Aplikasi GIS Dalam Menganggar Kadar Hakisan Tanih Menggunakan Model RUSLE: Kajian Kes Di Kampus UKM Bangi

Abstract

ABSTRAK

Hakisan tanah adalah satu cabaran serius alam sekitar yang dihadapi di Malaysia pada masa kini. Hakisan berlaku akibat permindahan kumin tanih oleh air dan angin, dan ia berlaku dalam kawasan Kampus Ukm Bangi di bawah pelbagai kegunaan tanah. Hakisan oleh air boleh menjadi lebih berkesan semasa peristiwa ribut dan boleh menjadi berbahaya apabila berlaku hakisan sungai kecil dan lembaran semasa hujan lebat. Kebanyakan kehilangan tanih banyak berlaku pada waktu tersebut. Hakisan tanih menyebabkan kumin-kumin tanih masuk ke dalam sungai dan akan berlakunya pemendapan sedimen, sekaligus akan merosakkan kualiti air. Satu kaedah yang mengintegrasikan penderiaan jauh dan Sistem Maklumat Geografi (GIS), dengan menggunakan model Revised Universal Soil Loss Equation (RUSLE) untuk menilai risiko, dilihat boleh membantu mengenal pasti dan menilai potensi hakisan tanah dan menganggarkan kehilangan tanah. Lapisan data GIS termasuk faktor erosiviti hujan (R), erodabiliti tanah (K), panjang cerun dan kecuraman cerun (LS), dan litupan tumbuhan (C) telah dikira untuk menentukan secara purata kehilangan tanah tahunan dalam kawasan kajian. Peta akhir hakisan tanah tahunan menunjukkan kehilangan tanah maksimum adalah 81.3216 t ha^-1 thn^-1. Berdasarkan peta potensi risiko hakisan tanih, hakisan tanih di kawasan kajian dapat dikelaskan kepada tiga kelas iaitu hakisan rendah (kurang 10 t ha^-1 thn^-1), hakisan sederhana (10-50 t ha^-1 thn^-1), hakisan sederhana tinggi (51-100 t ha^-1 thn^-1). Fungsi faktor C  boleh dikawal dan menjadi mitigasi kepada hakisan tanih serta boleh mengurangkan kehilangan tanah melalui pengurusan yang betul.

Kata kunci: Hakisan tanih, kadar kehilangan tanih, Model RUSLE, Penderiaan Jauh dan GIS

ABSTRACT

Soil erosion is a widespread environmental challenge faced in Malaysia nowadays. Erosion is defined as the movement of soil by water and wind, and it occurs in Ukm Bangi Campus under a wide range of land uses. Erosion by water can be dramatic during storm events and it can also be insidious, occurring as sheet and rill erosion during heavy rains. Most of the soil lost by water erosion is by the processes of sheet and rill erosion. Soil erosion will cause the soil particles wash into the river and sediment deposition will occurs, so that will affect the quality of water. A methodology that integrates Remote sensing and Geographic Information Systems (GIS), coupled with the use of Revised Universal Soil Loss Equation (RUSLE) model to assess risk, can identify and assess soil erosion potential and estimate the value of soil loss. GIS data layers including, rainfall erosivity (R), soil erodability (K), slope length and steepness (LS), and cover management (C) factors were computed to determine their effects on average annual soil loss in the study area. The final map of annual soil erosion shows a maximum soil loss of 81.3216 t h^-1 y^-1. Based on the result soil erosion was classified in to soil erosion severity map with three classes, which is low, moderate and high moderate. It is understood that functions of C factor that can be controlled and thus can greatly reduce soil loss through a good management.

Key Words: Soil Erosion, Soil Loss, RUSLE Model, Remote Sensing and GIS