The Upper Cau river basin that plays an important role in socioeconomic developments the North of Vietnam is sensitive to changes of climate influencing flows, erosion, and water resources. The main objective of this study is to assess and simulate impacts of climate change on erosion and water flow in the basin. Using a GIS database, and Soil, and Water Assessment Tool (SWAT) model, the water flow, and soil loss assessed with data in period 1980-1999 called the base period, then simulated until 2100 considering the medium emission scenario (B2). The simulation results showed that the total annual runoff and soil loss tends to increase compared to the base period. For flow, the change rate of the simulation period is higher than the base period; the water flow rate will increase by 0.22% (2020-2039) and up to 1.37% (2080-2100). The total annual soil loss of the simulation period at Gia Bay station tends to increase steadily compared to the baseline, namely by 6.2% (2020-2039) and 25.5% (2080-2100). Overall, the result in this study shows that effects of climate changes on the basin are severe enough under the scenario B2 that is useful for authorities for basin management.

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The main objective of this study is to assess geomorphic processes and active tectonics in the Day Nui Con Voi (DNCV) area of Vietnam. For this purpose, a spatial database was collected and constructed, including DEM (Digital Elevation Model) and a geological map. The hypsometric curve (HC) analysis method and its statistical moments were adopted to use for the assessment. These methods have been widely used for the assessment of geomorphic processes and active tectonics in many areas in the world showing promising results. A total of 44 sub-basins of the Red River and the Chay river were analyzed. The result shows that 3 curve-types such as "straight-shape", "Sshape", and concave were found; with the concave curve being the dominant and widely distributed in the northeast side and in the south of the southwestern side of the study area. The hypsometric integral (HI) values are rather small with the largest value is 0.37 and the smallest one is 0.128. Other statistical moments of the hypsometric curve, i.e. skew (SK), kurtosis (KUR), and the density function (density skew -DSK and density kurtosis-DKUR) show great values, which increased in the south direction of the area study. Accordingly, recent active tectonics (uplift-lower) in the study area is generally weak; however, they are also not completely homogeneous and can be distinguished by different levels. The southwestern side is being lifted higher than the northeastern side. The northern part is being lifted larger than the southern part. In the region, the uplift activities were increased gradually in the PlioceneQuaternary and could have stopped at certain time in the past. The current geomorphic processes are mainly headward erosion in the upstream.