimum monthly rainfall with a 5 year reperiod (Irrigation Network Planning, KP-01, 1986,165), with the following equation: Re = 0.7 × 1/15 × (R_80) (eq 9) Effective rainfall is a plumper rainfall that falls in an area and is used for growth crops.

Star
Primary data · flow velocity measurement · Geometric Channel Measurements

Data collection
Secondary data · Network Scheme · Climatology Data analysis Finish

Tools
The tools that are used in this study are: current meter, meter roll, stopwatch, measuring ruler.

The Measurement
Steps are: Measurement Steps on the Ground: 1. Current Meter Current velocity measurements are illustrated by the following measurement procedures: a) Measure the depth of the channel with the measuring pole of the current meter device b) Select the propeller corresponding to the channel depth, so it can be used for some vertical dots ie (0.2h, 0.6h, 0.8h) where h is the channel depth. c) The current meter is mounted on a static mast with a depth of 0.2h, 0.6h, and 0.8h, then the measuring rod is inputted into the water until the baseband is located at the bottom of the duct with the propeller facing the flow direction (water current). d) The number of turns per unit of time, which occurs at each water depth, is calculated.

Source of Data
Source of data used in this research are: 1. Primary Data Primary Data is data obtained by measuring the Geometric cross section of the velocity flow channel (V), and the channel length (L).

Secondary Data
Secondary data obtained from other parties or from existing reports and research, and which have relevance to the issues discussed, including the number and types of irrigation networks studied, the network scheme of the P3A existing in the Kobisonta Irrigation Area, data on water demand on irrigation area kobisonta, as well as data from several government agencies related among others Office of Public Works.

Data Analysis Technique
Data analysis techniques in this writing done through the stages as follows: 1. Analyze flow velocity by measuring instruments Current meters and or buoys. 2. Analysis of inlet and outflow discharge on secondary channel kobisonta, channel kobisonta, and channel setunder secondary, (equation 3).
3. Analysis of water loss in secondary channel kobisonta, channel kobisonta, and secondary channel seti, by the difference between inlet and outflow (equation 3) 4. Efficiency analysis on the secondary channel kobisonta, channel kobisonta, and secondary channel seti (equation 1).

Analysis of water needs in rice plants in Kobisonta
Irrigation Area.

IV. RESULT Description about the location
Administratively, Kobisonta Irrigation Area is located in Kobisonta village, North Seramsubdistrict of Seti, Central Maluku regency. This sub-district is an expansion of the District of North Seram through the Regional Regulation The average velocity performed on the intake door is done by using two (2) points method because the depth of the intake door ranges from 0.6 to 3 meters, where the average velocity is the average of velocity at 0.2 and 0.8 depth.

Fig.2: Measurement method of flow velocity
The research that is conducted at the intake door by using the Current Meter obtained the formula of the tool on the propeller current meter type that is: To prove the measurement data available with the formula of the tool then the researchers will describe the example calculation to get the value of speed on each segment:

Fig.3: Division of flow rate measurement segments in the field
While the mean velocity on the secondary channel that the researchers do only use the method one (1) point because the depth is at 0.0 -0.6 meters, which can only be used for shallow water where the method of two or more points can not be done. Speed is measured at 0.6 water depth.

Flow Debit Analysis
Calculation of the discharge in the channel in Kobisonta Irrigation area is intended to know how far the effectiveness of these channels in fulfilling the water requirement for paddy crop in paddy field. Based on the measurements with current meter in the field obtained the flow of water of each channel on the DI. Kobisonta as follows:

Water Loss
To calculate the amount of water loss that occurred in secondary channel in Kobisonta Irrigation area, the following equation is used :ℎ = −

Estimated evaporation
Evaporation is expressed as the evaporation rate given in millimeters per day. Evaporative measurements of the water surface can be done in several ways. The most used way to know the evaporative volume of the free water surface is to use an evaporating pan. The method used in kobisonta irrigation area is using class evaporation pans tool. The result of ET0 analysis using Software Cropwat 8.0

Water requirements for each field
Water requirement for rice crops seen from the maximum requirement that is at age of rice aged two months. The results of field measurements obtained data on the water requirement of each rice field plot in the age of paddy aged 0.5 months to 4 months as follows.   /dx.doi.org/10.22161/ijaers.4.11.7  ISSN: 2349-6495(P) | 2456-1908(O) The water requirements in the canals and areas in the study were performed when the actual 2-month-old rice was calculated by the following scheme: Table.14: Comparison of water requirements in the plot rice field with actual water discharge

Fig.4: Graph of Water Requirement comparisons
Based on the graph above, the actual debit on BS3, BKS9, BKS11 and BKS12 channels can meet the overall requirement of irrigation water in the irrigation area. In BS1, BS2, BKS8 and BKS10 channels, actual discharge has not been able to meet the irrigation water needs in its irrigation area.

Discussion
The area of rice fields in Kobisonta irrigation area of 3,150 ha has three secondary channels namely kobisonta secondary channel (BKS7, BKS8, and BKS9), secondary channel faces kobsionta (BKS10, BKS11 and BKS12) and secondary channel seti (BS1, BS2 and BS3) which take water from Bend WaeKobi. Each of the secondary channels studied has different irrigation areas, channel lengths, and wet cross-sectional areas.
In the dry season the farmers in Kobisonta village still plant rice, this is because the water supply in BendungWaeKobi is considered still able to meet the needs of irrigation. Management of irrigation water distribution that is less good or optimal cause some of its debit channel is not sufficient to meet the needs of irrigation of rice crops in the village kobsionta.
Lacks of the farmer's discipline in the distribution of water were found in many fields. Distribution of irrigation water in Kobisonta Village is done by opening the water gate as high as possible without taking into account the water requirement in every irrigation area. At each of irrigation in secondary irrigation area kobisonta has different efficiency value. According to Irrigation Secondary Irrigation Planning Standart is said to be efficient if the efficiency rate of irrigation above 90%. Based on the results in Table 8  In BKS11 channel the percentage value of water loss is 17% and BS2 channel value of water loss percentage is 15%, so for BKS11 and BS2 channels do not meet DPU standard because water loss percentage value is below 5-10%. This is due to the seepage on a part of the bottom of the drained channel, the amount of soil deposits, sand, loads of loads in the form of wood, foliage, the amount of garbage and the theft of water made by farmers that slows the flow of water in the secondary channel in the irrigation area kobisonta.
Based on 15 comparisons of debit requirements with the actual water debit, the actual debit on channel BS3, BKS9, BKS11, and BKS12 able to meet the requirement of irrigation water as a whole in irrigation area. In BS1, BS2, BKS8 and BKS10 channels, actual discharge has not been able to meet the irrigation water needs in its irrigation area In water supply for irrigation, there needs to be efficiency and effectiveness of water supply. Efforts that need to be made to improve the efficiency and effectiveness of irrigation are: 1. To reduce the impact of vegetation damage and channel cracking in Kobisonta Irrigation Area it is necessary to maintain by Margorejo P3A either regularly or periodically on each channel. 2. Need to be socialized about the process of water distribution by P3A to farmers so that farmers are expected to be more disciplined in implementing irrigation water taking schedule.

V. CONCLUSION AND SUGGESTIONS 5.1 Conclusions
Based on the results and discussion, then we obtained the following conclusions: In general, water loss in irrigation networks in the 5-10% secondary channel while in the 17% BKS.11 channel, and BS.2 15% has exceeded the water loss planning criteria. This is due to the seepage of some of the bottom of the eroded channel, the amount of soil sediment (sedimentation), waste and also because of the theft of water conducted by farmers resulted in the slow speed of water flow in the secondary channel DI. Kobisonta

Suggestions
1. The need for socialization to the water users farmers (P3A) Margorejo to understand and adhere to the way of distribution of irrigation water so as not to harm other farmers. 2. To improve the efficiency and effectiveness of water distribution there needs to be cooperation between the Public Works Department and the P3A. 3. Margorejo P3A is expected to always review the conditions of existing channels in the Kobisonta Irrigation System and repair the damaged channels, clean up the sludge, waste along the canal.