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One-third of the Earth in China is formed by Karst topography, which exposes different Karst landforms in three topography grades from southeast to northwest, corresponding to below several hundred meters for the first grade, one to two thousand meters for the second grade, and more than 4000 m for the in Qinghai-Tibet Plateau. Through the hydrochemical and D-18O stable isotopes of 64 water samples collected along two railway lines and the topography fractal characteristics of three typical Karst areas in different topography grades, the changes in Karst development degree, changes in groundwater activities, and the influence of tunnel excavation effects on groundwater environment were analyzed. The results indicated that: (1) the Karst development degree and the influence of Karst tunnel excavation on the groundwater environment are somehow similar in the first and second grades, while there are significant differences between the slopes area from second to third grade and the third grade area. (2) In detail, the relatively weaker Karst development degree and flow seeping in the second grade relatively weaken the influences of tunnel excavation, including the distribution pattern of water resources, the groundwater flow field, and water circulation, while the tunnel elevation has little room to rise. (3) There are many large faults in the north-southward direction in the third topography grade, and the transportation lines in the eastern-western direction will inevitably encounter them. In the intersection area, the tunnel excavation has great effects on the groundwater environment. (4) The lighter hydrogen and oxygen isotopes are enriched in Karst water from the first grade to the third grade, indicating that the recharge source of Karst water presents obvious elevation effect.

The eastern Himalayan syntaxis is the easternmost end of southern Tibet and undergoing the continental Indian-Eurasian collision. The occurrence of large amounts of geothermal waters with high temperatures along the regional active faults is a clear manifestation of an abnormal thermal structure of the crust. In order to further complement the distribution characteristics of hydrothermal activity in southern Tibet, geothermal waters were collected and the hydrochemical characteristics and genetic mechanisms were analyzed. In the eastern Himalayan syntaxis geothermal field, geothermal waters show different compositional features. The major ions are Na+, Ca2+ and HCO3−, SO42−, which are mainly controlled by water-rock interaction. Two peculiar hydrochemical characteristics of geothermal waters are proposed: ⅰ) the Cl− concentration of three water samples is abnormally high due to the likely contribution of magmatic water; ⅱ) the other three have a lower Cl− concentration but higher temperature because of flashing steam heating. The positive correlations between B, Li and Cl concentrations indicate that the geothermal waters originate in a parent geothermal liquid. The enthalpy-chloride diagram shows that the Cl− concentration and the enthalpy of the parent geothermal liquid are 283 mg/L and 1732 J/g (matching a temperature of 413.74 °C), respectively. Four cooling processes for the geothermal waters which ascend from reservoirs to surface were suggested, i.e., conductive cooling, adiabatic cooling, mixing with cold groundwater and the combination of these processes. The partial melting derived from crustal anatexis or crust-mantle mixing is the heat source for this geothermal field. The oxygen and hydrogen isotopic ratios indicate that the geothermal waters are meteorically-fed. The meteoric waters infiltrate via brittle tensional small-scale faults. According to the results of hydrochemical analysis, the evolution patterns of geothermal waters have been further summarized into seven patterns. Except for Pattern g, Patterns a to f are associated with the parent geothermal liquid.

Due to the inhomogeneity of the carbonate rocks and discreteness of the karst water, delineation of the groundwater flow within karst area remains a challenging task as yet. Based on KunCheng tunnel of a water diversion project in KunMing, multi-scale groundwater flow models were set upto simulate the groundwater flow. Large scale model was used to obtain the boundary conditions and hydrogeological parameters, which were then assigned to the small scale model.The small scale model was generalized as an equivalent continuous medium, and two karst pipelines are established by module River. After then, the multi-scale numerical modelswere used to simulate the groundwater seepage field and predict the recovery of groundwater after tunnel construction. The main results and conclusions are as follows.(1)Black karst pipeline and white karst pipeline systems share one recharge source but have two independent discharge systems. The recharge source is the exposed karst rock in the northeast part of study area. Obstructed by aluminum clay rock of P1d, groundwater discharge is divided into two parts during the runoff process.(2)During the tunnel construction process, the water level at the exit of White karst pipeline reduced 9m in pipe model B1 while reduced 10m in the solution fissure model B2, both two models suggest that the tunnel construction will cause the drainage of White karst pipeline exit. The water level at the exit of black karst pipeline reduced 1m in pipe model B1 while reduced 4m in the solution fissure model B2.(3)In model B1, total water discharge during tunnel construction is 69876m3/d, in model B2 , the total water discharge is 95817 m3/d and is much larger than model B1 due to the quick groundwater transporting and exchange in karst pipeline..(4)After the tunnel construction, exits of two pipelines and observation well see the water level recovery because of the formation sealing . The recovery trend is relatively rapid in the early stage, and slow in the later stage. It takes 8.5 years and 10 years for the exits of black and white pipelines and observation wells to reach the original water level, respectively. During the recovery process, groundwater exchange form was changing from pipe supplying aquifer to aquifer supplying pipe, which made model B2 recovered faster than model B1 in early stage, and vice versa.Using large scale model combining with secondary scale model, and the module River to generalize karst pipeline can reflect the flow dynamic characteristics of karst pipeline effectively.

A large number of thermal springs are widely distributed along the deep suture zones and faults in the north section of the Sanjiang Orogenic belt in southeast Tibetan Plateau, connecting the two high-temperature hydrothermal areas in southern Tibet and western Sichuan. Whether the genesis of all geothermal water in the north section of the Sanjiang Orogenic belt is consistent is still an unanswered question. In order to fill the research gap of the high temperature geothermal system in this region, in this study, we classified the geothermal springs into three geothermal fields (Jinsha, Lancang, and Nujiang geothermal fields) and attempted to find clues by comparing the hydrochemical and isotopic characteristics of geothermal fluids in the three geothermal fields. The δ2H and δ18O composition of geothermal springs suggest that all thermal springs are replenished by the meteoric water. Low content of trace elements and low degree of oxygen isotope shift indicate that the partial melting of the crust at a depth of about 20 km mainly provide heat for all thermal springs in the geothermal fields through conduction. But due to the difference of tectonic conditions, there are two formation patterns of geothermal waters in the study area, one was controlled by regional faults, the other was controlled by the folded complex. The geothermal waters controlled by regional faults were heated after deep circulation, and the reservoir temperatures calculated by the Silica-enthalpy mixing model are 175–200 °C and 200–225 °C, respectively. But the geothermal waters controlled by the folded complex were heated after shallow circulation, and the reservoir temperature is only 100–125 °C. Upon rising to the surface, the geothermal waters mixed with cold groundwater to different degrees. The dissolution of Na/K-silicates and carbonate rocks controlled the formation of Na-HCO3 and Ca·Mg-HCO3 type water, respectively. But dissolution of halite and gypsum (or anhydrite) in some areas can lead to further diversity of hydrochemical species, resulting in the formation of Na-Cl, Na-HCO3·Cl, Ca·Mg-SO4 and Na-HCO3.SO4 type waters.

This paper proposes a new sketch method for plant modeling, which combines parametric L-System, and Ball B-Spline Curves, which are objects derived from a parametric solid representation method. By taking the automatic property of L-system and the freedom property of sketching, the users can create realistic plants conveniently according to their willing.