1990-2013年挠力河流域耕地变化下水土资源平衡效应分析

为揭示挠力河流域耕地资源水分盈亏态势,该文以遥感数据、长时间序列气象数据和DEM数据为基本数据源,基于遥感和地理信息系统技术,从旱改水角度出发探讨1990-2013年间流域耕地变化下的水土资源平衡效应问题。结果表明:20多年间挠力河流域水田、旱地间变化极为剧烈,其变化以耕地内部转化为主;农田需水量由1990年的541 mm上升至2013年的581.82 mm,变化主要集中于流域西北部和中部地区,年实际蒸散量区间为438~587 mm,整体表现出"中间低,两头高"的分布特征;耕地水分盈亏程度变化明显,盈亏指数评价等级空间分布差异较大,除严重缺水耕地面积少量增加外,其余4种评价等级耕地变化强烈,其中正常缺水耕地的面积比例下降22.06%,其余3种评价等级耕地都出现较大面积的增加,表明流域耕地水分亏缺态势进一步加剧。该研究结果可为挠力河流域农田灌溉方案的制定提供借鉴和参考。

Farmland change induced land and water resource balance in Naoli River Basin from 1990 to 2013

Abstract: Since early 1990s, the agricultural structure of Naoli River Basin has been greatly adjusted with large amount of dry land changed into paddy field. This resulted in a set of problems in the utilization of water resources. To reveal the water profit and loss situation of the cultivated land resources in this river basin, the dynamic changes between the dry land and paddy field was analyzed and the farmland water requirements of the cultivated land in this basin was calculated in this article. By modeling the rice planting proportion coefficient which could show the structure of cultivated land, and using the contribution rate that was borrowed from the thought of economics, combing the results of established various types of crop, which was from the research of other scholars, the rate of paddy field and dry land proportion was determined. The remote sensing image data, the long-term sequenced meteorological data and the DEM data were used as its fundamental data resources in all the above analysis. By combining the planar climatic elements data which was attained from the dot data interpolation processing, the Penman-Monteith Model was used to create the computational condition of reference evapotranspiration (ET0) , which was generally agreed upon in the academic circles, the related model was used to analyze and compute the actual evapotranspiration (ET) for the condition of Naoli River basin, evaluation model of water profit and loss degree was established, and the order of evaluation standard was also structured to analyze the variation of area changes at different levels of moisture shortage. Fastly, the balance effect questions between the soil and water resources under the situation where the cultivated land constantly changed in the basin between 1990 and 2013 were discussed in this article. Results showed that the changes between the paddy field and the dry land in the Naoli River Basin were incredibly violent. The internal transformations between the paddy field and dry land were the primary changes. The dry land was the main source land for the increase of the paddy field; the farmland water requirements also increased from 541 mm in 1990 to 581.82 mm in 2013. These changes were mainly concentrated in the northwest and middle regions of this river basin and the range of the annual actual evapotranspiration was between 438-587 mm. Its overall distribution characteristic manifested itself as 'middle low, two ends high'; the change degree of the cultivated land's water profit and loss were obvious and the spatial distribution differences of the profit and loss index for evaluation grades were great. Except for the slight increase of the cultivated land with serious water shortage, the cultivated land area of the rest four evaluation grades all changed strongly. Among them, the area proportion of cultivated land with normal water shortage decreased 22.06% and the area proportions of cultivated land for the rest three evaluation grades all increased 4.74%, 9.61% and 7.72% successively. The above statement shows that the water deficit of the cultivated land in this river basin has been further intensified. These research results provide the references and consultancies for the farmland irrigation schemes in the Naoli River Basin.