FLOOD PROBLEM IN PADANG CITY: THE EFFECTIVENESS ?· Ahmad Junaidi, Nurhamidah Civil Engineering, Andalas…

  • View
    212

  • Download
    0

Embed Size (px)

Transcript

  • http://www.iaeme.com/IJCIET/index.asp 1210 editor@iaeme.com

    International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 10, October 2017, pp. 1210–1219, Article ID: IJCIET_08_10_124 Available online at http://http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=8&IType=10 ISSN Print: 0976-6308 and ISSN Online: 0976-6316 © IAEME Publication Scopus Indexed

    FLOOD PROBLEM IN PADANG CITY: THE EFFECTIVENESS SOLUTION

    Ahmad Junaidi, Nurhamidah

    Civil Engineering, Andalas University, Padang Indonesia

    ABSTRACT

    Padang is the most significant natural disaster in Padang City besides earthquake,

    storm surges, landslides and Tsunami from the perspective of population affected,

    frequency, area extent and disruption to socio-economic activities. Padang City and

    its surrounding alluvial lands still suffer from flood damage by frequent floodwaters.

    The main problems of flooding in Padang City are caused by regular river flooding

    and urban flash floods. Several engineering works have been implemented in the

    rivers, in and near Padang City aiming at mitigating the impacts of the floods.

    However, the city still faces problems with flooding during the rainy season. During

    the flood on December 25, 2007, three people died and thousands of houses were

    inundated. Flood problems in Padang City, present status of the ongoing management

    measures, their effectiveness and future in improvement of flood protection and urban

    drainage are described. Padang city has a history of vulnerability to floods. This

    situation will worsen due to changes in land use, impact of land subsidence and of

    climate change. Therefore an optimal urban drainage and flood protection will have

    to be developed, that is based on the present and expected future conditions and will

    be feasible from the economic point of view. Scenarios for efficient flood protection

    and urban drainage systems in Padang city will be presented.

    Keywords: natural disaster, flood vulnerable, flood protection, urban drainage

    Cite this Article: Ahmad Junaidi and Nurhamidah, Flood Problem in Padang City: the Effectiveness Solution, International Journal of Civil Engineering and Technology, 8(10), 2017, pp. 1210–1219 http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=8&IType=10

    1. INTRODUCTION

    We still may observe a rapid population growth, a significant increase in agriculture exploitation, urbanisation and industrialisation in lowland, flood prone areas. Due to this such areas become increasingly vulnerable for extreme weather conditions that will have their effect on the requirements for drainage and flood management. There are no indications that this tendency will change. In the rural areas we may observe improvements in agriculture production and an increase in the value of crops, farm buildings, water management facilities and infrastructure. Rapid urbanisation is especially ongoing in the emerging countries. Most of the areas are located in the flood prone zones. Due to urbanisation and industrialisation and the

  • Flood Problem in Padang City: the Effectiveness Solution

    http://www.iaeme.com/IJCIET/index.asp 1211 editor@iaeme.com

    improvement in the standard of living, the value of property, buildings and infrastructure has significantly increased and will further increase in future. Especially in flood prone areas in South and East Asia we may observe a very rapid growth of urban areas. In order to cope with this growth for new urban areas very often reclamation has taken place of low-lying areas in the neighbourhood of the existing urban area. From a water management and flood protection point of view this implies removal of storage area, increase in urban drainage discharges and in the need for adequate flood protection (Schultz, 2001 and 2006).

    Indonesia covers a land area of approximately 2 million km2 and has 237 (census in 2010) million inhabitants (Statistic Board of Indonesia, 2010). The occurrence of major floods is increasing, with casualties and substantial losses to the economy. This is caused by an increasing population, which results in rapid urbanisation, coastal and river basin degradation, encroachment of urban areas in ‘natural’ flood storage systems, reduction of natural retention for storm water runoff, and of potential diversion capacity. Moreover, higher population density and economic development increases the number of casualties and value of losses (Basuki, et al., 2005).

    As an archipelago area, Indonesia has a number of cities in coastal areas. Some cities, especially in Java Island, have rapidly developed. Cities like Jakarta, Surabaya and Semarang are nowadays subject to frequent suffering due to floods. In these cities, polder development is done with up to date technology by project developers on the one hand and using simple technology by the local people on the other hand. Unfortunately, so far this development was often not carried out based on a well-balanced approach between resources utilisation and valuation of ecological functions as called for in the principles of conservation. As a result urban drainage and flooding problems, salinity intrusion in the groundwater and land subsidence have increased significantly, both in the urban areas themselves as in the surrounding areas (Joint working group, 2009).

    2. FLOOD IN PADANG CITY

    Padang City as a capital of West Sumatra plays a key role as the centre of political and economic activities, a strategic point for air and sea routes in the western part of the island of Sumatra, Indonesia. The city is increasingly industrialized as the centre of development on the island of Sumatra.

    Flooding is the most significant natural disaster in Padang City-besides earthquakes, storm surges, landslides, and tsunamis-from the perspective of population affected, frequency, area extent and disruption to socio-economic activities. The main problems of flooding in Padang City are caused by regular river flooding and urban flash floods. Several engineering works have been implemented in the rivers, in and near Padang City aiming at mitigating the impacts of the floods. However, the city still faces problems with flooding during the rainy season.

    During the flood of 25 December 2007, three people died and thousands of houses were inundated. Due to the development as outlined above, decreasing flood conveyance and the low design standard, the risk of flooding is increasing seriously in the area of Padang City. Moreover more and more people settle in the floodplains and the areas prone to flooding. This is mainly caused by the rapid population growth in the area. The risk of a large number of casualties has become very serious and, due to the economic development, the potential damage is high, especially in the area close to the coast. Therefore, reducing flood risk is an important concern for the government and the communities responsible for the rivers and urban drainage systems. To improve flood control and urban drainage different measures can be implemented to reduce the flood risk.

  • Ahmad Junaidi and Nurhamidah

    http://www.iaeme.com/IJCIET/index.asp 1212 editor@iaeme.com

    2.1. Actual Conditions of Padang City

    The provincial capital of West Sumatra, Padang City has been a trade centre since the 16th century. During the 16th and 17th centuries pepper was cultivated and there was trade with India, Portugal, the United Kingdom and the Netherlands. In 1663 the city came under the authority of the Dutch. This ended in 1942.

    Padang City plays a key role as the centre of political and economic activities in the western part of Sumatra (Figure 1). It is also a strategic point for air and sea routes. Industries in Padang City and its environs are represented by agriculture and commerce, and the city is increasingly industrialized. The population influx from farming villages has activated commerce and economy. The city is rapidly expanding its urban districts through enhanced maintenance of roads and ports based on the master plan for urban development (Japan’s Official Development Assistance (ODA), 2005).

    Figure 1 The area of Padang City (Public Works Service, 2007)

    In 1945, the city had around 50,000 inhabitants. The population growth since then was largely a result of the migration to major cities as in so many developing nations(http://en.wikipedia.org/wiki/Padang, Indonesia). In 1981, the city had a population of 494,000, which resulted in an average population density was 765 persons/km2. In 2003, the population of Padang City had reached up to 765,000 and the population density increased to 1,101 persons/km2. The population of Padang City in 2007 was about 840,000 and the population density was about 1, 210 persons/km2. In Figure 2 the growth of the population in Padang City from 1998 – 2007 is illustrated.

    Figure 2 Population growth in Padang City (Padang Municipality and statiscal board, 2010)

  • Flood Problem in Padang City: the Effectiveness Solution

    http://www.iaeme.com/IJCIET/index.asp 1213 editor@iaeme.com

    Padang City has been suffering from flooding since the Dutch ages (1660). In 1797 Padang was inundated by a tsunami with an estimated flow depth of 5-10 metres, following a seaquake, estimated to have been 8.5-8.7 Mw (Moment Magnitude Scale). The shaking and flooding caused considerable damage and causalities. In 1833 another tsunami inundated Padang City with an estimated flow depth of 3-4 metres. This wa