Siti Fadzilatulhusni Mohd Sani et.al. 69 Malaysian Journal of Environmental Management 13(1) (2012): 69-79 Evaluation of Sediment Budget of Bukit Merah Reservoir and its Catchment Area, Perak, Malaysia. SITI FADZILATULHUSNI MOHD SANI, WAN RUSLAN ISMAIL, SUMAYYAH AIMI MOHD NAJIB & MOHAMAD ADAM OMAR ABSTRACT This article aim to describe the effort to use the concept of mass balance and develop the simple budget in the catchment areas upstream of Bukit Merah Reservoir (BMR). The budget was use to identify the inflow and outflow of sediment and the effectiveness and efficiency of a catchment as a mass trapping. As a black box model, the BMR is not very effective as the sediment trappers due to a lot more sediment is flushed out of the system compared to the incoming sediment. The sediment influx from the north pond was 1647 tonnes and 3791 tonnes of sediment loads in the south pond flowing out through the spillway, the Utama Canal and Selinsing Canal, compared to 1577 tonnes of sediment entering the pond. A sediment balance model diagram was constructed for BMR. Sg.Kurau contributed most of sediment input to the BMR even though almost 1629 tonnes or half of the total sediment input from the upper Sg.kurau was deposited in the catchment area. The sedimentbudget will be an aid to planners and engineers in managing the catchment in the future. Keywords: Bukit Merah Reservoir (BMR), sediment load, sediment mass balance ABSTRAK Artikel ini cuba menjelaskan satu usaha yang dijalankan dengan menggunakan konsep imbangan jisim untuk membina suatu imbangan sedimen bagi kawasan Kolam Takungan Bukit Merah (BMR). Konsep belanjawan digunakan untuk menentukan input dan output sedimen dan keberkesanan dan keefisyenan sesuatu kawasan tadahan dalam memerangkap sedimen. Sebagai sebuah model kotak hitam, BMR didapati bukanlah sebuah perangkap sedimen yang baik kerana banyak sedimen telah dikeluarkan daripada sistem berbanding sedimen yang memasuki ke dalam sistem. Influks sedimen adalah lebih banyak daripada kolam utara iaitu sekitar 1647 tan berbanding 3791 tan yang keluar daripada kolam selatan iaitu melalui alur limpah, terusan Utama dan terusan Selinsing, berbanding 1577 tan yang masuk. Satu rajah imbangan dibina bagi BMR dan kawasan tadahan Sg.Kurau merupakan penyumbang utama sedimen ke dalam kolam selatan, walaupun hampir setengah (iaitu 1629 tan) daripada influks dari hulu kawasan tadahan dimendapkan dalam kawasan tadahan. KOnsep belanjawan ini adalah penting bagi membantu para perancang dan jurutera untuk menguruskan kolam takungan dan kawasan tadahan pada masa hadapan. Kata kunci: Kolam tadahan Bukit Merah (BMR), beban endapan, imbangan sedimen INTRODUCTION Sedimen are loose particles detached away by eroding agent like running water. Surface runoff water on slopes removes and transport sediment downslope into streams and rivers and later on deposited in the lakes or estuaries. Thus, by calculating the amount of input from upland triburtaries and also the output from the catchment area we are able to estimate the sediment budget of the catchment area. According to Slaymaker (2003), studies on sediment balance has started since 1957, where researchers had listed out the sources of sediment in the upper Rhine valley, Germany. Then, the sedimen budget approach was used to investigate the sources of sediment and sediment movement from the catchment areas in the highlands and also at the polar region known as the Karkevagge