灌区中居民点与水土资源邻近关系——以张掖绿洲为例

干旱区内陆河流域的核心在于水,核心区域在于绿洲。灌区是构成绿洲的最基本单元。论文应用最邻近距离指数(NNI),分析了张掖绿洲灌区中居民点与水浇地及渠系之间的空间耦合关系,结果表明:在张掖大小共39个灌区中,有22个灌区的NNI值<0.5,灌区中居民点总体表现为聚集分布态势,但空间差异明显,沿山灌区居民点聚集程度明显高于绿洲中腹灌区,映射出不同灌区水资源的基本约束力。从微观角度考察,居民点与水浇地、渠系、道路之间的平均临近距离从沿山独立灌区-绿洲边缘灌区-绿洲中腹灌区逐步增加,说明沿山灌区水浇地、渠系与居民点的关系更密切。灌区中居民点与渠系、水浇地表现出显著的"亲水型"和"亲地型","质点"(居民点)-"廊道"(渠系和路网)-"域面"(土地)之间存在非常密切的相互依存关系。

Relationship between settlement and land-water resources in irrigated districts: a case of Zhangye Oasis

Heihe River Basin is the second largest inland river basin in the arid northwest China. In arid inland basin, the core problem is water resources, while the core area is an oasis. In modern oasis, the "water resource" of the actual use of the unit is "irrigated district". Oasis formed through the integration of complex irrigated areas. Under the strong control and guidance of the artificial canal system, water supply quantity determines irrigation district, and irrigated land determines population carrying capacity, water-soil-human systems exist a high degree of interdependence and symbiosis. One of the factors beyond the reasonable range, will be a profound impact on the system-wide coordination and stability as well as the direction of succession. Therefore, the law of formation and development of settlements from the coupling relationship between micro process, micro mechanism and the micro pattern, must be discussed to analyze the pattern of settlements which distributed in different types of irrigation district, to explore the coupling relationship between "Point"(settlements) "-corridor"(canal systems and road network)and "surface"(irrigated land). Applied nearest distance index, the paper analyzes spatial coupling relationship between the settlements and irrigated lands, as well as canal systems for 39 irrigation districts in Zhangye Oasis, Gansu Province, China. The results showed that:in the 39 irrigated districts,there are 22 irrigation districts in which NNI value is less than 0.5, settlements show aggregated distribution trend, but the space differences are significant. Hillside irrigation districts are often formed by independent river, its scale are smaller. They have limited water resources and poor level of assurance, water resource have stronger restrictive for human activities and settlements. Human activities are squeezed in a relatively limited space, which showed aggregated distribution of population and settlement. Irrigated districts located in abdomen of oasis, because of rich water resources and the development of a long history, detente human-land relationship,population and settlements showed discrete distribution trend. From the independence irrigated districts(Xinba Irrigated District)located in hillside to the irrigated district(Pinchuan Irrigated District)distributed in the oasis edge,and then to the irrigated district(Yinke Irrigated District)located in abdomen of oasis, the average near distance between settlements and irrigable land/canal system/road network are gradually increase, illustrate the relationship between irrigable land, and canal, as well as settlements come progressively closer. From the microscopic point of inspection, inside irrigation districts, settlements and water-land resources maintained very close relationship, the average nearby distance between settlements and irrigated land, settlements and canal systems, settlements and road network, are gradually increase. Settlements and the canal systems, as well as irrigated lands,exhibit significant feature of "hydrophilic type" and "pro-land type". "Point"(settlements) "-corridor"(canal systems and road network)-"surface"(land) exists a very close interdependence. Previous research on inland river basin in arid region, were often carried from the macro perspective of "mountain-oasis-desert", this paper, to break the routine, select micro scale(irrigated district)to study the coupling relationship between settlement and the water and land resources from micro mechanism, microscopic pattern, which allows people to see more clearly, water resource is how to influence the settlement distribution in oasis.