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Jiangjia Ravine and Debris Flows
The Jiangjia Ravine is located on the right side of the Xiaojiang River and developed in the area of the Xiaojiang fault. The area of Jiangjia Ravine is about 48.6 km2 and characterized by intense tectonism. About 80% of the exposed rocks are highly fractured and mildly metamorphosed. Both the sandstone and the slate are weak and easily weathered and broken into fragments. Colluvium and mantle rock are widely distributed on the slopes and in the channels in some sub-basins. Accumulated clastic detritus is the main source of the materials in the debris flows when an intense rainfall occurs. In fact, most of the recorded debris flows in China are triggered by rainfall. The annual rainfall in the Jiangjia Ravine ranges from 400-1000 mm but it is marked as being seasonal. About 85% of the total annual rainfall occurs between May and October. These conditions provide an ideal setting for recurrent debris flows and several debris flows occur there annually (maximum 28 debris flows). The measured maximum discharge and velocity of debris flow are 2820 m3/s (5 times of peak water discharge in Xiaojiang River) and 15 m/s, respectively; and the recorded highest density and sediment transporting are 2370 kg/m3 and 6.079´106 kg/s, respectively. The ravine is now called the “debris flow museum” in China and supplies advantageous research conditions.

The main channel of the Jiangjia Ravine is divided into three sections with different morphologic characteristics: (1) the erosion zone, 10 km long with a 17° slope on average; (2) the transportation zone, 1.3 km long with a 5.1° slope on average, with great cross-sectional variation up to 16 m in depth caused by scouring and silting of previous debris flows; (3) the deposition zone, 4.2 km long with a 3.7° slope on average. DDFORS is located in the transportation zone of the Jiangjia Ravine. The observations usually focus on a straight valley that is 270 m long on a 3.4° slope. The cross-section is rectangular and instruments are installed on two banks for observation and recording flow properties.

　　
　　Distribution of observation equipment in Jiangjia Ravine
　
 
 
 　　　　
Dynamics processes observation of debris flow

Field Study and Research Areas:

(1) Mechanisms of Soil/Slope Failure and Debris Flow Formation

(2) Dynamics of Debris Flow and Earth Surface Process

(3) Early-warning and Forecast

(4) Engineering Mitigation (Civil Engineering and Biology Engineering)

(5)Risk Assessment and Management

(6) River hydrology and Sediment transport

More information of DDFORS and its debris flow monitoring can be found below and in the Publications:

Cui, P., Chen, X., Wang, Y., Hu, K., & Li, Y. (2005). Jiangjia Ravine debris flows in south-western China. Debris-flow hazards and related phenomena, 565-594.

Hu, K., Wei, F., & Li, Y. (2011). Real‐time measurement and preliminary analysis of debris‐flow impact force at Jiangjia Ravine, China. Earth Surface Processes and Landforms, 36(9), 1268-1278.

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