Journal of Rangeland Science, 2019, Vol. 9, No. 3 Hutapea / 300 Archive of SID

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Research and Full Length Article: Assessment of Deli Watershed Flood Causing Damage in City,

Sumihar HutapeaA* AAgricultural Faculty, Medan Area University (UMA), Medan, Indonesia, [email protected]

Received on: 27/12/2018 Accepted on: 31/05/2019

Abstract. The watershed (DAS) Deli is one of the priority watersheds in the Medium Term Development Plan in 2010-2014 according to the Ministry of Forestry decree (SK 328/Menhut-II/2009), Indonesia. DAS is a complex ecological system in which there is a dynamic equilibrium between the incoming material energy (input) and the material out (output). Naturally, the change in input and output balance is slow and does not pose a threat to humans and environmental sustainability on a watershed system with continuous land-use dynamics from dense vegetation forms to rare vegetation forms or from vegetation forms to non-vegetation forms. It has been concluded that Deli watershed land destruction is dominated by biophysical factors, especially land use, slope, landform, and rainfall in upstream Deli sub-watershed. This is what causes flooding in Medan city, Indonesia. The cause is extreme rainfall so that a number of rivers such as Deli River and Babura River overflowed, the water level of the Deli and Babura Rivers almost reached the bridge section and this was scarce.

Key words: Deli River, Watershed, Flood, Damage, Erosion

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Introduction system to rainfall inputs is easier to cause The Watershed Daerah Aliran flooding. The morphometry of the Deli Sungai(DAS) Deli is one of the priority watershed is characterized by a river watersheds in the Medium Term gradient upstream of the Deli Basin (in Development Plan in 2010-2014 particular the Sibolangit Area) averaging according to the Ministry of Forestry 3.5%, in the center (Sibolangit decree (SK 328 /Menhut-II /2009), Namorambe) averaging 1.4%, and Indonesia based on a Joint Agreement downstream (Namorambe-Belawan) -1%, among Ministry of Forestry, Ministry of so the flow velocity is greater upstream Public Work and Ministry of Agriculture while downstream is relatively slow. The No. PKS.10 / Menhut V / 2007 and No. value of branches is smaller than 3, so it 06 / PKS / M / 2007 and No. 100 / has a tendency to increase the flood water TU.210 / M / 5/2007 On May 9, 2007 level rapidly, and the water level is low About Critical River Basin Rehabilitation (BPDAS Wampu Sei Ular, 2003). (DAS) for the conservation of land and In addition, headwater area of the water resources. This agreement is a watershed is dominated by the slope and follow-up to National Movement for mountainous plains where the majority of Forest and Land Rehabilitation (GN- the population with livelihoods as RHL/Gerhan) on 21 January 2004 and farmers cultivate 82% of farmland in National Movement for Water Rescue villages in the upstream Deli basin (BPS Partnership (GN-KPA) on 28 April 2005 , 2009). This situation will by President and National Declaration on cause vulnerability to erosion and Effective Water Management in disaster flooding in the downstream area if land management on 23 April 2004 by rehabilitation is not with Soil and Water Coordinating Minister for People Conservation (Sub-Pusat Rehabilitasi Welfare based on the fact that there are Lahan dan Konservasi Tanah / Bangun increased intensities of floods, landslides Tanah, 1998). However, as far as and droughts. In the Letter of Agreement, observations which have been conducted, the Deli watershed is one of the critical there has not been an optimally watersheds that require priority handling integrated watershed management as the target site for rehabilitation concept based on watershed / watershed (www.dephut.goid/files/328.pdf). The conservation studies in order to control determination of the Deli watershed as a flooding in a region. critical watershed is because the critical Deli River is one of the eight rivers in land area is almost half of the total Deli Medan, North Sumatera, Indonesia. In River area, which will theoretically affect 19th century, Deli River is used as an the sustainability of the land and water artery of trade for the sultanate to other resources of the Deli watershed area. In areas. The river flows in the northeastern addition, river flow is not normal due to area of with predominantly decreased potential infiltration. The tropical rainforest climate. The annual destruction of cover vegetation greatly average temperature in the area is 24°C. affects infiltration, runoff, rainfall The warmest month is January when the erosivities, which ultimately affects the average temperature is around 26°C, and rate of erosion (BPDAS Wampu Sei the coldest temperature is in December at Ular, 2003). 22°C. The average annual rainfall is 2862 The deleterious condition of the Deli mm. The wettest month is October with watershed in is due to an average of 446 mm rainfall, and the changes in watershed characteristics driest season is in June with 129 mm where the response of the watershed rainfall.

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Based on the result of soil watershed using ArcView GIS version 3.3 software, land delineation analysis obtained from the spatial distribution of units of soil Soil Sub Map of Land Rehabilitation and contained in each sub watershed Deli is Soil /Snake Soil Conservation (1999), listed in Table 1.

Table 1. Soil sub unit of Deli river basin Sub watershed Land Unit Group (Asosiasi) Wide (ha) (%) 1 2 3 4 Petani Dystrandept Eutrandept Dystrandept 3.865 30 Dystropept Dystrandept Tropudult 4.491 35 Dystropept Troporthent Tropudult 2.590 20 Dystropept Tropudult Troporthent 563 4 Hydrandept Eutropept Troporthent 1.313 10 Total 12.824 100 Simai-mai Dystrandept Eutrandept Dystrandept 785 24 Dystropept Dystrandept Haplorthox 652 20 Dystropept Dystrandept Tropudult 1.795 55 Total 3.233 100 Babura Andaquept Tropaquept 725 14 Dystrandept Eutrandept Dystrandept 1.045 21 Dystropept Dystrandept Tropudult 3.188 64 Total 4.959 100 Bekala Dystrandept Eutrandept Dystrandept 198 4 Dystropept Dystrandept Tropudult 4.346 95 Total 4.544 100 Deli Andaquept Tropaquept 2.259 35 Dystrandept Eutrandept Hydrandept 341 5 Dystropept Dystrandept Tropudult 2.303 35 Hydraquent Sulfaquent 751 11 Tropaquept Fluvaquent Tropohemist 509 8 Tropopsamment Tropaquent 282 4 Total 6.447 100 Sei Kambing Andaquept Tropaquept 2.607 61 Dystrandept Eutrandept Hydrandept 718 17 Dystropept Dystrandept Tropudult 938 22 Total 4264 100 Paluh Besar Andaquept Tropaquept 7.072 61 Hydraquent Sulfaquent 1.382 12 Tropaquept Fluvaquent Tropohemist 2.298 20 Tropopsamment Tropaquent 747 6 Total 11.498 100

Table 1 shows that the soil units found in unit area (Hardjowigeno and Deli watershed according to Soil Widiatmaka, 2007). Taxonomy Soil Survey Staff (1975) were According to Soil Taxonomy classified into 5 orders as Inceptisols, (Keputusan Menteri Kehutanan, 2010) Entisol, Ultisols, Oxisol, and Histosol. soil classification, 15 Inceptisol points These five orders were grouped into 10 were found, 2 Entisol order points and 1 sub-orders and 18 soil groups. The soil Ultisol order point, decreasing 5 great unit in the Deli watershed is an groups. The results of the spatial association of ground map units distribution of the Deli River watershed consisting of two or three main land are dominated by Inceptisol soil orders, types at the order level with the area of i.e., young soils with moderate each order not exceeding 75% of the land developmental soil pH is generally acidic

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J. of Range. Sci., 2019, Vol. 9, No. 3 Assessment of …/ 303 Archive of SID to neutral, sandy soil texture, clumped balance is slow and does not pose a threat earth structures and medium to very fast to humans and environmental permeability. Considering next order sustainability; but on a watershed system Entisol land especially on the riverside, with continuous land-use dynamics from the type of soil is relatively young dense vegetation forms to rare vegetation textured sandy loam (sandy loam). While forms or from vegetation forms to shapes the order of Ultisol soil and Oxisol on the non vegetation according to spatial land upstream, generally textured silty clay use spatial distribution, it will influence loam, low organic material content fluctuation of river flow (Asdak, 2004). developed from old parent material has a Besides being a water system, DAS is horizon of candy to order Utisol with the also an ecosystem, referred to as a amount of mineral easily decayed eligible watershed ecosystem. The elements the oxic horizon for the Oxisol order contained within the watershed include (Foth, 1990; Hardjowigeno, 2007). both natural and human resources. Natural resources act as objects Definition of Watershed (DAS) consisting of land, vegetation, and water, Watershed (DAS) in foreign terms is while with respect to the human element known as catchment area, drainage area, as the subject or perpetrator of the drainage basin, river basin, or watershed elements of natural resources between (Notohadiprawiro, 1999; Cech, 2005). In these elements, the process of mutual Indonesia, there are three terminologies relations occurs and influences each in accordance with the breadth and other. In the natural resources, soil, coverage namely: Catchment, Watershed water, and vegetation are interrelated to and Basin. There is no standard limit, but produce a certain product and certain it is understood that the catchment is water conditions that ultimately affect smaller than watershed, and the basin is a human life. On the other hand, human as large basin (Priyono and Savitri, 2001). the perpetrator of the utilization of Regarding the definition of a natural resources does a lot of actions or relatively diverse watershed according to changes on land and vegetation, so it individual goals, according to Dixon and reacts to the products, participation and Easter (1986), DAS means an area water results (Asdak, 2004). limited by ridges and rainwater falling by According to Soerianegara (1978), the a river system. According to Seyhan reflection or measurement of the (1990), the watershed is a land area hydrogeological conditions is determined bounded by a natural boundary of from the ability of water supply in terms topography that serves to accommodate, of quality and quantity and distribution store, and drain the water received to the by time. A good hydrogeological nearest river system that further leads to condition is when the watershed can reservoirs or lakes or seas. Another ensure the provision of water of good definition states that the watershed is a quality, sufficient quantity and uniform region located at a point on a river that by discharge distribution throughout the topographic boundaries drains water year. Watershed ecosystems are divided falling over it into the same river and into upstream, middle and downstream through the same point in the river watersheds. Biogeophysically, the (Brooks et al., 1989; Arsyad, 2010). characteristics of upper watershed are: DAS is a complex ecological system 1) It is a conservation area, in which there is a dynamic equilibrium 2) It has higher drainage density, between the incoming material energy 3) It is an area with a large slope (> (input) and the material out (output). 15%), it is not a flood zone, Naturally, the change in input and output

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4) The water used is determined by the of rain dispersion to the soil, the amount drainage pattern, and of surface flow and the strength of 5) The type of vegetation is generally a erosion and flow capacity. According to forest stand (Brooks et al., 1989). Government Regulations No. 38 in 2011 While the characteristics of downstream about the river, the definition of flooding watershed are: is the event of overflowing river water 1) It is an area of exploitation, a smaller over river troughs. A river is said to be drainage density, flooded if there is an increase in the flow 2) It is an area with a small to very small of a relatively larger flow or when the (<8%) slope, flow of abundant water is out the river 3) It is in some places a flooded area, channel and causes disruption to humans 4) The regulation of water consumption (Isnugroho, 2002). Maryono (2005) is determined by the irrigation building, states that flood events are caused by low and watershed retention capability, reduced 5) The dominant type of vegetation is retention along the river channel, reduced agricultural crops except the estuary area absorption area, and low socio hydraulic dominated by mangrove / peat forest. character (water culture). Cech (2005) The central watershed area is the argues that floods occur due to transition region of the two bio- precipitation and runoff that exceed the geophysical characteristics of different capacity of the river channel. Flood is a watersheds mentioned above. natural occurrence that occurs due to Based on the point of view of the heavy rain. The rain that falls on the hydrological system and the ecology of earth's surface partially enters the ground the upstream roles in the watershed, the while the rest becomes the surface continuity of the resource economy and stream. Consequently, the magnitude of the conservation of biodiversity in the the surface flow, which exceeds the study of hydrological and ecological capacity of natural or artificial channels, systems cannot be ignored. With these caused the overflow of water to flood in considerations, according to Pasaribu the area around the river. If the downpour (1999), DAS can be totally used and the cannot quickly flow into the drainage or upstream ecosystem development can be stream, then the water causes the puddle. implemented in accordance with Flooding due to river floods or puddles preservation, reservation, and will be a problem if the result of the conservation principles. Upper and puddle causes disruption to humans downstream areas of a watershed have a (Margianto, 2002). There are two factors biophysical linkage represented by the affecting run off related to rainfall hydrological cycle and nutrient cycle. (duration, intensity and distribution of The existence of biophysical linkages rain) and associated with the catchment making the watershed can be used as a area. Flood is a natural phenomenon that logical planning and evaluation unit for occurs when the intensity of rain falls the implementation of watershed very high where the ability of absorption management programs. into the ground has been exceeded, resulting in runoff with the number and Floods and Influential Factors rate of large flow which can become Flooding is defined as an incident of flooded. Flooding cannot be deemed as overflowing river flow on the left and an annual routine disaster. Floods can right of river flow either on riverside or damage various public facilities and on flood plains (Anonymous, 1999). The infrastructure must be repaired after amount of rainfall, intensity, and floods if there is a loss of life. At least, distribution of rain determine the strength seven public sectors are always affected

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J. of Range. Sci., 2019, Vol. 9, No. 3 Assessment of …/ 305 Archive of SID by flooding such as agriculture and Location of Study forestry, water resources and irrigation, The research was conducted at Deli transportation, housing and settlements, Watershed located in 3 regions / cities in environment and spatial planning, health North Sumatera as Karo Regency, Deli and social welfare. Thus, directly or Serdang and Medan City. indirectly, floods can have a serious Administratively, Deli watershed is effect on the efficient use of local and adjacent to DAS Percut in the East and national budgets. Many parties have done Belawan Watershed in the West. The various forms of activities to cope with Deli Watershed consists of 7 sub- flooding, but they have not shown any watersheds as: 1) Farmer's DAS Sub- real results (Pssl-Ugm, 2007). Waters, 2) Simai-mai Sub Watershed, 3) The aim of this research was to assess Deli Basin, 4) Babura Sub Watershed, 5) field survey method, and survey activity Sub Basin of Bekala, 6) Sub- Sei in the form of observation and kambing and Sub DA big hammer giving verification of characterization and the names of the sub-watershed in biophysical identification of each Deli accordance with the names of the watershed, Indonesia tributaries that flow in the area through which it passes. Based on its geographic Materials and Methods position, the Deli watershed is located A field survey method in the form of between 30 12'58 "LU - 30 47'15" LU observation, verification of and between 980 28'50 "BT - 980 characterization and biophysical 41'50"BT. Deli River Area is 48,162 ha. identification of each Deli watershed was The city of Medan as a downstream area carried out. Considering the parameters is the region most affected by the of land damage, soil observation by management of the Deli watershed. drilling and making minipit soil (land Medan city is the capital of North section or soil profile, but smaller size Sumatera Province which is located at and more shallow), the minipit soil size 030 29 '46 "LU - 030 46' 29" N and of 50 x 50 x 60 cm and minipit soil 98029'46 "BT- 980 35 '14" BT with samples were taken. Soil samples are altitude of 0-40 m above sea level. analyzed for several properties of the soil Geographically, the total area of Medan in the laboratory. Field surveys were City reaches 26,510 ha; the largest conducted by observing the types of land landuse pattern is for settlement (80%). use, climate data and hydrology. Survey Field research began in February 2010 to data and analysis of laboratory soil January 2011. properties are used to assess land damage. The land damage assessment is Research Tools (maps) based on the prediction of erosion and Materials used in the study includes: erosion hazard, land classification, land earth map, geology / lithology map, use classification, flood analysis, topography map, soil map, Landsat watershed conservation study /sub digital image of 2003, land use map, watershed followed by analysis of impact vegetation density map. Single computer of conservation guidance on the decrease device, Arcview GIS Software version of flood discharge and flood volume. The 3.3 and PC Software ArcGIS version 9.3 database and maps of area were prepared are used to make the image and MS using almost Geographic Information Office word / excel software for analysis System (GIS). and presentation of data, Flood Assessment Software (PSSL-UGM, 2007) for flood assessment, and cameras as a survey documentation. The tools

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used in the study include: 1) Stationeries, 2) Work Map Scale 1: 100,000, 3) Field Data Processing measuring tools (GPS Garmin, geological The in-depth studies covered aspects of compass, meter roll, soil drill, drill and rain analysis, hydrological analysis, permeability ring), and 4) work tools in erosion prediction analysis, and erosion the field (scopes, hoes, fork and crowbar, hazard, land criticality analysis, and land plastic bags, loops, field knives). use capability, flood analysis including flood potential and flood-prone areas, Field Survey analysis and erosion control strategies Field survey aims to check the suitability with selection of soil and water between the information on the map / conservation models that can control secondary data with existing conditions flooding. in the field. The survey is conducted to check the land characteristic data and the Results and Discussions biophysical characteristics of the Medan City is one of the administrative watershed / sub watershed Deli. The areas included in the Watershed (DAS) biophysical status of the watershed / sub Deli. It is 26510 ha total area of Medan watershed Deli is one of the City, which is included in the determinants, either directly or indirectly, management of Deli watershed 53.6% as one of the causes of flooding in the (14213 ha). Therefore, the flooding in city of Medan. The biophysical status of Medan City is strongly influenced by the the watershed / sub watershed Deli is condition of Deli watershed especially in generally reflected by the morphological the upstream areas where the critical land conditions (slope), soil type, land use, is getting wider, which can result in morphometry (including broad flooding of shipment. In addition, the parameters, river length, river main reduction of the catchment area is due to gradient, shape, flow density, and travel the penetration process, the development time), and other biophysical factors are of residential areas, industries and so on vegetation and climate (especially in the suburbs to the city center. The raindrops), and hydrology in surveying decline of the wet cross section of Deli field also identified flood or flood-prone and Babura River children is due to locations by setting control points for silting/ puddling, the number of slum inflow sources, and characteristics review neighborhoods around the riverbanks, of the flood hydrograph from the and due to the very poor condition of influence of each upstream sub- Medan city drainage (Hasibuan, 2007). watershed, and other sub watersheds. The city of Medan as the capital of North Required hydrological data include: Sumatra Province is flood-prone because rainfall data (intensity, duration of rain), it is lowland, flat with a height of 2.5-40 river flow, land use data, watershed area, m above sea level and a slope of 0-4%. In length of main river, slope, high addition, geographically, Medan City is difference between upstream and traversed by many rivers that divide the downstream, concentration time, flow Medan City to Deli river, Babura river, velocity flood average, with Rational Belawan river, Percut river, Serdang river analysis that will be obtained combined and other small rivers such as river runoff coefficient. The areas affected by Batuan, Badera River and Kera river; if floods and potentially for floods are not managed well, they are very determined, and the impacts of floods on vulnerable to flooding (Medan City both the environment and the Government of Medan II Region, 2000). circumstances surrounding communities Based on information from various are observed. parties such as the Meteorology and

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J. of Range. Sci., 2019, Vol. 9, No. 3 Assessment of …/ 307 Archive of SID Geophysics Agency (MGA), Satkorlak of North Sumatra Disaster Management and The Location and Position of DAS media coverage both nationally and Deli locally in North Sumatra, flooding River Basin (DAS) Deli is located in incident in Medan city routinely happens Karo Regency, Deli Serdang and Medan every year, even according to Hasibuan City, North Sumatera Province. The (2007) Medan city on average 10-12 upstream of Deli River is located in Karo times / year. Therefore, the problem of and Deli Serdang District while the flooding in Medan city is a serious middle and downstream areas are in problem that should be solved Medan City and , immediately because every flood event and empties into Belawan Harbor. Deli will threaten millions of people of Medan watershed is in the east bordering with City, both river dwellers and other DAS Percut. Based on its geographical residents whose activities are disrupted position, the Deli watershed is located by the flood. This will certainly be a bad between 30 12'58 "to 30 47'15" North image for the city of Medan as the capital Latitude and between 980 28'50 "to 980 of the province of North Sumatra, and 41'50" East Longitude (Figs. 1 and 2). one of the major cities in Indonesia.

Fig. 1. Location of river mouth on map of Sumatera, Indonesia

Fig. 2. The top view of Deli river

Based on the Administration of Deli Pancurbatu, Namorambe, Delitua, Watershed, it includes 27 Subdistricts of Sunggal, Patumbak, and Silver Overlay Merdeka District and Karo Deli Serdang District. Subdistrict Medan Regency. District Sibolangit, Sibiru-blue, Tuntungan, Medan Johor, Medan

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Amplas, Medan Selayang, Medan flooding in some districts of Medan from Polonia, Medan Baru, Medan City, Deli River killed a person. (b) On Medan Maimun, East Medan, Medan December 2002, puddles on the runway Petisah, Medan Helvetia, Medan Barat, of Polonia Airport stopped the flight for 2 Medan Deli, Medan Marelan, Medan days, (c) routinely happens every year, Labuhan and Medan Belawan in Medan puddles in the arterial roads and (BPDAS Wampu Sei Ular, 2003, collectors causing traffic congestion and (BPDAS Wampu Sei Ular, 2009). (d) flooding in the Medan Belawan and According to the Sub-Center for Land Medan Labuhan Sub-districts due to high Rehabilitation and Soil / Snake Soil tides that cause disruption to community Conservation (1998), the Deli Watershed activities and many other cases each year, consists of seven Sub-Watersheds: Sub- (Sub-Pusat Rehabilitasi Tanah dan Watershed, Simai-mai Sub-Basin, Deli Konservasi Tanah / Bangun Tanah, 1998, Sub-Basin, Babura Sub-Basin, Bekala BPDAS, 2003). Even the information Sub- DAS Sei Kambing and Sub DAS quoted from some mass media states in big hammer. 2007, already 3 times (May, September, Giving these names in accordance November) Medan city experiencing with the name of the tributaries that flow flood where river Deli, river of batuan in the area, the location of the watershed and Dead river back overflow and in the watershed is as follows: The thousands of houses along the river Farmers' DAS is located at the upstream, flooded water up to one meter. This kind the southernmost boundary of the Deli of routine happens every year since 2003 watershed. Simai-mai Basin is located in in the rainy season, the river banks in the the upper reaches of the eastern sub- city of Medan will be flooded initially a watershed of Farmer, directly adjacent to few hours later and water will recede but DAS Percut, Belawan Watershed and since 2005, the water lasted for 1-2 days. Deli, Simai-mai and Babura Sub- Then in early January 2011, precisely watersheds. The Deli Watershed is on January 6, 2011, a big flood also hit located in the middle to the downstream the city of Medan. Floods that occur of the Deli watershed and directly cover along the rivers that cross the city borders with almost all the sub of Medan, the river Deli, Babura, Bekala, watersheds in the Deli watersheds: Sub Sei Kambing and big hammer. Based on DAS of Farmers, Simai-mai, Kambing field observation, the location of the River, big hammer, Babura, and DAS floods that occurred includes 14 districts Percut. The Babura sub watershed is located in Medan City, and resulted in located in the central part of the Deli loss and misery for 49,010 people or watershed adjacent to the Farmers, 12,067 families who are in flooding Bekala, Deli and Seikambing Rivers. The affected areas. Inundation of floods in Bekala River Basin is also in the center each location varies from 30 cm to 4m, of the Deli Watershed, bordering the puddles from the streets to tens of Babura Sub-Basin, the Seikambing, and thousands of houses, especially those on Belawan Watershed. The Sei Kambing the banks of the Deli, Babura, Bekala and River Basin is located in the downstream Bedera rivers. Observations and watershed bordering the Babura sub interviews with flood-affected watershed. communities indicate that flood events begin with varying rainfall for each Multiple Recorded Flood Events location from 18.00 -22.00 WIB until Flooding in Medan caused hampering 03.00 - 07.00 WIB, so high rainfall lasts activities. It can be seen in the following 5-10 hours. Flood incident shocked the moments: (a) on 4 November 1997, people who become victims because the

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J. of Range. Sci., 2019, Vol. 9, No. 3 Assessment of …/ 309 Archive of SID rise of puddle is very fast and when the High flood puddles that occur in each people are resting, the time starts at 1.30 location also varies from 30 cm to 4 m, pm in the morning. Flood peak occurred puddles ranging from the streets to tens at 06.00 WIB. It gradually receded until of thousands of homes, especially those 17:00 pm, but there are several locations on the banks of the river. The location of of water remaining to survive until 2 the flood and the number of people days, especially in the basin areas such as affected and the high puddles, the Village Sukadamai District of Polonia. flooding time can be seen in Table 2.

Table 2. Location of flood and population of victims No. Location of Flood Information (Sub-district) The number of victims The High Time Cause KK Person of flood (m) flooding (WIB) (Family Card) 1 2 3 4 5 6 7 1. Medan Maimun 2843 11.372 Deli river flood overflowing - Hamdan 2,5-3,0 02.00-16.00 -Kampung Aur 3,0-4,0 01.30-17.00 -Jati 1,0-2,0 01.30-17.00 -Sukaraja 1,0-2,0 01.30-17.00 -Badur Bawah 2,0 –2,5 04.30-17.00 -Badur Atas 1,0 –1,5 03.30-18.00 -Kampung Baru 1,0 –1,5 04.00-17.00 - Sungai Mati 1,0-1,5 04.00-17.00 2. Medan Petisah 178 712 Deli river flood overflowing -Silalas 0,5–1,0 05.00-16.00 - Petisah Hulu 0,3-0,5 05.00-16.00 3. Medan Tuntungan 75 300 Deli river flood overflowing -Mangga 1,5-2 04.00-15.00 4. Medan Belawan 1.232 Deli river flood overflowing Jl Yos Sdarso 308 1,0-1,5 05.00-17.00 5. Medan Sunggal 717 3.868 Deli river flood overflowing -Jl Abadi 1,0-1,5 02.00 –15.00 -Jl Pinang Baris 1,0-1,5 02.00 –15.00 - Jl Perjuangan 1,0-1,5 02.00 –15.00 6. Medan Barat 29 116 Deli river flood overflowing 7. Medan Selayang 105 420 Deli river flood overflowing 8. Medan Polonia 617 2.130 Deli river flood overflowing -Sari Rejo 1,0-2,0 02.30-18.00 -Polonia 1,0-2,0 02.30-18.00 -Suka Damai 1,0-2,0 02.30-18.00 -Anggrung 2,0-3,0 02.30-18.00 -Madras Hulu 2,0-3,5 01.00-16.00 9. Medan Baru 1026 4.104 Deli river flood overflowing -Padang Bulan 0,5-1,0 00.30-14.00 -Pandau Hulu 0,5-1,0 00.30-14.00 -Darat 1,0-1,5 00.30-14.00 -Titi Rantai 1,0-1,5 00.30-14.00 -Merdeka 1,0-2,0 00.30-14.00 10. Medan Helvetia 2362 9.528 Bedera rivers overflowing flood -Cinta Damai 1,0-2,0 4.30-17.00 -Kelambir V 0,5-1,0 05.00-17.00 11. Medan Johor 438 1.752 The Bekala River overflowed -Kuala Bekala 2,0-3,0 01.30- 14.00 -Gedung Johor 1,0-2,0 01.30-16.00 -Pangkalan 1,0-2,0 01.30-16.00 Mashyur 1,0-2,0 01.30-16.00 12. Medan Marelan 186 744 The Deli River is overflowing -Rengas 0,5-1,0 05.00-17.00 13 Medan Deli 463 1.852 1,0-1,5 05.00-17.00 14. Medan Labuhan 2720 10.880 The Deli River is overflowing -Pekan Labuhan 1,5-2,0 05.00-16.00 -Martubung 1,0-2,0 05.00-16.00 -Jl Jermal 1,0-1,5 04.00-17.00 1,0-1,5 04.00-19.00 Source: Satkorlak data of north sumatra disaster management (2011), field data

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Interviews and field observations indicate BPDAS Wampu Sei Ular. 2009. Kajian Banjir that flooding and flooding times vary Kota Medan Distribusi Faktor Penyebab dan Arahan Penanganannya. Direktorat Jenderal widely due to floods occurring at night Rehabilitasi Lahan dan Perhutanan Sosial. when people are at rest, and the high Departemen Kehutanan pools are strongly influenced by the BPS, Badan Pusat Statistik Kabupaten Karo. distance of houses from riverbanks. In 2009. Kabupaten Karo dalam Angka. addition to causing harm to the urban Koordinator Statistik Kabupaten Karo. population, this flood also damages Brooks, K. N. 1989. Watershed Management several hectares of agricultural land, Project Planning, Monitoring, and Minnesota especially those located along the Bekala, Evaluation: A Manual for The ASEAN Region. University of Minnesota, St Paul, Babura, Deli and Bedera rivers for the Minnesota. second time in the same year, floods Cech, T. V. 2005. Principles of Water Resources struck Medan City on April 1, 2011 just History, Development, Management, and as January's high rainfall in Medan City Policy. Second Edition. Wiley. USA. caused the Deli, Belawan and Babura Dixon, A., and K. W. Easter. 1986. Integrated Rivers to overflow. Almost all areas in Watershed Management: An Approach to Medan City are flooded. The cause is Resources Management, Westview Press, Inc. extreme rainfall so that a number of Colarado. United States of America. rivers such as Deli river and Babura river Foth, H.D. 1990. Fundamental of Soil Science. John Wiley and Sons. overflowed, the water level of the Deli Hardjowigeno, S.danWidiatmaka. 2007. and Babura rivers almost reached the Evaluation of Land Suitability and Land Use bridge section and this is scarce. Planning.GadjahMada University Press, Yogyakarta. Conclusion Hasibuan, G. M. 2007. Model Koordinasi Deli land destruction is dominated by Kelembagaan Pengelolaan Banjir Perkotaan biophysical factors, especially land use, Terpadu. Disertasi Sekolah Pascasarjana Universitas SumateraUtara. Medan. slope, landform, and rainfall in upstream Isnugroho. 2002. Tinjauan Penyebab Banjir dan Deli sub watershed. This is what causes Upaya Penanggulangannya. Alami. Jurnal Air, flooding in Medan. The cause is extreme Lahan, Lingkungan dan Mitigasi Bencana. rainfall, so that a number of rivers such Vol. 7 No.2 Jakarta. p. 1 – 7. as Deli River and Babura River Keputusan Menteri Kehutanan. 2010. Penetapan overflowed, the water level of the Deli Daerah Alira Sungai (DAS) Prioritas Dalam and Babura Rivers almost reached the Rangka Rencana Pembangunan Jangka bridge section and this is scarce. Menengah (RPJM) 2010-2014. Margianto, T. D. S. 2002. Physical Handling of Flood Management. Natural. Journal of References Water, Land, Environment and Disaster Anonymous. 1999. Penyusunan Kriteria Mitigation. Vol. 7 No. 2. Jakarta. p. 40-45. Kerusakan Tanah. Prosiding Seminar. Deputi Maryono, A. 2005. Handling Drought and Bidang Pengendalian Kerusakan Lingkungan Environmental Floods. Gadjah Mada Hidup. Badan Pengendali Dampak University Press. Lingkungan. Jakarta. Notohadiprawiro, T., Rachman S., Azwar M., dan Arsyad, S. 2010. Water and Land Conservation, S. Yasni. 1999 Need for Research, Inventory IPB Press. and Coordination of Land Resource Asdak, C. 2004. Hidrologi dan Pengelolaan Management in Indonesia. Office of Ministry Daerah Aliran Sungai. Gadjah Mada of Research Technology and Higher University Press.Yogyakarta. Education. Jakarta. BPDAS Wampu Sei Ular. 2003. Rencana Pasaribu, H.S. 1999. DAS as an Integrated Pengelolaan Daerah Aliran Sungai Terpadu Planning Unit in Relation to Regional Deli. Direktorat Jenderal Rehabilitasi Lahan Development and Sectoral Development dan Perhutanan Sosial. Departemen Based on Soil and Water Conservation. Kehutanan. Annual Seminar of PERSAKI DAS 21 December 1999. Jakarta.

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Priyono, C. N. S, Dan S. A. Cahyono. 2001. Development Agency of Regional. Status and Strategy for Future Watershed Yogyakarta. Management Development in Indonesia. Seyhan. 1990. Basic of Hydrology. Yogyakarta: Natural. Journal of Water, Land, Environment Gadjah Mada University Press Yogyakarta. and Disaster Mitigation. Vol. 8 No.1. Jakarta. Soerianegara. 1978. Management of Water p. 1-5. Resources. Postgraduate College, IPB. Bogor. PSSL-UGM. 2007. Study of the Impact of Soil Survey Staff. 1975. Key Soil Taxonomy Monoculture Plants on Flood Disasters. Final USDA. Handbook 436. U.S. Govt. Printing Research Report. Center for the Study of Land Office. Washington. Resources at the University of Gadjah Mada, in collaboration with Research and

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ارزیابی خسارت ناشی از سیل حوزه آبخیز دلی شهر مدان در اندونزی

سوميهار هوتاپيا دانشکده كشاورزي، دانشگاه مدان )UMA(، مدان، اندونزي، پست الکترونيک: [email protected]

تاريخ دريافت: 1397/10/06 تاريخ پذيرش: 1398/03/10

چکیده: حوزه آبخيز دلي يک از حوزههاي داراي اولويت در طرح توسعهاي ميان مدت )DAS( در ميان سالهاي 1393 الي 1389، طبق دستور وزارت جنگلداري (SK 328/Menhut-II/2009) اندونزي است. DAS يک سيستم زيست محيطي پيچيده است كه در آن تعادل پويايي بين انرژي مواد ورودي و خروجي وجود دارد. بطور طبيعي تغيير تعادل بين مواد ورودي و خروجي آهسته است و اين وضعيت تهديدي براي پايداري تعادل بين انسان و محيط زيست نيست اما وقتي پويايي كاربري اراضي از شکلهاي پوشش گياهي متراكم به شکلهاي نادر يا به شکلهاي فاقد پوشش گياهي ادامه دارد در نتيجه تخريب اراضي حوزه آبريز دلي تحت تاثير عوامل بيوفيزيکي، به ويژه استفاده از زمين، شيب، شکل زمين و بارندگي در رودخانههاي زيرحوزههاي باالدست قرار ميگيرد. اين تغيير كاربري اراضي دليلي است كه باعث سيل در شهر مدان اندونزي ميشود. بارانهاي شديد باعث طغيان تعدادي از رودخانهها از جمله رودخانه دلي و بابرا ميشود كه سبب ميشود سطح آب رودخانههاي مذكور تقريباً به سطح پل برسد و اين يک اتفاق نادر است.

کلمات کلیدی: رودخانه دلي، حوزه آبخيز، سيل، خسارت، فرسايش

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