杭嘉湖地区淹水稻田氮素径流流失负荷估算

通过大田试验、定点观测等方法对现有的关于长江三角洲平原地区水田降雨径流产生模型进行验证，发现该模型在考虑排水堰的影响之后，基本能够模拟杭嘉湖平原水网区水田降雨径流产生过程，误差在-19.9%～+18.0%之间，同时提出了淹水稻田降雨径流氮素浓度模型（R=0.948），从而得到了该地区淹水稻田氮素径流流失负荷模型.在此基础上，搜集了该地区水稻田氮肥施用情况、30年逐日降雨量、1∶250000地形图、土地利用现状图和水系图等资，利用GIS技术对该地区淹水稻田氮素的径流流失负荷以及空间分布进行了估算和分析.结果表明，该地区淹水稻田氮素径流流失负荷平均高达35.26 kg N·hm^-2，约占当季水稻氮素施用量的12.69%，而且在空间上存在着明显的差异，安吉、余杭等地区氮素流失负荷和流失率明显高于其它地区，海宁地区的流失情况也较为严重.

Estimation of N loss loading by runoff from paddy field during submersed period in Hangjiahu area

As the largest bread basket in Zhejiang Province, Hangjiahu area is facing more and more serious water pollution, while the N loss loading by runoff from the paddy field during its submersed period is the main cause of the pollution. Through field experiment and fixed spot observation, the model of precipitation - runoff in Yangtze delta was testified, and the results showed that the precipitation - runoff model from HE Baogen was basically accorded with the fact after considering the impact of field overflow mouth, and the error was between - 19. 9% and + 18. 0%. The model of N concentration with precipitation - runoff in paddy field during submersed period was brought forward, with the R value being 0. 948. These two models consisted of the model of N loss loading by runoff from paddy field during submersed period. Based on this model as well as the past 30 years data of fertilization and precipitation, 1: 250,000 topography map, land use map, and water system map, the N loss loading and its distribution were estimated by using GIS method, and the results showed that the N loss loading was different from place to place, with an average of 35.26 kg N x hm(-2), and accounting for 12. 69% of the applied N. The N loss loading in Anji and Yuhang with obviously more precipitation was higher than that in other places, while Haining also had a serious N loss problem because of the huge amount of applied N.