【作者】 项国圣；

【导师】 钱鞠；

【作者基本信息】 兰州大学 ， 水文学及水资源， 2011， 硕士

【摘要】 张掖盆地位于黑河干流中游地区,是黑河流域水资源利用程度最高和利用量最大的地区,也是控制黑河流域水循环演化的关键地带。但由于水资源不合理的开发利用造成张掖盆地地表水被过度引用于农业灌溉,使得黑河流域水资源矛盾日益显著,并造成生态环境十分脆弱的下游地区情况更加恶化。为了拯救下游天然绿洲,改善生态环境,在国务院于2001年8月批准的《黑河流域近期治理规划》中明确规定了必须保证正义峡下泄水量。这就要求张掖盆地应加大区域地下水开采,增加地下水在总用水量中的比率,合理优化配置水资源。另外,近年来张掖甘州城区及周边地区出现地下水位持续上升现象,给城区建设带来较大危害,而有些灌区则存在较严重的超采现象,不同地段的地下水开发利用状况差异很大。对张掖盆地按灌区进行地下水开发风险评价,据此探讨出地下水资源可持续开发利用的途径,对研究区地下水资源合理开发利用有着重要的研究意义。本文围绕地下水开发风险问题,分析了其主要的影响因素。由于张掖盆地的地下水系统有其独特的特点,在地下水开发风险综合评估指标体系时综合参考了前人的研究成果以及研究区地下水系统的具体情况,所构建的地下水风险评价指标体系在结构上与前人有一定的共同点,同时也有其独特之处且适用于张掖盆地地下水开发风险的研究。采用地下水风险突变评价模型进行张掖盆地地下水开发风险评价。首先按照突变模型评价法的评价步骤,将各指标原始数值按隶属度函数法转换为0-1的突变级数,然后按归一公式由单项指标层向目标层逐层向上综合计算。评价结果显示,张掖盆地各灌区的地下水开发风险值介于0.6257-0.8339之间,按风险划分等级标准,均属中度风险区。为调控地下水开发风险,本文建立了地下水数值模拟模型。通过对模型的识别与校正,观测孔水位拟合误差符合精度要求,说明对张掖盆地含水层的概化、水文地质参数的确定、源汇项的处理是合理的,所建立的模型可以用来进行地下水数值模拟和动态预报。根据黑河流域中下游分水方案,按各灌区地下水的开采潜力状况设计地下水开采方案,并将其输入到校正好的数值模型中进行运行。结果表明：按规划增加地下水开采量,虽然泉水溢出量有减少的趋势(泉水溢出量有现状的56448×104m~3/a减少到51245×104m~3/a,减少了9.2%)；但由于地下水位的降低,潜水蒸发量得到有效控制,由28924×1041113降低到20683×104m~3,降低了28.5%。另外,增加地下水开采量,一方面激化了地表水对地下水的河道补给,补给量有现状年的31450×104m~3/a增加到34014×104m~3/a,；但另一方面由于地下水渠系利用系数高于地表水渠系综合利用系数,加大开采地下水可置换出地表水,根据地表水一地下水的换算关系计算出增加地下水开采量7600×104m~3,可节约地表水1.01×108m~3,扣除河道对地下水的补给增长量2564×104m~3,能使河道年径流量增加7536×104m~3,不仅提高了水资源利用效率,还保障了正义峡下泄水量。在化解地下水开发风险的同时,还获得环境和社会效益,实现水资源、生态环境和社会经济的可持续发展。更多还原

【Abstract】 Zhangye Basin is iocated in the middle reaches of Heihe River and is the area with the highest utilization degree and largest utilization amount of water resources in Heihe River Basin, it is also the key region controlling the evolution of water cycle in this basin area. However, surface water in Zhangye Basin was over irrigated which was caused by the population growth and economic development, making the Heihe River Basin water resources become more and more serious and the fragile ecological environment situation become worse and worse downstream. In order to save and improve the ecological environment of natural oasis downstream, the State Council approved the "Recent Management and Planning of Heihes River Basin" in August 2001 and clearly states the need to ensure the discharged water in Zhengyixia. This requires the increase of the exploitation of groundwater in Zhangye basin and the ratio of groundwater in the total water consumption, as well as the program to optimization and the allocation of water resources. In addition, in recent years, the groundwater level of Ganzhou City in Zhangye and the surrounding areas continued to rise, which brought greater harms to the city building; there exists the phenomenon of more serious over-exploitation in some irrigation and phenomenon of great variation within the development and utilization of groundwater in different sections. Therefore, making risk assessments of groundwater irrigation development in Zhangye Basin and thus exploring sustainable ways to the use and development of groundwater resources are of great significations to the study of rational development and utilization of groundwater resources in the research region.In this paper, our study focuses on the risk of groundwater development, with the analysis of its main effective factors. Due to the particular characteristics of groundwater system in Zhangye Basin, we have taken previous research results and specific circumstances of groundwater system into consideration within the comprehensive evaluation index system of groundwater development risks. Therefore, the index system is same to the previous system on the aspect of structure, however, its specific characteristics are suitable to the research of assessment of groundwater development risks. On the base of catastrophe theory, we use catastrophe evaluation model to evaluate the groundwater development risks in Zhangye Basin. Firstly, convert the original index value of membership function to mutation series of 0 to 1 in accordance with the evaluation steps. Then make comprehensive calculation from single index layer to target layer using normalized formula. Assessment results showed that risk values of groundwater development in each irrigation region within the groundwater system in Zhangye Basin were between 0.6257-0.8339, which belonged to the moderate risk area (0.5-0.85) according to the grade criteria of risk category.In order to control the groundwater development risks, numerical evaluation model was established. By the identification and calibration of this model we found that the water level values of observation wells were meet to the accuracy needs. Those above indicated that the generalization of aquifer layers, identification of hydrologic geology parameters and the treatment of terms of source and sink were reasonable. Therefore, the model established could be used to make simulation and dynamic forecasts of groundwater. According the scheme of diversion of water in the middle and lower reaches of Heihe River watershed, we determine the increase or decrease of the amount of groundwater development in accordance with the potentiality of each irrigation region and input values to the calibrated model. Results indicated that if we increase the amount of groundwater development according to the planning, there was a decline trend of spring water (spring water flow varied from 56448×104m~3/a down to 51245×104m~3/a, decreased by 9.2%). However, due to the decrease of groundwater level, phreatic evaporation was controlled effectively, which was reduced from 28924×104m~3/a reduced to 20683×104m~3/a, reduced by 28.5%. In addition, on the one hand, the increase of the amount of groundwater development could enhance the river recharge from surface water to groundwater, with the recharge amount increase from 31450×104m~3/a to 34014×104m~3/a. On the other hand, because the canal system usage efficient of surface water was higher to groundwater, then increase groundwater development amount could replace surface. According to the coupling relationship of surface water and groundwater we could calculate that when the development amount was 7600×104m~3, surface water could be saved by 1.01×108m~3, with the deduction of river recharge amount, 2564×104m~3 and runoff amount in river increased to 7536×104m~3. Those above not only could increase utilization efficiency, but ensure the discharge water amount in Zhengyixia. Along with the defuse of groundwater development risk, we could also obtain environment and society benefits, then we could achieve sustainable developments of water resources, ecological environment and socio-economy.更多还原