The assessment of climate change impact on streamflowis one of the most interesting issues in hydrological research [1].Changes in air temperature and precipitation cause a major impact on the hydrologic cycle directly and indirectly and moreover, the water resources [2].Climate change altering the amount, intensity, form, and timing of precipitation as well as the rate of evapotranspiration also affects hydrological regimes by affecting the volume, peak rate, and timing of river flow [3]. For studying the impact on the regional water resource availability, the estimation of changes in river flow is the most common and is considered for decision-making processes in water-resource management [4].Analysis of Streamflow Response to Changing
Myanmar is situated in the tropical climate regionwith three dominant seasons: the hot season (16 February to May), the wet season (June to September), and the cold season (October to 15 February) [5] and a region that is highly vulnerable to impacts from climate change. There are about 60 rivers in Myanmar[6],thecountry’s largest main river is Ayeyarwaddy and it is an important commercial waterway used for trade and transport. The Ayeyarwaddy River is divided into the upper and lower parts with the river confluence with the Chindwin River [7]. Upper Ayeyarwady river basin is one of the major river basins in Myanmar and consists of Central Dry Zone and the Northem Hilly Region. The central dry zone area is known as the “oil pot” of the country and the economic growth of the country through agricultural development is essential in prenatal economic life. However, current climate change effects such as high temperature,
scarce rainfall, etc. are now threatening agricultural crops and farmers’ livelihood. So, climatic condition in dry zone region is the key factor for the development of the agriculture and farmers’ livelihood [8]. In the northern hilly region, it is already experiencing the problems of flood and heavy rains [9] and this effect may be more severe in the future due to climate change [10]. Therefore, information about the future streamflow related to climate change for this river plays as a fundamental role. It is essential to quantify and understand climate changes in the Upper Ayeyarwady river basin and those likely to occur over the coming century. This is also a starting point that Myanmar’s stakeholders can use to plan for more summer monsoon rainfall in agriculture, hydropower, conservation areas, dams, flood management and so on [11].It is important to understand Information derived from Global Climate Models (GCMs) and general characteristics of GCMs for assessing both past and future likely changes in climate scenarios and for assessing the climate change impact on hydrological analysis [12]. Future climate scenarios were produced based on a statistical relationship between climate variables at one or more GCM grid points with the variable of interest at a particular station [13]. Scenarios are images of how the world is likely to evolve in the future in terms of greenhouse gas [14]. In this study, climate information obtained from Representative Concentration Pathways (RCPs) is used to forecast future hydrological changes. There are so many hydrological models for understanding the impact of climate change on the nature of hydrological flow and for calculation of water discharge more accurately, easily and quickly than the traditional measurement method. Soil and Water Assessment Tool (SWAT) is one of the most popular modelling software for assessing hydrologic impacts.Analysis of Streamflow Response to Changing
The main objective of this study is to forecast the impact of future climate projections on streamflow of the future period by using the projections of precipitation and temperature based on outputs of selected suitable climate models from downloaded 10 GCMs under RCP Scenarios across the Upper Ayeyarwaddy River Basin. The structure of this article is organized as follows: study area descriptions are presented in Section 1. Methodological framework is described in Section 2 and materials and methods of this study are described in Section 3. Section 4 presents the results and discussions of this study. Finally, conclusion is described in Section 5.1.1.Study Area In this study, climate change impacts on the water sector highlight the Upper Ayeyarwaddy river basin which is covering about 60% of the total area of Myanmar and originates at the confluence of the N’Mai Hka and Mali Kha rivers. The Upper Ayeyarwaddy is situated at 20 ̊22’ -28 ̊50’ north latitude and 94 ̊56’ -98 ̊42’ east longitude [15] and covered by Kachin State, Mandalay Division, the western part of Shan stateand Southeastern part of Sagaing Division as shown in Figure 1. The outlet of the whole basin was selected at Sagaing and the watershed area for this Upper Ayeyarwaddy River is 152,264km2.Analysis of Streamflow Response to Changing
Civil Engineering Journal Vol. 6, No. 2, February, 20201962.Methodological FrameworkThe objective of this study has combined two aspects: firstly, assessment of climate change impacts on the climate variables (rainfall and temperature) and secondly, assessment of the response on the river’s hydrologic system of climate variables. The Methodological Framework of this study is shown in Figure 2 and involves: (I) spatial and climate data preparation into SWAT format, (ii) model setup, including watershed delineation and Hydrologic Response Units (HRUs), (iii) model calibration and validation,and (iv) assessment of future climate change impacts on streamflow. SWAT model which is ArcGIS extension, ArcSWAT 2012 version was downloaded from the United States Department of Agriculture (USDA) website. SWAT is a partially distributed model and required digital elevation model (DEM), land use and soil map which are basic modeling requirements and daily weather data. Calibration and Validation were performed using the SWAT CUP program. At this stage, several hydrological model parameters were adjusted for achieving the best fit between the simulated and measured flow at the monitoring station.Finally, climate change impact on future streamflow is projected by using the SWAT model based on meteorological changes under climate change projection.Analysis of Streamflow Response to Changing
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