Management strategy of sustainable urban drainage in Pekanbaru City

The rapid growth of population and development has changes in the land use. A lot of opened land or forest has changed into the settlement or industry. This change had made the power of absorption function becomes low instead the surface run off which results in shorter time water retention so that accumulation of collected rainwater exceeds the existing drainage capacity. The basic concepts of sustainable drainage development is increasing the use of water, minimizing losses, improving and conserving the environment. Drainage management model developed is using eco drain approach, which is an integrated and comprehensive approach and incorporates ecological or environmental factors in every drainage management effort. This research aims to (1) analyze the characteristic of physical area, environment condition, economy and social community in Pekanbaru City, (2) analyze other important factors affecting the drainage performance that impacted ecology aspect, economy and social community in Pekanbaru City, (3) design the management strategy of sustainable drainage in Pekanbaru City. This research was carried out in Pekanbaru City. This research was a mixture of quantitative and qualitative research. The research methods used were survey and experiment methods. The method of data collection was done through field surveys, documentation, and questionnaire distribution. In quantitative research the data obtained based on questionnaires that were analyzed statistically. Based on data analysis and evaluation, needed strategies for sustainable drainage management in Pekanbaru City. The results showed that the existing drainage channel was unable to accommodate rainwater runoff discharge where (Qp) is greater than Q-exist. Based on the analysis that has been carried out, the sustainable drainage management strategy in the city of Pekanbaru includes 3 (three) aspects, (1) ecology, (2) social, (3) economy. Ecological aspects include drainage management strategies such as normalization of drainage channels and eco drain. Social aspects include participation and community empowerment that actively supports drainage management. Economic aspects include the participation of stakeholders such as the government and the private sector as well as the community in making efforts to manage and maintain drainage facilities and infrastructure.


Introduction
The rapid growth of population and infrastructure has caused changes of land use. The changes of land use from the open area into developed area causes decrease of the flow surface absorption function is increasing, that caused water concentration time) much shorter so the accumulated of collected rainwater is exceed the existing drainage capacity. This condition is often shown by the drainage overload in the city, even in the specific residence, so it becomes puddle or might be happened flood that disturb daily activities (Nurhapni, 2008). Besides, the land use change of forest (open area) into developed area can also increase the erosion.
The other factor that also has important role to the flood causal is society bad habit such as throwing garbage into water, drainage, river and the other riverbank. This behavior that almost becomes culture can also be done by the educated circles, the group that supposed to give example and model. Bad drainage condition is one of the flood causal and puddle in Pekanbaru City. This condition is concerned to be worse because there are lots of broken and non-functional drainage, piled-up garbage in drainage, and less society participation in keeping the drainage and residence area clean (Fajar Ramadhani, 2016).
Pekanbaru City is the capital city of Riau Province with width about 632.26 km 2 . The population about 800,000 people (2008) which had increased from 586,000 people (2000). The average population growth is about 4% each year. The number of population is predicted to increase into 1.3 million (2019) and 2 million (2026). The highest population especially in subdistricts in central town (City of Pekanbaru and Sukajadi), and the tendency of total population growth in the new residence area (Tampan, Marpoyan Damai,Tenayan Raya, etc.).
Topographically, Pekanbaru City is located in 5 meters above the sea level. In particular areas, the location is higher than the average height with the slope of 0 to 2% that has no potential flood. However, in fact, when it is raining in protocol road section and some locations always flooded that disturb public activities (Bureau of Statistic Center Pekanbaru City, 2017).
One of the floods causal is because the less-maximum drainage function system in Pekanbaru City. The lack of society awareness in keeping the environment is also affected the drainage condition. A lot of garbage sediment causes the drainage, which has function to drain the rainwater, cannot load the rain discharge each time the rain falls.
The drainage concept that is used earlier in Indonesia (old paradigm) is drainage removal which is removing the excess water (especially rainwater) into the closest water body. The excess water is immediately flowed to the drainage, then to the river and finally to the sea, so it will not cause puddle or flood. The removal concept is still practically done by society until now. In each drainage project, there is some effort to make sewer lane from the puddle to the river by the enough slope to drain the puddle. This kind of drainage removal is kind of drainage that is created before the comprehensive thought is developed, when the puddle problem, flood, drought and environmental damage still considered as local and sectoral problem that can be solved in term of local and sectoral without seeing the water resource and environment condition in the upstream, in the middle, and in the downstream comprehensively.
The conventional construction of the drainage is also one of the environmental damage sources; this is because it creates impact, such as (Suripin, 2004): a. The enhancement of flood discharge and the depletion of groundwater recharge. b. Water pollution. c. Groundwater contamination. d. Land surface downfall. e. The reduction of the aesthetic value and environmental health.
By the development of comprehensive thinking also encouraged by the spirit of anticipation, the changes of climate nowadays, then it needs the changes of conventional drainage concept for the environmental friendly drainage or eco-drainage (new paradigm). Drainage concept, rainwater excess is not rapidly removed to the nearest river. But, the rainwater can be loaded in some related location through many ways, so that it can directly use or later, can be used to fill the ground water conservation, to increase ecosystem and environment quality, and as the medium to decrease puddle and flood.
By the environmental friendly drainage, the possibility of puddle/flood in the related location, flood in downstream also drought in upstream is reduced. It is because most of the rainwater excess is held or absorbed in the upstream, middle stream, and downstream. According to the problem, the sustainable drainage construction basic concept is to increase water usability, minimalize the loss also improve and conserve the environment.
The accumulation between the fault impact in rainwater management and environment awareness gives the idea to improve the strategy of drainage management model, by eco drain approach. This approach can be called integralistic approach with the implementation of the effort to do comprehensive and integrated drainage management also includes the ecology/environmental factor in every drainage management efforts. Based on the description above, the writer tries to theme "The Strategy of Sustainable Urban Drainage Management in Pekanbaru City (Case Study of Eco Drain Application in Pekanbaru City)".
This purpose is going to be reached through three steps, they are: a. Analyze the characteristic of area physical, environment condition, economy, and society social in Pekanbaru; b. Analyze the important factors that affected drainage performance which is impacted to the aspect of ecology, economy and social in Pekanbaru City; c. Design the management strategy of sustainable urban drainage in Pekanbaru.

Sampling point
The research was done in Pekanbaru City. The location of this research that is taken from the Pekanbaru City Administration Map was located in geographical at coordinate of latitude 0º25´17.139˝ -0º41´18.556˝ and 101º19´24.199˝ -101º36´12.511˝, from Siak Riverbank Area with width of 588.234 km² (58,823.419 ha). The location of the sample collection is in Rumbai Coast Subdistrict and Tampan Sub-district.

Data collection
The collected data were primary and secondary data. The primary data was taken by: a) Field observation b) Documentation c) Questionnaire The secondary data was taken by: a.

Research approach
The research methods used in this research were survey and experiment method. In the survey method, the information gathering technique was by sorting some question list for the respondents. The data that was analyzed was the sample data of the population. Besides, the approach was done by experiment method (field experiment). In this research experiment, the researcher tried to find out the affection of the certain variables to the other variables in the strictly controlled condition. This research was based on the theoretical basis that related to the problem which were theories related to the urban drainage, planning and evaluation, local government policy and environment economy also responses and factors that affected the urban drainage system.
Then, by those theories, was appointed the variables that related to the problem, next, determine the indicators and was proven in the field through observation, interview and questionnaire to the This research was trying to find out accurate solution or model in solving the problem in the field (Problem Solving Research). Then, there will be created a management of sustainable urban drainage model later.

Data collection technique
The data collection technique was taken by observation and interview through questionnaire to the local society.

Population technique of sample collection
The sample calculation was calculated based on the population in Tampan and Rumbai Coast Subdistrict from the Bureau of Statistic Center data in Pekanbaru. Then the respondent that is calculated could use Taro Yamane formula (Riduwan, 2010) Description: n : total sample; N : total population; d : precision or fault tolerance limit of sample collection (0,05) The taken sample was flood prone zone which are 2 sub-districts of 12 sub-districts in Pekanbaru. The sample was presented in this Table 1.

Data analysis technique
This research was mix method of quantitative and qualitative. In quantitative research, the data that was collected based on the questionnaire was analyzed statistically. From the statistic calculation, SWOT analysis was used to find out the drainage management strategy. Besides, the qualitative data that was taken from the observation also used to find out the management strategy of sustainable urban drainage in Pekanbaru City.

2.6.1.
Physical Area Characteristic Analysis, Descriptive and quantitative topographic analysis in Pekanbaru, especially Tampan and Rumbai Coast Sub-district was done to get the topographic, hydrologic, geological condition Figure and drainage condition was the important factor in the general drainage management.

2.6.2.
Decreasing Drainage Performance Factor Analysis, This decreasing drainage performance factor analysis was scoped the aspect of environment, social, economy and institutional. This decreasing performance of drainage analysis had the purpose to know if each aspect had impacted the drainage in Pekanbaru City.

2.6.3.
Instrument Validity and Reliability Analysis, The good research instrument (questionnaire) has to be valid and reliable (Arikunto, 1993). In finding the instrument validity and reliability, instrument test should be done first (Faisal, 1981).
2.6.3.1. Validity Test, Validity test used to measure whether the questionnaire was valid or not. The questionnaire was valid when the question could reveal something that would be measured by the questionnaire. To measure the validity level in this research, it was done the correlation between score in each question to the total score construct. The test determined significance by comparing the value of r calculated to the r table in the degree of freedom = n-k in α = 0,05. When r calculated for each question was positive and greater than r table (correlated item value-total correlation), then the question was valid (Suyoto, 2008). From the table above, it could be explained that value of r calculated > r table based on significant test 0.05, which meant that the items was valid.

Product Moment Correlation Formula:
Description: r xy = coefficient between variable x and variable y; ∑xy = total multiplication variable x and variable y; ∑x 2 = square sum of x value ∑y 2 = square sum of y value (∑x) 2 = squared total x value (∑y) 2 = squared total y value 2.6.3.2. Reliability Test, The meaning of reliability was the measurement constancy (Walizer, 1987). Sugiharto and Situnjak (2006) stated that reliability led to an understanding that the instrument used in the research to gain information could be trusted as the data collection instrument and able to reveal the real information in the field. Ghozali (2009) stated that reliability was an instrument to measure questionnaire that was an indicator of construct. Questionnaire was considered reliable when the respondent answers toward the statement was consistent or stable continuously. The test reliability referred to the degree of stability, consistency, prediction, and accuracy. The measurement that had high reliability was the measurement that could result reliable data. According to Masri Singarimbun, reliability was index that showed how far was the measurement instrument could be trusted or reliable. When measurement instrument was used twiceto measure the same phenomenon and the result was consistent, then the measurement instrument was reliable. In other word, reliability showed consistency of measurement instrument for the same phenomenon. Empirically, reliability was shown by number that was called reliability coefficient. The high reliability was shown by r value closer to 1. The general agreement of satisfied enough reliability was when ≥ 0.700.
Instrument reliability test used Alpha Cronbach formula because this research instruments were questionnaire and multilevel scale. Alpha Cronbach formula was shown as follow: Description: r 11 = the reliability n = total tested question items ∑αt2 = total variants When the value of alpha > 0.7 it was meant sufficient reliability, while the value of alpha > 0.80 it suggested strong reliability consistence to all reliable item and test. Or, could also stated such as this:  When alpha > 0.90 it was perfect reliability.  When alpha between 0.70 -0.90 it was high reliability.  When alpha 0.50 -0.70 it was moderate reliability.  When alpha < 0.50 it was low reliability.  When alpha was low, it showed some item was not reliable.

2.6.4.
SWOT Analysis, SWOT analysis was strategy technique in evaluating strength, weakness, opportunity and threat that was applied in giving solution toward problem. This analysis was placed the circumstance and condition as the input factors, then classified based on each contribution. SWOT stood for: S = Strength (kekuatan) W = Weaknesses (kelemahan) O = Opportunities (Peluang) T = Threats (hambatan) There were 2 main factors that would affect the four basic components in SWOT analysis, they were: a. Internal Factor, they were Strength and Weaknesses. This internal factor would impacted better in the research when the strength was greater that the weakness. b. External Factor, they were Opportunities and Threats. This was outer entity factor that not directly involve in the research.
After SWOT analysis, it was done deeper research in evaluating ecological, environmental and social factor to the 3 (three) aspects, they were: (1) Value aspect, present condition factor value compared to the ideal condition; (2) Quality aspect, it was important factor value related to the drainage management execution; (3) Rating aspect, it was society ability to respond the condition.

Result and Discussion
Physical area characteristic of Pekanbaru City covers the condition of topography, geology and climate that become the main basic in drainage management system executed.

Topography
Topographically, Pekanbaru City is located in average height of 5 meter above sea level, only certain regions that located higher than the average height it is in the Sultas Syarif Kasim II Airport with height of 26 meter above the sea level and in the North and East of Pekanbaru City. Topography in Pekanbaru, based on the slope class can be classified into four parts they are plain, sloping to wavy, wavy to bumpy, bumpy to hill area.

Geology
Based on the Geological Map of Pekanbaru and the surrounding (M.C.G. Clarke, 1982.) by the scale of 1: 250.000, Pekanbaru City is generally form by sediment rock in age of Plistosen -Holosen, also alluvium sediment that the process of sedimentaion is still going until present. Lithostratigraphically, the forming rock that arrange the planning area is divided into four rock units they are mud stone (Tup), sand stone (Qpmi), old alluvium (Qp) and new alluvium (Qh). Geological structure that is found in Pekanbaru City consists of horizontal fault to Northwest -Southeast, Synclinal and Anticlinal fold of vertical fault to Northeast -Southwest. This geological structures is incuded in the Sumatera fault system, while the horizontal faults are included in the Semangko fault system, it is expected to happen during Middle Miocene. The geological structure with regional scale for example Semangko Fault that directed Northwest -Southeast or in the same direction of Sumatera Island can be an earthquake trigger in the fault.
Generally, the ground condition in Pekanbaru City has carrying strength (T ground) between 0,7 kg/cm 2 -1 kg/cm 2 , except in some location that near the confluent (T ground) between 0,4 kg/cm 2 -0,6 kg/cm 2 . The effective soil depth (top soil) is mosty less or same as 50 cm in the middle. The effective soil depth around 50 -75 cm is found in the South and more 100 cm is found in the North of Pekanbaru City.  Table 2, it can be concluded that the existing water discharge is not able to accomodate rainwater discharge. This becomes the decreasing performance factor of the drainage.   3.3.3.1. Ecological Aspect Analysis, based on survey and observation result that is taken from Bapedda and Public Work Service of Pekanbaru is described the ecological factor that causes water runoff is: a. Siak River Overflow, Flood that caused by Siak River overflowing is a phenomenon that annually happened. The rise of water face height of Siak River is caused by the sea water tidal (Siak River is overflowed). Some residence environment and activity that is located in north and south of Siak River that is flood prone and puddle, especially Rumbai and Rumbai Rumbai coast (north) and Senapelan, Lima Puluh, Bukit Raya, Tampan. Payung Sekaki, Sukajadi and the City of Pekanbaru (south part). Flood that caused by Siak River overflow is the phenomenon that happen annually. The rise of Siak River water face is caused by the sea tidal (Siak river overflow) and the high rainfall. b. Existing drainage condition in Pekanbaru City, The high level of vulnerabilty and also less awareness on the flood disaster become the high risk factor toward flood disaster. The greatest risk of flood is by living in the high vulnerability area, which are in the downstream areas with bulding location in the river border. Topographically, this area is considered low with the elevation height around (+1.50 -+2.50) m above the average sea level, and every rain season often flooding. The present drainage condition is facing some problems that made the drainage cannot flow water runoff, which are: a. Channel silting caused by sediment (garbage or society water waste); b. Green zone shifting into business and residence area, that made less absorption area and drainage clog; c. Development area that is out of RT/RW border; d. The drainage system has not well managed e. Many residences located in the basin area; f. The narrowing of primary channel in the downstream (bottleneck); g. The Drainage capacity is lower than flood discharge.

Social
Factor Analysis, flood and puddle problem in Pekanbaru area from social aspect is caused by social factor such as lower society role and participation.  Figure 3 it can be explained that the society is tended to not ignore the drainage. This is the reason that causes less well maintenance to the drainage. The questionnaire analysis result shows that the social factor that affected the flood causal is the less society awareness in maintaining the existing drainage.

Figure 4. Economical factor that cause runoff
Based on the questionnaire and observation result by Public Work Service of Pekanbaru City, and some information from the locals, it is going to be directly observed, economical factor that affected the flood causal is in the line to the questionnaire result are: -Drainage construction that is not optimized yet; -The uneven economic growth.

Figure 5. Concept of management strategy of urban drainage in Pekanbaru
Based on the concept of drainage management strategy in Figure 5 it can be described that this strategy consists of 3 (three) aspects which are: (1) environment, (2) 13 ecological aspect covers the drainage management strategy in the residences, public infrastructures, shops and offices. The social aspect covers the role of society that supports the drainage maintenance. Then, the economical aspect covers the role of the stakeholder such as government and personal also the society in the effort of managing and maintaining the drainage.
3.3.5. Improvement Strategy, based on the puddle causal factor, it can be arranged the alternative strategy based on the explanation in the previous chapter. This strategy is arranged as an alternative in solving drainage problem in Pekanbaru. The strategy arrangement used SWOT analysis by sum up the assessment score in one drainage management strategy improvement with environmental basis, such as the Figure 6 and Table 5. Based on the solving priority, it is formulated some concepts/ models that can be used to accommodate drainage management in Pekanbaru City which are:  The economic model is focused on financing the existing drainage management and maintenance in Pekanbaru City. Here are the financial concepts on drainage management: (1) The financing of Urban Drainage is set based on maintenance needs.
(2) The financial kind of Urban Drainage covers:  information system;  planning;  construction execution;  operation, maintenance; and  monitoring, evaluating and society empowerment. (

Conclusion
From the ;research result, it can be concluded that: 1. The existing drainage channel capacity in the location cannot contain rainwater in 2 years constantly, so it cause puddle in some point in Pekanbaru City when heavy rain happened.