| 摘要: |
| 土地利用对水质的影响关系在不同类型河流和不同时空尺度下存在差异，研究两者之间的定量影响差异可为不同类型河流水污染的有效控制提供科学依据。本文以喀斯特河流（乌江）和半喀斯特河流（嘉陵江）为研究对象，基于两条河流的水质监测数据和流域内的土地利用数据，选取河岸带缓冲区（100~500 m）和子流域六个空间尺度，采用冗余分析定量探讨不同类型流域土地利用对水质的多时空尺度影响差异。结果表明：（1）嘉陵江流域的土地利用主要以耕地为主，乌江流域的土地利用主要以林地为主。两流域的聚集度和最大斑块指数相差极小，聚集度在各空间尺度上差异不显著，最大斑块指数随空间尺度的上升而减小。嘉陵江流域的边缘密度高于乌江流域，且在流域内随空间尺度的上升而减小，乌江流域呈相反趋势。香农多样性的值在嘉陵江流域高于乌江流域，在嘉陵江流域内随空间尺度的上升而减小，而在乌江流域随空间尺度的上升先增大后减小；（2）多数水质指标浓度在雨季高于旱季，总氮是两流域水质污染的关键指标，总磷是潜在的营养物质污染物，整体上乌江流域水质优于嘉陵江流域，喀斯特地貌面积占比和土地利用差异是造成两流域水质存在差异的重要原因。（3）嘉陵江流域土地利用在旱季和河岸带400 m缓冲区对水质变量解释率最高，乌江流域土地利用在雨季和子流域对水质变量解释率最高，总体上乌江流域土地利用对水质变化的贡献率高于嘉陵江流域；（4）不同土地利用指数对水质的影响存在差异。建设用地、边缘密度、耕地和水域对嘉陵江水质影响显著，其中水域对水质具有正面效应，水域、香农多样性指数和耕地是影响乌江流域水质的关键指数，其中耕地对水质具有一定积极影响。因此，不同类型的河流应在最佳时空尺度范围内，根据流域内地貌特征合理规划耕地和建设用地面积，提升河岸带林地覆盖率，推行生态施肥技术和生态防治技术，从而促进河流水环境安全和水资源可持续利用。 |
| 关键词: 河流水质 景观格局 多尺度效应 冗余分析 喀斯特流域 |
| DOI： |
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| 基金项目:国家自然科学基金项目 (42407094); 重庆市自然科学基金项目 (2024NSCQ-MSX3061); 重庆市教委科学技术研究计划项目 (KJQN202200517); 重庆师范大学基金项目 (20XLB022) |
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| Impact differences of land use on river water quality at multiple spatial and temporal scales between Karst Rivers and Semiarid Karst River Basins |
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wang jing jing, liu rui, xie yu xin, zhang jing
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Chongqing Normal University
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| Abstract: |
| The relationship between land use and water quality exhibits variations across different river types and spatiotemporal scales. Quantitative analysis of these variations can provide scientific grounds for effective water pollution control in diverse river types. This study focused on the karst river Wujiang and the semi-karst river Jialingjiang, and utilized water quality monitoring data and land use data within their respective riparian buffer zones (100~500 m) and sub-watershed. Six spatial scales were considered, and redundancy analysis was employed to quantitatively explore the multi-scale impacts of land use on water quality in these different types of watersheds. The findings were as follows: (1) The land use in the Jialing River Basin was dominated by farmland land, while in the Wujiang River Basin, it was characterized by forest land.The differences in aggregation and the maximum patch index between the two basins were minimal. Aggregation showed no significant differences across spatial scales, and the maximum patch index decreased with increasing spatial scale. Edge density was higher in the Jialing River Basin than in the Wujiang River Basin, and it decreases with increasing spatial scale , showing an opposite trend in the Wujiang River Basin. The Shannon Diversity Index was higher in the Jialing River Basin than in the Wujiang River Basin, and it decreases with increasing spatial scale in the Jialing River Basin, while in the Wujiang River Basin, it first increases and then decreases with spatial scale. (2) The concentration of most water quality indicators was higher in the wet season than in the dry season. Total nitrogen was a key indicator of water quality pollution in both basins, and total phosphorus was a potential nutrient pollutant. Overall, the water quality in the Wujiang River Basin was better than that in the Jialing River Basin. The proportion of karst landform area and differences in land use were important reasons for the differences in water quality between the two basins. (3) Land use in the Jialing River Basin had the highest explanatory power for water quality variables in the dry season and at the 400 m riparian buffer zone. In the Wujiang River Basin, land use had the highest explanatory power for water quality variables in the wet season and at the sub-watershed scale. Generally, land use in the Wujiang River Basin contributed more to water quality changes than in the Jialing River Basin. (4) Different land use indices had varying impacts on water quality. Construction land, edge density, farmland, and water bodies significantly impacted the water quality of the Jialing River, with water bodies exerting a positive effect. Water bodies, the Shannon Diversity Index, and farmland were the key indices that affected the water quality of the Wujiang River Basin, with farmland having a certain positive impact. Therefore, different types of rivers should, within the optimal spatial scale, plan the area of farmland and construction land based on the landform characteristics of the basin, increase the forest coverage rate in riparian zones, and promote ecological fertilization and ecological control technologies to enhance river water environmental safety and sustainable water resource utilization. |
| Key words: riverine water quality landscape pattern multiple spatial and temporal scales redundancy analysis Karst River |
