Các thủy văn và tài nguyên nước các vấn đề ở Nam Á được thảo luận trong Chương 1. Đó là dự đoán rằng những vấn đề sẽ được làm trầm trọng hơn nếu nhiệt độ và lượng mưa trên toàn lưu vực sẽ thay đổi do biến đổi khí hậu. Định lượng những thay đổi có thể xả trên sông (có nghĩa là hoặc cao điểm) là đạt được với việc áp dụng mô hình thủy văn. Bốn loại của mô hình thủy văn - thực nghiệm, nước cân đối, khái niệm gộp tham số và các mô hình. | 2 Hydrologic Modeling Approaches for Climate Impact Assessment in South Asia M. MONIRUL QADER MIRZA INTRODUCTION The hydrologic and water resources problems in South Asia are discussed in Chapter 1. It is anticipated that the problems will be exacerbated if basin-wide temperature and precipitation would change due to climate change. Quantification of possible changes in river discharge mean or peak is achieved with the application of hydrologic models. Four types of hydrologic model - empirical water-balance conceptual lumped-parameter and process-based distributed models - are used for hydrologic modeling. A model is usually selected depending on the purpose of the application which includes runoff-simulation sediment transport and morphological changes estimating ground water and changes in ground water volume forecasting flood volume depth and duration assessing changes in land-use and assessing impacts of changes in climate. Availability of data and resources are also governing factors in a model selection process. This chapter discusses the comparative advantages and limitations of various hydrologic models and their suitability for estimating changes in mean annual and mean peak discharge under selected climate change scenarios for the river basins in South Asia. It examines reduction of input variables for empirical modeling through the sensitivity analysis of runoff to changes in temperature and precipitation. This chapter also discusses application of hydrologic models in Bangladesh as a case study to assess climate change impacts. HYDROLOGIC MODELS In planning for water resources and extreme events like floods and droughts it is essential to know the precipitation-runoff processes in the vegetation land surface and soil components of the hydrologic cycle. These processes differ in arid semi-arid and humid climates. Even within a single climate zone physical processes can vary widely because of the diversity of vegetation soils and microclimates. .
