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一、柳河地区土壤侵蚀模式 柳河地区位于北纬42°10′～43°00′,东经120°30′～122°30′,地处辽西与内蒙交界,面积7000多km~2,是全国水土保持重点区之一。从全国侵蚀分区看,柳河地区属风蚀、水蚀过渡区、春季风蚀严重,夏季水蚀严重;北部风蚀严重,南部水蚀严重,时空各异。 为了推算全区的土壤侵蚀量,我们首先建立风蚀、水蚀过渡区的侵蚀类型模式及不同类型条件下的侵蚀强度模式。设总侵蚀量为E,则 E=E水+E风 (1) 柳河地区是风蚀、水蚀的过渡类型区,过渡类型是典型的模糊数学问题,因此我们采用模糊集合即建立隶属度的方法来求土壤侵蚀类型模式。 在柳河地区的每一个地理位置上,设水蚀与风蚀的模糊集分别为U水、U风,与其相应的隶属函数为P水、P风。则有 P水+P风=1 (2) 由上式可见,只要确定P风即可求出P水。这里因缺少风蚀的定位观测资料,只得用经验推理法来求P风。分析影响风蚀隶属度的主导因素,得到隶属函数:
I. Pattern of Soil Erosion in Liuhe Region The Liuhe area is located at the latitude of 42 ° 10 ’~ 43 ° 00’ and the longitude of 120 ° 30 ’~ 122 ° 30’ east longitude and is located at the border of Liaoxi and Inner Mongolia with an area of over 7000 km ~ 2. It is a national soil and water conservation One of the key areas. From the national erosion zoning, the Liuhe area belongs to the transition zone of wind erosion and water erosion. The wind erosion in spring is serious and the water erosion is serious in summer. The wind erosion in the north is severe, and the water erosion in the south is serious with different time and space. In order to calculate the amount of soil erosion in the whole region, we first establish the erosion type pattern of wind erosion and water erosion transition zone and the erosion intensity pattern under different types of conditions. Let E = E water + E wind (1) Liuhe area is a transitional area of wind erosion and water erosion. The transition type is a typical fuzzy mathematics problem. Therefore, we use the fuzzy set to establish the membership degree Seeking soil erosion type patterns. In each geographical location in Liuhe area, the fuzzy sets of water erosion and wind erosion are assumed to be U-water and U-wind, respectively, and their corresponding membership functions are P-water and P-wind. Then P water + P wind = 1 (2) can be seen from the above equation, as long as P wind can determine the P water. Here due to the lack of wind erosion positioning observations, had to use empirical reasoning to find the P wind. Analyze the dominant factors affecting the membership degree of wind erosion and get the membership function: