Abstract: Seasonal rivers, which run through the mountain, Gobi, desert, wetland, are important geographical units to maintain biodiversity and ecosystem stability in arid regions in Northwest China. Because of remote location, severe condition, low development potential and lack of suitable monitoring equipment, few data are available for evaluating water resources of the seasonal rivers in the region accurately. In this study, automatic water level gauge was employed to collect the long term water level data of Duobagou which is a seasonal stream or flood ditch in the southeast margin of Kumtag Desert. Simultaneously, based on the artificial observation, the flow rate of Duobagou was estimated by the coupling relation between the water level and flow velocity. The results showed that rainstorm is the driving factor of flood in Duobagou. Most of the floods occurred in the period from June to September. The flood characteristics were basically consistent with the rainstorm flood occurring in other rivers in arid area. No floods occurred when a single precipitation was less than 5 mm. Meanwhile, the maximum flow rate of the flood was less than 0.3 m³·s^-1 when a single precipitation was less than 16 mm in spring or less than 10 mm in summer. Moreover, the spring runoff was risen steeply and fallen slowly in spring and autumn as no floods occurred. On the contrary, it was risen slowly and fallen steeply in summer. This paper provided not only an effective method for monitoring the hydrological dynamics of seasonal rivers, but also reliable data for studying eco-hydrological process and biological survival and evolution, which can help manage and make use of the water resources around the Kumtag Desert more effectively and efficiently.

Key words: arid area, seasonal river, duobagou, flow rate, flood, Kumtag Desert