Available online at www.sciencedirect.com ScienceDirect Procedia Engineering 154 ( 2016 ) 1064 – 1070 12th International Conference on Hydroinformatics, HIC 2016 Numerical Simulation of Land Surface Hydrological Process over Huaihe River Basin CHENG Xing-wua, ZHAO Jina, ZHANG Honga, WANG Kaia*, XU Minb aBureau of Hydrology of Huaihe River Commission, , Bengbu 233001,China b Anhui Climate Center, ,Hefei 230031,China Abstract The BATS (Biosphere Atmosphere Transfer Scheme) model was used to simulate the thunderstorm and flood events in the mountains and plains of the Huaihe River Basin in 1998. And the inherent relationship among runoff, soil moisture content, soil texture and vegetation distribution were exposed via the simulation of water exchange between land and atmosphere. Results show that the effect of soil moisture content in root layer, soil texture, and soil color on the runoff in the mountains is similar to that in the plains, whereas with different sensitivities. However, the effect of soil moisture content in deep layer and vegetation canopy ratio on the runoff in the mountains is opposite to that in the plains. The meteorological and land surface conditions are different between the mountains and the plains, so their hydrological characteristics are different, showing the different atmospheric-hydrological relationship. ©© 2016 2016 The The Authors. Authors. Published Published by Elsevierby Elsevier Ltd. LtdThis. is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-reviewPeer-review under under responsibility responsibility of theof theorganizing organizing committee committee of HIC of 2016 HIC 2016. Keywords:Huaihe River Basin; land surface hydrological process; BATS model; hydrological simulation 1. Introduction In recent years, hydrologists and meteorologists pay more and more attention to the effects of hydrology in geosphere – biosphere circle. In the process of seeking the interaction and feedback mechanisms between land hydrological process and atmosphere, we must consider the interaction between land and atmosphere in the general * Corresponding author. Tel.: +86-136-2552-7983; fax: +86-552-3093316. E-mail address:[email protected] 1877-7058 © 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of HIC 2016 doi: 10.1016/j.proeng.2016.07.597 Cheng Xing-wu et al. / Procedia Engineering 154 ( 2016 ) 1064 – 1070 1065 circulation model. In order to change the global climate model, we need to adjust meteorological model and study the changes of water resources through the authentic description of land surface hydrological process. A lot of land surface process model[1-2] have been developed in weather patterns, such as SiBUC which was used in the study of HUBEX-GEWEX by Fujiyoshi and Ding[3], DHSVM which was used in the simulation of Sea Luanhe River mountain area by Wang Shourong[4] and SHE, HBV, VIC which were mentioned by Chen Haishan and Sun Zhaobo[5], and they all obtained good results. Regional hydrological simulation research has been significantly improved with the development of land surface model, Ding Biao and Zeng Xinmin[6] has improved the surface water model according to the regional characteristics in China. In addition, a lot of research[7-8] aimed at short-term climate and land surface hydrology has also been carried out. In hydrometeorology coupling model, the description of hydrological cycle is the weakness of the current global climate model. The coupling model has been weighted heavily toward meteorological factors, whereas the description of the land surface process is too simple, especially for the local hydrological process [9-10]. From the most simple model—the bucket model to the multi-layer soil vegetation system at present, the effect of different terrain on the runoff yield and concentration has not been considered, real physical approach of water and heat quantity exchange between the atmosphere and soil has been accurately described though. The study which was carried out by Qi Dan[11] and Zhang Hongping[12] show that terrain and soil characteristics have an important influence on runoff. Therefore, atmosphere, land surface and surface water should be studied as a complete system[13] and the real description of the hydrological cycle process should be paid attention to, which can improve climate patterns change with time scale and its response to the water cycle on the one hand, on the other hand, the impact of climate on hydrology can be evaluated. The two difficult points in the hydro meteorological coupling model are: first, the fast changing process of the meteorological factors are not suited to the slow variation of the hydrological factors, second, the meteorological large scale uniform space field and the inhomogeneity of the hydrological space field is difficult to coordinate. In order to solve the coupling problem of the two, high-quality flux description between the land and atmosphere must be obtained. Therefore, considering the advantages of the BATS land surface model in the analysis of different terrain and land use, as well as the convenience of the usage of the available data, based on the Biosphere Atmosphere Transfer Scheme, this paper selected BATS surface process model for calculation. This paper selected two areas with typical hydrological characteristics, which are hilly area and plain area in Huaihe River Basin. Encryption data in 1998 of the global energy and water cycle test Huaihe River Basin experimental area (HUBEX) were used to simulate the storm flood process during flood season in 1998. The relation and interaction between atmosphere and land hydrology, as well as the intrinsic relation between runoff, soil moisture content, soil texture and vegetation distribution were revealed from the angle of land - atmosphere water exchange. 2. BATS land surface model Land surface process model is composed of different physical processes, including the parameterization of the dynamic characteristics associated with vegetation shape, the transmission of long and short wave radiation in the canopy and rainfall interception, photosynthesis, transpiration associated with vegetable physiological process, physical process in soil with water and heat transfer, soil chemical process[13] and so on. The development and perfection of these physical processes have greatly enriched the contents of the land surface process model. The species diversity in ecological system and the difference of vegetation, topography lead to the complexity of climate ecology. More importantly, it is not possible to use consistent explicit physical equation constraints, increasing the difficulty of vegetation parameterization. In the development of the land surface process model, the BATS model has a certain representativeness, which uses the integrated model to simplify the land surface process model. The BATS model is very detailed in the description of the land, from bare soil to vegetation, from the snow cover to the canopy, from the land surface to the underground, using a large number of parameters (Fig.1). This model uses vegetation cover index to describe the vegetation, in which the process of rainfall interception, air hole block and the transmission of radiation use a whole set of parameters. Major formulas and parameters please refer to the references [14-16]. 1066 Cheng Xing-wu et al. / Procedia Engineering 154 ( 2016 ) 1064 – 1070 Fig.1 Structure of boundary layer and ground circumstance in the BATS model [9] 3. Model application Huaihe River Basin is located in the eastern part of China, between the Yangtze and Yellow River Basin, with a total area of about 270,000km2, across the four provinces of Henan, Anhui, Jiangsu and Shandong. The terrain of the Huaihe River Basin is generally inclining from the northwest to the southeast. Funiu Mountain and Tongbai Mountain area which are in the west of the basin, Dabie Mountain area in the south and Yimeng Mountain area in the northeast with elevation from 200 to 500 m form the mountain areas of the basin. Hilly regions are extension of the mountain areas mainly, mountain and hilly areas accounted for about one-third of the total area. The rest are vast plain areas, including the plain area in the north of Huaihe River, the western plain of Nansihu Lake and the river network plain of Lixiahe River, accounts for about two-thirds of the total area. Therefore, hilly areas and plain areas in the basin have formed different hydrological and meteorological characteristics [17]due to the different terrain conditions. 3.1. Study area In this study, hilly areas and plain areas with representativeness in Huaihe River Basin were selected respectively: Shiguan River Sub Basin in the north of the Dabie Mountains and Guo River Sub Basin in the Huaibei Plain (Fig.2). Fig.2 Shiguan River and Guo River in the Huaihe River basin of China Shiguan River is one of the main tributaries on the south bank of the Huaihe River, and the area of the Shiguan River Basin is 5930 km2withJiangjiaji as its outlet control station. The soils are mainly yellow brown soil and paddy soil in the Shiguan River Basin, in the south of this basin are high mountains, on both sides are hilly areas, and in the Cheng Xing-wu et al. / Procedia Engineering 154 ( 2016 ) 1064 – 1070 1067 north are vast plain areas. The vegetation in mountain areas is a mixed forest, and high stalk plants are the main vegetation along the river and in hilly or plain areas. The terrain is high in the south and low in the north of the baisn with large gradient ratio, so, once there is precipitation, it will produce large amount of runoff, and the runoff concentration of the river is fast. Therefore, this basin is an area with typical hydrological characteristics in mountain areas (Fig. 2).