Determinate the runoff of a watershed is a challenge due to the complexity of representing all “inlets” and “outlets” involved in a rainfall–runoff model. Therefore, methodologies applied for this purpose should have a good representation of the variables that most influence in this process. One of the models used to calculate the design flow is the (USDA in Urban Hydrology for Small. Technical release, no 55 (TR-55). Soil Conservation Service. Washigton, DC, http://scholar.google.com/scholar?hl=en&btnG=Search&q=intitle:Urban+Hydrology+for+Small+watersheds#1, 1986), which considers the analysis changes in soil coverage, time of concentration (tc), and recurrence period (T). In this way, this study sought to evaluate the hydrological behavior of a watershed with an increase in soil waterproofing. These modifications were correlated with the variation of runoff coefficients (CN), modifications of the periods of recurrence indicated by the literature, and different equations of the time of concentration. Its application was carried out in the Ribeirão do Suru watershed, Santana de Parnaíba, SP, Brazil. The CN {75; 80; 85; 90} increased 3.14, 5.61, 10.90 and 15.85%, respectively. In the most critical situation, runoff was 15.85% higher in estimated CN. The variation of precipitation as a function of T (2, 5, 10, 25, 50, 100 and 500) and application of 11 time of concentration methods designed 132 hydrographs and flow values that were statistically treated in T of Student and in the Analysis of Variance (ANOVA). Except for Bransby Willians associated Cinematic Method, Dooge with Johnstone and CTH with Tsuchyia, the pairs showed degrees of correlation below 59%. The greatest correlation was observed in Jonhstone with Dooge (90%), followed by the Kinematic Method with the Soil Conservation Service Method (83%) and with Dodge (74%). As a result, it was possible to demonstrate the behavior of the SCS parameters to minimize subjectivities and revealing how each parameter impacts the flow of the watershed. Finally, the sensitivity attributed to T was the highest among the three analyzed.

由于表示降雨-径流模型中涉及的所有“入口”和“出口”的复杂性，确定流域的径流是一个挑战。因此，为此目的应用的方法应能很好地表示在此过程中影响最大的变量。用于计算设计流量的模型之一是（美国农业部小型城市水文学。技术发布，第55号（TR-55）。土壤保护局，华盛顿特区，http：//scholar.google.com/scholar ？hl = zh-CN＆btnG = Search＆q = intitle：“城市+水文+小+小流域”，1986年），它考虑了土壤覆盖率，浓缩时间（tc）和复发期（T）的分析变化。通过这种方式，本研究试图评估随着土壤防水性增加的流域水文行为。这些修改与径流系数（CN）的变化，文献所指出的复发期的修改以及浓缩时间的不同方程式相关。它的应用是在巴西SP桑塔纳deParnaíba的Ribeirãodo Suru流域进行的。CN {75; 80; 85; 90}分别增加了3.14、5.61、10.90和15.85％。在最关键的情况下，估算的CN径流量增加了15.85％。降水量随T（2、5、10、25、50、100和500）的变化以及11次浓缩方法的应用设计了132个水位图和流量值，这些水位和流量值在学生的T和分析中得到了统计处理方差分析（ANOVA）。除了布兰斯比·威廉斯（Bransby Willians）关联的“电影方法”，“杜奇（Dooge）与约翰斯通（Johnstone）”和克萨斯（CTH）与“奇奇亚”（Tchychyia），两对之间的相关度低于59％。在琼斯通中，与Dooge（90％）的相关性最大，其次是运动学方法与土壤保护服务方法（83％）和Dodge（74％）。结果，有可能证明SCS参数的行为以最小化主观性，并揭示每个参数如何影响分水岭的流量。最后，归因于T的敏感性在三个分析中最高。