Abstract

The Koraiyar River basin is located in Tiruchirappalli city, one of the fastest-growing medium-sized cities in south India. Over the decades, the city has experienced sporadic flooding in vast areas due to the breaching of bunds when the river is in spate. The objective of this investigative study is to simulate rainfall–runoff in the Koraiyar basin watershed through the reliable Hydrologic Modelling System developed by the Hydrologic Engineering Center (HEC-HMS). Land-use and land-cover constantly change due to increasing population taken as one of parameter, its influence on CN, and their impact on surface runoff is analyzed in this study. The specified hyetograph method is adopted for the meteorological modelling; the Soil Conservation Services-Curve Number (SCS-CN) is selected to calculate the loss rate, and the SCS unit hydrograph method is adopted to simulate the runoff rate. Calibration and validation of the model are done to simulate assessed peak discharge values for comparison with actual observed values. The Nash–Sutcliffe efficiency coefficient is between 0.5 and 0.6, which indicates that the hydrological modelling results are satisfactory and acceptable for simulation of rainfall–runoff. The peak discharge is obtained for the single maximum rainfall event of about 100 mm in a day over the past 40 years, and hydrographs are generated.

Highlights

• It is the first integrated rainfall–runoff modelling to be studied in Ungauged Koraiyar basin with scarce data.

• The methodology adopted for simulating selected extreme events can be used for similar hydrological and meteorological conditions.

• For ungauged catchments like Koraiyar basin characteristics where enough data is not available, HEC-HMS can be used as a reliable tool for rainfall runoff and flood flow simulation.

中文翻译：

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基于事件的水文模型模拟非流域集雨-径流过程：以印度蒂鲁吉拉伯利市科赖亚尔盆地为例

摘要

Koraiyar流域位于Tiruchirappalli市，该市是印度南部增长最快的中型城市之一。几十年来，由于在河水泛滥时破坏了外滩，该市发生了大面积的零星洪水。这项调查研究的目的是通过水文工程中心（HEC-HMS）开发的可靠的水文建模系统来模拟Koraiyar流域的降雨-径流。本研究分析了以人口增加为参数之一的土地利用和土地覆盖面积不断变化的情况，它对CN的影响及其对地表径流的影响。气象模拟采用指定的hyperograph方法；选择土壤保育服务曲线编号（SCS-CN）来计算损失率，采用SCS单位水文法模拟径流率。进行模型的校准和验证以模拟评估的峰值排放值，以便与实际观测值进行比较。Nash-Sutcliffe效率系数在0.5到0.6之间，这表明水文模拟结果令人满意，可以接受降雨径流的模拟。在过去的40年中，每天约有100毫米的最大降雨事件获得了峰值流量，并生成了水文图。这表明水文模拟结果令人满意，可以接受降雨径流的模拟。在过去的40年中，每天约有100毫米的最大降雨事件获得了峰值流量，并生成了水文图。这表明水文模拟结果令人满意，可以接受降雨径流的模拟。在过去的40年中，每天约有100毫米的最大降雨事件获得了峰值流量，并生成了水文图。

强调

• 这是在Ungauged Koraiyar流域使用稀缺数据进行研究的第一个综合降雨-径流模型。

• 用于模拟某些极端事件的方法可用于类似的水文和气象条件。

• 对于没有足够数据的诸如科赖亚尔盆地特征之类的未集水流域，HEC-HMS可以用作降雨径流和洪水流量模拟的可靠工具。