[A-HW24] 流域圏生態系における物質輸送と循環：源流から沿岸海域まで

[AHW24-18] Estimation of soil erosion under major land covers of Inle Lake Watershed in Shan State, Myanmar

*Nang Yu War¹、Mya Thandar Toe²、Shin-ichi Onodera¹ (1.Graduate School of Advanced Science and Engineering, Hiroshima Universiity、2.University of Forestry and Environmental Science, Yezin)

キーワード：soil erosion, RUSLE, Inle Lake, land covers

Inle Lake in Shan State, Myanmar is threatened by serious water surface area loss due to many factors. Soil erosion and sedimentation are also the factors for the reduction of open water surface area in Inle Lake. This study aimed to estimate the rate of soil erosion and sediment transport under different land covers in the Inle Lake watershed area for the fulfillment of the management objective to control erosion. Out of the four perennial streams flowing into Inle Lake, Than Daung (Kalaw) and In Dein (Upper Bilu) were chosen to calculate the soil erosion rate; to clarify areas of high erosion risk; to compare the soil erosion rate and risk under major land covers using Revised Universal Soil Loss Equation (RUSLE). The results found that the soil erosion rate of In Dein is higher than Than Daung. The higher rainfall intensity, the longer stream length and wider stream width, and the slightly higher LS value of In Dein is the likely reason for such difference. When comparing the soil erosion rate under major land covers, forests showed the lowest soil erosion rate, followed by shrubland, settlement, and cropland. Regarding soil erosion risk, on average, over 90% of forest cover and over 40% of cropland fall under low erosion risk. In In Dein, 37% of cropland is under extreme erosion risk while 25% of cropland is under extreme erosion risk in Than Daung.