BebasBanjir2015

Purwanti Sri Pudyastuti

Bersama Kita Mengelola Banjir

Oleh : Purwanti Sri Pudyastuti

Sumber : http://www.republika.co.idPublished on 6 Februari 2007

Banjir yang melanda Jakarta awal Februari 2007 menambah deretan bencana yang telah datang bertubi-tubi melanda negeri ini. Sekilas, sepertinya permasalahan banjir merupakan masalah sederhana karena telah rutin dialami setiap tahun. Kenyataannya, permasalahan banjir merupakan permasalahan kompleks yang tidak dapat dianggap sederhana. Dampak negatif akibat banjir sangat merugikan di banyak sektor. Banjir menyebabkan aktivitas perekonomian hampir lumpuh, infrastruktur telekomunikasi dan transportasi terganggu, ancaman penyakit, penyediaan air bersih terganggu, aliran listrik terputus, dan masih banyak lagi kerugian yang harus ditanggung akibat banjir.

Jika dihitung dalam rupiah, kerugian yang ditanggung saat banjir melanda dan biaya yang dibutuhkan untuk perbaikan pascabanjir di Jakarta akan berjumlah miliaran rupiah. Padahal tidak hanya Jakarta yang dilanda banjir, namun banyak daerah lain di Indonesia yang dilanda banjir tahun ini sehingga alokasi dana banyak terserap untuk penanganan masalah banjir.

Banjir, sebenarnya adalah fenomena alam yang tidak dapat dihilangkan sama sekali, namun setidaknya dapat dikurangi potensi dan resikonya. Menurut Associated Programme on Flood Management (APFM, 2006), masalah banjir merupakan hasil interaksi antara fenomena alam dengan lingkungan, proses sosial, dan proses ekonomi. Proses sosial-ekonomi seperti pembangunan di segala bidang memberikan dampak kepada kondisi lingkungan suatu daerah.

Sebagai contoh, penebangan hutan untuk memenuhi kebutuhan kayu sebagai bahan kontruksi rumah pascabencana tsunami di Aceh telah menyebabkan kerusakan hutan yang menyebabkan daya rusak air berupa banjir di daerah tersebut tidak dapat dikendalikan. Pengalihfungsian daerah resapan air di Puncak, Cipanas, Jawa Barat, menjadi bangunan-bangunan seperti vila juga merupakan satu contoh proses sosial-ekonomi yang menjadi pendukung terjadinya banjir di Jakarta.

Keterkaitan antara daerah hulu dan hilir juga tidak dapat diabaikan dalam pengelolaan banjir karena dalam suatu daerah aliran sungai (DAS) secara alamiah air pada semua badan air yang ada di DAS akan mengalir dari arah hulu menuju hilir. Oleh karena itu, setiap aktivitas yang berinteraksi dengan air dan tanah di daerah hulu akan memberikan dampak pada daerah hilir. Beralihfungsinya daerah resapan air di Bogor menjadi daerah kedap air merupakan satu contoh aktivitas di hulu yang memberikan dampak di daerah hilir.

Pendekatan multidisiplinerPengelolaan banjir yang dilakukan selama ini mayoritas adalah upaya pengendalian banjir yang masih terpusat pada upaya-upaya teknis seperti pembuatan tanggul, drainase, atau bendungan. Ketika daya tampung drainase dan sungai dalam mengalirkan debit air tidak lagi dapat diandalkan, maka fungsi pengendalian banjir saluran-saluran tersebut pun seolah-olah hilang.

Selain itu, upaya perbaikan lingkungan sebagai pendukung upaya pengendalian banjir seperti rehabilitasi lahan kritis selama ini tidak dilakukan secara terpadu dengan melibatkan semua pihak terkait. Sebagian besar upaya tersebut dilakukan sendiri-sendiri. Upaya penyelamatan hutan misalnya hanya dilakukan oleh Dinas Kehutanan tanpa sinergi dengan institusi lain yang terkait dengan pengelolaan lahan dan sumberdaya air.

Permasalahan banjir tidak dapat diselesaikan hanya dengan mengandalkan ego sektoral, karena ada banyak faktor yang mempengaruhi terjadinya banjir, seperti faktor meteorologi, hidrologi, dan manusia. Selain itu, daya rusak air yang dipresentasikan oleh kejadian banjir mempunyai keterkaitan dengan kondisi lingkungan sebagai dampak dari aktivitas manusia dalam memperlakukan lingkungan dan sumberdaya yang ada di dalamnya.

Menurut APFM (2006), upaya pengelolaan banjir akan efektif jika dilakukan secara terpadu dengan melibatkan partisipasi masyarakat luas, berbasis daerah aliran sungai (DAS), menggunakan pendekatan multidisipliner dan berwawasan lingkungan. Selain itu, pengelolaan banjir secara terpadu seharusnya dilakukan dalam satu kerangka dengan pengelolaan sumberdaya air terpadu dan bersinergi dengan pengelolaan daerah pantai terpadu.

Dalam pengelolaan banjir terpadu, keterkaitan antara aspek teknik, sosial, budaya, ekonomi, kelembagaan, perundangan, dan lingkungan harus dipertimbangkan. Dalam penelitian yang dilakukan di beberapa negara, APFM (2006) melaporkan bahwa pengelolaan banjir terpadu yang menggunakan pendekatan multidisipliner akan lebih menghemat biaya dibandingkan dengan pengelolaan banjir yang hanya mengandalkan ego sektoral.

RTRW dan pengelolaan banjirSetiap daerah (pada tingkat kabupaten atau kota) semestinya mempunyai rencana tata ruang wilayah (RTRW). Dalam RTRW suatu daerah, biasanya ditetapkan kawasan-kawasan seperti kawasan rawan banjir, kawasan rawan longsor, kawasan lindung, dan kawasan resapan air. Semua kegiatan pembangunan di suatu daerah termasuk pengelolaan sumberdaya air yang di dalamnya mencakup pengelolaan banjir, semestinya terpadu dengan RTRW.

Namun kenyataannya, di Indonesia seringkali dijumpai adanya ketidakterpaduan antara RTRW dan kegiatan pembangunan. Untuk mendukung keberhasilan pengelolaan banjir maka keterpaduan antara RTRW dengan kegiatan pembangunan harus diwujudkan. Namun hal ini hanya bisa terwujud jika masyarakat luas dilibatkan dan ada dukungan dari sektor perundangan, hukum, dan kelembagaan.

Mencermati bencana banjir yang kejadiannya terus meluas di beberapa daerah di Indonesia, sepertinya sudah saatnya kita harus meninggalkan ego sektoral dalam pengelolaan banjir dan beralih ke pendekatan multidisipliner. Dengan begitu, program pengelolaan banjir terpadu dapat diwujudkan dan manfaatnya tidak hanya dirasakan dalam jangka pendek namun juga dalam jangka panjang. Bersama kita (seharusnya) bisa mengelola banjir.

Purwanti Sri Pudyastuti, Pengajar Jurusan Teknik Sipil UMS, Alumnus Water, Engineering, and Development Centre, Loughborough University, Inggris

Sumber : http://www.republika.co.idPublished on 6 Februari 2007, 08:01

Key to Jakarta’s floods: Basin flood management

Purwanti Sri Pudyastuti , Surakarta | Sat, 03/22/2008 1:40 PM | Opinion

Sumber: http://www.thejakartapost.com/

Flooding is an annual event in Jakarta during the wet season, and the flooding has become more devastating recently. Even the turnprike to Soekarno-Hatta International Airport was recently flooded.

Several areas in northern Jakarta, located near the coast, were inundated for several weeks in the last few months, according to media reports.

It seems the government is not serious in its attempt to reduce the flood risk because flooding is widespread and has become more devastating. Yet, communities living in flood prone areas have become accustomed to flooding.

The flood problem in Jakarta is complex, and needs a comprehensive approach to solve it.

According to Andjelkovic (2001), flooding is caused by extreme natural events occurring within a drainage basin, also referred to as a river basin, a catchment area or a watershed.

Drainage basins can be rural and urban, and, therefore, flooding can be rural and urban.

The implementation of flood management for urban areas is not the same for rural areas, because the characteristics of urban and rural areas are significantly different.

Jakarta is located in the downstream area of the Ciliwung River basin, and is affected by the characteristics and conditions of the upstream area. Furthermore, Jakarta is an urban area with complex socio-economical problems indirectly contributing to triggering a flood event.

Jakarta’s population density has increased rapidly due to a growing urbanization rate, increasing the risk of floods.

Urbanization has many definitions. One of the more simplified definitions says urbanization is a process of artificial land use alteration occurring through time. Artificial land use alteration, due to population density increase in urban areas, converts pervious natural surfaces to impervious artificial surfaces, such as human settlements, transportation infrastructure and shopping centers.

The decreasing infiltration capacity and natural water storage capacity of the soil, due to the conversion of natural surfaces to artificial surfaces, increases the storm-water runoff rate and the total runoff volume, shortens the runoff travel time, reduces groundwater recharge and base flow, and increases peak runoff rate, leading to flood control problems.

Urbanization also increases wastewater and waterborne wastes, raises water demand, deteriorates water quality, and leads to pollution control problems.

Flooding in Jakarta is not only affected by changes in land uses, but is also caused by some factors such as long-lasting moderate rainfalls saturating the soil, inadequate land use, channelization of natural waterways, surcharge due to blockage of drains and street inlets, inflow from the river during high stages into urban drainage system, conversion of floodplain to human settlement, and domestic solid waste thrown away in the river.

Furthermore, urban flooding is not only affected by climate, but also affected by social, economical, cultural and technical factors. Therefore, a multidisciplinary approach to integrated flood management (IFM) is needed to reduce the flood risk.

Traditionally, flood control has been reactive focusing on structural measures and has been mono-disciplinary in nature.

Recently there has been evidence suggesting structural measures have disturbed the ecological balance. Therefore, it is widely recognized a paradigm shift is required to move from defensive to proactive action.

According to Global Water Partnership (GWP, 2006), the IFM approach aims to maximize the net benefits from flood plains and at the same time reduce the loss of life caused by flooding, flood vulnerability and risks, and preserve ecosystems and their associated biodiversity within the overall framework of integrated water resources management (IWRM).

Associate Program on Flood Management (APFM, 2007) reported a close relationship between water resources management, river management, land use management, forest management, erosion control, agriculture, urban drainage and sewerage within a river basin.

If the characteristics of the catchment changes, it will influence the characteristic and magnitude of the flood regime.

In some cases, flood management measures may impact the magnitude of floods downstream, transferring the flood risks. Therefore, flood management measures should take account the entire basin from upstream to downstream, and strategy for flood risk reduction should be realized through a basin flood management plan.

According to APFM (2007), the basin flood management plan presents a clear picture of the causes and effects of floods. The objectives of the basin flood management plan are to protect life and property from flood risks and enhance socio-economic development in a basin through IFM.

Data is required before arranging a basin flood management, according to APFM (2007). This includes meteorological data, hydrological data, geomorphologic data, environmental data, land use practices in the catchment including flood plains, pattern of human settlements in and around flood plains, demographic profile of flood plain inhabitant, infrastructure in the flood plains, future development plan in the basin and socio-economic damages in past floods.

A successful project requires stakeholder participation. The experiences of some developing countries, regarding water-related projects, shows stakeholder involvement had an important role in building partnerships and a sense of ownership (World Bank, 2004).

APFM (2007) reported stakeholder participation promotes individual and community ownership, commitment, and helps the sharing of risks among various entities.

Stakeholders involved in arranging a basin flood management plan could include local governments, water resources management boards, NGOs, departments of public works, local universities, community representatives, departments of forestry.

In the case of trans-boundary river basin such as Ciliwung river basin, the national government and related local governments should be involved.

A river gives benefits for the upstream inhabitant as well as downstream, and the upstream characteristics influence the downstream. Therefore, the basin should be managed integrally involving all stakeholders in the basin.

The writer is a lecturer at the Civil Engineering Department, Muhammadiyah University, Surakarta. She is an alumni of Water, Engineering, and Development Centre (WEDC), Loughborough University, England.

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