基于不同土地利用情景下的汉江流域生态需水量研究

发布时间：2018-10-19 18:02

【摘要】：生态需水是流域水资源分配中的重要组成部分,是保证流域生态系统健康稳定、正常发挥的基本需水量。在现代生产生活需水量越来越大的条件下,很多区域出现了生产生活需水大量挤占生态需水的情况。因此,研究流域生态需水量,保证流域生态需水量可以达到一定生态要求,是进行流域水资源合理分配的重要条件。湖北省境内的汉江流域工农业发达、人口集聚度高,流域内的水资源相对比较丰富。但是受南水北调中线工程的影响,流域内的来水量会有所减少,那么流域的生态需水量势必也会受到影响,进而影响流域的生态环境健康。因此,本文设置了调水和不调水两种情景,分别研究这两种不同情景下流域未来的生态需水量,并对研究结果进行对比,比较其差异。本文关于生态需水量的计算是以未来各土地利用类型的面积为基础,因此,首先必须对流域内未来的土地利用变化进行模拟。土地利用变化的模拟基于CLUE-S模型,该模型对中小尺度土地利用的模拟具有较高准确性。利用模型,在调水和不调水两种情景下模拟了未来30年6大土地利用类型的变化情况,其主要的步骤有：在Arcgis平台上对CLUE-S模型所需的数据处理后,利用CLUE-S模型自带的转换工具,将所有数据转换为模型可以识别的ASCII文件,再将模型所需的所有文件放入模型文件夹下,运行模型,得出两种情景下未来30年的土地利用情况。将得出的结果再放入Arcgis中,转换为土地利用图。根据模拟结果,对流域生态系统进行分类,主要分为林地、草地、农田、城镇和水域这五大类。其中林地、草地和农田系统根据模型模拟的土地利用面积计算生态需水量,城镇系统的生态需水量以公共绿地面积为主,水域系统生态需水量的计算则主要利用Tennant法和最小月平均径流量法。在计算出各子系统的生态需水量后,根据生态需水整合原则,整合出整个流域系统的生态需水量。本研究的结论主要如下： (1)模型模拟结果显示,在预设的两种情景下,研究区未来的耕地和建设用地都表现为增长的趋势,林地、水域和未利用地都表现为减少的趋势,草地则没有发生变化,但调水情景的土地面积变化幅度明显小于不调水情景。 (2)在各大系统中,水域系统生态需水量最大,其次是农田系统和林地系统,这三大系统是流域生态需水的最主要类型。水域系统生态需水量的大小直接决定了整个流域生态需水量的大小。 (3)两种情景相比,不调水情景下,流域整体的生态需水量随着时间的推移缓慢增加,即未来流域生态需水量的需求不断增多；调水情景下,流域未来的生态需水量随着时间的推移大幅减少。即南水北调工程实施后,流域的生态需水量将会大幅减少。这样的结果表明,调水工程的实施会对整个流域生态系统的安全性,稳定程度带来较大威胁。
[Abstract]:Ecological water demand is an important part of the allocation of water resources in the basin, and it is the basic water demand to ensure the healthy and stable ecosystem of the basin. Under the condition of increasing water demand in modern production and life, the production and living water demand accounts for ecological water demand in many areas. Therefore, it is an important condition for the rational allocation of water resources to study the ecological water demand of the watershed to ensure that the ecological water demand of the basin can reach a certain ecological requirement. The Hanjiang River basin in Hubei Province is developed in industry and agriculture with high population concentration and relatively abundant water resources. However, due to the influence of the South-to-North Water transfer Project, the amount of water in the basin will decrease, so the ecological water demand of the basin will also be affected, which will affect the ecological environment of the basin. Therefore, this paper sets up two scenarios of water transfer and non-water transfer, studies the future ecological water demand of the watershed under these two different scenarios, and compares the results of the study and compares their differences. In this paper, the calculation of ecological water demand is based on the area of each land use type in the future. Therefore, it is necessary to simulate the future land use change in the watershed. The simulation of land use change is based on CLUE-S model, which has high accuracy for the simulation of small and medium scale land use. The model is used to simulate the changes of the six major land use types in the next 30 years under the two scenarios of water transfer and no water transfer. The main steps are as follows: after processing the data needed for the CLUE-S model on the Arcgis platform, using the conversion tools brought with the CLUE-S model. All the data are converted into ASCII files which can be recognized by the model, and then all the files required by the model are put into the model folder to run the model, and the land use in the next 30 years under the two scenarios is obtained. The results are then put into Arcgis and converted into land use maps. According to the simulation results, the watershed ecosystem is classified into five categories: woodland, grassland, farmland, town and water area. The ecological water demand of woodland, grassland and farmland system is calculated according to the land use area simulated by the model, and the ecological water demand of urban system is mainly public green space area. The Tennant method and the minimum monthly average runoff method are used to calculate the ecological water demand of the water system. After calculating the ecological water demand of each subsystem, the ecological water demand of the whole watershed system is integrated according to the principle of ecological water demand integration. The main conclusions of this study are as follows: (1) the model simulation results show that the future cultivated land and construction land in the study area are increasing trend under the two scenarios. Both the water area and the unused land showed a decreasing trend, while the grassland did not change, but the range of land area change in the water transfer scenario was obviously smaller than that in the non-water transfer scenario. (2) among the major systems, the water system had the largest ecological water demand. Secondly, farmland system and woodland system, which are the most important types of ecological water demand. The water system ecological water demand directly determines the whole watershed ecological water demand. (3) compared with the non-water transfer scenario, the whole watershed ecological water demand increases slowly with the passage of time. That is to say, the demand of future watershed ecological water demand is increasing continuously; under the water transfer scenario, the future ecological water demand of the basin will decrease significantly with the passage of time. That is, after the implementation of the South-to-North Water transfer Project, the ecological water demand of the watershed will be greatly reduced. The results show that the implementation of the water transfer project will threaten the security and stability of the whole watershed ecosystem.
【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV213.4;X143

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