【作者】 潘欢迎；

【导师】 万军伟；

【作者基本信息】 中国地质大学 ， 水文学及水资源， 2014， 博士

【摘要】 我国是世界上碳酸盐岩分布最广的国家,由此产生了规模不同和形式多样的岩溶地下暗河系统。流域内的岩溶地下暗河和地表水系共同构成的空间区域(包括地表和地下水循环系统)称为岩溶流域。岩溶流域内发育极为丰富的地下水资源,也具有十分复杂的岩溶流域水循环机理。宏观上表现为地表-地下水转化频繁、含水介质空间上明显变异和水流状态多变的特征。因此,岩溶流域内水资源的时空分布极不均匀,增大了水资源开发利用的难度。从理论研究现状看,预测岩溶流域水文过程的成果不多,且精度难以满足实际应用的要求。因此,合理构建岩溶流域水文过程的物理和数学模型,准确评价和预测流域水循环过程,对于开发利用岩溶流域水资源和防治地下工程岩溶水害都具有重要的理论价值与现实意义。湖北恩施蛤蟆颈流域是我国西南地区的典型岩溶流域,其流域面积不足1OOkm2。根据《水利水电工程设计计算规范》(SL 44-2006),按集总式流域水文模型推算的设计洪峰流量是实际洪峰流量的4倍,设计误差远超过了允许的标准,是何原因?经实地岩溶水文地质调查发现,该流域岩溶极为发育,水循环过程十分复杂,已经超出了传统“小流域”水文地质分析的概念模型。以蛤蟆颈流域为例,研究中小型岩溶流域地下水赋存和循环的水文模型,定量评价和预测流域内水资源,对于我国西南地区水资源的合理开发利用和科学管理具有参考价值。蛤蟆颈流域从上游向下游,地貌由峰丛洼地向峰丛谷地过渡,两类地貌分布有不同性质的子流域。峰丛洼地分布一些小的封闭的子流域,它们不发育常年地表水系,主要通过地下暗河沟通。峰丛洼地多为裸露岩溶区,垂向上可划分为三个水文带：皮下带、渗流带和管流带。峰丛谷地主要表现为岩溶坡立谷,区内地形平坦,地表水系发育,并且有部分落水洞、漏斗出露于地表,地表水系和地下暗河共同构成水流通道。此外,也可见覆盖型岩溶,垂向上可划分为四个水文带：覆盖层带、皮下带、渗流带和管流带。由此可见,流域内的岩溶管道由单一分支向树枝状逐渐过渡。区内两次连通试验显示,岩溶管道内的地下水平均流速约1115m/d和1811m/d,其流速远低于一般非岩溶地区的地表水系的流速,可见,暴雨后地表水系和岩溶管道产生的洪峰存在时间差,是该流域设计洪峰流量误差的一个主要原因。根据蛤蟆颈流域构建了独立的产汇流岩溶子流域系统,并通过地下岩溶管道将这些子流域串连成一个完整的地表-地下水系统。为了合理地刻画这一岩溶流域水文系统,基于TOPMODEL模型提出了改进的KARST-TOPMODEL模型(K-T模型),该模型的思路为：通过现有的TOPMODEL模型分析各独立岩溶子流域内的水文过程,然后利用马斯京根汇流模型对所有岩溶子流域系统进行汇流得到总流域出口的水文过程。。利用K-T模型分析了蛤蟆颈流域的岩溶分布式水文模型,并与传统集总式流域水文模型的分析结果对比,验证了K-T模型的可靠性。论文取得了以下研究成果。(1)蛤蟆颈流域总体上可以分为三个支流和108个子流域,三个支流为东支的袁头沟水系、中支的长滩河水系和西支的夹沙溪水系,三支水系均包含地表河段和地下暗河段,并通过岩溶管道流入蛤蟆颈水库。根据斯特拉勒(Strahler)河流分级方法,蛤蟆颈流域可分为54个河源构成的河网结构,其最高河级为5级,流域内水系的量级很高,水系结构复杂。(2)蛤蟆颈流域的峰丛洼地以锥形、蝶形为主。洼地内都发育落水洞,但无地表水系,降雨产流后经落水洞和地下暗河流入主河道。流域内峰丛谷地常堆积一层含水量较高的厚覆盖层,谷地汇集大量大气降水,经覆盖层后通过底部的落水洞或者竖井流入地下暗河。(3)改进后提出的K-T模型考虑了岩溶负地形汇水-蓄水、岩溶地下暗河汇水-输水-蓄水的水文过程。利用2003年～2005年四次典型暴雨过程的水文观测资料对模型的参数进行率定和验证,其精度较之前集总式水文模型有了大幅度的提高。将模拟数据以天为步长,与2003年～2005年的实测数据对比显示,二者拟合较好,精度满足设计要求。(4)K-T模型分析不同频率降雨强度下,蛤蟆颈流域模型的设计洪水过程与实测的洪水过程十分接近,其最大洪峰量较集总式水文模型的计算结果更加接近实测最大洪峰量。(5)模拟2005年7月11日降雨洪水过程显示,岩溶滞洪模块能够很好地反映岩溶洼地滞洪的现象。该洪水过程在白鹤洞暗河入口、长滩河暗河入口和夹沙溪暗河入口顺序地出现滞洪,最大滞洪量分别是69.48万m3、56.39万m3和150.36万m3,模拟结果与研究区的实际观测基本一致。(6)当降雨量较小时,实测洪水过程与K-P模型不考虑滞洪的模型基本一致,呈现出双峰形态。随着降雨量增大,采用K-P模型的岩溶滞洪模块,模拟得到的洪峰形态更扁平,洪水过程持续的时间更长,岩溶流域的削峰调蓄功能更明显。本次研究将水文地质学与水文学的理论与方法相结合,对岩溶流域的复杂水循环过程进行了较全面的描述和表征,主要特色和创新体现为：1)以岩溶动力学理论为指导,开展了岩溶子流域和岩溶水系特征的研究,分析岩溶水水循环特征和渗流、产流机制。然后分析TOPMODEL模型在岩溶流域应用中的优缺点,在TOPMODEL模型的基础上改进构建KARST TOPMODEL模型,并将该模型应用到蛤蟆颈流域。(2)将岩溶水文地质调查与洪水水文调查-监测方法相结合,获得了主要岩溶地下暗河的极限过水能力,并在流域水文模型中增设了滞洪模块,更加真实有效地再现了天然岩溶水系统的削峰滞洪特征,使得模拟过程和实际过程更加接近,岩溶削峰调蓄功能得到显现。更多还原

【Abstract】 There are many carbonate rocks widely distributed in China, especially in southwest China. In these areas, different sizes and forms of karst underground river system, with addition of the basin surface water system, were known as karst watershed. The abundant water resource in these karst watersheds has become an important pillar of economic development. However, due to the complex mechanism of karst basin water cycle, the transformation of surface-groundwater and space variability of karst aqueous medium changed frequently. The very unevenly distribution of karst water resources in time and space caused water shortages in these areas. Thus, for rational planning of the development and utilization of regional water resources, assessment and modeling of hydrological processes are essential. Base on the former methods with superior difficulty and low accuracy, in-depth study of karst features and mechanism of karst basin water cycle, with respect to construction of the physical and mathematical model of karst hydrological processes, accurate assessment and prediction of river basin water cycle are the main study content of this thesis. And it has important theoretical and practical significance, especially to the rational utilization of water resources and underground karst water damage prevention.In this thesis, a typical karst watershed, Hamajing watershed, in southwestern China was studied. This watershed belongs to a small valley basin in Karst area, with a sound hydrological monitoring facilities and meteorological data. Based on "Water Resources and Hydropower Engineering design calculations norms (SL 44-2006) ", the design flood was estimated by the use of heavy rains in this area. However, according to the contract between actual measurement flood and design flood, the maximum peak measured values were only about one-fourths of the design flood peak. Although the norm proposed the use of "sinkhole rate" to calibrate designed flood, the amount of the corrected amount of flood still has large difference with the measured peak. Therefore, it is necessary to build a distributed hydrological model in karst areas.In the study area, there are different types of Karst morphology such as karst depressions, karst funnel, hole, karst conduit and other well developed karst forms. These forms are the product of water and carbonate rock interaction. The process is actually the transformation process of carbonate rocks by water. Some main controlling factors, including soluble carbonate rocks, water dissolution ability, permeability rock, water flow and so on, are interrelated.According to field investigation, Hamajing watershed can be divided into two kinds of combination types, i.e. peak cluster depressions and peak cluster valleys. Peak cluster depression contains some small closed basin without perennial surface water. Depressions which have thin layers of coverage and exposed bed rock are connected by underground rivers. And In the vertical profile, it can be divided into three main hydrological belts as subcutaneous belt, vadose zone and pipe flow belt. Peak cluster valleys, mainly slope Rift Valley, contain a plenty of soil coverage. Typically there are surface rivers developed in the area. Some of the sinkholes, funnel directly exposed on the surface. In the vertical profile, it can be divided into four hydrological belts with that overlay zone, subcutaneous belt, vadose belt and pipe flow.Karst pipes are a widespread groundwater storage and drainage systems in karst area, especially in South China Karst. Karst conduit flow is the underground water moving in the karst pipes. According to the formation mechanism, karst conduit is not only constrained by many factors such as lithology, structure, geomorphology, hydrology etc., but also have their own complex features. The Karst valley conduit of toad neck is developed from a single branch to a network flow. According to the field trials tracing, it takes 64.6h that surface water of Jiasha Creek go through underground river system to Wuliping river export, with an average flow rate of about 1115m/d. And it takes 26.5h that surface water of Xiangxiping go to Gaoyan underground river export, with an average velocity of about 1811m/d. That is, the inj ection of rainfall from Jiashaxi to the toad neck reservoir need around 4days, which means that the pipe flow rate is lower than the velocity of surface water.TOPMODEL model is constructed by spatial variation of terrain. Based on DEM derived topographic index (Lnα/tanβ), this model was used to describe the flow trends and reflect the impact of changes in the hydrological cycle terrain basin. According to the principle of gravity drainage of runoff along the slope movement principle, runoff area changes such as changes of saturated water in surface or underground area, were simulated by this model. TOPMODEL model structure and the concept is relatively simple with less parameters, taking advantage of the terrain data readily available, and can be used to calculate runoff yield in basin with no information. But in the Karst region, TOPMODEL has the following shortcomings:1) There is no direct contact between topographic index distribution and underground river flows out of the way. That is, the space distribution of groundwater systems is not controlled by topography, but mainly depends on geological underground karst fissures, pipes or underground river. Therefore, the truth will be distorted or failed relying on DEM model in karst water system.2) It is too simple to reflects the groundwater hydrology cycle in this model. In karst regions, groundwater karst aqueous medium are usually pipes or ground rivers, or their spatial distribution are complex and irregular, or its permeability is usually changes over time. But these are not to be described in this model.3) Due to the impact of ground river entrance, river water capacity is limited. The hysteresis of flood can not be resolved by this model.Base on these results of this study, the main conclusions obtained in this thesis are as follows.1) Toad neck Basin can be divided into three general tributaries and 108 sub-basins. The three tributaries are the Yuantou River in the east, the Long Beach river in the middle and Jiashaxi River in the west. There are both surface and underground river segments in all three rivers. Finally, they are converged into the toad neck reservoir through karst conduits. According to Strahler river classification method, constituted river basin structure with 54 headwaters and 5 classified levels of Hamajing watershed has been devided, which reflect this small size basin is a high magnitude water systems with complex structure.2) The toad neck basin can be divided into peak cluster depressions and peak cluster valleys. In peak cluster depression areas, sinkholes are developed in depression and there is no surface water exists. Surface water was converged into the main river through the dark underground river. On the flat bottom of depressions, red clay often deposited as relatively high moisture layer. The depressions drainage flows into the ground river through the main sinkholes or vent shaft. In Karst Valley region, the terrain is relatively flat with surface watershed, while valley with steep edges often covered with corrosion residual brown, red clay or drifting alluvium at the bottom. The water sources are from karst springs, eventually flowing into the underground river. Due to limited data base, distributed watershed model parameters are divided into two zones in order to facilitate the setting of the model parameters.3) The Hamajing watershed hydrology model constructed by the using of KARST-TOPMODEL was used to simulate the 11 July 2005 flood events. According to the measured data, the flood is equivalent to P=2% of the rainstorm (i.e. once in fifty years). There are three detention entrance was founded with flood hysteresis. Baihe Dong river entrance was the first one. Followed by Long Beach River river entrance, Jiasha creek was the last one. The largest capacity of flood hysteresis is 694,800 m3,563,900 m3 and 1,503,600 m3 respectively. Although the capacity of flood hysteresis is affected by the water capacity flowed from upstream river, the critical reason is the ratio of the area occupied by the relevant karst depressions. With high area ratio, the flood regulation and storage effect of karst depressions is stronger, and its weakening effect on the peak of flood is more obvious.4) By calibration and validation of three different flood process from 2003 to 2005 combined with fitting these year hydrological processes, it was proved that the improved KARST-TOPMODEL is reasonable. And its parameter calibration was reliable.5) By using of Hamajing watershed model constructed by the KARST-TOPMODEL, flood processes with different frequencies and rainfall intensity were simulated. When rainfall is small, the process of flood is consistent with detention process without considering the flood hysteresis. But as rainfall increases, the peak shape becomes increasingly flat and the flood process becomes longer. In other words, regulation and storage functions of karst watershed become apparent.The main feature of this thesis is reflected in three aspects.1) Base on field karst hydrogeology survey, combined with DEM model building, the whole basin was divided into 108 sub-basin. Then each sub-basin was calculated separately by using of TOPMODEL model. These results of the various sub-river basins were converged to calculate export. The model convergence was on the use of Muskingum method. The difference between karst underground pipes and surface runoff process can be detected.2) Set the blood hysteresis process in the detention program. It can make the simulation process is more closer as the actual process. And the regulation and storage functions of karst watershed become apparent.更多还原