微观尺度分析挠力河流域耕地利用水土资源匹配时空动态

该文基于供给与需求视角,构建了微观尺度下的水土资源匹配指数测算模型,在综合考虑区域气候和水资源变化、耕地利用结构调整、作物各生育期需水量差异等因素基础上,研究2000—2015年挠力河流域作物全生育期和各生育期耕地利用水土资源匹配的时空动态。结果表明:除作物生育前期需水量围绕2.92×10~9 m~3上下波动和作物生育后期耕地利用水资源有效供给量波动降低外,作物全生育期和各生育期需水量和水资源有效供给量均呈增长态势。作物全生育期耕地利用水土资源匹配程度总体较低,其指数主要分布在0.45以下,但呈现出升高趋势且差异化增强。作物各生育期耕地利用水土资源匹配指数变化复杂,以2010年为界,表现出明显的阶段性特征;作物需水量、水资源有效供给量和水土资源匹配指数均呈现出其高值区由流域中游东部向流域中游西部和流域下游转移并扩张的空间动态特征。研究可为挠力河流域耕地利用水土资源高效利用提供参考。

Spatiotemporal dynamics of land and water resources matching of cultivated land use based on micro scale in Naoli River Basin

Abstract: Water and soil are the core of cultivated land use. Their matching in space and time is closely related with sustainable use of cultivated land and grain security. In this study, we analyzed the spatiotemporal dynamics of land and water resources matching of cultivated land use based on micro scale in Naoli River Basin. The crop evapotranspiration was calculated as the index of cultivated land water demand. The available water supply was calculated based on water balance equation in dryland and paddy field. The data of cultivated land use during main growing stages of crops (corn and rice) were derived from Landsat TM/OLI. Meteorological and crop growth data were from local meteorological stations. From the perspective of supply and demand, a land and water resources matching index model was built. The research unit of 30 m by 30 m grid was used to quantitatively analyze spatiotemporal distribution and dynamics of water demand, available water supply and land and water resources matching index of cultivated land in the whole crop growing stage and different crop growing stages from 2000 to 2015, which was based on the comprehensive consideration of factors such as regional climate and water resource change, planting structure adjustment, the difference in available water supply between dry and paddy field, and the difference of water demand of cultivated land in different crop growing stages. The results showed that: 1) Cultivated land in the study area continued to increase. Its area increased by 15.79% from 2000 to 2015. The proportion of paddy field in the total cultivated land increased to 36.28% in 2015 from 22.70% in 2000 and the proportion of dryland in the total cultivated land decreased to 63.72% in 2015 from 77.30% in 2000. The increased paddy field was mainly distributed in the west of the middle reaches and lower reaches of Naoli River Basin. 2) The water demand and available water supply of cultivated land use in the whole crop growing stage and each crop growing stage all showed upward trend, except that water demand fluctuated around 2.92×109 m3 in the early crop growing stage and available water supply decreased in the late crop growing stage. 3) The variation range of land and water resources matching index of cultivated land use increased but mainly distributed below 0.45 in the whole crop growing stage, the degree of land and water resources matching increased and its differentiation enhanced in the study area. The change of land and water resources matching index in each crop growing stage was complex and it showed obvious periodic characteristics taking 2010 as a boundary, land and water resources matching index of cultivated land increased slowly in early and middle crop growing stages while decreased rapidly in late crop growing stage from 2000 to 2010, and the land and water resources matching index of cultivated land use increased rapidly in early and middle crop growing stage while decreased slowly in late crop growing stage from 2010 to 2015. 4) Under the influence of the structure and distrubution of cultivated land use, the spatial dynamic change of water demand, available water supply, land and water resources matching index of cultivated land use in Naoli River Basin were all characteristiced with high values transfering and expanding from the eastern middle reaches to the western middle reaches and the lower reaches. The study will provide valuble information for efficient utility of cultivated land and water resources in Naoli River Basin.